Tuesday, January 8, 2013

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 081622
SWODY1
SPC AC 081621

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1021 AM CST TUE JAN 08 2013

VALID 081630Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF SRN/SERN
TX...

...SYNOPSIS...

THE PRIMARY FEATURE OF INTEREST IS A MID AND UPPER-LEVEL LOW WHICH
WILL TRACK ACROSS NRN MEXICO THROUGH 09/12Z. THIS SYSTEM WILL BE
ATTENDED BY A CORRIDOR OF 500-MB HEIGHT FALLS APPROACHING 100M/12 HR
WHICH WILL GRADUALLY OVERSPREAD THE LOWER RIO GRANDE VALLEY DURING
THE LATTER HALF OF THE FORECAST PERIOD. IN THE LOW LEVELS...15Z
SURFACE ANALYSIS SHOWS A WARM FRONT FROM BETWEEN MFE AND LRD
EXTENDING NEWD TO OFF THE TX COAST S OF CRP BEFORE STRETCHING ENEWD
ALONG THE SHELF WATERS OF THE NWRN AND N-CNTRL GOM. THIS WARM FRONT
WILL CONTINUE TO PROGRESS INLAND AHEAD OF A FRONTAL WAVE WHICH IS
FORECAST TO DEVELOP FROM THE LOWER RIO GRANDE VALLEY/DEEP S TX INTO
THE TX HILL COUNTRY BY THE END OF THE D1 PERIOD.

...CNTRL/SRN/SERN TX...

SCATTERED...ELEVATED TSTMS ARE LIKELY TO PERSIST ACROSS THE REGION
TODAY TO THE N OF SURFACE WARM FRONT WHERE LOW-LEVEL WARM THERMAL
AND MOISTURE ADVECTIONS ARE ENHANCED ALONG AND NEAR THE LLJ AXIS.
12Z SOUNDING DATA FROM DRT...BRO...AND CRP SHOWED ONLY MODEST MUCAPE
VALUES OF GENERALLY LESS THAN 1000 J/KG...SUGGESTING ONLY A MINIMAL
HAIL THREAT WITH THE ELEVATED STORMS. SURFACE-BASED STORM FORMATION
WITHIN THE INLAND-DEVELOPING WARM SECTOR REMAINS MORE UNCERTAIN AT
LEAST THROUGH THIS AFTERNOON OWING TO THE POTENTIAL FOR A
STRENGTHENING CAP AS OBSERVED BY THE 12Z SOUNDING AT MONTEREY
MEXICO. STILL...A CONDITIONAL RISK FOR SUPERCELLS CAPABLE OF
DAMAGING WINDS AND A COUPLE TORNADOES EXISTS GIVEN THE PRESENCE OF
MLCAPE OF AROUND 1000 J/KG AND MODESTLY STRONG LOW-LEVEL AND
DEEP-LAYER SHEAR.

A NOTABLE INCREASE IN BOTH ELEVATED AND SURFACE-BASED STORM
DEVELOPMENT IS ANTICIPATED BY LATE AFTERNOON INTO THIS EVENING ALONG
THE INTERNATIONAL BORDER S/SE OF DRT AS HEIGHT FALLS/FORCING FOR
ASCENT IMMEDIATELY DOWNSTREAM FROM THE UPPER LOW BEGIN TO OVERSPREAD
THE LOW-LEVEL MOISTURE/INSTABILITY AXIS DEVELOPING NWD/NWWD. LATEST
CONVECTION-ALLOWING MODEL GUIDANCE SUGGESTS THE POTENTIAL FOR
UPSCALE GROWTH OF STORMS INTO A N-S ORIENTED QLCS WHICH WILL ADVANCE
ACROSS ERN PARTS OF THE EDWARDS PLATEAU THROUGH THE HILL COUNTRY AND
DEEP S TX OVERNIGHT TO ALONG THE MID/UPPER TX COAST BY 09/12Z. THE
STRONGEST STORMS ARE EXPECTED WITHIN THE SRN PORTION OF QLCS...IN
CLOSER PROXIMITY TO THE MORE MOIST AND UNSTABLE BOUNDARY LAYER.
HERE...A MIX OF SUPERCELLS AND BOWING STRUCTURES WILL BE POSSIBLE
WITH AN ATTENDANT THREAT FOR DAMAGING WINDS AND PERHAPS A TORNADO OR
TWO.

..MEAD/LEITMAN.. 01/08/2013

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