Tuesday, March 16, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161229
SWODY1
SPC AC 161227

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0727 AM CDT TUE MAR 16 2010

VALID 161300Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

MORNING SATELLITE IMAGERY SHOWS A FAST MOVING COLD UPPER TROUGH
APPROACHING THE COAST OF THE PAC NW...WITH A HIGHLY AMPLIFIED RIDGE
OVER THE INTERMOUNTAIN W. FARTHER DOWNSTREAM...AN UPPER IMPULSE IS
MOVING S INTO THE CENTRAL PLAINS...WHILE A WEAKENING UPPER TROUGH
RESIDES OVER TX. AS THE DAY PROGRESSES...THE PAC TROUGH IS FORECAST
TO MOVE ACROSS NWRN ORE AND WA...WHILE THE TX TROUGH CONTINUES TO
WEAKEN/DE-AMPLIFY AS IT MOVES E INTO THE NRN GULF OF MEXICO.

...WA/NWRN ORE COASTS...

AS A FAST MOVING UPPER TROUGH BRUSHES THE COASTS OF WA/NWRN ORE
DURING THE LATE AFTERNOON/EVENING...COLD MID LEVEL TEMPERATURES WILL
OVERSPREAD THE REGION...WITH 500 MB TEMPERATURES DECREASING FROM
AROUND -20 DEG C AT MID-DAY TO -30 DEG C DURING THE NIGHT. MODEL
FORECAST SOUNDINGS INDICATE A HUMID BOUNDARY LAYER AIRMASS COMBINED
WITH STEEPENING LAPSE RATES WILL YIELD SEVERAL HUNDRED J/KG OF
MUCAPE. POSITIVE AREA ON THESE SOUNDINGS EXTENDS INTO THE CHARGE
SEPARATION ZONE...SUGGESTING ISOLATED LIGHTNING STRIKES WILL BE
POSSIBLE.

...PORTIONS OF S-CENTRAL/SERN TX AND ADJACENT COASTAL PLAIN...

LARGE SCALE ASCENT IS FORECAST TO GRADUALLY WEAKEN DURING THE DAY AS
UPPER TROUGH APPROACHES THE GULF OF MEXICO. HOWEVER...A MID LEVEL
DRY SLOT DEPICTED IN MORNING WV IMAGERY IS BEING ENTRAINED INTO THE
UPPER CIRCULATION. AS A RESULT...POTENTIAL INSTABILITY MAY INCREASE
BENEATH AND IMMEDIATELY AHEAD OF THIS FEATURE DURING THE MID TO LATE
AFTERNOON...WITH MODIFIED 12Z DRT SOUNDING FOR A SURFACE TEMPERATURE
AROUND 60 AND DEWPOINTS HOLDING IN THE UPPER 40S/LOW 50S YIELDING
200-500 J/KG OF MUCAPE. IN ADDITION...A ZONE OF WEAK LOW LEVEL
CONFLUENCE IS FORECAST TO RESIDE ACROSS PORTIONS OF S-CENTRAL/SERN
TX AND THE ADJACENT COASTAL PLAIN...WHICH MAY ACT TO FOCUS THE
DEVELOPMENT OF A FEW THUNDERSTORMS.

..GARNER/EVANS.. 03/16/2010

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