SWODY1
SPC AC 220541
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT FRI MAY 22 2009
VALID 221200Z - 231200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
STRONGLY ANOMALOUS...PERSISTENT...NATIONWIDE LACK OF ORGANIZED
SEVERE TSTMS SHOULD CONTINUE THROUGH THIS PERIOD...AS UNFAVORABLE
UPPER AIR AND SURFACE PATTERN PERSISTS.
IN MID-UPPER LEVELS...NEARLY ZONAL NRN STREAM FLOW BELT WILL
CONTINUE FROM PAC NW TO UPPER GREAT LAKES AND NEW
ENGLAND...PERTURBED MAINLY BY POSITIVELY TILTED SHORTWAVE TROUGH NOW
OVER WRN SASK. THIS TROUGH SHOULD MOVE ESEWD ACROSS NRN ONT THROUGH
END OF PERIOD...ITS SRN FRINGES CROSSING PORTIONS NRN MN. FARTHER
S...DEEP-TROPOSPHERIC LOW IS FCST TO CONTINUE MOVING SLOWLY NWWD
ACROSS NERN GULF TOWARD VICINITY EXTREME SERN LA OR MS COAST.
RATHER MESSY AND NEBULOUS THERMODYNAMIC PATTERN WILL EXIST
TODAY...ONCE AGAIN CHARACTERIZED BY HORIZONTAL DISPLACEMENT OF MOST
FAVORABLE LAPSE RATES AND FLOW ALOFT FROM ROBUST LOW LEVEL MOISTURE.
SFC COLD FRONT IS ANALYZED FROM LOWER MI WSWWD ACROSS SERN IA AND
NWRN MO...BECOMING QUASISTATIONARY OVER SERN NEB...AND
N-CENTRAL/W-CENTRAL KS TO SERN CO. THIS FRONT SHOULD BECOME
DIFFUSE...SEGMENTS OF WHICH MAY MOVE NWD AND MERGE WITH
SECONDARY/WEAK COLD FRONT MOVING SWD OVER MN/SD/NRN NEB.
...E-CENTRAL GULF COAST...
AS DEEP-LAYER LOW APCHS COAST LATE IN PERIOD...LOW LEVEL SHEAR IS
FCST TO INCREASE WITH TIME. HOWEVER...COUNTERBALANCING KINEMATIC
EFFECT WILL BE WEAKENING PRESSURE GRADIENTS AND THEREFORE OVERALL
DIMINISHING TREND IN SYSTEM-RELATIVE FLOW AROUND THIS FEATURE...AS
NOTED IN NHC TROPICAL WEATHER DISCUSSION UNDER WMO HEADER AXNT 20
KNHC. INSTABILITY ALSO WILL BE QUESTIONABLE...WITH DIABATIC COOLING
TREND INLAND...YET SOME SFC-BASED EFFECTIVE INFLOW PARCELS POSSIBLE
ALONG IMMEDIATE COASTAL AREAS AMIDST 70S F SFC DEW POINTS. IF
RELATIVELY DISCRETE STORM MODE CAN OCCUR WITHIN STRONGLY CURVED LOW
LEVEL HODOGRAPHS...SOME TORNADO POTENTIAL MAY EXIST.
ATTM...HOWEVER...THAT THREAT APPEARS TOO CONDITIONAL TO ASSIGN
PROBABILITIES.
...CENTRAL HIGH PLAINS...
WIDELY SCATTERED TO SCATTERED TSTMS MAY DEVELOP INVOF WRN FRONTAL
SEGMENT WITH AFTERNOON HEATING OF HIGHER ELEVATIONS...PRODUCING STG
GUSTS. SFC DIABATIC HEATING MAY CONTRIBUTE TO SOMEWHAT HIGHER SFC
TEMPS THAN FCST BY MOST OPERATIONAL MODELS...AND SOME POTENTIAL FOR
WELL MIXED SUBCLOUD LAYERS SUPPORTING GUSTY DOWNDRAFTS. ATTM IT
APPEARS THAT WEAK MIDLEVEL LAPSE RATES -- RELATED TO ADVECTION OF
AIR ALOFT FROM CONVECTIVELY OVERTURNED...SWRN MONSOONAL TYPE REGIME
-- WILL SIGNIFICANTLY LIMIT BUOYANCY EVEN WITH SUCH HEATING. GIVEN
THIS FACTOR...ALONG WITH MRGL LOW LEVEL MOISTURE AND WEAK WINDS
THROUGH DEEP TROPOSPHERE...SVR PROBABILITIES APPEAR TO BE TOO
WEAK/CONDITIONAL TO DRAW 5 PERCENT UNCONDITIONAL AREA ATTM.
..EDWARDS/GRAMS.. 05/22/2009
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment