Jump to content
  • Member Statistics

    17,541
    Total Members
    7,904
    Most Online
    Gonzalez Brittany
    Newest Member
    Gonzalez Brittany
    Joined

May 24 Plains/MW Severe Threat


Helicity

Recommended Posts

  • Replies 1.6k
  • Created
  • Last Reply

Tuesday is easily the most impressive setup since April 27 IMO.

Ugh. I don't like seeing you say that. Hopefully things will change. I have not looked too much myself but apparently I should.

Link to comment
Share on other sites

Ugh. I don't like seeing you say that. Hopefully things will change. I have not looked too much myself but apparently I should.

Well we haven't really had much in the way of any severe events since that date, so it wasn't much of a stretch. However, even after today's Joplin tragedy, I still stand by that statement.

This kind of low-amplitude, progressive shortwave can cause all kinds of problems. The trough itself has some similarities to the May 10, 2010 trough. There appears to be slightly more instability over a much wider warm sector this time around, but the wind fields aren't quite as crazy. At this point, I'm leaning towards this becoming a Day 1 High Risk event.

Link to comment
Share on other sites

OK and southern KS are ground zero and where the CAPE/SRH/Shear combos will best located. Supers will likely erupt off the dryline late afternoon and spread east into a highly sheared environment. It really has potential to be major.

I have an e-mail group I send forecasts to on a regular basis. They like my e-mails because I try not to play everything up like some of the local media do. The only time I have really used strong wording to them was during our last 2 blizzards and May 10, 2010, which was warranted. I remember 5/10/10 having insane wind fields, but Tuesday looks too have a much more volatile thermodynamic environment. Now to figure out how to relay this info to my friends and family.

Link to comment
Share on other sites

ACUS02 KWNS 230542

SWODY2

SPC AC 230540

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1240 AM CDT MON MAY 23 2011

VALID 241200Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS LATE TUE AFTN INTO TUE NIGHT

ACROSS CENTRAL AND EASTERN OKLAHOMA...MUCH OF CENTRAL AND EASTERN

KANSAS...PARTS OF SOUTHWEST MISSOURI...NORTHWEST ARKANSAS AND NORTH

CENTRAL TEXAS...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK

AREA ACROSS MUCH OF THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI

VALLEY...EASTWARD THROUGH PARTS OF THE LOWER OHIO AND TENNESSEE

VALLEYS...AND NORTHEASTWARD THROUGH THE NORTHERN MID ATLANTIC COAST

STATES AND HUDSON VALLEY...

...AN OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES IS POSSIBLE

LATE TUESDAY AFTERNOON AND EVENING...

..SYNOPSIS

MODELS INDICATE THAT THE LARGE-SCALE TROUGH...NOW DEVELOPING INTO

THE WESTERN U.S...GRADUALLY SPLITS...WITH A SIGNIFICANT SOUTHERN

PORTION SLOWLY LIFTING EAST NORTHEASTWARD OUT OF THE SOUTHERN

PLATEAU BY EARLY TUESDAY...AS ANOTHER LARGE AND STRONG IMPULSE

APPROACHES THE PACIFIC COAST. THE LEAD TROUGH...WITH AT LEAST A

COUPLE OF SIGNIFICANT EMBEDDED SMALLER SCALE IMPULSES...IS PROGGED

TO EVOLVE INTO A CLOSED LOW AS IT MIGRATES ACROSS THE SOUTHERN

ROCKIES INTO THE CENTRAL PLAINS LATER TUESDAY AND TUESDAY NIGHT.

ASSOCIATED FORCING FOR UPWARD VERTICAL MOTION APPEARS LIKELY TO

CONTRIBUTE TO FURTHER DEEPENING OF A SURFACE CYCLONE OVER THE SOUTH

CENTRAL PLAINS. THIS IS EXPECTED TO BE ACCOMPANIED BY A

STRENGTHENING SOUTHERLY LOW-LEVEL JET IN EXCESS OF 50 KT AT 850 MB

BY EARLY TUESDAY EVENING...FROM NORTH CENTRAL TEXAS INTO EASTERN

KANSAS...AS A CYCLONIC AND GENERALLY WESTERLY 70 KT 500 MB JET

STREAK NOSES INTO AND THROUGH THE SOUTHERN PLAINS RED RIVER VALLEY

REGION.

AT THE SAME TIME...A LARGE COLD UPPER VORTEX WITH SEVERAL STRONG

EMBEDDED SHORT WAVE IMPULSES WILL LINGER OVER MUCH OF EASTERN

CANADA. AN ASSOCIATED SIGNIFICANT COLD FRONT APPEARS LIKELY TO

ADVANCE SOUTHEAST OF THE GREAT LAKES THROUGH MUCH OF THE

NORTHEAST...AS ANOTHER IMPULSE...PERHAPS CONVECTIVELY

ENHANCED...WITHIN THE SOUTHERN BRANCH OF THE SPLIT UPPER

FLOW...LIFTS OUT OF THE OHIO VALLEY THROUGH SOUTHERN NEW ENGLAND BY

12Z WEDNESDAY.

GIVEN THE CONTINUING PRESENCE OF A SEASONABLY MOIST BOUNDARY LAYER

AIR MASS IN THE WARM SECTOR OF THE PLAINS CYCLONE...AND ALONG AND

AHEAD OF THE EASTERN COLD FRONT...DESTABILIZATION PROBABLY WILL

BECOME SUFFICIENT TO SUPPORT CONSIDERABLE STRONG/SEVERE STORM

DEVELOPMENT DURING THIS PERIOD. ASIDE FROM SOME SEA BREEZE STORMS

IN THE SOUTHEAST...THIS WILL MOSTLY REMAIN WEST AND NORTH OF

PERSISTENT SUBTROPICAL RIDGING CENTERED JUST EAST OF THE SOUTH

ATLANTIC COAST.

..CENTRAL/SOUTHERN PLAINS

LINGERING VARIABILITY AMONG THE MODELS AND ENSEMBLES CONCERNING THE

TIMING AND TRACK OF THE TROUGH EMERGING FROM THE SOUTHWEST CONTINUES

TO COMPLICATE THE FORECAST. BUT IT APPEARS THAT THIS WILL ONLY

IMPACT THE EXACT PLACEMENT OF THE HIGHEST SEVERE PROBABILITIES...AS

THE EVOLVING LARGE-SCALE PATTERN SEEMS SUPPORTIVE OF A FAIRLY

CLASSIC SEVERE WEATHER OUTBREAK. AND ENOUGH COMMON GROUND APPEARS

TO EXIST TO JUSTIFY AN UPGRADE TO MODERATE RISK SEVERE PROBABILITIES

ACROSS MUCH OF CENTRAL/EASTERN KANSAS AND OKLAHOMA...PORTIONS OF

NORTH CENTRAL TEXAS...NORTHWEST ARKANSAS AND SOUTHWEST MISSOURI.

SURFACE DEW POINTS AROUND 70F ARE PROGGED IN THE WARM SECTOR OF THE

DEEPENING CYCLONE...ALONG AND EAST OF A SHARPENING DRY LINE DURING

THE LATE AFTERNOON HOURS...WHEN PEAK AFTERNOON HEATING AND

STEEPENING LAPSE RATES ASSOCIATED WITH MID-LEVEL COOLING PROBABLY

WILL CONTRIBUTE TO MIXED LAYER CAPE OF 2000-4000 J/KG. AS THE

MID-LEVEL JET NOSES INTO THE RED RIVER VALLEY...THE DRY LINE IS

EXPECTED TO BECOME THE FOCUS FOR THE PRIMARY STORM DEVELOPMENT AS IT

SURGES NORTHEASTWARD OUT OF SOUTH CENTRAL KANSAS...AND EASTWARD OUT

OF CENTRAL OKLAHOMA...THROUGH MUCH OF EASTERN KANSAS AND OKLAHOMA BY

LATE EVENING. GIVEN THE ANTICIPATED WIND PROFILES...EXHIBITING

STRONG DEEP LAYER SHEAR AND LARGE CLOCKWISE CURVED LOW-LEVEL

HODOGRAPHS...THE ENVIRONMENT IS EXPECTED TO BECOME CONDUCIVE TO

LONG-LIVED SUPERCELLS CAPABLE OF PRODUCING VERY LARGE HAIL AND

STRONG TORNADOES. THIS THREAT MAY CONTINUE THROUGH MUCH OF THE

EVENING...PERHAPS INTO THE 06-09Z TIME FRAME...GRADUALLY SPREADING

TOWARD THE LOWER MISSOURI VALLEY AND OZARKS...BEFORE DIMINISHING IN

THE PRESENCE OF A MORE STABLE OR STABILIZING BOUNDARY LAYER.

..NORTHERN MID ATLANTIC STATES INTO THE LOWER HUDSON VALLEY

WEAK TO MODERATE DESTABILIZATION ALONG AND AHEAD OF THE

SOUTHEASTWARD ADVANCING COLD FRONT...AND WITHIN THE PRE-FRONTAL LEE

SURFACE TROUGH...IS EXPECTED TO PROVIDE THE FOCUS FOR VIGOROUS

CONVECTIVE DEVELOPMENT WITH THE APPROACHING UPPER IMPULSE TUESDAY

AFTERNOON. MODELS ARE A BIT MORE UNCLEAR CONCERNING THE STRENGTH OF

THE VERTICAL SHEAR...BUT IT SHOULD BE ENOUGH TO SUPPORT POTENTIAL

FOR ORGANIZED STORM CLUSTERS...AND ISOLATED SUPERCELLS MAY NOT BE

OUT OF THE QUESTION. THIS COULD IMPACT MUCH OF THE URBAN

CORRIDOR...FROM WASHINGTON D.C./BALTIMORE TO NEW YORK CITY...BEFORE

CONVECTION DIMINISHING/SPREADS OFFSHORE WITH UPPER FORCING BY

TUESDAY EVENING.

..KERR.. 05/23/2011

post-972-0-48922100-1306129666.gif

Link to comment
Share on other sites

Just pushed out a target area forecast for tommorrow based on my Smart Model output. Tracking the highest areas running from a Tulsa to Ponca City to Oklahoma City to McAlester to Fort Smith, AR. Then a second area running from Wichita to Blue Mound to Independence, KS. Again very good instability across all the the Midwest, just pinning down the highest areas. Potential for numerous EF2, Isolated EF3 type Tornadoes, Convective Gusts up to 80 knots, and hail up to 3" diameter. Thoughts?

usa.jpg

Link to comment
Share on other sites

wow. 0z-06z tues on the NAM/GFS is ridiculous. SREF takes it a bit higher than the others.

SREF_prob_combined_sigtor__f051.gif

SREF really going gangbusters on the Warm Front on Tuesday.

Oh and looking at Wednesday with the SREF I think the Day 3 will be worded strongly

SREF_prob_combined_sigtor__f075.gif

Link to comment
Share on other sites

ICT weighs in

TUES:

SOME MODEL DIFFERENCES IN THE WIND FIELDS FOR TUESDAY BETWEEN THE

GFS AND NAM/WRF...BUT BOTH MODELS SHOW A STRONG MID LEVEL SHORTWAVE

PUSHING INTO THE PLAINS FOR TUE AFTN. SFC DIFFERENCES WILL MAINLY

AFFECT THE PLACEMENT OF THE BEST SEVERE WEATHER CHANCE ON THIS

DAY...AS UNSTABLE AIRMASS WILL BE IN PLACE...AS 0-8KM SHEAR

INCREASES TO 60-80KTS BY TUE AFTERNOON. FOCUS OF CONVECTIVE

DEVELOPMENT WILL BE ALONG A DRYLINE EXPECTED TO SHARPEN ACROSS WRN

SECTIONS OF THE COUNTY WARNING AREA...AS THE MAIN SFC LOW DEEPENS

OVER SW KS AND LIFTS TO THE NORTHEAST. ALL SIGNS ARE BEGINNING TO

COME TOGETHER FOR AN OUTBREAK OF SEVERE WEATHER FOR THE AREA FOR TUE

EVENING. FORECAST SOUNDINGS SUGGEST AREA WILL BE CAPPED FOR A GOOD

PORTION OF THE DAYTIME HOURS...BUT THE SIGNIFICANT SHORTWAVE WILL

WEAKEN THIS CAP ENOUGH FOR WIDESPREAD SUPERCELL DEVELOPMENT TUE

EVENING. WILL HAVE TO KEEP AN EYE ON THIS...AS 0-8KM SHEAR AND

DIRECTIONAL SHEAR SUGGESTS A CHANCE FOR LONG TRACK SUPERCELLS AND

POSSIBLE TORNADOES. STAY TUNED.

Link to comment
Share on other sites

This has major tornado outbreak stamped all over it, and my confidence is high that this will end up being a High Risk. One of the most classic setups you can draw up for the Southern Plains. A low-amplitude wave with an associated mid-level jet streak of 60+ kt slams into an extremely unstable warm sector, with the LLJ intensifying during the late afternoon and early evening hours.

I vaguely remember a time when I used to get excited about such things...

Link to comment
Share on other sites

This has major tornado outbreak stamped all over it, and my confidence is high that this will end up being a High Risk. One of the most classic setups you can draw up for the Southern Plains. A low-amplitude wave with an associated mid-level jet streak of 60+ kt slams into an extremely unstable warm sector, with the LLJ intensifying during the late afternoon and early evening hours.

I vaguely remember a time when I used to get excited about such things...

Even as a weather enthusiast, I'm tired. Tired of the massive destructive tornado hits to population centers. It's not fun seeing this. At least with a hurricane you have advance warning. Tornadoes are difficult to deal with, before, during, and after.

Link to comment
Share on other sites

With the apparent trend toward a sharper and more negative-tilt shortwave for tomorrow (May 24), directional shear seems just a bit less than ideal over parts of the dryline. I fully expect a significant event, but the latitudinal extent of long-track tornadic supercells could possibly be limited by this factor, IMO. Right now, I like a 50-75 mi. radius around ICT for the best chance of something truly high-end, based upon the more backed low-level flow depicted on the GFS/NAM (compared with the OKC area).

Link to comment
Share on other sites

With the apparent trend toward a sharper and more negative-tilt shortwave for tomorrow (May 24), directional shear seems just a bit less than ideal over parts of the dryline. I fully expect a significant event, but the latitudinal extent of long-track tornadic supercells could possibly be limited by this factor, IMO. Right now, I like a 50-75 mi. radius around ICT for the best chance of something truly high-end, based upon the more backed low-level flow depicted on the GFS/NAM (compared with the OKC area).

I think late May, good moisture return, steep lapse rates approaching dry (I saw a mention, maybe FWD's disco about near 9ºC/Kg) and temps well into the 80s and 90s, the less than ideal shear, more often found in May, may be balanced by high instability. I can think of a late season Texas outbreak that included an F-5 that had modest shear but very, very high CAPE.

On second thought, GFS OKC sounding for tomorrow, the only negative for huge tornadoes is a fairly high LCL. But EHI of 10? No shortage of helicity there if correct.

post-138-0-03387200-1306167983.gif

Link to comment
Share on other sites

I think late May, good moisture return, steep lapse rates approaching dry (I saw a mention, maybe FWD's disco about near 9ºC/Kg) and temps well into the 80s and 90s, the less than ideal shear, more often found in May, may be balanced by high instability. I can think of a late season Texas outbreak that included an F-5 that had modest shear but very, very high CAPE.

I agree, and as I said before, I expect a significant event with at least a fair number of tornadoes. Just trying to pin down the area most at risk for more of a "once in years" type outcome.

On second thought, GFS OKC sounding for tomorrow, the only negative for huge tornadoes is a fairly high LCL. But EHI of 10? No shortage of helicity there if correct.

Yeah; there's not much to nitpick about on that sounding besides the cap, which is not really a concern given the forcing that will arrive by tomorrow evening. An LCL height in the 800 m range is plenty low enough for significant tornadoes. It is worth mentioning that an ideal hodograph for areas along and W of I-35 features more backed 850 mb winds, such that shear in the lowest 1.5 km is almost entirely of the speed variety (rather than directional). Still, SSW flow at 850 mb has not precluded significant high-CAPE events like 2010-05-10 or 2003-05-08 in the OKC area.

Link to comment
Share on other sites

I'm a little concerned about moisture mixing out south of I-40. Otherwise, it looks like a strong cap strong forcing day, similar to 5/10/10.

Forecast soundings out of southern KS look absolutely incredible right now.

edit: A little concerned about possibility that convection initiates early (lets say 20-21Z) in a weak low-level shear environment and storm mode goes bonkers. We'll see.

Link to comment
Share on other sites

Strong wording

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1216 PM CDT MON MAY 23 2011

VALID 241200Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM NWRN TX TO SRN NEB...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK OVER

THE SRN/CNTRL PLAINS THROUGH THE OH/TN VALLEY TO SRN NY...

...TORNADIC OUTBREAK POSSIBLE ACROSS THE CENTRAL AND SOUTHERN PLAINS

TUESDAY. AN UPGRADE TO HIGH RISK MAY BE WARRANTED AS SITUATION

BECOMES MORE CERTAIN...

A CLASSIC PLAINS TORNADIC OUTBREAK APPEARS TO BE EVOLVING ACROSS THE

CNTRL/SRN PLAINS...ESPECIALLY FOR KANSAS AND OKLAHOMA. LATEST MODEL

GUIDANCE IS CONSISTENT REGARDING THE PROGRESSION OF A VERY STRONG

MID LEVEL SHORTWAVE TROUGH...CURRENTLY DIGGING ESEWD ACROSS SRN

CA...INTO THE SWRN U.S./SRN ROCKIES BEFORE EJECTING INTO THE PLAINS

BY PEAK HEATING. A VERY DIFFLUENT UPPER FLOW REGIME WILL OVERSPREAD

THE PLAINS AS 30-60M 12HR HEIGHT FALLS EDGE EWD.

ADDITIONALLY...H5

SPEED MAX APPROACHING 80-90KT...AS NOTED IN THE GFS...WILL RACE TO A

POSITION OVER NWRN TX/SWRN OK BY 25/00Z WHICH WILL GENERATE VERY

STRONG SHEAR ACROSS THE WARM SECTOR FOR AREAS NEAR THE RED RIVER

REGION...NWD INTO KS AND EVEN SRN NEB. NEEDLESS TO SAY A VERY

DYNAMIC SHORTWAVE TROUGH SHOULD TIME FAVORABLY FOR RAPID SEVERE

THUNDERSTORM INITIATION ALONG/AHEAD OF THE DRYLINE AS ATMOSPHERIC

HEATING IS MAXIMIZED.

I am right in the middle of it all. I am starting to almost hate tornadoes. It seems like history keeps repeating itself this year as deadly tornadoes strike large cities.

Link to comment
Share on other sites

I'm a little concerned about moisture mixing out south of I-40. Otherwise, it looks like a strong cap strong forcing day, similar to 5/10/10.

Forecast soundings out of southern KS look absolutely incredible right now.

edit: A little concerned about possibility that convection initiates early (lets say 20-21Z) in a weak low-level shear environment and storm mode goes bonkers. We'll see.

I'd be very careful taking these wind profiles at face value though. If we would've done that for 4/27... as late as the 12Z NAM the day of the outbreak, we would've been expecting 0-1 km SRH over Alabama to remain under 250 m2/s2 during peak heating. This bias in the NAM and GFS seems to be one of the most persistent biases that they both have. Use extreme caution with this...

Link to comment
Share on other sites

I'd be very careful taking these wind profiles at face value though. If we would've done that for 4/27... as late as the 12Z NAM the day of the outbreak, we would've been expecting 0-1 km SRH over Alabama to remain under 250 m2/s2 during peak heating. This bias in the NAM and GFS seems to be one of the most persistent biases that they both have. Use extreme caution with this...

The NAM and GFS have a tendency to underdo low-level helicity?

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...