08 Apr 1999 - 05:55:36 UTC 
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ZCZC MKCSWODY1 000
ACUS1 KMKC 080555
MKC AC 080555

CONVECTIVE OUTLOOK...REF AFOS NMCGPH94O.

VALID 081200Z - 091200Z

REF WW NUMBER 0129...VALID TIL 0900Z
REF WW NUMBER 0130...VALID TIL 1000Z

THERE IS A HIGH RISK OF SVR TSTMS THIS AFTERNOON AND EVENING FOR
THE EASTERN HALF OF MISSOURI...PARTS OF WESTERN ILLINOIS...
NORTHEAST ARKANSAS...AND SMALL PORTIONS OF NORTHWEST TENNESSEE AND
WESTERN KENTUCKY. THE HIGH RISK AREA IS TO THE RIGHT OF A LINE
FROM 20 SW JBR 45 WSW ARG 35 WNW UNO 30 WSW JEF 45 NE SZL 20 SE P35
30 NNW IRK BRL 20 WSW PIA 20 W DEC 10 SE SLO 30 E MDH 40 S PAH 20
SE DYR 35 N MEM 20 SW JBR.

SURROUNDING THE HIGH RISK...THERE IS A MDT RISK OF SVR TSTMS THIS
AFTERNOON AND EVENING FOR SOUTHERN IOWA...EXTREME EAST CENTRAL
NEBRASKA...PORTIONS OF WESTERN MISSOURI...NORTH CENTRAL AND EAST
CENTRAL ARKANSAS...CENTRAL AND SOUTHEAST ILLINOIS...SOUTHWEST
INDIANA...WESTERN AND CENTRAL KENTUCKY...AND MUCH OF WEST
TENNESSEE. THE MDT RISK AREA IS TO THE RIGHT OF A LINE FROM 20 NE
MKC 10 ENE FNB 40 ESE LNK 25 W OMA 30 NE OMA 10 NW DSM MLI
25 SW MMO 10 NE DNV 20 NE BMG 15 N SDF 40 E BWG 20 SSE BNA
45 S MKL 25 NE LIT 45 S HRO 25 SE UMN 55 NW SGF 20 NE MKC.

SURROUNDING THE HIGH AND MDT RISK AREAS...THERE IS A SLGT RISK OF
SVR TSTMS TO THE RIGHT OF A LINE FROM 30 WNW HLC 30 ESE IML 40 WNW
LBF 35 SSE ANW 20 SSE YKN 25 NE FOD DBQ 20 W CGX 15 NNW FWA 35 NW
CMH 15 NNW HTS 35 SW 5I3 20 NE TYS 20 WNW CHA 25 SW HSV 25 WNW CBM
35 NNW GLH 35 WSW HOT 40 ENE DUA 30 N ADM 10 ESE OKC 10 ESE END 55
NNW P28 30 WNW HLC.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 15 SSW MYR 35 N SAV
25 NE CSG 15 NW CBM 20 WSW PBF 35 S MLC 30 N ADM 10 ESE OKC
10 E END 50 NNW P28 20 W HLC 20 SE SNY 55 E 4DG 20 W PHP
25 WNW BKX 25 WSW MSP 40 WNW OSH 45 SW HTL 65 NE MTC ...CONT...
20 NNW JHW 50 WSW ELM 10 ENE ABE 25 E NEL.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 25 NNW LAS 60 W DRA
45 W BIH 35 ENE SAC SVE 30 SW ENV 30 E PUC 35 N 4BL 30 S U17
35 W PGA 40 S SGU 25 NNW LAS.

---AN OUTBREAK OF SEVERE THUNDERSTORMS INCLUDING A FEW STRONG
TORNADIC SUPERCELLS IS LIKELY OVER PORTIONS OF THE MIDDLE
MISSISSIPPI RIVER VALLEY THIS AFTERNOON AND EVENING---

...SYNOPSIS...

A RATHER DEEP CYCLONE IS FORECAST TO MOVE ACROSS NEBRASKA AND IOWA
DURING THE PERIOD...WITH SURFACE PRESSURE FALLING TO ABOUT 985 MB. 
STRONG 12 HOUR 500 MB HEIGHT FALLS ON THE ORDER OF 200 METERS
INDICATE THE DEGREE OF DYNAMIC FORCING ASSOCIATED WITH RAPIDLY
EJECTING UPPER TROUGH. BY 09/00Z...THE WEST-EAST WARM FRONT IS
EXPECTED TO LIFT INTO NORTHERN MISSOURI AND CENTRAL ILLINOIS...WITH
THE COLD FRONT SURGING EAST INTO CENTRAL MISSOURI AND CENTRAL
ARKANSAS. MEANWHILE...A DEEP TROUGH WILL MOVE INTO THE GREAT BASIN
DURING THE PERIOD. 

...SEVERE THUNDERSTORM FORECAST DISCUSSION...

...MIDDLE MISSISSIPPI RIVER VALLEY...

00Z SOUNDINGS INDICATED THAT STEEP MID LEVEL LAPSE RATES HAVE
SPREAD AS FAR EAST AS ILLINOIS...WITH 700-500 MB VALUES OF 
7 TO 8 C/KM. LATEST SURFACE ANALYSIS INDICATES GULF AIRMASS IS IN
PLACE WITH DEWPOINTS IN THE 60S F EXTENDING FROM OKLAHOMA INTO WEST
TENNESSEE. AS SURFACE LOW MOVES ACROSS NEBRASKA AND SOUTHERLY FLOW
INCREASES DURING THE DAY ACROSS THE CENTRAL STATES...MOISTURE
SHOULD SPREAD RAPIDLY NORTH INTO SOUTHERN IOWA AND CENTRAL
ILLINOIS. WITH DIURNAL HEATING...MODERATE INSTABILITY SHOULD
DEVELOP WITH ETA MUCAPE RANGING FROM 1500 J/KG IN SOUTHERN IOWA TO
ABOUT 3000 J/KG IN THE MEMPHIS TN AREA.  

00Z ETA FORECASTS AN 80-100 KNOT 500 MB WIND MAX TRANSLATING ACROSS
KANSAS DURING THE MORNING AND REACHING SOUTHERN MISSOURI BY THE
EARLY EVENING HOURS. MEANWHILE...A 60 KNOT 850 MB JET WILL
INTERSECT THE MID LEVEL JET OVER SOUTHEAST MISSOURI BY 09/00Z.  

FORECAST HODOGRAPHS SHOW IMPRESSIVE LOW LEVEL VEERING OF WINDS WITH
HEIGHT AND STRONG DEEP LAYER SHEAR. ESTIMATED 0-3 KM STORM
RELATIVE HELICITIES OF 300-600 M2/S2 AND BRN SHEAR VALUES AROUND
100 M2/S2 INDICATE STRONG POTENTIAL FOR SUPERCELLS INCLUDING
ISOLATED STRONG TORNADOES.    

STRONG/SEVERE THUNDERSTORMS WITH LARGE HAIL AND PERHAPS DAMAGING
WINDS ARE POSSIBLE DURING THE MORNING HOURS OVER EASTERN KANSAS AND
NORTHEAST OKLAHOMA. HOWEVER...THE MOST INTENSE THUNDERSTORMS WILL
LIKELY DEVELOP ALONG THE COLD FRONT DURING THE EARLY AFTERNOON
HOURS FROM WESTERN MISSOURI INTO NORTH CENTRAL ARKANSAS. AS THE
COLD FRONT AND UPPER DRY SURGE SPREAD RAPIDLY EASTWARD DURING THE
LATE AFTERNOON AND EVENING...THE ACTIVITY WILL LIKELY SPREAD
QUICKLY INTO MIDDLE MISSISSIPPI RIVER VALLEY BETWEEN 08/20Z AND
09/03Z.  

...EASTERN NEBRASKA AND SOUTHERN IOWA...

POTENTIAL FOR ISOLATED TORNADIC SHALLOW SUPERCELLS IS RATHER HIGH
NEAR SURFACE LOW AND EAST ALONG SURFACE WARM FRONT DURING THE
DAY...DESPITE MARGINAL INSTABILITY AND WEAKER VERTICAL WIND SHEAR. 
DIURNAL HEATING WITHIN THE DRY SLOT OVER KANSAS WILL CREATE STEEP
LOW LEVEL LAPSE RATES...WHICH WILL INTERSECT THE NARROW MOISTURE
TONGUE NEAR THE SURFACE LOW.    

A PUBLIC WEATHER OUTLOOK...MKCPWOMKC...WILL BE ISSUED AROUND 1000Z.
 
..CRAVEN.. 04/08/99

NNNN


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