2009 Severe Weather thread

[AirNik]

It's been a while since I've seen any big storms down here, might get some today.

[Dave]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0656 AM CST WED FEB 18 2009

VALID 181300Z - 191200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF LA...MS...AL...GA
AND THE FL PANHANDLE...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM LA INTO PARTS OF TN...GA...NRN FL AND THE S ATLANTIC CST...

...SYNOPSIS...
FAST WSW FLOW WILL PREVAIL OVER THE S CNTRL AND SE U.S. TODAY/
TONIGHT...ON SRN FRINGE OF NRN STREAM TROUGH AMPLIFYING SE ACROSS
THE UPR GRT LKS/MID MS VLY. S OF THE TROUGH...EXISTING SRN BRANCH
JET...NOW EXTENDING FROM NM TO AR...WILL DEVELOP ESEWD. THIS WILL
ENHANCE MID LVL FLOW OVER THE SERN STATES TODAY...WITH MORE
SUBSTANTIAL STRENGTHENING EXPECTED TONIGHT/EARLY THURSDAY.

AT THE SFC...LOW ASSOCIATED WITH NRN STREAM IMPULSE SHOULD TRACK NE
TO NEAR LK HURON THIS EVE AS TRAILING COLD FRONT CONSOLIDATES AND
ACCELERATES SE ACROSS THE OH...TN...AND LWR MS VLYS. AHEAD OF THE
FRONT...LATEST HAND AND STREAMLINE ANALYSES SUGGEST PRESENCE OF A
CONFLUENCE ZONE ATTM EXTENDING FROM NEAR MEM SW TO NEAR SHV.
SATELLITE PW AND VWP DATA SUGGEST THAT THIS FEATURE MAY MARK WRN
LIMIT OF POTENTIAL STORM DEVELOPMENT TODAY AS WINDS APPEARED TO HAVE
VEERED BEHIND IT...AND DRYING IS OCCURRING TO ITS W.

...TN VLY TO CNTRL GULF CST/GA/N FL...
POTENTIAL EXISTS FOR SIGNIFICANT SVR STORMS THIS AFTN THROUGH EARLY
THURSDAY AHEAD OF AFOREMENTIONED COLD FRONT AND CONFLUENCE ZONE.

LATEST SATELLITE PW DISPLAY SHOWS PW AXIS WITH VALUES AOA 1 INCH
EXTENDING FROM SE TX AND LA NE INTO MIDDLE TN. THIS MOISTURE AXIS
SHOULD CONTINUE TO PIVOT CLOCKWISE ACROSS THE CNTRL GULF CST STATES
TODAY AS HEIGHTS SLOWLY FALL OVER REGION ON SRN FRINGE OF AMPLIFYING
TROUGH.

ALTHOUGH THE INCREASING MOISTURE WILL ENHANCE LIKELIHOOD FOR
STORMS...SEVERAL FACTORS ARGUE AGAINST MORE THAN ISOLD ACTIVITY IN
THE SLGT AND MDT RISK AREAS UNTIL PERHAPS LATE THIS AFTN AND THIS
EVE. FIRST /1/ MORNING RAOBS AND MODEL FCSTS SHOW THAT MID LVL
LAPSE RATES ARE AND LIKELY WILL REMAIN ONLY MODESTLY STEEP...WITH A
WARM NOSE AROUND 750 MB. IN ADDITION.../2/ CLOUDS WITH S-DRIFTING
SUBTROPICAL JET WILL LIMIT SFC HEATING THROUGH AT LEAST PART OF THE
DAY NEAR THE GULF CST. THIRD /3/ DEEP FORCING FOR ASCENT WILL BE
WEAK AS UPLIFT LIKELY WILL BE CONCENTRATED ON CYCLONIC SIDE OF SRN
STREAM JET...I.E. OVER THE OH VLY/CNTRL APPALACHIANS.

NEVERTHELESS...COMBINATION OF SFC HEATING...ESPECIALLY IN THE TN
VLY...WITH PERSISTENT LOW LVL CONFLUENCE SHOULD BE SUFFICIENT TO
OVERCOME NEGATIVE FACTORS AND SUPPORT AT LEAST WIDELY SCTD STORMS
ALONG CONFLUENCE ZONE OVER PARTS OF LA...MS AND AL. A SEPARATE AREA
OF ISOLD TO WDLY SCTD STORMS ALSO MAY FORM ALONG COLD FRONT IN
TN/KY.

GIVEN INTENSITY AND EXPECTED INCREASE IN DEEP WSWLY FLOW /SPEEDS AOA
70 KTS AT 500 MB/...EXPECT ANY SUSTAINED UPDRAFTS THAT DO FORM WILL
QUICKLY BECOME SVR SUPERCELLS. DESPITE LARGELY UNIDIRECTIONAL
FLOW...LENGTH OF HODOGRAPHS /60-70 KT 0-6 KM SHEAR/ COULD YIELD
ISOLD STRONG TORNADOES...IN ADDITION TO BOWING SEGMENTS WITH HIGH
WIND.

ALTHOUGH THE STORMS ALONG THE COLD FRONT SHOULD DIMINISH UPON
ENCOUNTERING LESS FAVORABLE LOW LVL THERMODYNAMIC ENVIRONMENT IN THE
SRN/CNTRL APPALACHIANS...THOSE THAT FORM ALONG PRE-FRONTAL
CONFLUENCE BAND COULD STRENGTHEN THROUGH THE EVE AS /1/ MORE
SUBSTANTIAL HEIGHT FALLS OVERSPREAD REGION AND /2/ LOW LVL MOISTURE
INFLOW CONTINUES TO INCREASE ALONG THE CNTRL/ERN GULF CST. SOME OF
THE STORMS COULD MOVE/DEVELOP E ACROSS CNTRL/SRN GA AND N FL GIVEN
DEEP UNIDIRECTIONAL FLOW.

..CORFIDI.. 02/18/2009

[AirNik]

Things will probably start to pop later this afternoon, probably between 2-4pm.

.SHORT TERM...(TODAY AND TONIGHT)...LOOKS LIKE A POTENTIALLY BUSY
DAY SHAPING UP AS WE ARE EXPECTING A RISK OF SVR WEATHER OVER ALL OF
THE FCST AREA THIS AFTERNOON AND EARLY EVENING. THE STORM PREDICTION
CENTER HAS HIGHLIGHTED A MODERATE RISK OF SVR STORMS ROUGHLY ALONG
AND NORTH OF A WAYNESBORO...EVERGREEN...ANDALUSIA LINE WITH A SLIGHT
RISK OF SVR STORMS HIGHLIGHTED FOR THE REMAINDER OF THE FCST AREA.
INTENSIFYING SURFACE LOW PRESSURE SYSTEM MOVING OUT OF MISSOURI AND
INTO ILLINOIS THIS MORNING WILL LIFT TO THE EASTERN GREAT LAKES BY
THIS EVENING. THIS WILL BRING THE ASSOCIATED COLD FRONT TOWARD OUR
AREA TODAY...MOVING INTO OUR NWRN ZONES BY AROUND 00Z THU...THEN
ACROSS OUR FCST AREA THIS EVENING. IN ADVANCE OF THIS FRONT...AND
INCREASING MOIST AND UNSTABLE AIRMASS WILL BE BUILDING NORTH ACROSS
THE REGION. BY THIS AFTERNOON...MODELS INDICATE MUCAPES INCREASING
TO THE 600-800 J/KG RANGE ACROSS MUCH OF THE FCST AREA (ESPECIALLY
NORTH WHERE THE MODERATE RISK IS ADVERTISED) WHILE AT THE SAME TIME
0-3KM STORM RELATIVE HELICITIES INCREASE INTO THE 200-400 M^2/S^2
RANGE. A 50-60 KT H85 JET THIS MORNING WILL WEAKEN TO 40-45 KTS THIS
AFTERNOON. WITH THIS...EXPECT THE POTENTIAL FOR DISCRETE TORNADIC
SUPERCELLS CAPABLE OF PRODUCING A FEW STRONG TORNADOES ACROSS THE
MODERATE RISK AREA FROM LATE THIS MORNING THROUGH THE AFTERNOON AND
INTO THE EARLY EVENING HOURS...PRIMARILY OVER PARTS OF INTERIOR
SOUTHEAST MISSISSIPPI AND MUCH OF SOUTHWEST ALABAMA. IN THE MID TO
LATE EVENING HOURS...SLIGHTLY DIFFLUENT FLOW ALOFT WILL RESULT IN A
TRANSITION TO A MORE LINEAR STRUCTURED LINE OF THUNDERSTORMS THAT
WILL LIKELY AFFECT PRIMARILY OUR FAR SOUTHEASTERN ALABAMA ZONES EAST
OF I-65 AND WESTERN FLORIDA ZONES DURING THE MID TO LATE EVENING
HOURS. ANY SEVERE THREAT WITH THIS LINE OF STORMS WILL BE MORE OF A
STRAIGHT LINE DAMAGING WIND AND HAIL EVENT. MOST OF THE THUNDERSTORM
ACTIVITY IS EXPECTED TO EXIT THE FCST AREA TO THE EAST SHORTLY AFTER
MIDNIGHT TONIGHT. FOR TEMP FCST...WENT WITH MAVMOS MAX/MIN FOR TODAY
AND TONIGHT. 12/DS

[AirNik]

MESOSCALE DISCUSSION 0119
NWS STORM PREDICTION CENTER NORMAN OK
0953 AM CST WED FEB 18 2009

AREAS AFFECTED...PORTIONS OF WRN AND CNTRL KY INTO MIDDLE TN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 181553Z - 181730Z

THE THREAT FOR ORGANIZED...SEVERE STORMS APPEARS TO BE INCREASING
ACROSS THE DISCUSSION AREA AND CONVECTIVE TRENDS ARE BEING MONITORED
FOR A WW.

VISIBLE SATELLITE AND RADAR DATA INDICATE DEEPENING CUMULUS/TSTM
DEVELOPMENT OCCURRING IN SHORT WSW-ENE ORIENTED BANDS OVER WRN KY
INTO NWRN TN AS OF 1540Z. THIS ACTIVITY IS OCCURRING AHEAD OF
SURFACE COLD FRONT WITHIN A ZONE OF FAIRLY RAPID BOUNDARY LAYER
WARMING/MOISTENING PER 3-HR CHANGE FIELDS. MOREOVER...WATER VAPOR
IMAGERY SUGGESTS THAT THIS AREA IS ALONG THE SRN FRINGE OF A BAND OF
ASCENT ASSOCIATED WITH A VIGOROUS SHORT WAVE TROUGH CURRENTLY MOVING
THROUGH IL/IND.

BASED ON 12Z LIT SOUNDING...ENVIRONMENT IS ALREADY UNCAPPED WITH
MLCAPE OF 500-700 J/KG. CONTINUED HEATING/MOISTENING IN ADVANCE OF
COLD FRONT SHOULD SUPPORT FURTHER AIR MASS DESTABILIZATION TODAY
WITH MLCAPE APPROACHING 1000 J/KG. VERTICAL SHEAR IS QUITE STRONG
/EFFECTIVE BULK SHEAR OF AROUND 70 KT/ WITH GENERALLY
LONG...STRAIGHT HODOGRAPHS. AS SUCH...ENVIRONMENT WILL BE
SUPPORTIVE OF SPLITTING SUPERCELLS CAPABLE OF DAMAGING WINDS AND
HAIL. A TORNADO OR TWO WILL BE POSSIBLE WITH ANY MORE INTENSE
CYCLONIC UPDRAFTS. AS SUCH...1630Z OUTLOOK WILL BE EXPANDED FARTHER
NWD IN KY AND A WW MAY BE NECESSARY.

..MEAD.. 02/18/2009


ATTN...WFO...MRX...JKL...LMK...OHX...PAH...

LAT...LON 36848737 37358619 37658524 37718476 37288466 36598478
36028513 35818568 35758649 36168741 36848737

[Ivanhater]

Crap, wasnt expecting this..

[AirNik]

MESOSCALE DISCUSSION 0120
NWS STORM PREDICTION CENTER NORMAN OK
1114 AM CST WED FEB 18 2009

AREAS AFFECTED...PORTIONS OF NERN AND CNTRL MS INTO NWRN AND W-CNTRL
AL

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 181714Z - 181845Z

THE POTENTIAL FOR SEVERE STORMS CAPABLE OF LARGE HAIL...DAMAGING
WINDS AND PERHAPS A FEW TORNADOES IS EXPECTED TO INCREASE THIS
AFTERNOON. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

LATEST TRENDS IN VISIBLE SATELLITE IMAGERY INDICATE DEEPENING
CUMULUS BANDS ORIENTED WSW-ENE WITHIN PRE-FRONTAL WARM SECTOR FROM W
OF THE I-65 CORRIDOR IN MIDDLE TN SWWD INTO CNTRL MS. WHILE
BOUNDARY LAYER IS NOT OVERLY MOIST /DEWPOINTS IN THE UPPER 50S TO
LOWER 60S/...STRONG DAYTIME HEATING IS CONTRIBUTING TO THE
DEVELOPMENT OF STEEP LOW-LEVEL LAPSE RATES AND RESULTANT MLCAPE OF
AROUND 500 J/KG. OF CONCERN TO STORM INITIATION ARE: 1/ WEAK
CONVERGENCE ALONG COLD FRONT...AND 2/ INFERRED MIDLEVEL SUBSIDENCE
AND RESULTING POOR MIDLEVEL LAPSE RATES PER WATER VAPOR IMAGERY AND
RUC OBJECTIVE FIELDS. THUS...CONSIDERABLE UNCERTAINTY EXISTS WITH
REGARD TO THE TIMING AND LOCATION OF ANY ADDITIONAL STORM
DEVELOPMENT TO THE S OF ONGOING STORMS OVER S-CNTRL KY INTO MIDDLE
TN.

ONCE STORMS DEVELOP AND BECOME SUSTAINED...THE PRESENCE OF 60-70 KT
DEEP LAYER SHEAR AND LONG...STRAIGHT HODOGRAPHS WILL SUPPORT
SUPERCELL DEVELOPMENT /SOME SPLITTING/ WITH THE THREAT FOR DAMAGING
WINDS...LARGE HAIL AND PERHAPS A FEW TORNADOES.

[AirNik]

[RL3AO]

GFS hinting at another system around Thursday.

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0335 AM CST FRI FEB 20 2009

VALID 231200Z - 281200Z

...DISCUSSION...
UPPER AIR PATTERN FCST TO DEAMPLIFY OVER MOST OF CONUS AFTER
DAY-4/23RD-24TH...AS DEPARTURE OF EASTERN TROUGH LEAVES BEHIND
RELATIVELY LOW-THETAE/CONTINENTAL AIR MASS IN LOW LEVELS. MARINE
MODIFICATION OVER GULF WILL BE CRITICAL TO SVR POTENTIAL WITH
SUBSEQUENT TRAIN OF SHORTWAVES EXPECTED IN MORE FLATTENED/ZONAL
PATTERN THROUGH REST OF PERIOD. SOME PART OF NERN PACIFIC UPPER LOW
IS FCST TO EJECT EWD AS OPEN WAVE ACROSS PORTIONS W-CENTRAL CONUS TO
CENTRAL PLAINS DURING DAYS 6-7/25TH-27TH TIME FRAME...BUT WITH
CONSIDERABLE DIFFERENCES IN AMPLITUDE AMONG ECMWF/UKMET/SPECTRAL
MODELS AND MREF MEMBERS. SUFFICIENT MOISTURE RETURN TO SUPPORT SVR
SHOULD OCCUR OVER SRN PLAINS/MS DELTA BY DAY-6/25TH-26TH...BUT
CATEGORICAL OUTLOOK IS PRECLUDED BY UNCERTAINTIES REGARDING
STRENGTH/TIMING OF PERTURBATION ALOFT AND RESULTANT RESPONSE OF LOW
LEVEL MASS FIELDS.

..EDWARDS.. 02/20/2009

[RL3AO]

Way out there, but the past few runs of the GFS have been hinting at something big around the March 6-8 timeframe.

Of course a model nailing an outbreak 14 days out would probably be more impressive than the outbreak its self.

[CrazyC83]

It's getting to be that time of year though...the end of February is typically when activity quickly heats up.

[RL3AO]

The National Severe Weather Workshop is in Norman that week. Could be interesting for some of them.

[srainhoutx]

Watching the first week of March carefully. Ensembles are "hinting" a severe outbreak possible in the Southern Plains to Ohio Valley as well as the Mid South. We shall see.

[Ed Mahmoud]

Euro shows a nice low level jet on Thursday mid-South to Western Ohio Valley, but rather unimpressive upper support.


Too soon to get excited.

[Dave]

Slight Risk - Thursday Feb 26 2009



DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1144 PM CST TUE FEB 24 2009

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
MID-SOUTH AND MIDWEST...

...MID-SOUTH AND MIDWEST...
MID-LVL DISTURBANCE APCHG THE PAC NW/NRN CA CST EARLY WEDNESDAY
MORNING IS EXPECTED TO AMPLIFY OVER THE CNTRL PLNS/MS VLY ON THU AS
IT PHASES WITH THE NRN STREAM. THIS TROUGH WILL THEN TRANSLATE
QUICKLY EWD THROUGH THE MIDWEST AND TN VLY BY 12Z FRI. ASSOCD SFC
LOW OVER THE MO VLY EARLY THU WILL DEVELOP EWD ACROSS NRN MO AND
INTO NRN IND/SRN LWR MI BY LATE THU NIGHT. TRAILING THE LOW...A
CDFNT WILL SWEEP SEWD ACROSS THE PLNS AND INTO THE MIDWEST/MID-SOUTH
BY EARLY FRI MORNING.

LLVL MOISTURE IS EXPECTED TO CONTINUE SPREADING NWD FROM THE SRN
PLNS INTO THE MIDWEST ALONG/AHEAD OF THE CDFNT. BY THU AFTN...SFC
DEW POINTS WILL RANGE FROM THE LWR 50S IN IND/IL TO NEAR 60 DEG F IN
THE MID-SOUTH. A FAIRLY STOUT ELEVATED MIXED LAYER WILL LIKELY
RESIDE WELL EAST INTO THE OH/TN VLYS ATOP THIS MSTR...SUGGESTING
THAT SFC-BASED TSTM INITIATION WILL PROBABLY BE DELAYED UNTIL
MID-LATE AFTN WHEN STRONGER LARGE SCALE ASCENT ARRIVES. FIRST
STORMS SHOULD DEVELOP ACROSS SRN IA/NRN MO DURING PEAK HEATING ALONG
THE FRONTAL INTERFACE...THEN QUICKLY MOVE ENEWD THROUGH THE MIDWEST.
STORMS WILL TEND TO BACKBUILD SWWD INTO PARTS OF MO/AR DURING THE
EVE INTO STRONGER CINH. RELATIVELY COLD TEMPERATURES ALOFT...45-50
KTS OF DEEP LAYER SHEAR AND STRONG LINEAR FORCING WILL FAVOR A
FORCED LINE OF STORMS WITH POSSIBLE LEWPS/BOWS GIVING DMGG WIND
GUSTS AND HAIL.

NRN EXTENT OF THE ACTIVITY WILL LIKELY WEAKEN ACROSS IND/OH AS
STORMS OUTRUN THE STRONGER LLVL THETA-E AXIS THU NIGHT. HOWEVER...
TSTMS MAY MAINTAIN/GROW STRONGER ACROSS THE MID-SOUTH OVERNIGHT AS
THE SRN PERIPHERY OF STRONGER HEIGHT FALLS SKIRT THE MORE ROBUST
INSTABILITY.

..RACY.. 02/25/2009

[Dave]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PADUCAH KY
441 AM CST WED FEB 25 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHERN
ILLINOIS...SOUTHWEST INDIANA...WESTERN KENTUCKY AND SOUTHEAST
MISSOURI.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL BE POSSIBLE AFTER MIDNIGHT TONIGHT TO
THE SOUTHWEST OF A FAIRFIELD ILLINOIS TO CALHOUN KENTUCKY LINE.
ANY THUNDERSTORMS SHOULD REMAIN BELOW SEVERE LEVELS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A LINE OF STRONG TO SEVERE THUNDERSTORMS IS EXPECTED TO MOVE
THROUGH THE ENTIRE REGION AHEAD OF A COLD FRONT THURSDAY
NIGHT...GENERALLY LATE IN THE EVENING THROUGH THE OVERNIGHT HOURS.
A FEW OF THE STORMS MAY PRODUCE DAMAGING WINDS AND LARGE HAIL.

IN ADDITION A FEW...MORE ISOLATED...THUNDERSTORMS WILL BE
POSSIBLE MAINLY OVER THE NORTHERN HALF OF THE QUAD STATE DURING
THE DAY THURSDAY. IF A THUNDERSTORM DOES DEVELOP ON
THURSDAY...LARGE HAIL WILL BE A POSSIBILITY.

SOUTHERLY WINDS WILL BE SUSTAINED AT 20 TO 25 MPH AHEAD OF THE
COLD FRONT THURSDAY AFTERNOON AND EVENING. SOME GUSTS UP TO 40
MPH WILL BE POSSIBLE...ESPECIALLY THURSDAY EVENING OVER WEST KENTUCKY
AND SOUTHWEST INDIANA.

[somethingfunny]

HEY WEATHER!

Normally, the storm season begins in the south AND THEN moves northward. Feb/March/April - Texas/Oklahoma/Southern US.....April/May/June - Kansas/Nebraska/Midwest.....May/June - Dakotas/Upper Midwest/Northeast.

WHY ARE YOU SKIPPING US?

I demand an investigation!

[soonertwister]

Something to keep an eye on for folks in Alabama, Georgia, South Carolina, North Florida and environs...

http://www.spc.ncep.noaa.gov/products/exper/day4-8/

SPCSWOD48 ALL
ACUS48 KWNS 250920
SPC AC 250920

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0320 AM CST WED FEB 25 2009

VALID 281200Z - 051200Z

...DISCUSSION...
MODELS CONTINUE TO INDICATE AMPLIFIED TROUGH SHIFTING ACROSS THE EAST COAST THIS WEEKEND...PUNCTUATED BY STRONG IMPULSE DIGGING SEWD ACROSS THE SOUTHEASTERN STATES SATURDAY AND SUNDAY WITH ASSOCIATED 50+ KT MID LEVEL JET. PRECEEDING THIS IMPULSE...SURFACE FRONT IS EXPECTED TO STALL SOMEWHERE OVER THE DEEP SOUTH FRIDAY. ECMWF REMAINS FARTHER SOUTH WITH ITS POSITION OF STALLED SURFACE FRONT OVER THE CENTRAL GULF COAST STATES FRIDAY...WHILE THE GFS AND MREF-MEAN STALL THE FRONT FARTHER NORTH OVER THE SRN APPALACHIANS AND MID SOUTH. REGARDLESS...EXTENDED MODELS ARE CONSISTENT IN DEVELOPING A SURFACE LOW NEAR THE FRONT SATURDAY WHICH TRACKS EWD ACROSS PORTIONS OF GA/SC WITH TRAILING COLD FRONT ACCELERATING ESEWD ACROSS THE CENTRAL GULF COAST STATES AND INTO NRN FL BY SATURDAY NIGHT. INTENSE LOW LEVEL AND DEEP LAYER SHEAR...ALONG WITH -14C TO -16C H5 TEMPS...WILL LIKELY FAVOR SQUALL LINE DEVELOPMENT AND POSSIBLY SUPERCELLS SATURDAY INTO EARLY SUNDAY OVER THE SOUTHEASTERN STATES AS PRE-FRONTAL AIRMASS UNDERGOES MODEST DESTABILIZATION. AT LEAST AN ISOLATED SEVERE THREAT COULD PERSIST SWD ACROSS FL IN SOME FORM THROUGH SUNDAY MORNING...ATTENDANT TO SEWD MOVING SQUALL LINE...ALTHOUGH COVERAGE/MAGNITUDE OF THREAT REMAINS LESS CERTAIN ATTM.

IN THE WAKE OF THIS SYSTEM...BEYOND DAY 5...MODELS IN GENERAL AGREEMENT IN DEVELOPING BROAD TROUGH OVER THE WRN STATES AND FAST/ZONAL FLOW ACROSS THE SERN 1/4 OF THE COUNTRY. IN ADDITION... PATTERN SHOULD FAVOR GULF MOISTURE RETURN OVER PORTIONS OF THE SRN PLAINS INTO THE LOWER/MID MS RIVER VALLEY BY THE END OF THE FORECAST PERIOD...UNDER STRENGTHENING WESTERLIES ALOFT. HOWEVER...FAR TOO MANY UNCERTAINTIES REMAIN ATTM TO ADDRESS ANY PARTICULAR SEVERE THREAT INTO EARLY NEXT WEEK.

..EVANS.. 02/25/2009

[Ed Mahmoud]

30% area in the early SWODY2 in the Central Gulf area, it'll be interesting to see what the 12Z models and soundings, and the 11:30 am CST update brings...


snip

DURING THE DAY FRI...EXPECT ADDITIONAL DEVELOPMENT WITH SFC HEATING
ALONG OUTFLOW BOUNDARY AND/OR STALLING FRONT ASSOCIATED WITH MORNING
ACTIVITY. A FEW SFC-BASED STORMS WILL BE POSSIBLE.
RESIDUAL/ELEVATED MIXED LAYER WILL MAINTAIN CONSIDERABLE CIN DURING
THIS PERIOD. THIS SHOULD RESULT IN A FAIRLY SHARP SRN AND WRN
CUT-OFF TO THE STORMS. BUT AMPLE /50 KT/ DEEP WLY SHEAR...MOISTURE
/MID 60S F SFC DEWPOINTS/...AND LOW LVL CONVERGENCE SHOULD BE
PRESENT TO SUPPORT SUSTAINED SUPERCELLS. DEEP FORCING FOR ASCENT
WILL...HOWEVER...REMAIN WEAK UNTIL UPR IMPULSE APPROACHES LATE IN
THE DAY.

DEEP UVV AND LOW LVL CONVERGENCE SHOULD INCREASE ACROSS THE LWR MS
VLY E INTO AL AND GA FRI NIGHT/EARLY SAT AS CYCLOGENESIS OCCURS OVER
NRN LA. COMBINATION OF INCREASING ASCENT WITH CONTINUED SFC-BASED
MOISTURE INFLOW AND STRENGTHENING SWLY LLJ MAY SUPPORT OVERNIGHT
STRENGTHENING OF STORMS...AND POSSIBLE DEVELOPMENT OF ONE OR TWO
CONVECTIVE CLUSTERS. THESE SYSTEMS SHOULD MOVE GENERALLY E...WITH
EMBEDDED STORMS POSING A THREAT FOR SVR HAIL...WIND AND ISOLD
TORNADOES.

..CORFIDI.. 02/26/2009

Sadly (not that I need hail damage or anything, but I sure do need the rain) it looks like SE Texas will be solidly capped.

Models show front in area near peak heating time tomorrow, but a dry frontal passage.

Pronounced warm nose from 900 to 700 mb ( a low enough cap to preclude even streamer showers under the cap) and -200 Joules/Kg of inhibition, a Texas Drought Watch thread is in order (if not already started)

[CrazyC83]

Saturday looks most interesting for sure.

[CrazyC83]

2 watches now out: both severe thunderstorm watches (one of them mentioned it could be upgraded to a tornado watch)