Thursday, September 18, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 182000
SWODY1
SPC AC 181959

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
ISSUED BY AFWA OFFUTT AIR FORCE BASE BELLEVUE NE
0259 PM CDT THU SEP 18 2008

VALID 182000Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
LATEST WATER VAPOR IMAGERY SHOWS A CLOSED LOW APPROACHING THE W
COAST...A CLOSED LOW OVER THE OK PANHANDLE WITH ASSOCIATED TROUGH
EXTENDING SWD ACROSS E TX...AND A TROUGH APPROACHING THE E COAST.
A SHORTWAVE TROUGH IS TRACKING EWD ACROSS ERN MT. THE LATEST
SURFACE ANALYSIS SHOWS A STATIONARY FRONT ACROSS CNTRL FL EXTENDING
WWD INTO THE GULF. A WEAK SURFACE TROUGH IS LOCATED OVER ERN MT AND
NERN WY. A LEESIDE TROUGH EXTENDS FURTHER S ACROSS ERN CO AND NERN
NM. HIGH PRESSURE DOMINATES THE REST OF THE COUNTRY.

...SRN CA INTO ERN GREAT BASIN/ROCKY MTN REGION...
MONSOONAL MOISTURE COUPLED WITH DAYTIME HEATING...MID-LEVEL COLD
POOL AND OROGRAPHIC LIFT HAS INITIATED THUNDERSTORMS OVER THE ERN
GREAT BASIN...SRN/CNTRL ROCKY MTNS...AND FOUR CORNERS REGION.
LATEST LIGHTNING DETECTION SHOWS CONVECTION TO BE CURRENTLY MOST
ACTIVE OVER THE WRN TWO-THIRDS OF CO AND N/CNTRL NM. LATEST VISUAL
SATELLITE SHOWS CU FIELDS INCREASING TO THE W INTO ERN NV AND S
ACROSS MUCH OF NM/AZ AND SOME OVER SRN CA. THUS EXPECT TSTM
ACTIVITY TO INCREASE OVER THE REST OF THE FORECAST TSTM AREA. TSTMS
OVER THE FRONT RANGE SHOULD TRACK SEWD INTO THE HIGH PLAINS OF CO
AND NM DUE TO NWLY FLOW ALOFT. MOST ACTIVITY SHOULD DECREASE SHORTLY
AFTER SUNSET.

...NRN ROCKIES INTO THE NRN PLAINS...
THE SHORTWAVE TROUGH AND SURFACE TROUGH OVER ERN MT SHOULD HELP
INCREASE THE THREAT FOR TSTMS AS THIS SYSTEM MOVES INTO MORE
UNSTABLE AIRMASS ACROSS THE DAKOTAS AND WY. ISOLATED TSTMS ARE
ALREADY DEVELOPING OVER WY THAT IS ALSO ASSOCIATED WITH THE ACTIVITY
TO THE S. AS UPPER DIVERGENCE INCREASES AND LOW-LEVEL CONVERGENCE
INCREASES EXPECT THE CAP IN THE REGION TO ERODE ALLOWING TSTMS TO
DEVELOP OVER THE DAKOTAS AND MN LATER THIS AFTERNOON AND THIS
EVENING. THE NAM INDICATES CAPES OF 1500 J/KG WITH 30 KTS OF
1000-500MB VERTICAL SHEAR INDICATING AN ISOLATED POTENTIAL FOR SMALL
HAIL OVER SERN ND...NERN SD WITH ANY STORM THAT FORMS IN THIS AREA.
A LOW-LEVEL JET WILL DEVELOP LATER TONIGHT AND WILL SUPPORT
NOCTURNAL TSTMS OVER THE ERN DAKOTAS AND MN WITH SOME POTENTIAL FOR
ISOLATED SMALL HAIL.

...FL...
THE STATIONARY FRONT AND UPPER TROUGH IS SUPPORTING ISOLATED TSTMS
OVER FL. INSTABILITY ALONG THE GULF COAST HAS THE POTENTIAL TO
INITIATE TSTMS OVER SRN GA...SRN AL...AND EXTREME SRN MS AND SERN
LA.

THE TWO UPPER TROUGHS OVER THE S/CNTRL AND SE COUPLED WITH THE
STATIONARY FRONT IN THE GULF OF MEXICO AND FL WILL SUPPORT TSTMS
OVER THIS AREA. ABUNDANT GULF MOISTURE AND CAPE OF 1000-2000 J/KG
IN THIS AREA WILL ALSO BE FAVORABLE FOR TSTMS IN THIS AREA. WEAK
VERTICAL SHEAR INDICATES A LOW POTENTIAL FOR SEVERE.

..AFWA.. 09/18/2008

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