Flash Flood Warning 62, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
315 AM CDT SAT SEP 1 2001

MODELS CONTINUE TO BE IN GOOD AGREEMENT ON MAINTAINING A WET PATTERN
ACROSS THE LOWER MISSISSIPPI VALLEY REGION THROUGH LABOR DAY. THEY
ARE ALSO IN GOOD GENERAL AGREEMENT THAT HEAVY RAIN WILL DEVELOP OVER
THE NORTHWEST HALF OF THE AREA TODAY...AND WILL EXTEND THE FLASH
FLOOD WATCH ACCORDINGLY.

00Z RUNS OF AVN/ETA INDICATE A MID LEVEL SHORTWAVE TROF WILL SLOWLY
TRANSLATE EASTWARD FROM CNTRL TX TO THE ARKLAMISS REGION BY LATE
SUNDAY. THE AVN IS A BIT FARTHER NORTH WITH 850-700MB CLOSED
LOW...BUT SEEMS A BIT TOO BULLISH WITH QPF (SO SURPRISE WITH AVN).
IN ANY CASE...GOOD INFLOW FROM THE WRN GULF WILL EXIST AHEAD OF THE
MID LEVEL TROF AXIS WITH PRECIP WATER CONTINUING AOA 2 INCHES. GOOD
UPPER DIVERGENCE ASSOC WITH RIGHT ENTRANCE OF UPPER LEVEL JET OVER
THE TN VALLEY WILL PROVIDE SUPPORT FOR HEAVY RAIN DEVELOPMENT OVER
NE LA/SE AR/NWRN MS TODAY. IN ADDITION...MESOSCALE CONVECTIVE VORTEX
(ON SMALLER SCALE THAN PRIMARY SHORTAVE TROF) NOTED ON KSHV 88-D
NOTED ATTM ENTERING WRN LA WILL PROVIDE ADDITIONAL SUPPORT AS IT
MOVES EASTWARD IN CONFLUENT FLOW...AND SHOWER/TSTMS ARE CURRENTLY
INCREASING OVER WRN CO/PARISHES OF FORECAST AREA. ANTECEDENT SOIL
CONDITIONS CONTINUE TO WORSEN AND FLASH FLOOD GUIDANCE NUMBERS ARE
GENERALLY DOWN TO 1.5 TO 2.5 IN/HR IN WATCH AREA. THANKS TO SHV AND
LZK FOR COORDINATION ON WATCH.

EXPECT CONVECTION TO BE MORE BROKEN IN COVERAGE OVER SE PORTIONS OF
THE AREA WITH LESSER CHANCE FOR TSTM TRAINING. WILL GO WITH HIGHEST
(CATEGORICAL) POPS NW GROUPINGS THRU TONIGHT...WITH MENTION OF
THREAT FOR LOCALLY HEAVY RAIN IN ALL ZONES TODAY. BY LATE SUNDAY
INTO LABOR DAY...EXPECT BEST DYNAMICS WILL SHIFT FARTHER SOUTHEAST
(MODELS CONSISTENT IN THIS FORECAST) AND WILL PLACE HIGHER POPS SE
ZONES.

IN THE EXTENDED...00Z RUNS OF AVN/MRF/UKMET PROVIDE NO REASON TO
CHANGE THE CURRENT WET EXTENDED FORECAST.

PRELIM NUMBERS...
JAN 85/73/85/72 9774
MEI 85/72/85/72 7684

.JAN...
MS...FFA TODAY ZNS 018-019-025>029-034>037-040>042-047-053-059>061
LA...FFA TODAY ALL ZONES.
AR...FFA TODAY ALL ZONES.

43

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
021200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
521 AM CDT SAT SEP 01 2001

...THUNDERSTORMS...
THUNDERSTORMS WILL OCCUR TODAY AND TONIGHT OVER THE JACKSON
FORECAST AREA. THUNDERSTORMS ARE NOT EXPECTED TO BE SEVERE...BUT
SOME MAY PRODUCE TORRENTIAL RAINFALL...FREQUENT LIGHTNING
STRIKES...AND WIND GUSTS TO 35 MPH. THE AIRMASS OVER THE REGION
CONTINUES TO BE VERY MOIST AND SOMEWHAT UNSTABLE...AND SUPPORTIVE
OF SCATTERED TO NUMEROUS THUNDERSTORMS THROUGH TONIGHT.

...FLOODING...
TORRENTIAL RAINFALL...NEAR THREE INCHES PER HOUR...MAY OCCUR OVER
EXTREME SOUTHEAST ARKANSAS...PORTIONS OF NORTHEAST
LOUISIANA...ALONG WITH WESTERN AND NORTH CENTRAL PORTIONS OF
MISSISSIPPI. THIS WILL INCLUDE LOCATIONS GENERALLY WEST AND NORTH
OF A BUDE...TO MAYERSVILLE...TO KOSCIUSKO...TO WALTHALL LINE.
SOILS IN THIS REGION ARE NEAR SATURATION...AND SUCH HEAVY
RAINFALL COULD CAUSE FLOODING OF SMALL STREAMS AND LOW-LYING
AREAS. ELSEWHERE...ACROSS CENTRAL AND EASTERN PORTIONS OF
MISSISSIPPI...RAINFALL WILL NOT BE AS WIDESPREAD...BUT LOCALLY
HEAVY RAINFALL WILL CAUSE PONDING OF WATER ON ROADWAYS AND
LOW-LYING AREAS.

MOTORISTS SHOULD EXERCISE EXTREME CAUTION ON ROADWAYS AND NOT
DRIVE INTO WATER OF UNKNOWN DEPTH...ESPECIALLY AT NIGHT...WHEN IT
IS DIFFICULT TO GAUGE THE DEPTH OF WATER.

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL
SHOULD NOT BE NEEDED THROUGH TONIGHT.

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/JAN. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.