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Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 4

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hmmm, another ULL for the NM Mtns...that thing is sitting and spinning right over ABQ...i should go check the conditions at Sandia Peak and Angel Fire

Angel Fire reported 163" for the ski season...they are now closed

Sandia Peak reported 115" for the ski season...they are now closed

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Morning e-mail from Jeff:

A risk for severe thunderstorms this afternoon and tonight mainly along and north of US 59.

An upper level storm system over New Mexico and Colorado this morning will move slowly into the plains today with the west TX dryline/Pacific front (currently noted by very low dewpoints in the 10’s and 20’s over W TX) surging eastward into central and SE TX late this afternoon and tonight. Air mass east of the dryline will become extremely unstable by mid afternoon with CAPE values of 2500-3500 J/Kg and LI’s of -6 to -8 with capping weakening due to lifting from the incoming cooling aloft and increasing surface moisture. Expect storms to rapidly develop along the dryline late this morning into the early afternoon as heating and an impulse noted nearing SW TX currently in the base of the upper trough breaches the remaining capping in the mid levels. Storms will develop and go rapidly severe with favorable shear and instability in place across the region east of the dryline. Storms will develop/move ESE late this afternoon into the evening hours and approach/move into our western and northern counties.

Main question across the coastal bend into SE TX is to what degree does the capping inversion aloft erode today and to have this happen…how much heating will we get. A look out the window shows partly cloudy skies with low level stratus racing NW in the low level flow (not a solid deck and a deck that would allow plenty of heating today). Trigger temperatures are in the mid 80’s across this region, and these values appear to be achievable. Water vapor does show a pocket of dry air aloft behind the departing mid level circulation that crossed the area yesterday, but this is moving off to the ENE this morning with deeper moisture aimed to move into our western counties later this morning. With all this said, meso scale and convection allowing models are not showing much in the way of activity developing over SE TX and keep most of the activity that develops over central TX along and north of I-10 this evening before weakening. These models have performed poorly of late with MCS activity and their related cold pools helping to drive convection most robust and further east than the models suggested would happen.

Feel the best threat for strong to severe thunderstorms today will be along and NW of a line from Columbus to Conroe to Livingston where capping will be weakest and approaching storms from central TX have the best shot at reaching before weakening. With that said, if activity becomes well organized over central TX, the threat will need to be expanded across much of the region. Strong instability coupled with good shear will support vigorous updrafts with large hail being the main severe threats…a few extreme hail reports will be possible. Damaging winds to 60mph will also be possible with tornadoes the lower end threat today…but not non-existent.

Current thinking is that some sort of activity may linger overnight into early Wednesday as the weak cool front stalls near the coast acting as a trigger for showers/thunderstorms. The upper trough will move into the plains and this will allow a drier and more stable air mass to gradually spread into the region ending rain chances by midday. Nice…but warm weather will be on tap Thursday-Friday as ridging at the surface and aloft allows temperatures to warm into the mid to upper 80’s over lows in the 60’s. Moisture begins to increase over the holiday weekend and rain chances may return at some point as convection fires off in the late afternoon over W/SW TX/NE MX and translates eastward into portions of SC and S TX.

Monday Storm Reports:

Impressive MCS/bow echo moved across the area on Monday morning with damaging winds common over the coastal bend. Storms redeveloped Monday afternoon with hail being the main impacts.

Port Lavaca, Calhoun: 80mph Downburst. Widespread wind damage with trees and power lines downed along with some roof damage in the City of Port Lavaca. Wind damage path was ½ of a mile wide by 2 miles in length (roughly from Alcoa Dr extending NE to Travis St south of HWY 35)

Port O Connor, Calhoun: 69mph wind gust recorded at marine mesonet site with sustained wind of 51mph

Seadrift, Calhoun: nickel to quarter sized hail

Rockport, Aransas: Pea size hail and 55mph winds

Port Aransas, Nueces: 52mph winds

Hungerford, Wharton: Damaging winds destroyed a trailer home and shed near the intersection of CR 216 and CR 225. Estimated winds of 70mph

BUSH IAH, Harris: 1.0 inch diameter hail reported by NWS employee at airport

Bellaire, Harris: Nickel size hail

Houston, Harris: Nickel to dime size hail along the south 610 loop between I-45 and SH 225

Galena Park, Harris: Dime size hail near I-10 and Federal

Kingwood, Harris: quarter to golfball size hail

The Woodlands, Montgomery: 1.0 inch diameter hail at the intersection of FM 1488 and FM 2978

Liberty, Liberty: Dime to quarter size hail fell for 7-8 minutes at the Liberty County Sheriff’s Office.

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SPC MCD, winds going light, lack of pressure rises behind the outflow boundary, and dewpoints actually drifting upward make me one eight glass full optimistic that all the fun won't be confined to Galveston County today, and my palms and citrus will see some beneficial rainfall.

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From Jeff:

Severe Thunderstorm Watch has been issued for locations along and south of US 59 until 800pm

Air mass south of stationary frontal boundary has become very unstable with CAPE of 3000-400 J/kg and little to no capping. SW moving outflow boundary is colliding with this boundary and has produced a tornadic sueprcell over western Galveston County currently.

With continued heating this afternoon and inland moving seabreze which will collide with the stationary boundary near/along US 59 new thunderstorms may develop and become quickly severe. Boundary enhanced low level shear may provide an enhanced tornado threat near any low level boundaries that are in place across the region. Otherwise the main threats will be large damaging hail and strong winds.

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FWD highlighting the two systems next week:

FOR LATE WEEK...THE UPPER RIDGE DAMPENS DRAMATICALLY WITH A STRONG

SHORTWAVE ROTATING THROUGH THE CENTRAL ROCKIES AND OUT ONTO THE

PLAINS ON THURSDAY...PULLING A DRYLINE INTO THE AREA BY THURSDAY

EVENING WITH A COLD FRONT OVERTAKING THE DRYLINE LATE THURSDAY

NIGHT INTO FRIDAY. THE CANADIAN AND ECMWF ARE FURTHER SOUTH WITH

THE TRACK OF THE BETTER DYNAMICS AND LIFT...WITH STRONGER SURFACE

FORCING WHICH COULD LEAD TO MORE SIGNIFICANT SEVERE WEATHER

RISK...WHILE THE GFS IS MUCH FURTHER NORTH WITH A FLAT ZONAL TYPE

FLOW AND A MORE BENIGN WEATHER EVENT. NEGATIVE AND POSITIVE HEIGHT

ANOMALIES ALONG EAST COAST WILL BEGIN TO SHOW A SLIGHT SHIFT AND

FEEL THIS COULD ALLOW THE FURTHER SOUTH AND MORE DYNAMIC ECWMF

SOLUTION TO COME TO PASS WITH A MORE SUBSTANTIAL SEVERE WEATHER

LATE THURSDAY/THURSDAY NIGHT.

DRY AND COOLER CONDITIONS WILL OCCUR FRIDAY WITH A NICE START TO

THE FOLLOWING WEEKEND...HOWEVER A VERY DEEP TROUGH BEGINS TO TAKE

SHAPE OVER THE WESTERN STATES AS NEXT WEEKEND PROGRESSES. THIS

COULD LEAD TO ANOTHER SUBSTANTIAL SEVERE WEATHER EPISODE BY LATE

SUNDAY OR MONDAY. TIMING AND ENVIRONMENTAL DISCREPANCIES ABOUT

THIS FAR OUT BEING THAT IT IS IN THE 7-10 DAY RANGE AND CONFIDENCE

IS VERY LOW AT THIS TIME. IT DEFINITELY APPEARS AT LEAST THE

FIRST HALF OF APRIL WILL BE ACTIVE AND THIS IS NOT OUT OF THE

ORDINARY FOR NORTH TEXAS AND THE SOUTHERN U.S.

Looking at the Euro for the first system, I certainly see where they are coming from....

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I'd watch N Central TX along the dry line Sunday. The WRF is suggesting storms developing. We will see...

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DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0230 AM CDT SAT APR 07 2012

VALID 091200Z - 101200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PART OF THE SRN PLAINS

TO THE ARKLATEX REGION...

...SYNOPSIS...

A BLOCKING PATTERN WILL PERSIST OVER NORTH AMERICA ON MONDAY AS AN

UPPER RIDGE SHARPENS OVER THE FULL EXTENT OF THE ROCKIES BETWEEN A

DEEP LONGWAVE TROUGH LOCATED ALONG AND OFF THE WEST COAST...AND A

LONGWAVE TROUGH PERSISTING EAST OF THE ROCKIES.

AT THE SURFACE...THE TRAILING PORTION OF A FRONT ATTENDANT TO A FAST

MOVING SHORTWAVE TROUGH TRANSLATING THROUGH THE GREAT LAKES AND NERN

STATES ON DAY 2/SUNDAY IS EXPECTED TO EXTEND WSWWD FROM THE MID MS

VALLEY INTO SRN KS BY THE START OF DAY 3/MONDAY. GIVEN A NWLY FLOW

REGIME BECOMING BETTER ESTABLISHED ACROSS THE PLAINS STATES...THIS

SURFACE BOUNDARY IS EXPECTED TO SETTLE SLOWLY SWD THROUGH OK AND THE

TX PANHANDLE...WHILE THE ERN EXTENT REACHES THE MID SOUTH TO SRN

APPALACHIANS BY 12Z TUESDAY.

...SRN PLAINS TO THE ARKLATEX...

LOW LEVEL FLOW IS EXPECTED TO BECOME BETTER ESTABLISHED ACROSS THE

SRN PLAINS ON MONDAY. THIS WILL SUPPORT BOTH MOISTURE RETURN AND

LOW LEVEL WAA BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES /AROUND

7.5-8.0 C PER KM/ EXTENDING ESEWD ACROSS THE TX/OK PANHANDLES INTO

OK...RESULTING IN MODERATE INSTABILITY. DESPITE THE LACK OF STRONG

FORCING ALOFT...MODELS AGREE THAT A WEAK IMPULSE SHOULD TRACK SEWD

INTO OK BY PEAK HEATING. THIS COMBINED WITH LOW LEVEL WAA AND

SURFACE HEATING WEAKENING INHIBITION THROUGH THE DAY WILL SUPPORT

TSTM DEVELOPMENT MONDAY AFTERNOON INVOF THE SWD MOVING FRONT.

STRENGTHENING BULK SHEAR THROUGH THE DAY /40-50 KT/ WILL RESULT IN

ORGANIZED STORMS...WITH VERTICALLY VEERING WIND PROFILES SUPPORTING

ROTATING UPDRAFTS AND THE POTENTIAL FOR HAIL AND STRONG WIND GUSTS.

A TORNADO THREAT CANNOT BE RULED OUT...GIVEN LOW LEVEL HODOGRAPH

CURVATURE. MODELS SUGGEST CONTINUED LOW LEVEL WAA INTO MONDAY

EVENING/OVERNIGHT SHOULD SUPPORT A CONTINUE THREAT FOR TSTMS AND

SOME SEVERE AFTER DARK WITH THE FORMATION OF ONE OR MORE MCSS.

..PETERS.. 04/07/2012

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Guidance has come into a bit better agreement regarding the weekend into next Monday as yet another deep Western trough and upper low drop S into the AZ/NM region suggesting a dry line developing across W Texas providing a focal point for a severe weather outbreak.

Storms appear to begin out W late Saturday and slowly sag E in time as the dry line/Pacific frontal boundary takes shape and begins to progress E on Sunday across N Central/Central TX and points N and E. The SPC has been suggesting for several days a possible significant severe weather episode will unfold for parts of the Lone Star State into OK and KS. What remains to be seen is imbedded short wave impulses rounding the base of the trough/H5 low providing a trigger for rounds of strong to severe storms and the potential for super cells as rich Gulf moisture returns in earnest late week.

The main threat appears to be strong damaging winds with large hail and isolated tornadoes as the storms become linear in nature Sunday night into Monday for areas along and E of the I-35 Corridor. We’ll need to watch the Metroplex and points N and E for the potential of additional super cells developing during the day on Monday as the dry line pushes E.

For SE TX, the main threat appears to be a squall line with strong storms along and N of the I-10 Corridor for Monday as the upper dynamics head into the Plains. We’ll need to monitor future guidance output for any subtle changes/mesoscale features that cannot be determined this far out regarding the sensible weather we can expect.

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Nuisance sprinkles possible for the Saturday evening show at the Great American Racetrack, but, thankfully, the models have settled in on generally decent weather for the race weekend.

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Morning e-mail from Jeff:

Calm spring weather of late will transition back to stormy by the end of the weekend and early next week as the next storm system moves toward the state.

Upper level trough will dig into the western US over the weekend and then eject into the plains early next week. Short waves lifting out into the plains ahead of the main trough will produce daily rounds of severe thunderstorms over the high plains from western TX into the central plains. Saturday is looking likely a particularly dangerous day from northern TX into the central plains where a significant threat for dangerous long tracked tornadoes appears at least possible.

Surface low pressure developing in the lee of the Rockies over the next 24 hours will encourage stronger SE surface flow off the Gulf of Mexico starting on Friday through the weekend. Fairly pleasant humidity levels will rise into the sticky range by late Friday and remain through the weekend as dewpoints rise into the upper 60’s. Gusty SE winds of 15-25mph will be common each day Fri-Sun. Rain chances will be on the low side through much of the weekend until Sunday afternoon/evening when advancing short wave energy may skirt close enough to the region to allow thunderstorms to develop.

Bigger event appears slated for the Sunday night-Monday time period as the main upper trough lifts into the plains dragging a cold front eastward across TX. Thunderstorms are likely to developing along and ahead of this feature Sunday afternoon over west/central TX and progress eastward toward SE TX overnight into Monday. Track of the main upper trough toward the central plains instead of the southern plains may result in a lessened severe threat this far south along with potential for portions of the area to be dry slotted. Still several days to watch how event may unfold and adjust both the timing and intensity of the potential event.

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This looks like a pretty potent trough on Monday...in SE Texas we are approaching one of the last cold fronts of the season...until maybe September. I still miss after many years those backdoor cold fronts in the mid-Atlantic during late Spring.

Then our 75 day popcorn shower season begins before we're completely capped...

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This looks like a pretty potent trough on Monday...in SE Texas we are approaching one of the last cold fronts of the season...until maybe September. I still miss after many years those backdoor cold fronts in the mid-Atlantic during late Spring.

Then our 75 day popcorn shower season begins before we're completely capped...

Meh, my hunch is the tropics will offer a bit of excitement this summer before those fall fronts return.

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Who needs tropics? while the strong fun-derstorms are mainly well North, GFS and Euro both see impressive rainfall totals, and as long as it doesn't actually flood, banana plants growing like crazy, what isn't there to like?

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Meh, my hunch is the tropics will offer a bit of excitement this summer before those fall fronts return.

Right. It's a tightrope between wishing for late summer rain and a major cyclone. With ENSO- subsiding things could kick up this year

anomp.4.12.2012.gif

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Still don't know how a squall line might shake out for Sunday for SETX, but benefitical rains still seem on track. Soundings from GFS ahead of the line looks not whammydyne for severe, but not without potential, and a PW of 1.8" in April, I'd shake hands with that.

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Morning e-mail from Jeff:

Excessive rainfall/flash flood event unfolding across the coastal bend into SE TX overnight/this morning.

Extremely narrow corridors of very heavy rainfall developed throughout the night producing excessive amounts of rainfall in parts of Brazoria County and between Corpus Christi and Victoria. Doppler radar estimates rainfall amounts of 5-8 inches in a narrow corridor over southern Brazoria County.

Frontal boundary has stalled along the US 59 corridor from Livingston to Spring to Katy to Wharton to Alice with several outflow boundaries moving in various directions across the area per radar and surface observations. Unstable air mass continues to support periods/waves of thunderstorms developing in training bands across the region from south of San Antonio to western LA. Recent upward trend in radar coverage W/SW of the region over the coastal bend and SC TX appears to be the result of favorable diffluence aloft and an approaching impulse out of NE MX. Additionally, thunderstorms overnight have left behind a boundary near the coast which has been a good focus for the flooding rainfall over Brazoria County, although repeated development has ended on this boundary in the last 2 hours.

While the global models have a decent handle on the situation the event is highly mesoscale driven with slow moving low level boundaries focusing very heavy rainfall in small narrow SW to NE oriented bands. Where these bands set up and drop 2-4 inches of rainfall in a few hours is extremely difficult to forecast until it is underway. Would think the main frontal boundary would be the primary focus, and recently (past 1-2 hours) it has become that. With the near coastal activity weakening, better moisture may begin to push back northward toward the main frontal boundary focusing more sustained development in this region (near or just north of US 59). This is what some of the shorter term meso models are suggesting, but they have not preformed overly well with this event.

With moisture levels remaining high and the threat for cell training, some high totals in narrow corridors are possible. This is more of a localized flash flood threat than a widespread flood threat….but where those training bands set up those locations could easily get over 5 inches in a few hours.

Tail end of the upper trough and stalled boundary will remain over the area for the next 12-18 hours and this will continue the threat of storms and heavy rainfall. Larger scale models are even more sluggish in clearing the region…not until later on Tuesday. Will trend toward the storms gradually ending this evening as the air mass becomes overturned (worked over) and the best dynamics and moisture shift south and east with time.

Nice weather by late Tuesday-early Thursday with another faster moving system which may bring a rounds of showers and thunderstorms again Thursday night-Friday.

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From NESDIS:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 04/16/12 1243Z

SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678

LATEST DATA USED: GOES-13 1230Z KUSSELSON

NOAA AMSU:0830Z/1028Z

.

LOCATION...SE TEXAS...

.

ATTN WFOS...HGX...CRP...

ATTN RFCS...WGRFC...

.

EVENT...HIGH MOISTURE AND UPPER LEVEL FEATURE COMING ACROSS TEXAS AND

ALLOWING CONVECTION HANG IN ALONG THE COAST AND S CENTRAL TEXAS...

.

SATELLITE ANALYSIS AND TRENDS..THIS MORNING IT'S ONE OF THOSE DEALS

WHERE THE DEEP MOISTURE IS HAVING A HARD TIME MAKING ANY EAST PROGRESS

AND ACTUALLY HAS SETTLED FOR REMAINING AND PERSISTING S TO SE TX AT THE

SAME TIME AN UPPER LEVEL FEATURE WAS ROUNDING AND NOW OUT AHEAD OF WESTERN

TEXAS TROUGH TO HELP DESTABILIZE AREA ENOUGH TO KEEP THE CONVECTION GOING

ALONG OLD OUTFLOW BOUNDARIES. THIS HAPPENING CENTERED ON SAN PATRICIO

COUNTY THIS MORNING. SATELLITE RAIN ESTIMATES DISPLACE THE HEAVY RAIN

FURTHER NORTHEAST WITH AMOUNTS OF NEAR 4"/6HRS. EXPERIENCE SAYS THAT

HIGH CLOUDS DISPLACING HVY RAIN TOO FAR EAST...SO THINK AMOUNTS ESTIMATED

ARE OKAY..BUT JUST DISPLACED TO FAR NORTHEAST...SO FF A GOOD POSSIBILITY

CENTERED ON SAN PATRICIO AND ENVIRONS.

ALSO EYEING SW TO NE CONVECTIVE WEDGE JUST TO THE WEST...IE NEAR MCMULLEN

COUNTY BUT MOISTURE NOT QUITE AS GOOD. OTHER AREAS ARE EITHER MOVING

OR RAINFALL NOT AS HEAVY OR PERSISTENT AS IN SAN PATRICIO COUNTY.

.

AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION THREAT AREA

SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED BELOW IN APPROXIMATELY

10-15 MINUTES.

.

SHORT TERM OUTLOOK VALID 1245-1545ZZ...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...AS LONG AS DEEP MOISTURE IS IN PLACE AND FORCING TO WEST

WITH NOW A JET MAX SHOWING...BOUNDARY CAN BE ACTIVE AND SAN PATRICIO IS

THE SPOT AT LEAST IN IMMEDIATE TERM.

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Update from NESDIS:

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 04/16/12 1437Z

SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-763-8678

LATEST DATA USED: GOES-13 1415Z KUSSELSON

NOAA AMSU:0846Z/0838Z DMSP SSMIS: 1310Z

.

LOCATION...SE TEXAS...

.

ATTN WFOS...LCH...HGX...CRP...

ATTN RFCS...WGRFC...

.

EVENT...CONVECTIVE WEDGE COMPLEX CONTINUES HANGING IN ALONG THE CENTRAL

TX GULF COAST...MESO CELL FROM THAT COMPLEX PUSHING THROUGH BRAZORIA

COUNTY...

.

SATELLITE ANALYSIS AND TRENDS...WITH UPPER LEVEL TROUGH STILL WAY BACK

CLOSE TO THE CO-

TX-NM BORDER...SWLY FLOW OVER CONCERN AREA CONTINUES AND THAT MEANS

CONVECTIVE WEDGE HANGING IN THERE AND BEING FUELED BY DEEP LAYERED

MOISTURE. LATEST MAX GPS PW ALONG MID TX COAST JUST SOUTH OF KCRP WAS

CLOSE TO 2.0" AND THAT WELL ABOVE 2 STANDARD DEVIATIONS ABOVE NORMAL...12Z

KCRP SOUNDING HAD 1.8" VALE AND THAT RIGHT AT 2 STANDARD DEVIATIONS.

AND THAT ALONE WOULD BE A CONCERN FOR CONTINUED HEAVY RAIN...BUT THEN

THERE ARE THE MESO JET PUSHING THRU CENTRAL TEXAS JUST AHEAD UP AN UPPER

LEVEL AND THAT FORCING EXTENDING ITS REACH TO NEAR THE HIGHEST MOISTURE.

ACTIVITY COULD GO ON FOR A SEVERAL MORE HRS WITH NO REAL KICKER TO

THE WEST.

CELL/COLD CLOUD TOP THAT CAME OUT OF THE COASTAL CONVECTIVE WEDGE NOW

SPREADING COLD TOP HEAVY THROUGH AREA CENTERED ON BRAZORIA COUNTY AND

RAIN RATE IN THE 1-1.5"/HR RANGE...BUT THERE COULD BE SOME ISOLATED

HIGHER RATES...BUT PROBABLY NOT AS HIGH AS WITH THE SAN PATRICIO COUNTY

CELLS THAT ARE FEEDING ON EXISTING AND ANOMALOUS MOISTURE CONTENT.

.

AN ANNOTATED SATELLITE GRAPHIC SHOWING THE HEAVY PRECIPITATION THREAT AREA

SHOULD BE AVAILABLE ON THE INTERNET ADDRESS LISTED BELOW IN APPROXIMATELY

10-15 MINUTES.

.

SHORT TERM OUTLOOK VALID 1430-1800Z...MEDIUM CONFIDENCE FACTOR IN SHORT

TERM OUTLOOK...NO KICKER...EXCESSIVE MOISTURE...BUT DIURNAL SHOULD SAY

WEAKEN...BUT IT IS NOT AND SAN PATRICIO AT THE EPICENTER OF EXCESSIVE

RAINFALL. MOISTURE TRANSPORT, EVEN THOUGH IT IS NOT GREAT IN THE

IMMEDIATE VIC...IS PRETTY GOOD CLOSE BY IMPORTING HIGH MOISTURE JUST

OFF S COAST AND BRING IT INLAND TO THE MID TX COAST...SO HVY RAIN THAT

FALLS IS KIND OF REPLENISHED AND CAN CONTINUE MOST OF THIS PERIOD WITH

CONTINUED FLOODING.

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Update from Jeff:

Stalled frontal boundary along HWY 35 from north of Port Aransas to Port Lavaca to Bay City to Angleton then offshore of Galveston Island continues to be the focus for near continuous thunderstorm formation and heavy training rainfall.

Favorable position of the upper level trough over W TX and continued feed of very moist high PWS air mass inland off the western Gulf of Mexico is resulting in very heavy rainfall in a band from just north of Corpus Christi to Matagorda Bay to Galveston County. Extremely heavy rainfall has focused over San Patricio County this morning around Portland and Gregory where rainfall estimated over 8-12 inches has fallen (at the intersection of the frontal boundary and moist low level feed of untapped air over S TX).

With additional upstream energy moving through the upper through expect to continue to see thunderstorms develop and train ENE to E along the coastal counties and possibly the US 59 corridor through much of the day. Air mass remains very capable of producing rapid short term rainfall amounts of 1-2 inches in a hour. Where cell training develops flooding is likely with this kind of rainfall. Additionally, the duration of the event is starting to result in watershed responses along the coastal creeks and smaller scale rivers and some will likely rise to flood stage with continued slow moving excessive rainfall under training cells.

Additional rainfall of 1-3 inches across the coastal counties is likely with isolated totals upwards of 4-6 inches on top of what has already fallen. Would not be surprised to see a few storm totals since yesterday evening approach and exceed 10-12 inches along/near the Hwy 35 corridor.

Note:

Severe Thunderstorm Watch has been issued from Matagorda Bay southward to deep south TX as air mass in that region is becoming increasingly unstable ahead of southward sagging frontal boundary. Intersection of this boundary with strong low level inflow has produced a few severe and at time rotating tornadic cells this morning from north of Corpus to north of Brownsville….in fact the public reported a tornado over King Ranch earlier this morning.

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I'd say the drought worries are almost officially over in San Patricio County.

There was hail (damaging even), but ground truth seems to support 15 inch rainfall.

000

NWUS54 KCRP 161630

LSRCRP

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE CORPUS CHRISTI TX

1129 AM CDT MON APR 16 2012

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...

..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....

..REMARKS..

1023 AM FLASH FLOOD 7 S BAYSIDE 27.97N 97.24W

04/16/2012 SAN PATRICIO TX EMERGENCY MNGR

MORE THAN 15 INCHES OF STORM TOTAL RAINFALL.

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Update from Jeff:

NWS has issued a Flash Flood Watch for the following counties: Galveston, Brazoria, Matagorda, Wharton, and Jackson

Stalled surface boundary continues to produce near continuous rainfall along the coast early this afternoon. Radar indicates rainfall amounts of 4-6 inches have fallen over portions of Jackson, Matagorda, and Brazoria Counties overnight and this morning and thunderstorms continue to develop and train over these counties. A few locations in southern Brazoria County are nearing 8 inches of rainfall. Additional rainfall of 2-4 inches is likely in the watch area this afternoon as storms develop and track over the same areas.

With grounds saturated run-off will be increasing with the threat for more widespread flooding. Flash Flood Warning is in effect for Brazoria and Matagorda Counties until 145pm.

Note:

Large HP supercell over San Patricio County has finally moved offshore after dropping 10-15 inches of rainfall over the Portland and Gregory areas this morning. San Patricio emergency manager reported more than 15.0 inches of total rainfall since 400am this morning 7 miles south of Bayside and this matches well with radar rainfall estimates. Severe flooding is in progress over eastern San Patricio County.

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What a change from last year when we were already in the grip of a drought and early Spring heat. It was 52F here this morning. Some 40's are likely this weekend for SE TX with frost warnings for portions of the Lone Star State. Must be April.

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Morning e-mail from Jeff:

Upper air pattern will become highly amplified for mid April this weekend sending a strong low pressure system and cold front through TX on Friday.

At the surface winds will swing around to the south later today starting the return of Gulf moisture back into the region ahead of a late Friday frontal passage. Air mass will moisten on Friday, but forecast soundings show a decent capping inversion in place and very dry mid level air mass. With that said, the incoming front will have strong lift and the boundary will be moving through at least part of the area during peak heating. Feel at least a few strong to severe thunderstorms will develop along a thin band of convection with the boundary. Best chances for any severe weather will be from roughly Galveston to Katy to College Station and southwestward into deep S TX where instability will be greatest.

This system is fairly fast moving and should clear the area before sunrise Saturday. The surface low will begin to deepen over the NC Gulf of Mexico Saturday while strong high pressure builds into TX from the north. A very tight pressure gradient will be in place Saturday over eastern TX producing strong winds. Additionally, clearing skies will allow downward momentum transfer of some higher winds aloft during the day. Expect winds to rapidly come up Saturday morning out of the north into the 15-25mph range and then increase into the 20-30mph range by early afternoon with gust at or above 40mph. Cold air advection on Saturday will keep highs only near 70 (about 10 degrees below average) even under full sun.

Extended:

Cool surface high pressure will settle over the region Sunday with lows falling into the 50’s and possibly upper 40’s in some locations and highs in the mid 70’s. Nice weather with low humidity will continue into early next week.

Fire Weather:

Very strong winds expected on Saturday across the area along with low afternoon RH values in the 20-30% range. Typically this would be of some concern, but wet grounds and healthy vegetation cover should mitigate any significant fire weather concerns.

MS 150:

All storms will be east of the area by Saturday morning, but very strong winds out of the N and NW will blast the route all day Saturday. Winds will rapidly increase Saturday morning and remain strong and gusty all day sustained in the 20-30mph range and at times gusting 35-40mph. Air mass will be very dry with low RH and temperatures in the 60’s to lower 70’s. Sunday should feature calmer winds early, then breezes picking back up out of the N and NE by late morning into the 10-15mph range.

SPC Day 2 (Friday) Severe Weather Outlook:

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 183

NWS STORM PREDICTION CENTER NORMAN OK

640 PM CDT THU APR 19 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

SOUTH CENTRAL OKLAHOMA

WESTERN NORTH TEXAS

EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 640 PM

UNTIL 100 AM CDT.

HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 55

STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES WEST OF

MINERAL WELLS TEXAS TO 20 MILES NORTHEAST OF OKLAHOMA CITY

OKLAHOMA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.

DISCUSSION...THUNDERSTORMS ARE BEGINNING TO FORM ALONG SURFACE COLD

FRONT/DRYLINE OVER WESTERN NORTH TX...AND ARE EXPECTED TO FORM IN

THE NEXT 1-2 HOURS OVER PARTS OF SOUTHWEST OK. THIS ACTIVITY WILL

BE IN A REGION OF RELATIVELY WEAK LOW LEVEL SHEAR. BUT...SUFFICIENT

EFFECTIVE SHEAR VALUES AND MODERATE CAPE WILL PROMOTE SUPERCELL

STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS. ACTIVITY MAY

PERSIST NEAR THE RED RIVER FOR MUCH OF THE EVENING.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 27030.

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MESOSCALE DISCUSSION 0571

NWS STORM PREDICTION CENTER NORMAN OK

1235 PM CDT FRI APR 20 2012

AREAS AFFECTED...PORTIONS MIDDLE-UPPER TX COASTAL PLAIN...WRN LA.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 201735Z - 202000Z

ELEVATED CONVECTION BEARING HAIL RISK HAS INCREASED IN

COVERAGE/INTENSITY OVER PORTIONS E TX AND SHOULD MOVE INTO WRN LA

WITH CONTINUED/SPORADIC RISK OF SVR HAIL. POTENTIAL IS INCREASING

FOR MORE ORGANIZED/SFC-BASED TSTMS FARTHER SW ACROSS MID-UPPER TX

COASTAL PLAIN...WITH RISK FOR DAMAGING GUSTS AND OCNL LARGE HAIL.

16Z SFC MESOANALYSIS SHOWED SFC COLD FRONT FROM SWRN AR AND NE TX

SWWD ACROSS CENTRAL TX BETWEEN ACT-CLL...JUST S HDO...THEN RIO

GRANDE VALLEY BETWEEN DRT AND EAGLE PASS. SEPARATE TROUGH/WIND

SHIFT LINE WAS DRAWN FROM SAT AREA SSWWD ACROSS LRD TO NEAR MMMY.

FRONT SHOULD CONTINUE SEWD...IMPINGING ON BOUNDARY LAYER THAT WILL

BE DESTABILIZING AND WEAKENING CINH WITH TIME. MOISTURE CHANNEL

IMAGERY AND OVERLAID VWP/PROFILER DATA SHOW WELL-DEFINED SHORTWAVE

TROUGH ACROSS CENTRAL OK...TX HILL COUNTRY AND RIO GRANDE VALLEY

NEAR DRT. AS RELATED PLUME OF LARGE-SCALE ASCENT SHIFTS ESEWD OVER

DISCUSSION AREA...AND AS POCKETS OF RELATIVELY STG SFC DIABATIC

HEATING CONTINUE...INITIALLY STG CAPPING WILL ERODE RAPIDLY. THIS

WILL LEAVE BOUNDARY LAYER PRONE TO RAPID DEVELOPMENT AND UPSCALE

GROWTH OF TSTMS...ESPECIALLY ALONG COLD FRONT...BUT PERHAPS INVOF

LOCALIZED SEA-BREEZE CONVERGENCE MAXIMA AS WELL. RESULTANT

STEEPENING OF LOW-MIDDLE LEVEL LAPSE RATES...JUXTAPOSED WITH SFC DEW

POINTS MAINLY MID-60S F...YIELD MLCAPE 2000-3000 J/KG IN MODIFIED

RAOBS AND RUC FCST SOUNDINGS.

EFFECTIVE SHEAR IS RATHER WEAK OVER MOST OF DISCUSSION AREA...DUE TO

STG VEERING/BACKING PROFILE IN LOW-MIDDLE LEVELS AND LACK OF MORE

ROBUST BOUNDARY-LAYER WINDS INLAND. THIS SHOULD REMAIN TRUE OVER

MID-UPPER TX COASTAL PLAIN...THOUGH VERTICAL SHEAR MAY BECOME MORE

FAVORABLE THIS AFTERNOON IN AREA OF DEEP S TX TO BE COVERED IN

SEPARATE MCD LATER. EFFECTIVE SHEAR ALSO WILL BE STRONGER FOR

CONVECTION BEHIND SFC FRONT. CLUSTERED AND LINEAR STORM MODES

APPEAR MOST PROBABLE...WITH GREATER WIND THREAT ALONG/AHEAD OF FRONT

AND HAIL RISK WITH CONVECTION ON BOTH SIDES OF FRONT.

..EDWARDS.. 04/20/2012

ATTN...WFO...LCH...SHV...HGX...CRP...EWX...

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