SWOMCD
SPC MCD 150715
ARZ000-LAZ000-TXZ000-OKZ000-150945-
MESOSCALE DISCUSSION 2109
NWS STORM PREDICTION CENTER NORMAN OK
0215 AM CDT THU OCT 15 2009
AREAS AFFECTED...PORTIONS SERN OK...SWRN/S-CENTRAL AR...EXTREME NWRN
LA...NE TX.
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 150715Z - 150945Z
TSTMS ARE EXPECTED TO CONTINUE DEVELOPING AND TO GROW IN COVERAGE
ACROSS DISCUSSION AREA THROUGH REMAINDER OVERNIGHT
HOURS...INCREASING POTENTIAL FOR STG-SVR GUSTS AND PERHAPS MRGL HAIL
OVER ARKLATEX AREA AND ADJOINING PORTIONS OK.
SFC MESOANALYSIS SHOWS COMPLEX PATTERN OF BOUNDARIES...FEATURING
PRIMARY/QUASI STATIONARY SFC FRONT FROM WEAK LOW NW FTW...ENEWD
ACROSS DUA-DEQ AREAS. NRN BRANCH OF THIS FRONT IS ANALYZED FROM
SWRN PUSHMATAHA COUNTY OK NEWD ALMOST TO FSM...BECOMING DIFFUSE IN
AR. COLD FRONTAL SEGMENT OVER NERN OK AND NWRN AR MAY MERGE WITH
NRN STATIONARY FRONTAL BRANCH BY 10Z WITH SOME SEWD MOTION OF
COMBINED BOUNDARY. TROUGHING EXTENDS NEWD ACROSS AR TO
SECONDARY/WEAK LOW. EFFECTIVE INFLOW PARCELS S OF MAIN FRONT...AND
BETWEEN IT AND NRN FRONTAL BRANCH OVER SERN OK...APPEAR TO BE WEAKLY
CAPPED AND EITHER AT OR VERY NEARLY SFC-BASED...WITH DEW POINTS
LOW-MID 70S S OF MAIN FRONT AND 68-70 F S OF NRN FRONTAL SEGMENT.
THIS RICH LOW LEVEL MOISTURE OFFSETS WEAK LAPSE RATES ALOFT ENOUGH
TO YIELD MLCAPE AROUND 1500 J/KG INVOF MAIN SFC FRONT...AND ALSO
MUCAPES 1000-1500 J/KG NWD ACROSS MUCH OF SERN OK AND SWRN
AR...ROOTED ABOVE SFC.
THROUGH 12Z..SFC LOW SHOULD MOVE EWD TOWARD AREA BETWEEN
GVT-TXK...WHILE COLD FRONT TRAILING WSWWD FROM LOW MOVES SEWD ACROSS
N-CENTRAL TX. ZONE OF STRONGEST LOW-LEVEL WAA AND DEEP-LAYER ASCENT
IS EXPECTED TO SHIFT EWD AND SEWED ACROSS THIS REGION...SUPPORTING
INCREASING STRENGTH/DENSITY OF CONVECTION FROM SERN OK ACROSS
PORTIONS SWRN AR...NE TX AND PERHAPS NWRN LA. WEAK/SELY SFC WINDS
AND 20-30 KT WLY 850 MB FLOW ALONG AND S OF MAIN FRONTAL SEGMENT
OVER NE TX AND IMMEDIATE RED RIVER AREA OF SE OK WILL SUPPORT
ENLARGED LOW LEVEL HODOGRAPHS WITH EFFECTIVE SRH 150-350
J/KG...ALTHOUGH DEGREE OF JUXTAPOSITION OF CONVECTION WITH THAT
FAVORABLE LOW LEVEL SHEAR IS IN QUESTION. DEEP-LAYER SHEAR WILL BE
FAVORABLE OVER BROADER MESOSCALE AREA...WITH EFFECTIVE SHEAR
MAGNITUDES COMMONLY 45-55 KT IN FAVOR OF POTENTIAL FOR SUPERCELL AND
BOW STRUCTURES...ALTHOUGH MESSY/CLUSTERED CONVECTIVE ORGANIZATION
MAY LIMIT POTENTIAL FOR SUSTAINED SUPERCELLS. RELATIVELY WARM
PROFILES AND WEAK LAPSE RATES INDICATE LIMITED HAIL
POTENTIAL...MAINLY WITH MOST SUSTAINED/INTENSE CELLS...WITH PRIMARY
CONCERN BEING ISOLATED DAMAGING GUSTS. TORNADO POTENTIAL APPEARS
VERY MRGL/CONDITIONAL ATTM.
..EDWARDS.. 10/15/2009
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LZK...SHV...TSA...FWD...OUN...
LAT...LON 35159677 35359560 35039396 34649270 34229202 33269215
32629318 32829460 33319595 34059624 35159677
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