SWODY2
SPC AC 051734
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1234 PM CDT MON MAY 05 2008
VALID 061200Z - 071200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS UPPER MIDWEST TO
CENTRAL/SRN GREAT PLAINS...
...SYNOPSIS...
PROGRESSIVE UPPER AIR PATTERN WILL FEATURE MID/UPPER LEVEL LOW --
NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OFFSHORE NRN BAJA. THIS
PERTURBATION IS FCST TO PIVOT EWD AND MOVE ONSHORE NRN BAJA
DAY-1...THEN GENERALLY ENEWD TO SRN HIGH PLAINS NEAR TX/NM BORDER BY
7/12Z. NRN STREAM SHORTWAVE TROUGH -- NOW OVER PACIFIC NW -- SHOULD
MOVE EWD TO WRN/CENTRAL ND BY 7/00Z...THEN ACROSS NRN/CENTRAL MN BY
END OF PERIOD.
MEANWHILE...AT SFC...MOIST ADVECTION NWD THROUGH CENTRAL/SRN PLAINS
WILL CONTRIBUTE TO SHARPENING DEFINITION OF DRYLINE THROUGH EARLY
PART OF PERIOD. BY 7/00Z...DRYLINE SHOULD EXTEND FROM NRN COAHUILA
NNEWD ACROSS W-CENTRAL TX...CENTRAL/ERN TX PANHANDLE...WRN KS. OVER
SWRN NEB...DRYLINE SHOULD INTERSECT COLD FRONT THAT...IN TURN...WILL
EXTEND NEWD INTO SFC CYCLONE INVOF SERN ND. WARM FRONT SHOULD
EXTEND ESEWD FROM THAT LOW ACROSS MN/WI...LIFTING NWD ACROSS UPPER
MI AS LOW DEEPENS AND MOVES TOWARD LS...AHEAD OF APCHG NRN STREAM
PERTURBATION ALOFT.
...CENTRAL/SRN HIGH PLAINS...
MATURE ELEVATED MIXED-LAYER AIR MASS WILL BE IN PLACE...LEADING TO
STG CAPPING THROUGH MOST OF AFTERNOON OVER DRYLINE REGION.
HOWEVER...STG HEATING/MIXING OF BOUNDARY LAYER WILL ACT IN COLLUSION
WITH WRN FRAGMENTS OF MOIST TRAJECTORIES TO WEAKEN CAP
LOCALLY...LEADING TO POTENTIAL FOR TSTM DEVELOPMENT VIRTUALLY
ANYPLACE UP AND DOWN DRYLINE BETWEEN WRN KS AND S OF MEX BORDER.
MOST FAVORABLE AREA...HOWEVER...MAY BE WHERE OUTFLOW BOUNDARIES FROM
ANY MORNING ACTIVITY INTERSECT DRYLINE...E.G. WRN KS.
SOME WEAKNESSES IN LOW LEVEL WINDS ARE PROGGED THAT MAY LIMIT
HODOGRAPH SIZE...HOWEVER DEEP-LAYER SHEAR AND LARGE BUOYANCY SHOULD
COMBINE TO FAVOR AFTERNOON/EARLY EVENING SUPERCELLS...WITH MLCAPES
UP TO 3000 J/KG E OF DRYLINE AND 1500-2500 J/KG ALONG IT.
LARGE/DAMAGING HAIL WILL BE POSSIBLE...ALONG WITH SVR WINDS.
TORNADO POTENTIAL MAY BE ENHANCED NEAR AREAS OF BOUNDARY
INTERACTIONS...WHERE LOW LEVEL VORTICITY/SRH ARE MAXIMIZED...AS WELL
AS IN SOME 2-3 HOUR TIME WINDOW IN LATE AFTERNOON/EVENING WHEN LCLS
LOWER DUE TO COOLING SFC TEMPS...YET EFFECTIVE LIFTED PARCELS STILL
ARE ROOTED AT SFC. ONE OR TWO NOCTURNAL TSTM COMPLEXES MAY DEVELOP
FROM THIS ACTIVITY -- MOST PROBABLY ACROSS KS AND/OR SRN NEB AGAIN.
RELATIVE CONCENTRATION OF SVR WITH DAMAGING WIND...OCCASIONAL HAIL
AND A FEW TORNADOES MAY OCCUR WITH ANY RESULTANT MCS MOVING EWD
ACROSS CENTRAL PLAINS.
...UPPER MIDWEST...
ALTHOUGH LOW LEVEL MOISTURE WILL NOT BE AS RICH IN THIS AREA AS
FARTHER S...IT SHOULD REMAIN SUFFICIENT TO SUPPORT POTENTIAL FOR
TSTMS TO DEVELOP ALONG/AHEAD OF SFC COLD FRONT. OTHER CONVECTION
MAY FORM INVOF SFC LOW WHERE SFC CONVERGENCE WILL BE
MAXIMIZED...ALONG WITH BACKED LOW LEVEL WINDS SUPPORTING ENHANCEMENT
TO STORM-RELATIVE INFLOW. ACCORDINGLY...EFFECTIVE BULK SHEARS AND
LOW LEVEL HODOGRAPHS MAY BE FAVORABLE FOR SUPERCELLS NEAR LOW AND
WARM FRONT. LOW LEVEL WINDS FARTHER S...AHEAD OF COLD
FRONT...SHOULD BE RELATIVELY WEAK...SUPPORTING POTENTIAL
OUTFLOW-DOMINANT MODES AND DAMAGING WIND THREAT IN TANDEM WITH WELL
MIXED SUBCLOUD LAYERS.
THIS AREA APPEARS SOMEWHAT CONDITIONAL ATTM...GIVEN UNCERTAIN
EFFECTS OF ANY EARLY CONVECTIVE PROCESSES FARTHER S ACROSS KS/NEB ON
BOTH RETURNING MOISTURE AND DIABATIC HEATING/DESTABILIZATION.
...SRN PLAINS...LATE PERIOD...
AFTER 7/06Z...STG BELT OF LARGE-SCALE ASCENT ALOFT -- ASSOCIATED
WITH PRONOUNCED DPVA PLUME -- IS FCST TO SHIFT EWD ACROSS SRN HIGH
PLAINS AND TO IMPINGE UPON FAVORABLY MOIST LOW LEVEL RETURN FLOW/WAA
REGIME. AS THIS OCCURS...SCATTERED-NUMEROUS TSTMS ARE EXPECTED TO
DEVELOP RATHER QUICKLY...AND MOVE EWD TO NEWD ACROSS MUCH OF
W-CENTRAL/NW TX AND WRN OK. INCREASING MERIDIONAL COMPONENT OF
GRADIENT FLOW IS FCST IN MID-UPPER LEVELS AS UPPER LOW AND
ACCOMPANYING HIGH-AMPLITUDE SHORTWAVE TROUGH APPROACH...YIELDING
BACKING WIND PROFILES WITH HEIGHT FROM LOW-MIDDLE LEVELS. THIS
SHOULD CONTRIBUTE TO TREND FOR LINEAR STORM MODES...WITH ASSOCIATED
POTENTIAL FOR DAMAGING GUSTS AND OCCASIONAL HAIL GIVEN FCST
SOUNDINGS THAT SHOW EFFECTIVE INFLOW PARCELS ROOTED AT OR VERY NEAR
SFC OVER IMMEDIATE PRE-STORM AIR MASS.
...CENTRAL LOW PLAINS...EARLY PERIOD...
SCATTERED TSTMS IN CLUSTERS MAY BE ONGOING AT 6/12Z ACROSS PORTIONS
CENTRAL PLAINS -- MOST PROBABLY SOME PORTIONS WRN/CENTRAL KS INTO
S-CENTRAL NEB...AND PERHAPS NRN OK. ALTHOUGH SHORTWAVE RIDGING IS
FCST ACROSS THIS AREA...WITH RELATIVELY WEAK MIDLEVEL WINDS AND WEAK
EFFECTIVE SHEAR...INSTABILITY AND MOISTURE SHOULD BE SUFFICIENT TO
SUPPORT MRGL SVR HAIL THREAT. MODIFIED NAM-KF FCST SOUNDINGS
SUGGEST APPROXIMATELY 1500 J/KG ELEVATED MUCAPE. POTENTIAL SHOULD
SHIFT EWD TOWARD LOWER MO VALLEY DURING 6/12-6/18Z TIME FRAME...AND
WEAKEN ALONG WITH LLJ.
..EDWARDS.. 05/05/2008
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment