SPC Day 2 Thunderstorm Outlook Issued 0830Z 20040128

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ZCZC SPCSWODY2 ALL
ACUS02 KWNS 280815
SPC AC 280815

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0215 AM CST WED JAN 28 2004

VALID 291200Z - 301200Z

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 50 S CRP 45 NNW NIR
30 E AUS 50 S TYR 45 WSW MLU MCB 35 SSW GPT.

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A PROGRESSIVE SPLIT FLOW PATTERN WILL PREVAIL THIS PERIOD...WITH THE
MAIN POLAR JET CONTINUING FROM BC AND THE NRN RCKYS ACROSS THE NRN
HALF OF PLNS/MS VLY TO THE MID ATLANTIC CST.  FARTHER S...SRN BRANCH
JET SHOULD CONTINUE FROM BAJA CA AND MEXICO ENE ACROSS THE NRN/CNTRL
GULF OF MEXICO.

A FAIRLY STRONG SHORTWAVE IMPULSE IN THE SRN BRANCH...NOW OVER CNTRL
CA...SHOULD REACH NRN SONORA BY 12Z THURSDAY.  UPSTREAM RIDGING OVER
THE E PACIFIC SUGGESTS THAT A MAJOR PART OF THIS SYSTEM WILL TRACK
SEWD DEEP INTO MEXICO...POSSIBLY CLOSING OFF IN THE PROCESS.  THIS
SCENARIO MORE OR LESS HAS BEEN CONSISTENTLY FORECAST BY THE LAST 3
RUNS OF THE ECMWF.  THE GFS/ETA...WHICH HAD PREVIOUSLY DEPICTED A
WEAKER/FASTER-MOVING SYSTEM...ARE BOTH NOW CONVERGING TOWARD THE
ECMWF SOLUTION. 

AT LOWER LEVELS...EXPECT THAT APPROACH OF SRN BRANCH TROUGH WILL BE
ACCOMPANIED BY SOME DEGREE OF SURFACE CYCLOGENESIS OVER THE WRN/NWRN
GULF.  THE DETAILS OF THIS SCENARIO ARE DEPENDENT UPON HOW MUCH OF
THE CA SYSTEM DIGS SE INTO MEXICO.  A PART OF THE CA IMPULSE WILL
PROBABLY BREAK AWAY AND TURN MORE E ACROSS S TX/NRN MEXICO.  THIS
WILL FAVOR AT LEAST WEAK SURFACE DEVELOPMENT INVOF COASTALLY-INDUCED
INVERTED TROUGH OFF THE LOWER TX GULF CST.  MORE SIGNIFICANT
CYCLOGENESIS WILL...HOWEVER...LIKELY AWAIT EJECTION OF MAIN UPPER
IMPULSE FROM CNTRL MEXICO...AND WILL OCCUR BEYOND THE DAY 2 PERIOD. 


...SRN/SERN TX...
STRONG COLD ADVECTION IN THE PAST 24 HOURS HAS SWEPT MODIFIED POLAR
AIR DEEP INTO THE BAY OF CAMPECHE.  BUT SATELLITE AND SURFACE DATA
ALREADY SHOW ONSET OF RETURN FLOW IN PROGRESS OVER NE MEXICO AND THE
FAR WRN GULF.  SLY LOW LEVEL FLOW SHOULD STRENGTHEN OVER THIS REGION
AND THE SERN HALF OF TX DURING THE NEXT 36-48 HRS AS CA UPPER SYSTEM
CONTINUES SEWD.  THIS WILL EVENTUALLY SPREAD PARTIALLY MODIFIED GULF
AIR WITH SURFACE DEWPOINTS IN THE UPPER 50S TO LOW 60S NWD ACROSS
THE TX GULF COASTAL PLN.  

THE BOUNDARY LAYER MOISTURE...ARRIVING BENEATH GRADUAL WARMING IN
THE 850-700 MB LAYER...WILL LIKELY BE ACCOMPANIED BY WIDESPREAD
STRATUS WHICH WILL LIMIT SURFACE HEATING.  THUS...WHILE MID LEVEL
TEMPERATURES WILL BE RATHER COOL /ON THE ORDER OF MINUS 18C AT 500
MB/...IN ABSENCE OF STRONG MESOSCALE ASCENT...POTENTIAL FOR
THUNDERSTORM INITIATION OVER INLAND AREAS SHOULD REMAIN MINIMAL.

SOMEWHAT STRONGER MESOSCALE FORCING WILL...HOWEVER...EXIST INVOF
INVERTED SURFACE TROUGH EXPECTED TO DEVELOP BY THURSDAY OFF THE
MIDDLE AND S TX GULF CST.  PERSISTENT LOW LEVEL WARM ADVECTION ALONG
THIS FEATURE...COUPLED WITH MODEST UPLIFT ASSOCIATED WITH PART OF
UPPER SYSTEM MOVING E ACROSS NRN MEXICO/S TX...MAY SUPPORT
DEVELOPMENT OF A FEW EMBEDDED THUNDERSTORMS THURSDAY AFTERNOON ALONG
THE MIDDLE TX GULF CST.  THIS ACTIVITY SHOULD CONTINUE THROUGH
THURSDAY NIGHT/EARLY FRIDAY AND SPREAD NWD/NEWD INTO PARTS OF SE
TX/SRN LA AS WEAK UPPER TROUGH CONTINUES EWD.  SUFFICIENT ELEVATED
CAPE WILL PROBABLY NOT BE PRESENT TO SUPPORT SEVERE HAIL.

..CORFIDI.. 01/28/2004

...NOTICE...
FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.

$$