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Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 5


wxmx

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Our string of Chamber of Commerce weather will transition to a unsettled pattern this week with a chance of rain every few days as short wave energy traverses the Region throughout the upcoming work week. Temps will remain mild with lows in the 50's and highs in the low to mid 70's.

 

A pattern change lurks later in the week as a potent N Pacific storm system arrives onshore next Thursday and drops into the Great Basin and a trough becomes established to our W. There remains some uncertainty in the forecast late next week as the Euro is a bit more progressive ejecting a cold core upper low into the Plains while the GFS is a full 12-18 hours slower and leaves energy behind buried along the US/MX border in Arizona. The end result will have some rather important impacts on the sensible weather expected Friday into next weekend. A slower more cut off solution tends to favor a potential severe weather event and a strong cold front as cyclogenesis occurs over the Panhandle while a progressive or faster moving storm system would favor a drier solution and less of an intrusion of 'colder' air. There are strong indications that the 500mb upper low will be very chilly with temps near the-32F range aloft. The HPC favors a slower/stormy pattern to our W with a return to a Winter like pattern with bouts of heavy snow across the Great Basin, Southern/Central Rockies into the Plains and lower elevation rains across the Pacific NW and California as well as a 7 Day QPF potential of near 1 inch for the Rio Grande Valley into Central Texas increasing to 2 to 3 inches along Coastal SE Texas into Louisiana and the Northern Gulf Region. We will need to monitor the trends this week as there remains a lot of uncertainty in the medium forecast and any potential severe episode for next weekend.

 

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The 12Z suite of operational and ensemble guidance continues to advertise an unsettled zonal split flow throughout the week with a couple of short waves moving across the Region. One weak disturbance is crossing the area near SE OK/NE TX area today with a bit stronger wave moving S of Arizona at this hour across Northern Mexico and should spark off additional showers and isolated storms Wednesday. The next short wave appears a bit stronger and with a boundary oscillating across Central Texas, a better chance of rainfall is looking likely.

 

Looking ahead to the weekend, the guidance is fair agreement that a long wave trough and attending 500mb storm develops near the CA/AZ/MX border. Embedded short waves are depicted to drop SE toward the base of a SW to NE or positive tilted trough axis that will extent from the Baja Region of NW Mexico on NE to the Great Lakes/Mid West. The ensembles are still suggesting a cut off upper low will linger into Monday suggesting showers and storms, some possibly severe will develop across W Central Texas Saturday and very slowly transition E into Monday, should the cut off solution verify. Winter Storm RECON has been tasked and is scheduled to make 13 drops across the NE Pacific to sample the environment beginning February 6th at 00Z.

 

WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0100 PM EST MON 04 FEBRUARY 2013
SUBJECT: WINTER STORM PLAN OF THE DAY (WSPOD)
         VALID 05/1100Z TO 06/1100Z FEBRUARY 2013
         WSPOD NUMBER.....12-066

I.  ATLANTIC REQUIREMENTS
    1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
    2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS
    1. FLIGHT ONE -- NOAA 49
       A. P56/ DROP 7 (44.3N 151.0W)/ 06/0000Z
       B. NOAA9 07WSC TRACK56     
       C. 05/1900Z
       D. 13 DROPS ON TRACK NORTH OF 37.0N WITH SPACING
          BETWEEN DROP POINTS SET AT APPROXIMATELY 90 NM.
       E. 41,000 TO 45,000 FT/ 06/0600Z

    2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

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The next short wave disturbance appears to be very vigorous and has abundant moisture and some instability to work with. Heavy rainfall and even some strong to possibly severe storms with training heavy rain is not out of the question for Wednesday into early Thursday across much of the Southern half of Texas into Louisiana. PW's have increased to the 1.5+ range and the HPC is suggesting QPF may approach the 2-3+ inch mark for portions of the Rio Grande Valley into S Central/SE Texas as well as Louisiana. We may get close to Flood Advisory Criteria if the trends continue today as this short wave is tracking further S across Old Mexico and a boundary is draped over or just N of the Hill Country.

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Morning e-mail from Jeff:

 

Fairly active WSW to SW flow aloft will bring a few chances of rainfall to the region this week in an overall unsettled pattern.
 
Patchy dense fog across portions of the area is lifting into more of a low deck of stratus clouds, except near the coast and in the bays where thicker sea fog is currently in place. Will continue to deal with the threat for periods of dense sea fog along the coast for the next 24 hours as fairly light to moderate winds combined with warm moist air flowing over the cooler nearshore waters promotes fog development. SE TX will be in between systems today with only a few scattered showers possible mainly E of I-45 and south of I-10.

 

Attention will focus on the Wednesday afternoon and overnight period as a fairly strong short wave trough in the SW flow aloft moves out of Mexico and into SW and then SC TX on Wednesday and Wednesday afternoon. Low level moisture is already increased over the area in response to a weak short wave passage yesterday afternoon which was able to squeeze out a few fast moving showers. This next incoming system appears more well defined and stronger in the model guidance with both the global and shorter term meso models showing a fair amount of upstream thunderstorms development on Wednesday late morning into the early afternoon over the Rio Grande plains into SC TX and then spreading ESE into the coastal bend and SE TX during the afternoon and into the overnight hours. While the low level flow backs to the ESE enhancing the low level shear late Wednesday, the amount of available instability appears to be lacking for a significant severe weather threat. Additionally clouds will hamper early day heating and forecast soundings only show a small amount of instability through the air column. For now, this looks like an isolated severe weather threat mainly south of I-10, but any modest heating on Wednesday could result in SPC upgrading parts of the area into a slight risk. 
 
Of greater importance is the threat for heavy rainfall mainly over the southern ½ of the region Wednesday-Wednesday night. Short term meso models are suggestive of a couple of bands of training convection over SE TX during this period as the lift from the short wave combines with the southerly low level jet and copious Gulf moisture. Moisture levels will be high with PWS of 1.5 inches but not excessive. Meso models are attempting to develop activity along some sort of boundary near the coast…could be a weak coastal front or air mass change zone due to more surface heating over S TX on Wednesday. I will follow along with the TX TECH WRF model which did well with the early Jan 2013 rainfall event and this model places at least of couple of lines of thunderstorms across the area well into Wednesday night. South of I-10 rainfall amounts of 1-2 inches will be possible with isolated amounts of 3 inches while north of I-10 amounts will generally average .5 to 1 inch. Should see rains come to an end Thursday morning…but there may be some left over showers especially near the coast early before drier air arrives from the west.
 
Area will be dry from Thursday afternoon-Friday ahead of a major SW US storm system that begins to approach the plains over the weekend. Moist southerly flow begins on Saturday, but minus any undetected disturbances in the upper level flow Saturday should be a fairly dry day. With moisture increasing off the Gulf, will throw in a 20% rain chance for any streamer showers on Saturday. Rain chances begin to increase Sunday-Monday as increasing lift from the large storm system spreads into the plains. Still some timing and thermodynamic uncertainties in the forecast for this system in terms of potential capping and severe weather parameters.  

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The best chances for cold in our region are those that arise from a pattern in which we get an EPO ridge, which morphs into a W coast ridge, ie. Feb 2011...this time it looks like the other way around, a west coast ridge that transforms into an EPO ridge...this means the first wave will lack a real cold air source...we can get the EPO ridge go back to a west coast ridge, but I'm not losing my sleep about that possibility. Still, air may be cold enough for wintery precip for parts of C to N TX (or mountains in MX or N MX) if there's a strong enough storm.

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The best chances for cold in our region are those that arise from a pattern in which we get an EPO ridge, which morphs into a W coast ridge, ie. Feb 2011...this time it looks like the other way around, a west coast ridge that transforms into an EPO ridge...this means the first wave will lack a real cold air source...we can get the EPO ridge go back to a west coast ridge, but I'm not losing my sleep about that possibility. Still, air may be cold enough for wintery precip for parts of C to N TX (or mountains in MX or N MX) if there's a strong enough storm.

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The best chances for cold in our region are those that arise from a pattern in which we get an EPO ridge, which morphs into a W coast ridge, ie. Feb 2011...this time it looks like the other way around, a west coast ridge that transforms into an EPO ridge...this means the first wave will lack a real cold air source...we can get the EPO ridge go back to a west coast ridge, but I'm not losing my sleep about that possibility. Still, air may be cold enough for wintery precip for parts of C to N TX (or mountains in MX or N MX) if there's a strong enough storm.

 

Seeing signs on the op ECMWF, op GFS (especially yesterday's 12z), and nearly all the GFS ensembles for a significant punch of colder air in about 12 to 15 days, potentially the coldest of this winter season. I'm not sure about all the teleconnective signals though. Also, with very active storm track, things could get interesting quickly. Not so impressed with weekend or early next week storm system for DFW for any winter precip (at least not yet). Also, not impressed for any severe weather either. That should stay south and east of the Metroplex (if any).

 

Going on a tangent about one of my weather pet peeves: The overall severe weather impact for DFW tends to be grossly overdone this time of year and kinda overdone in general. It has kinda gotten to where we call every thunderstorm severe to the point where most people don't even pay attention to the warning/watches anymore. I think this to be because of how we define a severe thunderstorm. I very much think this is an area that needs to be looked at and redefined and parameters raised a bit in terms of wind speed and hail size. Obviously, if it is a tornadic threat that would trump everything else. It is almost next to impossible to ascertain the mesoscale environment this far in advance to accurately pinpoint potential severe weather. Not every rain and thunderstorm event is going to produce severe weather. This is one area I think forecasters tend to cry wolf far too often, especially around the DFW area.

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Morning e-mail from Jeff:

 

Active weather already in progress this morning as a potent short wave over NW TX interacts with increased moisture over southern TX.
 
Radar shows several batches of rainfall moving across SE TX this morning with the first batch weakening along the I-45 corridor and the next batch incoming over Wharton County. Further upstream south of San Antonio radar shows stronger activity and storms have pulsed to severe levels in the past hour in this area. Surface analysis indicates a weak coastal trough of low pressure is situated from offshore of Galveston Island to Matagorda Bay and then inland north of Corpus Christi. PWS range from 1.4 over the Matagorda Bay region to 1.1 over the Lake Livingston areas but a large mass of values of 1.6-1.7 are moving northward over deep south TX at this time and should reach the Matagorda Bay area by late morning (CRP AM sounding very came in with 1.57in PW. Instability has increased overnight across the TX coastal bend with 500-1000 J/Kg of CAPE located from west of Houston to near Corpus Christi (AM CRP sounding had 1143 J/KG of surface CAPE). Interestingly, the current severe supercell south of San Antonio is just west of this axis of greater instability.

 

As lift continues to be provided over the area by the short wave trough aloft and surface low pressure trough expect numerous showers and thunderstorms to continue for much of the day. Supercell activity currently south of San Antonio will likely grow upscale into a Mesoscale Convective System (MCS) by mid morning as this feature moves into greater moisture and instability. This is supported by several of the meso models showing an ENE moving MCS developing over SC TX this morning and then moving E to ESE into the TX coastal plains this afternoon and evening. The severe threat is fairly marginal but a few severe storms will be possible especially right near the coast and offshore. Main threat would be large hail and damaging winds. In fact the TX TECH 3KM WRF shows several “bowing” line segments in the storms as they progress toward the coast this afternoon/evening. Additionally, instability will be greatest near the coast with the best chances of storms becoming surface based.
 
Other item is the heavy rainfall potential. Moisture levels will be increasing through the day as a low level jet on the order of  20-25kts transports the deep moisture over S TX northward. The air mass will become increasingly saturated across the area with rainfall production peaking this afternoon. Nearly stationary coastal boundary/surface trough should act as the focus for training thunderstorms and heavy rainfall this afternoon and do not expect this feature to lift much northward today. Thus far this morning most of the activity has been north of this boundary, but expect the development of an MCS over SC TX in the next 3-6 hours to help focus downstream development closer to the coast with a large light to moderate rain shied covering most inland locations. Rainfall amounts will average 1-2 inches between US 59 and the coast and generally an inch or less inland (NW) of US 59. Grounds are fairly dry as rainfall has been lacking over the past 3 weeks with much of what falls today being able to be absorbed into the soil. Could see some minor flooding in urban areas if/when heavy rainfall rates of 1-2 inches per hour develop.
 
Series of short waves will move east of the area tonight with dry westerly flow developing on Thursday and continuing into Friday. No cold front with these systems suggest no air mass change with lows remaining in the 60’s and highs in the 70’s. Light winds and warm dewpoints over cool nearshore waters will continue to promote dense sea fog formation after the rainfall passes today. Visibilities will hover in the .25 to .75 of a mile range from early Thursday possibly into the weekend for the coastal locations and inland bay areas. Will see the sea fog bank spread inland each night from the coast reaching at least I-10.
 
After a break in the rainfall Thursday and Friday, rain chances begin to increase again on Saturday as southerly winds return and moisture begins to increase ahead of a large SW US storm system. Looks like the main upper trough hangs back into the SW US into early next with a cold front moving down the plains and into the coastal TX area on Sunday. Not very confident where this front will stall out, but it is possible that it stalls across the region with a series of weak disturbances riding up and along the frontal slope Monday/Tuesday. Will onset scattered rain showers Saturday afternoon and increase rain chances into Sunday as the front moves into the area.  

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MESOSCALE DISCUSSION 0115
   NWS STORM PREDICTION CENTER NORMAN OK
   0648 AM CST WED FEB 06 2013
  
   AREAS AFFECTED...LOWER TO MIDDLE TX COASTAL PLAINS
  
   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
  
   VALID 061248Z - 061415Z
  
   PROBABILITY OF WATCH ISSUANCE...20 PERCENT
  
   SUMMARY...AN ISOLATED SEVERE THREAT WILL BE POSSIBLE ALONG THE LOWER
   TO MIDDLE TX COASTAL PLAINS OVER THE NEXT FEW HOURS. THE MAIN THREAT
   WILL BE FOR HAIL AND STRONG GUSTY WINDS. WW ISSUANCE IS NOT
   ANTICIPATED THIS MORNING ACROSS SCNTRL TX.
  
   DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A FRONTAL BOUNDARY
   LOCATED FROM NEAR LAREDO EXTENDING NEWD TO NEAR VICTORIA WITH SFC
   DEWPOINTS ALONG THE BOUNDARY IN THE MID 60S F. AN ISOLATED STRONG TO
   SEVERE THUNDERSTORM IS LOCATED JUST TO THE NORTH OF THE BOUNDARY. IN
   SPITE OF THE MOIST BOUNDARY LAYER...OBJECTIVE ANALYSIS SUGGESTS THAT
   INSTABILITY IS WEAK ACROSS SCNTRL TX WITH MLCAPE VALUES IN THE 250
   TO 500 J/KG RANGE. HOWEVER...REGIONAL WSR-88D VWPS SHOW 50 KT OF
   DEEP LAYER SHEAR WHICH SHOULD BE ENOUGH FOR AN ISOLATED
   SUPERCELL/BOW ECHO THREAT THIS MORNING. SHEAR AND LIFT ARE BEING
   ENHANCED BY THE LEFT EXIT REGION OF A MID-LEVEL JET ANALYZED OVER
   SCNTRL TX. ALTHOUGH THE CELL CURRENTLY IN MCMULLEN COUNTY APPEARS TO
   BE TO THE NORTH OF THE BOUNDARY AND SLIGHTLY ELEVATED...THE CELL
   COULD BECOME INCREASINGLY SFC-BASED AS IT MOVES EWD ONTO THE MIDDLE
   TO UPPER TX COASTAL PLAIN. IN THIS CASE...AN ISOLATED WIND DAMAGE
   THREAT COULD PERSIST IN ADDITION TO THE HAIL THREAT.
  
   ..BROYLES/EDWARDS.. 02/06/2013
  
  
   ATTN...WFO...CRP...EWX...
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From Nesdis:

 

SATELLITE PRECIPITATION ESTIMATES..DATE/TIME 02/06/13 1019Z
SATELLITE ANALYSIS BRANCH/NESDIS---NPPU---TEL.301-683-1404
LATEST DATA USED: GOES-E 1015Z   GOES-W 1000Z GG
.
LOCATION...S TEXAS...
.
ATTN WFOS...HGX...CRP...EWX...
ATTN RFCS...WGRFC...
.
EVENT...TRAINING...BACKBUILDING
.
SATELLITE ANALYSIS AND TRENDS...WV LOOP SHOWS E-W SLIGHTLY ELONGATED
UPPER LOW ACROSS CENTRAL WEST TEXAS IS LIFTING SLOWING NEWARD AND WITH A
DEEP WSWLY FLOW WITH EMBEDDED WEAK S/W  AND ASSOCIATED WIND SPEED MAXIMA
AIDING LOW LEVEL CONVERGENCE AND SLIGHT PRESSURE FALLS.   ADDITIONALLY
SUPPORTING INCREASING LOW LEVEL FLOW ALONG THE COASTAL FLATLANDS OF NE
MEXICO INTO S TX WITH AN INCREASE OF PWS FROM 1-1.25" EARLY THIS MORNING
TO AROUND 1.4-1.6" ACROSS THE SAME AREA.    FIRST IMPULSE HAS ROTATED
THROUGH WITH THE NOSE OF THE 80KT SPEED MAX LEADING TO TRIGGERING OF
THE SECOND CURRENT OVER ATASCOSA COUNTY.

THESE COMPLEXES HAVE BEEN PRODUCING 1-1.5"/HR RATES GIVEN RELATIVELY
WARM TOPS AND MODERATE AVAILABLE MOISTURE... LEAVING A SWATH OF 2-3"
TOTALS ACROSS WEBB AND LASALLE EVENTUALLY TO KARNES BUT NOT ENOUGH TO
REACH FFG VALUES ATTM.
.
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 1200-1800Z...MEDIUM CONFIDENCE FACTOR IN SHORT
TERM OUTLOOK... PERSISTENT CONVECTION COULD BE LEADING TO THE DEVELOPMENT
OF A COLD POOL POTENTIALLY LEADING TO INCREASED FRONTOGENSIS ACROSS
S TX...  WITH PERPENDICULAR 20-25KT 925MB FLOW... ISENTROPIC FORCING
ACROSS THIS ENHANCED BOUNDARY COULD INCREASE COVERAGE AND INCREASE MST
FLUX FOR MORE EFFICIENT CELLS.     WITH OR WITHOUT THIS FRONTOGENETICAL
FORCING... CONTINUED UPSTREAM MIDLEVEL FORCING CONTINUES TO SUPPORT
BACKBUILDING CELLS INTO THE FRONT RANGE OF THE SIERRA MADRE.   WIND
PROFILES ALOFT WILL ALSO SUPPORT CONTINUED ENELY MOVEMENT FOR CONTINUED
TRAINING... EVENTUALLY ECLIPSING THE HIGH FFG VALUES IN THE AREA.

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Looking toward the weekend into mid next week concerning our Region. The 12Z Euro is suggesting strong storms and a potential squall line developing Sunday and moving SE along the frontal boundary that stalls along the Texas Coast. Early next week as upper level energy hangs back to our W across the Great Basin and additional short wave activity dives SE into the base of the trough, over running heavy precip develops N of the boundary and increases on Tuesday as the 500mb low/trough axis begins to slowly shift E. There are some indications that wintry mischief may be possible across the Panhandle, N Central/NE TX into OK and AR as well as Northern LA Tuesday into Wednesday.

 

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Unless that little something in the Hill Country gets substantially more substantial, this is somewhat of a bust as far as rain.

 

But at least we got some locally.  And couple more opportunities in the next week.  And the NYC and New England subforums will make for awesome lurking end of week/weekend.

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A very complex and complicated forecast period is ahead as a potentially Historic Nor'easter develops today across the Great Lakes and NE and a deep trough with embedded short wave energy dives S into the Great Basin to our W. Early morning WV Imagery shows these to weather makers very well and the stage is set for possible record breaking snowfall for Boston and locations along the I-95 Corridor and inland areas of New England.

 

To the W, snow and lower elevation rains begin in earnest across the Great Basin/Intermountain West as a deep trough with rich Pacific moisture will linger into the Tuesday of next week time frame before shifting E mid next week. The SPC has outlined a Slight Risk for severe storms on Saturday roughly from Del Rio to Austin to near the Dallas/Ft Worth area. Storms should begin to fire during the late afternoon on Saturday along a dry line and march E developing into a squall line.  The SPC has also outlined a Day 3 Slight Risk for SE/E TX and Louisiana. A stalling frontal boundary will near the Coast on Sunday bringing cooler air and setting the stage for an over running rain event for early next week.

 

Abundant Pacific moisture and a wave of low pressure appear to develop near Corpus Christi Monday night into Tuesday and slowly ride the stalled boundary ENE. Meanwhile to our W, additional short wave upper air disturbances drop SE from the Pacific NW into a positive tilted trough axis pulling down much colder air. The trough and upper level vort max and a sharp Canadian front will finally push across Texas late Tuesday into Wednesday. There is a slight chance for wintry mischief along and N of I-20 Tuesday as a cold pocket aloft near the-30 degree range moves E, if enough moisture is available. That will need to be monitored the next several days. Skies finally clear by late Wednesday setting the stage for possible near freezing temps late next week. Clouds and moisture may return for the following weekend with below normal temps as a much stronger cold front arrives with yet another strong upper low and Western trough developing.

 

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Progressive GFS vs the lot slower Euro? Again, they are at odds...0z Euro looked like it was going to cave to the GFS, but 12z Euro retracted big time, while 18z GFS slowed a bit...Canadian in the middle. Personally, I like the Euro a bit more, but not because I have data to back it up, but because is colder and more humid in the south. Not expecting snow in the city, but it can conveniently happen in a weekend where I can go up to 8000ft ;)

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  MESOSCALE DISCUSSION 0130   NWS STORM PREDICTION CENTER NORMAN OK   1112 PM CST SAT FEB 09 2013      AREAS AFFECTED...CENTRAL AND N CENTRAL TX      CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE       VALID 100512Z - 100715Z      PROBABILITY OF WATCH ISSUANCE...60 PERCENT      SUMMARY...A GRADUAL INCREASE IN STORM COVERAGE/INTENSITY IS EXPECTED   THE NEXT 2-3 HOURS...WITH THE POSSIBILITY OF SEVERE TSTM WATCH   ISSUANCE BY 06-07Z.      DISCUSSION...A BAND OF WEAK ELEVATED CONVECTION HAS BEEN SLOWLY   EXPANDING/STRENGTHENING FROM ROUGHLY SJT TO SPS.  THE CONVECTION   APPEARS TO BE FORMING ALONG THE LEADING EDGE OF THE MIDLEVEL HEIGHT   FALLS ASSOCIATED WITH THE MIDLEVEL TROUGH EJECTING ENEWD OVER THE   SRN/CENTRAL PLAINS...COINCIDENT WITH A 50-55 KT SSWLY LLJ AXIS AND   THE CORRIDOR OF STRONGEST LOW-LEVEL MOISTURE TRANSPORT.  ASCENT AND   MOISTENING ALONG THIS CORRIDOR APPEAR TO BE WEAKENING THE CAP NOTED   IN 00Z OBSERVED AND SHORT-TERM MODEL FORECAST SOUNDINGS...SUCH THAT   THUNDERSTORM COVERAGE SHOULD INCREASE IN THE NEXT FEW HOURS.    MEANWHILE...THE SURFACE WARM SECTOR CONTINUES TO SPREAD NWD FROM   CENTRAL INTO N TX WHERE THE SURFACE TEMPERATURES/DEWPOINTS HAVE BEEN   INCREASING BY 1-2 F PER HOUR.  WITH INSTABILITY BECOMING ROOTED AT   OR VERY NEAR THE SURFACE...THE STRONG VERTICAL SHEAR PROFILES WILL   FAVOR ORGANIZED LINE SEGMENTS WITH SOME POTENTIAL FOR EMBEDDED   ROTATING STORMS.  AT THIS TIME...THE PRIMARY SEVERE THREATS APPEAR   TO BE ISOLATED LARGE HAIL AND PERHAPS A FEW STRONG/DAMAGING   GUSTS...AND THIS AREA WILL CONTINUE TO BE MONITORED FOR THE   POSSIBILITY OF A WATCH IN THE NEXT 1-2 HOURS.      ..THOMPSON/KERR.. 02/10/2013         ATTN...WFO...FWD...OUN...SJT...
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The Pacific front just passed NW Harris County with a whopping 12 degree drop to 61F. Only light rains so far up here and a few rumbles of thunder, but it does look like we are in for a damp couple of days and even some elevated storms possible across Central and E Texas Monday into Tuesday with some accumulating snow in Northern New Mexico, The Texas/Oklahoma Panhandles on E across Central and Eastern Oklahoma into Arkansas, depending on the eventual storm track of the next upper air disturbance currently over Southern California and Arizona.

 

 

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Morning e-mail from Jeff:

 

Periods of showers and thunderstorms will be likely over the next 24-36 hours.

 

Weak frontal boundary which passed across the region yesterday has stalled just offshore overnight. A shallow dome of cool air is in place across the region with light N winds. Above the surface strong SW flow is pulling moisture over the top of this surface cold dome resulting in modest lift. Sub-tropical jet stream is anchored across the region and within this flow small disturbances are rippling through the flow resulting in enhanced lift. One such disturbance is currently crossing the area leading to decent coverage of showers and thunderstorms. Both Corpus and Lake Charles soundings show decent mid level instability this morning suggestive of elevate thunderstorms and this is being confirmed on the lightening data maps showing increasing lightening strikes over the region. A few storms could reach strong levels this morning with small hail and gusty winds.
 
Current shortwave aloft (disturbance) will move east of the region by late morning and a gradual downward trend in rainfall is expected this afternoon. It is interesting to note that some of the short range guidance does redevelop activity this afternoon across the area. A look at water vapor images upstream over Mexico does not reveal any shortwave that I can see in the upper level flow (not saying it is not there). Such patterns tend to produce rounds of rainfall about every 6-12 hours.
 
Other item which continues to be a problem along the coast is sea fog. As the weak boundary lifts slowly northward today, dewpoints will surge into the mid and upper 60’s over the coastal waters. As this warm air flows across the cool waters it will chill to saturation allowing dense sea fog to form. Think mainly the coastal locations will have the biggest issues with sea fog, but it could spread as far inland as Liberty to Pearland to Bay City this evening depending on how quickly the coastal front backs northward. Visibilities over the coastal waters and bays will average between .50 of and mile and 0. 
 
Tonight into Tuesday much better rain chances are likely as the main upper level trough over the 4 corners area ejects eastward into the central plains. Strong lift will come to bear across the region late tonight through Tuesday morning with widespread showers and thunderstorms likely. A few of these storms could be on the strong side. Rain should end by midday Tuesday as the system progresses to our east and a colder/drier air mass sweeps into the region from the NW.
 
Rainfall amounts today-Tuesday will average .5 to 1.0 inches across the region with isolated totals up to 2.0 inches especially east of I-45.
 
Rest of the forecast from Tuesday evening onward looks cool and dry with surface high pressure in control (lows in the 40’s and highs in the 60’s). Stronger cold front looks to arrive late Friday and usher in a colder air mass for the weekend with temperatures possibly near freezing across some of our northern counties Saturday morning. GFS model is trying to generate some post frontal light precipitation, but this is not supported by other guidance and for now will leave a dry forecast for Friday night into Saturday. 

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06z GFS and 0z Euro did a 180 and now are the complete opposite of what they were a couple of days ago, with the GFS being a lot colder and the Euro a lot warmer. Ukie supports the Euro and the Canadian is more on the side of the GFS. Americans vs Europeans.

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