Tuesday, May 19, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 191257
SWODY1
SPC AC 191253

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT TUE MAY 19 2009

VALID 191300Z - 201200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
THE WLYS WILL REMAIN CONFINED TO THE PACIFIC NW AND THE FAR NRN TIER
OF STATES THIS PERIOD AS HI PLNS RIDGE DRIFTS SLOWLY E TO THE OH
VLY. UPR LOW NOW OVER VANCOUVER ISLAND EXPECTED TO ELONGATE NE INTO
THE CANADIAN RCKYS...ENHANCING WSWLY MID LVL FLOW OVER THE NRN
RCKYS/NRN HI PLNS. FARTHER S...A WEAKER LOW WILL DRIFT E TOWARD SRN
CA...AND UPR LOW WILL CONTINUE TO LINGER OFF THE W FL CST.

AT LWR LVLS...A COLD FRONT WILL MOVE ACROSS THE NWRN STATES IN
ASSOCIATION WITH THE VANCOUVER UPR LOW. THE FRONT...AND HEIGHT
FALLS WITH THE GLANCING INFLUENCE OF THE UPR TROUGH...WILL FOSTER
SCTD STORM DEVELOPMENT AND AN ISOLD SVR THREAT OVER THE NRN
INTERMOUNTAIN REGION.

...MT SWD INTO SE ID/WRN WY AND NRN UT...
WDLY SCTD TSTMS SHOULD FORM WITH DIURNAL HEATING OVER MUCH OF THE
INTERMOUNTAIN WEST. ACTIVITY MAY BE MOST CONCENTRATED ALONG BAND OF
PRE-FRONTAL 700 MB CONFLUENCE EXTENDING FROM UT INTO WRN WY. OTHER
STORMS MAY FORM OVER THE HIGHER TERRAIN OF WRN MT AND SPREAD NEWD.

LOW-LVL MOISTURE WILL REMAIN LIMITED...BUT LOW TO MID LVL LAPSE
RATES WILL BE STEEP. COUPLED WITH MODERATE/STRENGTHENING WSWLY MID
LVL FLOW...SOME OF THE STORMS COULD ORGANIZE INTO SMALL CLUSTERS.
EMBEDDED SMALL BOWING SEGMENTS COULD YIELD GUSTY/EVAPORATIVELY-
ENHANCED WINDS.

ISOLD STRONG TO PERHAPS SVR CELLS ALSO MAY DEVELOP NEAR COLD FRONT
IN MT/ERN IS AND POSSIBLY NW WY LATE THIS AFTN THROUGH THIS EVE.
DEEP WIND FIELD ON SE SIDE OF PROGRESSIVE UPR TROUGH WILL BE AMPLE
FOR STORM ORGANIZATION/SUSTENANCE...AND MAY SUPPORT ISOLD STORM
ROTATION. AS A RESULT...A LOW PROBABILITY THREAT WILL EXIST FOR
STRONG WINDS/HAIL. SPARSE MOISTURE SHOULD...HOWEVER...LIMIT OVERALL
SVR THREAT. THE STORMS SHOULD WEAKEN LATER TONIGHT AS THEY SPREAD E
INTO ERN MT.

..CORFIDI/JEWELL.. 05/19/2009

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