Severe Thunderstorm Warning 634, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
230 PM CDT TUE SEP 5 2000

CHANCES LOOKING BETTER AND BETTER FOR PRECIPITATION IN THE
FORECAST...BUT NOTHING POINTING TO DROUGHT BUSTING RAIN.
FIRST...LET/S TAKE A LOOK AT THIS MORNING/S UPPER AIR ANALYSIS.
STUBBORN HIGH PRESSURE STARTING TO RELEASE IT/S GRIP OVER THE DEEP
SOUTH AS SOUTHERN END OF MEAN UPPER TROUGH OVER EASTERN CONUS/CN
SLOWLY PUSHES WEST. DECENT CLOSED UPPER LOW CENTERED OVER
NORTHEASTERN OR CREATING SOME HELPING SHOWERS OVER EASTERN
OR/WA...NORTHERN ID AND WESTERN MT AT THIS TIME. IN THE LOWER
LEVELS...HIGH PRESSURE JUST NORTH OF THE GREAT LAKES AND LOW
PRESSURE OVER NORTHEASTERN GULF HELPING TO CREATE A NICE NORTHERLY
BREEZE OVER LOWER MISSISSIPPI RIVER VALLEY...PUSHING IN COOLER AIR.
TEMPERATURES AS OF NOONTIME AROUND TEN DEGREES COOLER THAN PREVIOUS
DAYS. PRECIP H20 AMOUNTS SLOWLY ON THE INCREASE...BUT STILL NEAR
NORMAL OVER THE LOWER MISSISSIPPI RIVER VALLEY. VISIBLE SATELLITE
LOOPS SHOWING A PRETTY GOOD AREA OF ISENTROPIC SURGE CREATED STRATUS
OVER NE AR/TN INTO THE MID ATLANTIC STATES. OF GREATEST DEBATE IS
CURRENT POSITION OF SURFACE FRONT. NORTHERLY FLOW OVER THE LAST
SEVERAL DAYS HAS WIPED ANY SEMBLANCE OF A WIND SHIFT. CLOUD
SHIELD/LESSER HUMIDITIES OVER NORTHERN SECTIONS OF STATE..SO HOLDING
POSITION OVER NORTHERN SECTIONS OF STATE. STARTING TO SEE SOME
ACTION OVER SOUTHWEST AL...IN BETTER MOISTURE/LOW LEVEL CONVERGENCE
AND CLOSER TO BETTER DYNAMICS.

MODELS ALL LOOK TO BE INITIALIZED WELL IN THE SYNOPTIC
SCALE...THOUGH SHORTWAVE ON MODEL ANALYSIS/ SUPPOSEDLY OVER MS AT
THIS TIME IS EITHER MIS-ANALYZED OR IS BEING WASHED OUT BY MEAN
TROUGH AND SHORTWAVE OVER CENTRAL PLAINS. ALL SHORT RANGES MODELS
ADVERTISING THE CONTINUED BREAKING OFF AND MEANDERING WEST OF
SOUTHERN PORTION OF EASTERN TROUGH. MODELS ALSO CONSISTENT IN
SWITCHING LOW LEVEL FLOW TO A MORE EASTERLY DIRECTION WITH PRECIP
H20 AMOUNTS INCREASING TO 2.1" OVER SOUTHEASTERN SECTIONS OF STATE
BY WED NIGHT. BEST CONVERGENCE AND DYNAMICS LOOKS TO BE ALONG THE
COAST.

AVN MOS NUMBERS SEEM TO BE TOO COOL IN THE SHORT TERM...AND USING
NGM NUMBERS FOR A START. WILL PROBABLY DO SOME FINAGLING TO ACCOUNT
FOR CLOUD COVER. POPS...WILL GRADUALLY INCREASE THROUGH THE PERIOD
AS TROUGH SHIFTS WEST. WILL PUT BEST CHANCES SOUTHEAST THROUGH
PERIOD...STARTING WITH WIDELY SCATTERED TONIGHT SOUTHEAST...
INCREASING TO SCATTERED BY THURSDAY.

QPF DISCUSSION: AGREE WITH MODELS AND NCEP INDICATING A FEW BASIN
AMOUNTS OF .10 INCH OVER SERN PORTIONS FIRST 6 HOURS OF THIS
FORECAST AND THEN HINTING AT SIMILAR VALUES BLEEDING INTO THE SE
SECTIONS WEDNESDAY AFTERNOON(NGM A BIT OVERDONE). BETTER CHANCES OF
RAIN HOLD OFF UNTIL WEDNESDAY NIGHT OR THURSDAY.

IN THE EXTENDED...LOW LEVEL FLOW SWITCHING BACK TO SOUTHEAST TO
SOUTH BEGINNING OF EXTENDED WITH WEAK REMNANTS OF UPPER TROUGH
MEANDERING AROUND. BEST CHANCES FOR POPS LOOKS TO BE SOUTH WITH
CANADIAN/NOGAPS DECREASING CHANCES THROUGH EXTENDED. HPC THINKING IS
MRF...THUS MRF MOS OVERDONE. LOOKS LIKE A BELOW CLIMO FORECAST FOR
POPS WITH TEMPS ABOVE NORMAL. |

PRELIM NUMBERS:
JAN 073/092 069/089 071 0223
MEI 072/089 071/088 071 0234

.JAN...
AR...NONE.
LA...NONE.
MS...NONE.

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