Chance for Severe Weather 1/27/10 and 1/28/10

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1/27/10

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1122 AM CST WED JAN 27 2010

VALID 281200Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF SWRN THROUGH S
CNTRL AND SERN TX...

...SYNOPSIS...

SPLIT FLOW UPPER PATTERN WILL PREVAIL INTO THURSDAY. A BROAD UPPER
LOW WILL PERSIST OVER SERN CANADA AND THE NERN STATES...WHILE THE
SHORTWAVE TROUGH CURRENTLY LOCATED OVER NRN BAJA ADVANCES ENE INTO
THE SRN PLAINS. AT THE SURFACE...AN ARCTIC FRONT WILL CONTINUE SWD
INTO THE TN VALLEY AND SRN PLAINS. BY LATE THURSDAY AFTERNOON THE
FRONT WILL LIKELY EXTEND FROM NRN PORTIONS OF THE SERN STATES WWD
THROUGH NRN AND WRN TX. THE WRN EXTENSION OF THIS BOUNDARY WILL
CONTINUE SEWD THROUGH MUCH OF TX OVERNIGHT.

...SW THROUGH CNTRL AND SERN TX...

BOUNDARY LAYER OVER THE WRN GULF IS STILL UNDERGOING MODIFICATION
WITH NEAR 60F DEWPOINTS. SLY LOW-LEVEL JET WILL STRENGTHEN TONIGHT
INTO EARLY THURSDAY OVER THE SRN PLAINS WITHIN HEIGHT FALL ZONE
DOWNSTREAM FROM ADVANCING SHORTWAVE TROUGH. THIS WILL RESULT IN NWD
ADVECTION OF PARTIALLY MODIFIED GULF AIR WITH LOW TO MID 60F
DEWPOINTS LIKELY ACROSS S AND S-CNTRL TX AND MID TO UPPER 50F
FARTHER WEST TOWARD THE BIG BEND AREA. A RESERVOIR OF 7-8 C/KM
MID-LEVEL LAPSE RATES WILL ADVECT EWD ABOVE THE MOIST AXIS AND
CONTRIBUTE TO DESTABILIZATION. HOWEVER...SURFACE BASED INSTABILITY
WILL BE LIMITED BY FORMATION OF WIDESPREAD LOW CLOUDS WITHIN THE
THETA-E ADVECTION REGIME WITH MLCAPE FROM 500-1000 J/KG. MID-LEVEL
INVERSION ALREADY EVIDENT ON THE 12Z RAOBS FROM WRN THROUGH S TX
WILL LIKELY PERSIST INTO THURSDAY. THIS SUGGESTS THE WARM SECTOR
WILL PROBABLY STAY CAPPED UNTIL ZONE OF DEEPER FORCING ATTENDING THE
SHORTWAVE TROUGH AND SEWD ADVANCING FRONT INTERCEPT THE MOIST AXIS.
CURRENT INDICATIONS ARE THAT ACTIVITY WILL GROW UPSCALE INTO AN MCS.
STORMS DEVELOPING ALONG THE SRN END OF THE MCS WILL BE BASED NEAR
THE SURFACE. STRONG VERTICAL SHEAR AND LARGE 0-1 KM HODOGRAPHS WILL
SUPPORT POTENTIAL FOR EMBEDDED LEWP AND SUPERCELL STRUCTURES.

1/28/10

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0115 AM CST WED JAN 27 2010

VALID 291200Z - 301200Z

...SRN LA/TX COASTAL PLAIN...
AN UPPER-LEVEL TROUGH IS FORECAST TO MOVE ACROSS THE SRN PLAINS
FRIDAY AS A COLD FRONT ADVANCES SEWD ACROSS THE TX COASTAL PLAINS
INTO THE WRN GULF OF MEXICO. THUNDERSTORMS SHOULD BE ONGOING FRIDAY
MORNING ALONG THE LOWER TO MIDDLE TX COAST AND SHOULD MOVE QUICKLY
OFFSHORE BY MIDDAY. THE NERN PORTION OF THE LINE IS FORECAST TO MOVE
ACROSS SE TX AND SRN LA WHERE A MARGINAL SEVERE THREAT MAY EXIST
FRIDAY MORNING. FORECAST SOUNDINGS IN SRN LA AT 18Z SHOW 50 KT OF
0-6 KM SHEAR...SFC DEWPOINTS AROUND 60 F AND ABOUT 40 KT OF FLOW AT
1 KM. THIS MAY SUPPORT AN ISOLATED WIND DAMAGE THREAT. THE SEVERE
THREAT MAY INCREASE SOMEWHAT DUE TO WARMING SFC TEMPS BY EARLY
AFTERNOON AS THE LINE MOVES INTO SERN LA. HOWEVER...INSTABILITY
SHOULD STILL BE WEAK SUGGESTING THE THREAT WILL REMAIN MARGINAL.

..BROYLES.. 01/27/2010

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MESOSCALE DISCUSSION 0070
NWS STORM PREDICTION CENTER NORMAN OK
0505 AM CST THU JAN 28 2010

AREAS AFFECTED...PORTIONS W TX.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 281105Z - 281330Z

TSTMS ARE FCST TO CONTINUE DEVELOPING AND MOVING NEWD ACROSS
DISCUSSION AREA THROUGH MID-MORNING...AS PRIMARY CONVECTIVE REGIME
MOVES/EXPANDS EWD. OCCASIONAL...MARGINALLY SVR HAIL IS EXPECTED.

MOISTURE CHANNEL IMAGERY INDICATES STG SHORTWAVE TROUGH MOVING NEWD
ACROSS ERN SONORA AND WRN CHIHUAHUA...EJECTING AWAY FROM BASE OF
CYCLONIC FLOW ASSOCIATED WITH AZ UPPER LOW. RELATED LARGE-SCALE
ASCENT IN MID-UPPER LEVELS IS STARTING TO OVERSPREAD STG LOW LEVEL
WAA/MOISTURE TRANSPORT REGIME ACROSS PORTIONS W TX...CONTRIBUTING TO
INCREASINGLY FAVORABLE ENVIRONMENT FOR ELEVATED CONVECTION AND AT
LEAST MRGL HAIL POTENTIAL. MODIFIED 00Z RAOB ANALYSES...OBSERVED
GPS PW TRENDS AND FCST SOUNDINGS SUGGEST WAA/MOISTURE TRANSPORT
PLUME IS EXPANDING NWD ACROSS W TX ON EITHER SIDE OF 30-40 KT
LLJ...WITH PW EXCEEDING 1 INCH ACROSS MOST OF W-CENTRAL TX DURING
LAST 4-6 HOURS...SUBSTANTIAL COOLING AND REMOVAL OF CINH IN 700-600
MB LAYER...AND WARMING NEAR 800 MB. THIS RESULTS IN GREATER DEPTH
AND MAGNITUDE OF ELEVATED BUOYANCY THAN DEPICTED BY RUC...WHICH
SHOWS ALMOST NO CAPE WHERE TSTMS INITIALLY ARE BEING OBSERVED
BETWEEN FST-INK. ETA-KF APPEARS MORE REPRESENTATIVE BUT MAY BE
SLIGHTLY UNDER-FORECASTING INSTABILITY AND CAPE ALOFT. BUOYANCY
SHOULD REMAIN ELEVATED FOR PARCELS ON BOTH SIDE OF SFC COLD FRONT --
ANALYZED FROM NEAR DUA WSWWD TO NEAR SNK AND CENTRAL LEA COUNTY NM.

MODIFYING FCST SOUNDINGS ACCORDINGLY YIELDS MUCAPE TRANSITIONING
FROM AROUND 700 J/KG INVOF RIO GRANDE NW OF DRT TO LESS THAN 100
J/KG N OF DISCUSSION AREA OVER NW TX. THIS ALSO INCREASES EFFECTIVE
SHEAR MAGNITUDE TO AROUND 50 KT VIA DEEPENING OF POSITIVE AREA IN
SOUNDINGS...GIVEN VWP OBSERVATIONS AND FCST SOUNDINGS SHOWING STG
DIRECTIONAL AND SPEED SHEAR FROM ELEVATED INFLOW REGION TO AROUND
500 MB. STORM-RELATIVE LOW-LEVEL FLOW ALSO WILL BE FAVORABLE...FOR
CONVECTION MOVING NNEWD TO NEWD INTO W TX LLJ. MAIN LIMITING
FACTORS BEFORE 15Z WILL BE LACK OF MORE ROBUST BUOYANCY...AND
INCREASING COVERAGE OF CONVECTION/PRECIP ACROSS VAST AREA OF SRN
HIGH PLAINS AND SW TX.

..EDWARDS.. 01/28/2010

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MESOSCALE DISCUSSION 0075
NWS STORM PREDICTION CENTER NORMAN OK
0147 PM CST THU JAN 28 2010

AREAS AFFECTED...PARTS OF THE RIO GRANDE VALLEY AND EDWARDS PLATEAU

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 281947Z - 282145Z

TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN INCREASING
SEVERE THREAT AND THE NEED FOR A WW...WHICH COULD OCCUR AS EARLY AS
21-23Z.

WITH A SIGNIFICANT SHORT WAVE IMPULSE JUST BEGINNING TO PIVOT AROUND
THE SOUTHWESTERN PERIPHERY OF THE SOUTHERN PLATEAU CLOSED
LOW...MOIST LOW-LEVEL UPSLOPE FLOW AND WARM ADVECTION PERSIST ACROSS
THE REGION IN THE WAKE OF ONE SHORT WAVE NOW LIFTING THROUGH THE
SOUTHERN HIGH PLAINS. THIS FORCING FOR ASCENT... COUPLED WITH
DIFLUENT AND AT LEAST WEAK DIVERGENT UPPER FLOW... APPEARS TO BE
MAINTAINING AN ENVIRONMENT FAVORABLE FOR VIGOROUS STORM
DEVELOPMENT...AS BOUNDARY LAYER WARMING PROGRESSES BENEATH A COLD
MID-LEVEL AIR MASS WITH 500 MB TEMPERATURES AT OR BELOW -20C. MIXED
LAYER CAPE COULD APPROACH 1000 J/KG LATE THIS AFTERNOON.

A LINGERING LOW-LEVEL CONFLUENCE ZONE IN THE WAKE OF THE DEPARTING
CONVECTIVE CLUSTER COULD SERVE TO FOCUS INTENSIFYING STORMS WITHIN
THE NEXT FEW HOURS...SOUTH OF SAN ANGELO INTO THE HIGHER TERRAIN OF
MEXICO. ADDITIONAL MORE DISCRETE ACTIVITY ALSO APPEARS POSSIBLE OFF
THE HIGHER TERRAIN TO THE SOUTH OF THIS BOUNDARY...WHICH WILL
PROBABLY SPREAD ACROSS THE RIVER INTO TEXAS ...AIDED BY 50-70 KT
WESTERLY 500 MB FLOW. ALTHOUGH THE STRONGER LOW-LEVEL JET IS
BEGINNING TO SHIFT EASTWARD TOWARD THE I-35 CORRIDOR OF THE SOUTHERN
PLAINS...HODOGRAPHS WILL REMAIN FAVORABLE FOR SUPERCELLS. LARGE
HAIL/LOCALIZED DAMAGING WIND GUSTS WILL BE POSSIBLE...PERHAPS AN
ISOLATED TORNADO.

..KERR.. 01/28/2010

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MESOSCALE DISCUSSION 0076
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CST THU JAN 28 2010

AREAS AFFECTED...N CNTRL...NE TX

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 282043Z - 282215Z

A SHORT-TERM WATCH IS BEING ISSUED FOR THE DALLAS-FORT WORTH
AREA...BUT THE SEVERE THREAT APPEARS LIKELY TO DIMINISH AS ACTIVITY
SPREADS EAST OF THE METROPLEX LATE THIS AFTERNOON.

MODELS ARE SUGGESTIVE THAT MID-LEVEL FORCING SUPPORTING ONGOING
VIGOROUS STORM CLUSTER WILL LIFT ACROSS NORTH CENTRAL/NORTHEAST
TEXAS INTO THE RED RIVER VALLEY BETWEEN NOW AND 23-00Z... WEAKENING
AS IT DOES. THE STRONGEST PORTION OF THE LINE APPEARS FOCUSED JUST
SOUTH OF STALLED EAST-WEST ORIENTED FRONT...WHERE MID 50S SURFACE
DEW POINTS COULD BE CONTRIBUTING TO VERY WEAK SURFACE OR NEAR
SURFACE BASED INSTABILITY. THIS ACTIVITY COULD MAINTAIN STRENGTH
ACROSS THE DALLAS-FORT WORTH METROPLEX BETWEEN 21-22Z...WITH
CONVECTIVE DOWNDRAFTS STILL STRONG ENOUGH TO ENHANCE THE DOWNWARD
TRANSFER OF MOMENTUM NEAR A 40-50 KT SOUTHERLY 850 MB JET AXIS.
HOWEVER...IT DOES APPEAR THAT THE CONVECTION IS ADVANCING EASTWARD
FASTER THAN THE LOW-LEVEL JET AND BOUNDARY LAYER MOISTURE RETURN.
SO...IT SEEMS THAT ACTIVITY PROBABLY WILL BEGIN TO WEAKEN AS SYSTEM
RELATIVE INFLOW EMANATES FROM INCREASINGLY DRIER AIR EAST OF DALLAS
AFTER 22Z.

..KERR.. 01/28/2010

[nightrider]

SEL4

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 14
NWS STORM PREDICTION CENTER NORMAN OK
315 PM CST THU JAN 28 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

SOUTH CENTRAL TEXAS

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 315 PM UNTIL
1000 PM CST.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES EITHER SIDE OF A LINE FROM 80 MILES EAST NORTHEAST OF
JUNCTION TEXAS TO 15 MILES WEST OF DEL RIO TEXAS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU4).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND 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.

OTHER WATCH INFORMATION...CONTINUE...WW 13...

DISCUSSION...ISOLATED THUNDERSTORMS ARE DEVELOPING ALONG A SURFACE
BOUNDARY EXTENDING FROM EAST OF SJT TO WEST OF DRT. OTHER STORMS
ARE EXPECTED TO FORM OVER THE HIGHER TERRAIN OF NORTHERN MEXICO AND
TRACK INTO WATCH AREA DURING THE NEXT FEW HOURS. RATHER STEEP MID
LEVEL LAPSE RATES AND FAVORABLE VERTICAL SHEAR PROFILES WILL PROMOTE
A RISK OF SUPERCELLS CAPABLE OF VERY LARGE HAIL AND DAMAGING
WINDS...ALONG WITH THE POTENTIAL FOR ISOLATED TORNADOES.

AVIATION...TORNADOES AND 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 24035.

[nightrider]

MESOSCALE DISCUSSION 0085
NWS STORM PREDICTION CENTER NORMAN OK
1003 AM CST FRI JAN 29 2010

AREAS AFFECTED...SRN LA...SRN MS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 291603Z - 291730Z

A WATCH IS NOT CURRENTLY ANTICIPATED. BUT...IT IS NOT OUT OF THE
QUESTION THAT CONDITIONS COULD BECOME MORE FAVORABLE FOR DAMAGING
WIND GUSTS WITH CONVECTION SPREADING ACROSS THE REGION THROUGH EARLY
AFTERNOON.

VIGOROUS CONVECTIVE DEVELOPMENT PERSISTS WITHIN A RELATIVELY NARROW
BAND ACROSS THE CENTRAL GULF COAST/LOWER MISSISSIPPI VALLEY
REGION...PERHAPS FOCUSED WITHIN A PRE-FRONTAL LOW-LEVEL CONFLUENCE
ZONE. ORIENTED GENERALLY PARALLEL TO 40-50 KT MEAN DEEP LAYER
SOUTHWESTERLY FLOW...THIS ACTIVITY APPEARS LIKELY TO CONTINUE
SHIFTING ONLY SLOWLY EASTWARD ACROSS PARTS OF SOUTHERN LOUISIANA AND
SOUTHWESTERN MISSISSIPPI THROUGH THE 18-20Z TIME FRAME.

SOUTHERLY LOW-LEVEL INFLOW OF MOISTURE...CHARACTERIZED BY
PRECIPITABLE WATER IN EXCESS OF 1.5 INCHES...IS CONTRIBUTING TO WEAK
TO MODERATE CONDITIONAL AND CONVECTIVE INSTABILITY BENEATH MODESTLY
STEEP LAPSE RATES ASSOCIATED WITH AN ELEVATED MIXED LAYER BASED
AROUND 700 MB. INLAND OF THE COAST...STORMS ARE BASED ABOVE A
RESIDUAL STABLE SURFACE LAYER. THIS COULD REMAIN THE CASE THROUGH
MID DAY AND BEYOND...EVEN WHERE THE SURFACE BASED COLD LAYER IS
SHALLOWEST ACROSS SOUTHEAST LOUISIANA...AS CLOUD COVER IMPEDES
SURFACE HEATING. WHILE THIS STILL APPEARS A LIMITING FACTOR TO
SEVERE POTENTIAL...IT IS NOT OUT OF THE QUESTION THAT THERMODYNAMIC
PROFILES COULD BECOME MORE FAVORABLE FOR CONVECTIVE DOWNDRAFTS TO
REACH THE SURFACE. IF THIS OCCURS ...THE DOWNWARD TRANSFER OF
MOMENTUM ASSOCIATED WITH A WEAKENING BUT STILL STRONG /40-50+ KT/
850 MB JET MAY CONTRIBUTE TO POTENTIALLY DAMAGING SURFACE GUSTS.

[Joe-Nathan]

Great!!!

Just about the time that I pick up the kids from school