Tuesday, August 3, 2010

MESO: Mesoscale Discussion 1550

ACUS11 KWNS 032256
SWOMCD
SPC MCD 032256
SDZ000-NEZ000-040100-

MESOSCALE DISCUSSION 1550
NWS STORM PREDICTION CENTER NORMAN OK
0556 PM CDT TUE AUG 03 2010

AREAS AFFECTED...PORTIONS SRN SD AND NRN-WRN NEB.

CONCERNING...SEVERE THUNDERSTORM WATCH 561...562...

VALID 032256Z - 040100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
561...562...CONTINUES.

DAMAGING WIND POTENTIAL WILL CONTINUE AT LEAST THROUGH SCHEDULED 02Z
EXPIRATION TIME OF WW 562...PRIMARILY IN CORRIDOR LOCATED INVOF
NEB/SD BORDER...FROM NRN TIER NEB COUNTIES TO VICINITY I-90.
ADDITIONAL OR EXTENDED WW MAY BE NEEDED FARTHER E BEFORE WW 562
EXPIRES AT 02Z.

CONVECTION CONTINUES TO AGGREGATE AND BECOME BETTER ORGANIZED ON
MESOBETA SCALE ACROSS SWRN SD...WITH HERETOFORE SUB-SVR PORTION
EXTENDING SWWD ACROSS NRN/CENTRAL PANHANDLE OF NEB. PORTION OF MCS
N OF PRIMARY BOW PRODUCED 57 KT GUST AT PHP AT 2144Z. TEMP/THETAE
DEFICITS AND VELOCITY DATA INDICATE VERY ROBUST AND MATURE COLD POOL
WITH THIS SYSTEM...DENSITY CURRENT WITH WHICH SHOULD MAINTAIN STG
CONVECTIVE-SCALE LIFT INTO FAVORABLY UNSTABLE CORRIDOR TO ITS E.
DEEP-SHEAR AND MEAN WIND VECTORS ARE ALIGNED ZONALLY...NEARLY NORMAL
TO ORIENTATION OF MCS...FURTHER SUPPORTING MAINTENANCE OF
FORWARD-PROPAGATING SYSTEM. FOREGOING/PRECONVECTIVE AIR MASS IS
CHARACTERIZED BY SFC DEW POINTS UPPER 60S TO MID 70S
F...CONTRIBUTING TO MLCAPE 2000-2500 J/KG OVER S-CENTRAL SD
INCREASING TO AROUND 3500 J/KG VICINITY FSD. REFLECTIVITY
ANIMATIONS AND VIS IMAGERY ALSO INDICATE DEVELOPMENT OF
WARM-ADVECTION WING OF CONVECTION NE THROUGH E OF PRIMARY BOW...FROM
SRN JONES COUNTY SD SEWD TO NRN TRIPP COUNTY...THEN BLEND OF DEEP
TCU AND SMALL/NEWLY GLACIATED CB IN BAND EXTENDING EWD TO BETWEEN
9V9 AND NRN CHARLES MIX COUNTY. SECONDARY AREA OF CONVECTION ALSO
IS FORMING INVOF PIR. PRE-MCS ACTIVITY MAY INCLUDE SHORT-LIVED
SUPERCELL STRUCTURES WITH LOCALLY ENHANCED HAIL RISK...AS WELL AS
DAMAGING DOWNDRAFTS...BEFORE BEING OVERTAKEN BY PRIMACY COMPLEX.
ISOLATED TSTMS FORMING OVER W-CENTRAL NEB -- JUST S WW 562 -- ARE IN
ENVIRONMENT OF RELATIVELY WEAK LOW-MIDLEVEL FLOW BUT FAVORABLE
BUOYANCY...WITH MLCAPE AROUND 3000 J/KG...AND ABOUT 50 KT FLOW NEAR
ANVIL LEVEL. ISOLATED SVR HAIL/GUSTS ALSO ARE POSSIBLE IN THAT
AREA. HOWEVER...RELATIVELY STABLE AIR MASS OVER CENTRAL/NERN NEB
LEFT BY EARLIER CLOUDS/PRECIP WILL LIMIT EWD EXTENT OF SVR POTENTIAL
FROM THESE TSTMS.

FINALLY...BRIEF/ISOLATED DEVELOPMENT OF ELEVATED/HAIL-PRODUCING
TSTMS CANNOT BE RULED OUT OVER SRN PORTIONS OF COLD POOL BEHIND
INITIAL MCS...MAINLY IN NEB. HOWEVER...OVERALL/ORGANIZED SVR THREAT
WILL DIMINISH ENOUGH THAT MOST OF WWS MAY BE CLEARED BEHIND MCS.

..EDWARDS.. 08/03/2010

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FSD...ABR...GID...LBF...UNR...CYS...

LAT...LON 42080361 43080194 43790157 44560145 44830007 44539866
44529680 43479661 43089683 43009848 42489955 41899978
41449943 40920002 40990162 41580359 42080361

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