MESO: Mesoscale Discussion 0236

ACUS11 KWNS 230428
SWOMCD
SPC MCD 230428
MNZ000-IAZ000-SDZ000-230730-

MESOSCALE DISCUSSION 0236
NWS STORM PREDICTION CENTER NORMAN OK
1128 PM CDT SUN MAR 22 2009

AREAS AFFECTED...PORTIONS CENTRAL/SRN MN...EXTREME ERN SD...NRN IA.

CONCERNING...HEAVY RAINFALL

VALID 230428Z - 230730Z

RAIN RATES NEAR 1 INCH/HOUR ARE POSSIBLE WITHIN PLUME OF CONVECTION
MOVING NEWD ACROSS THIS REGION. ISOLATED RATES IN 1.5-2.5
INCHES/HOUR RANGE ARE LIKELY WITHIN HEAVIEST TSTMS...WHICH WILL MOVE
SLOWLY. AS LOW LEVEL CYCLONE CONSOLIDATES...DEEPENS AND LIFTS NEWD
OVER PORTIONS CENTRAL HIGH PLAINS...AND WEAK VORTICITY LOBE NOW
EVIDENT NEAR FSD LIFTS NEWD...PRECIP PLUME AND SUPPORTIVE ZONE OF
STRONGEST ASCENT WILL MOVE NEWD ACROSS CENTRAL/SRN MN WHILE PERHAPS
BACKBUILDING OVER IA.

SFC ANALYSIS SHOWS WARM FRONT FROM W-CENTRAL SD SEWD ACROSS
E-CENTRAL/SERN MEB AND NWRN MO. FRONT SHOULD DECELERATE WITH LITTLE
MOVEMENT THROUGH OVERNIGHT HOURS AS STG PRESSURE FALLS CONTINUE TO
ITS SW ACROSS CENTRAL HIGH PLAINS. STG LOW LEVEL WAA/ISENTROPIC
LIFT REGIME IS EVIDENT OVER UPPER MIDWEST IN ASSOCIATION WITH 50-60
KT SLY LLJ...WHICH IS FCST TO CHANGE LITTLE IN INTENSITY AND
DRIFT/EXPAND EWD THROUGH AT LEAST 09Z. LLJ IS ALIGNED NEARLY
PARALLEL TO RELATED PLUMES OF ENHANCED LOW LEVEL MOISTURE VALUES AND
MOISTURE TRANSPORT...EACH OF WHICH WILL CONTINUE TO BE LIFTED
ISENTROPICALLY TO LFC...AMIDST ELEVATED MUCAPES GENERALLY 200-500
J/KG. WITHIN ROUGHLY 150-175 NM WIDE MOIST PLUME -- CENTERED NEAR A
LINE FROM SPS-TOP-OMA-FSD...GPS SENSORS...MODIFIED RAOBS AND RUC
FCST SOUNDINGS EACH INDICATE PW IN 1-1.25 INCH RANGE.
STRONGEST/ELEVATED LOW LEVEL ASCENT WILL CONTINUE TO OCCUR N OF
WHERE LLJ CROSSES WARM FRONT -- I.E. N OF NWRN MO. THREAT FOR
EMBEDDED TSTMS WITH HEAVY RAIN LIKEWISE MAY EXTEND SWD FROM MN
ACROSS PORTIONS IA.

ALSO REF HPC EXCESSIVE RAIN DISCUSSION UNDER FOUS30 KWBC FOR
GUIDANCE ON THIS EVENT VALID LONGER TERM -- THROUGH 24/00Z.

..EDWARDS.. 03/23/2009

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

ATTN...WFO...ARX...MPX...DMX...FGF...FSD...ABR...

LAT...LON 42159393 43409521 43979616 44419719 45759676 46169532
45809344 43759280 42439289 42099330 42159393

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