Severe Thunderstorm Warning 365, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
300 AM CDT SAT JUN 17 2000

IN THE UPPER LEVELS OF THE ATMOSPHERE A BROAD AREA OF HIGH PRESSURE
IS CENTERED OFF THE SOUTHEAST COAST WITH A WEAK AREA OF LOW PRESSURE
IN THE NORTHERN GULF. AT THE SURFACE AREA OF HIGH PRESSURE IS ALSO
CENTERED OFF THE SOUTHEAST COAST...WITH A SLOW MOVING COLD FRONT
EXTENDING FROM NORTHEAST TEXAS TO NORTHWEST ARKANSAS AND THROUGH THE
OHIO VALLEY. WATER VAPOR IMAGERY SHOWS PLENTY OF MOISTURE FEEDING
INTO THE AREA ON THE BACK SIDE OF THE HIGH. PRECIPITABLE WATER
READINGS WERE AROUND 2.2.00 INCHES AT 00Z. MODELS SIMILAR WITH THE
LARGE SCALE FEATURES...BUT THE AVN SEEMS TO CONTINUE TO HAVE THE
BEST HANDLE ON THE TRACK AND STRENGTH OF THE UPPER LOW AS WELL AS
THE MOISTURE FIELD OVER THE AREA.

THE UPPER LOW WILL CONTINUE TO MOVE WEST THROUGH TODAY...BECOMING
LESS OF A FACTOR IN OUR WEATHER. THE HIGH PRESSURE ALONG THE COAST
WILL START TO BUILD WESTWARD IN RESPONSE TO STRONG TROUGH MOVING
ALONG THROUGH THE GREAT LAKES AND THE NORTHEAST. MOISTURE LEVELS
WILL REMAIN HIGH AS FLOW CONTINUES OFF THE GULF. PWS WILL REMAIN IN
THE 1.75 TO 2.25 IN RANGE THROUGH 48 HOURS. THE FRONTAL BOUNDARY
WILL REMAIN NORTH OF THE FORECAST AREA AND MAKE VERY LITTLE
SOUTHWARD PROGRESS OVER THE NEXT TWO DAYS.

WITH NO PRIMARY FOCUSING MECHANISM IN PLACE...CONVECTION WILL BE
FUELED MAINLY BY DAYTIME HEATING. SEVERAL LITTLE WEAK VORT MAXS
WILL ALSO MOVE ACROSS THE NORTHERN GULF AND ALONG THE COAST TO AID
IN DEVELOPMENT. MODELS HAVING SOME TROUBLE HANDLING THE SITUATION
ACROSS THE REGION. AVN KEEPS CATEGORICAL/LIKELY POPS THROUGH 48
HOURS WHILE THE OTHER MODELS ARE LESS AGGRESSIVE WITH LIKELY/CHANCE
POPS THROUGH SUNDAY. WILL TRIM AVN POPS AND GO WITH A BLEND OF POPS
AND TEMPS FROM FAN/FWC GUIDANCE..AS CATEGORICAL POPS SEEMS TOO HIGH WITH
DAYTIME HEATING AS THE ONLY TRIGGER.

QPF DISCUSSION: AVN MODEL HAS BEEN CONSISTENT WITH RISING
PRECIPITABLE WATER VALUES OF EXCEEDING 2 INCHES THROUGH SUNDAY
MORNING...WHILE THE ETA/NGM HAS AN AVERAGE VALUE OF 1.75 INCH. THE
AVN SEEMED TO BE A LITTLE DRY...QPF AMOUNTS OF .15 TO .45 INCH FOR
24 HOURS. THE ETA/NGM HAD .25 TO AROUND .75 INCH. NCEP HAD AMOUNTS
OF .25 TO .50 INCH...WITH THE HIGHER AMOUNTS IN THE NORTHWEST
SECTION. SO WITH THIS IN MIND WILL GO WITH NCEP WHICH IS A
COMPROMISE.

EXTENDED DISCUSSION:
WILL NOT MAKE ANY MAJOR CHANGES TO THE EXTENDED AT THIS TIME. WITH
THE STRENGTHENING OF THE BERMUDA HIGH ACROSS THE SOUTH EXPECT PRECIP
TO BECOME MORE SCATTERED IN NATURE WITH A RISE IN TEMPERATURES.

PRELIM NUMBERS...
JAN 088/072 087/072 087 6464
MEI 087/071 088/072 087 6464

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

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
180400-

AREA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
955 AM CDT SAT JUN 17 2000

AN UPPER LEVEL LOW WILL CONTINUE TO SPIN ITS WHEELS OFF THE
LOUISIANA AND MISSISSIPPI COASTS THROUGH TONIGHT. A COUPLE OF UPPER
LEVEL DISTURBANCES WILL MOVE ACROSS THE REGION LATER THIS AFTERNOON.
AS THESE DISTURBANCES INTERACT WITH THE AMPLE LOW LEVEL MOISTURE
DURING MAXIMUM DAYTIME HEATING...EXPECT SHOWERS AND THUNDERSTORMS TO
BECOME MORE NUMEROUS LATER TODAY.

MODERATE INSTABILITY WILL EXIST OVER THE LOWER MISSISSIPPI VALLEY
THROUGH LATE AFTERNOON...HOWEVER WIND SHEAR IS EXPECTED TO REMAIN
WEAK. AS COOLING ALOFT OCCURS FROM THE UPPER LEVEL DISTURBANCES...A
FEW THUNDERSTORMS MAY BECOME STRONG LATER TODAY. WIND GUSTS IN
EXCESS OF 40 MPH...SMALL HAIL AND VERY HEAVY RAINFALL WILL BE
POSSIBLE WITH THESE ISOLATED...STRONGER THUNDERSTORMS. HOWEVER...
...ORGANIZED SEVERE WEATHER IS NOT EXPECTED.

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

FOR MORE INFORMATION...PLEASE VISIT OUR INTERNET WEB SITE AT
HTTP://WWW.SRH.NOAA.GOV/JAN WHICH INCLUDES AN EXPERIMENTAL GRAPHICAL
HAZARDOUS WEATHER OUTLOOK.