Friday, May 22, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 230054
SWODY1
SPC AC 230051

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 PM CDT FRI MAY 22 2009

VALID 230100Z - 231200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
SYNOPTIC PATTERN WILL REMAIN CHARACTERIZED BY NRN STREAM FLOW BELT
ALOFT...ALONG CANADIAN BORDER...WHILE BROAD/DIFFUSE UPPER CYCLONE
CONTINUES TO AFFECT MUCH OF SWRN CONUS. DEEP-TROPOSPHERIC CYCLONE
OVER NERN GULF IS FCST TO CONTINUE MOVING NWD TO NWWD...CENTER OF
WHICH SHOULD APPROACH GULF COAST BETWEEN SERN LA AND WRN FL
PANHANDLE AROUND END OF PERIOD. REF NHC TROPICAL OUTLOOK UNDER WMO
HEADER ABNT20 KNHC FOR ADDITIONAL FCST REASONING ON THIS SYSTEM.

AT SFC...SERIES OF SMALL LOWS IS EVIDENT JUST E OF ROCKIES BETWEEN
SERN WY AND NERN NM...WITH SOME CONSOLIDATION OF BETTER DEFINED LOW
POSSIBLE OVER CENTRAL/ERN CO OVERNIGHT. COLD FRONT -- ANALYZED AT
23Z FROM NWRN MN AND SERN ND SWWD ACROSS SWRN SD AND SERN WY --
SHOULD MOVE SEWD OVER MN AND MOST OF REMAINDER OF SD...SETTLING SWD
SLOWLY ACROSS WRN NEB. QUASISTATIONARY FRONT IS ANALYZED GENERALLY
E-W ACROSS NEB SANDHILLS TO CENTRAL IA.

...CENTRAL HIGH PLAINS...
SCATTERED TO WIDELY SCATTERED TSTMS HAVE DEVELOPED ACROSS PORTIONS
S-CENTRAL/SERN WY...NWRN CO TO N-CENTRAL NEB...NEAR FRONTAL ZONES
AND ON SRN FRINGE OF MID-UPPER LEVEL WLYS CONTRIBUTING TO 25-35 KT
EFFECTIVE SHEAR. MRGL SVR HAIL HAS BEEN REPORTED WITH A COUPLE
TSTMS IN THIS REGIME. ADDITIONAL PULSES OF ENHANCED ORGANIZATION
FAVORABLE FOR HAIL STILL MAY OCCUR WITH STRONGEST CELLS...ESPECIALLY
INVOF BOUNDARY INTERACTIONS. REF SPC MESOSCALE DISCUSSION 856 FOR
MORE NEAR-TERM DETAILS. COVERAGE/INTENSITY OF CONVECTION IS FCST TO
DIMINISH AFTER ABOUT 04Z AS BOUNDARY LAYER DESTABILIZES...FROM
COMBINATION OF SFC DIABATIC COOLING AND INCREASING COVERAGE OF
CONVECTIVE OUTFLOWS.

...GULF COAST...AL AND PORTIONS FL PANHANDLE...
TIME SERIES OF FCST SOUNDINGS AND MODEL CROSS SECTIONS IN 0-3 KM
LAYER REASONABLY INDICATE THAT WINDS JUST ABOVE SFC WILL INCREASE
OVERNIGHT AS INNER NERN SECTOR OF DEEP-LAYER LOW -- NOW WELL
OFFSHORE -- MOVES TOWARD COAST...THEREBY ENLARGING LOW LEVEL
HODOGRAPHS AND BOUNDARY LAYER SHEAR. MODIFIED ETA-KF AND RUC
SOUNDINGS SUGGEST SFC DEW POINTS ABOVE 70 F WITH MID 70S SFC TEMPS
MAY MAINTAIN SFC-BASED EFFECTIVE INFLOW PARCELS ALONG COAST.
BRIEF/MRGL TORNADO RISK MAY EXIST WITH ANY RELATIVELY DISCRETE TSTMS
MOVING ONSHORE...HOWEVER POTENTIAL APPEARS TOO LOW AND CONDITIONAL
FOR CATEGORICAL OUTLOOK. WEAK INSTABILITY AND MOSTLY
DISORGANIZED/MULTICELLULAR CONVECTIVE MODES WILL BE LIMITING
FACTORS.

..EDWARDS.. 05/23/2009

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