Severe Thunderstorm Warning 509, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
236 PM CST FRI NOV 15 2002

FORECAST CHALLENGES FOR THIS PACKAGE...CLOUD COVER AND TEMPS. FREEZE
POTENTIAL SUNDAY NIGHT.

CURRENTLY...COMPLEX OF SHOWERS AND THUNDERSTORMS THAT AFFECTED THE
CWA THIS MORNING HAS MOVED INTO ALABAMA. AT 100 PM...THUNDERSTORMS
HAD DEVELOPED OVER THE SOUTHERN AND EASTERN PORTIONS OF THE CWA
AHEAD OF A COLD FRONT WHICH EXTENDED FROM JUST WEST OF TUPELO
SOUTHWESTWARD OVER JACKSON AND JUST WEST OF MCCOMB. THUNDERSTORMS
MAY REACH SEVERE LIMITS OVER SOUTHEASTERN ZONES THROUGH ABOUT 6PM.
LINGERING LIGHT SHOWERS/DRIZZLE ARE SCATTERED ACROSS THE REMAINDER
OF THE CWA.

TONIGHT...THE COLD FRONT WILL EXIT THE CWA LEAVING LIGHT SHOWERS AND
DRIZZLE SCATTERED THROUGHOUT THE MUCH OF THE REGION. COLD AIR
ADVECTION WILL BEGIN IN EARNEST AS NORTH-NORTHWESTERLY WINDS TAKE
HOLD. TEMPERATURE-WISE...USING MAV GUIDANCE WITH LOWS AT OR JUST
ABOVE 40.

SATURDAY AND SATURDAY NIGHT...RAW DAY ON TAP. CLOUDY..BREEZY
CONDITIONS WILL PREVAIL WITH NOT MUCH OF A DIURNAL SWING IN
TEMPERATURES. STICKING CLOSE TO THE MAV GUIDANCE WITH MUCH OF THE
CWA PEAKING IN THE UPPER 40S AND SOUTHERNMOST ZONES REACHING THE LOW
50S. ANY LINGERING LIGHT SHOWERS OR DRIZZLE WILL DISSIPATE BY
MIDDAY. POTENTIAL FOR FIRST FALL FREEZE EXISTS AS TEMPERATURES WILL
DROP TO NEAR THE FREEZING MARK IN MOST LOCATIONS. AS MENTIONED IN
PREVIOUS DISCUSSIONS...MITIGATING FACTORS WILL BE PARTIAL CLOUD
COVER AND WINDS BETWEEN 5 AND 10 KTS.

SUNDAY AND SUNDAY NIGHT...MIX OF SUN AND CLOUDS WITH BELOW NORMAL
TEMPERATURES. NOT AS RAW AS SATURDAY AS WINDS WILL PROGRESSIVELY
BECOME LIGHTER DURING THE DAY. USING A BLEND OF MAV/MEX
TEMPERATURES. BY SUNDAY NIGHT...CLEAR SKIES AND CALM WINDS WILL
RESULT IN THE COLDEST MORNING OF THE SEASON TO THIS POINT. MODEL
GUIDANCE SUGGESTS THAT WEAK SOUTHWESTERLY FLOW WILL MANIFEST ITSELF
JUST ABOVE THE SURFACE. BELIEVE THAT LOW TEMPERATURE GUIDANCE IS
AFFECTED BY THIS FLOW RESULTING IN LOWS ONLY REACHING THE 30-35F
RANGE. HOWEVER IT IS EXPECTED THAT THE SURFACE BOUNDARY LAYER WILL
BECOME DECOUPLED...ALLOWING PRIME RADIATIONAL COOLING CONDITIONS AND
LOWS RANGING FROM THE UPPER 20S TO LOW 30S.

IN THE EXTENDED...MODEL GUIDANCE AGREES ON CALM CONDITIONS WITH
BELOW NORMAL TEMPERATURES THROUGH ABOUT MIDWEEK. THEREAFTER THERE IS
SOME DIVERGENCE IN SOLUTIONS. THE EUROPEAN...GFS...CANADIAN...AND
NOGAPS ARE IN GENERAL AGREEMENT WITH A LARGE SCALE RIDGE OVER THE
WESTERN STATES AND TROUGH OVER THE EASTERN STATES.
PERIODICALLY...SHORTWAVE TROUGHS ARE EJECTED FROM A LOW OVER THE
GULF OF ALASKA THAT MOVE ALONG THE RIDGE IN THE WEST AND THROUGH THE
BASE OF THE LONG WAVE TROUGH IN THE EAST. THE AFOREMENTIONED MODEL
GUIDANCE DOES NOT INDICATE THE THE NORTHERN JET STREAM WILL ACT IN
CONCERT WITH THE SOUTHERN JET STREAM TO AMPLIFY ANY PARTICULAR
WAVE...HOWEVER THE UKMET INDICATES THAT THIS PHASING WOULD OCCUR
WITH A DEEPENING TROUGH MOVING INTO THE MIDWEST BY MIDWEEK.  THE
UKMET IS A DEPARTURE FROM PREVIOUS FORECASTS...BUT IT IS NOTEWORTHY
AS A REDUCTION IN CONFIDENCE FOR THE FORECAST FROM MIDWEEK ONWARD.
AT THIS POINT...CONFIDENCE IS PLACED WITH THE
EUROPEAN...GFS...CANADIAN ...AND NOGAPS WITH TEMPERATURES MODERATING
TO AT OR SLIGHTLY ABOVE NORMAL THROUGH WEEKS END. A MODEL SHIFT
TOWARD THE UKMET SOLUTION WOULD RESULT IN A MORE ACTIVE PATTERN FROM
MID TO LATE WEEK...HOWEVER THERE IS PLENTY OF TIME TO MONITOR ANY
SUCH SHIFT.

PRELIMINARY NUMBERS.
JAN EB 043/048 031/050 029 25410
MEI EB 044/049 031/050 027 25630

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

25/17

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
161200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
1133 AM CST FRI NOV 15 2002

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS

.DAY ONE...

...THUNDERSTORMS...
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE...MAINLY
ACROSS AREAS EAST OF I-55 THROUGH 5 PM. ISOLATED SEVERE STORMS
WILL BE POSSIBLE THROUGH THE SAME TIME FRAME...GENERALLY ALONG
AND SOUTHEAST OF A LINE FROM BROOKHAVEN TO TAYLORSVILLE TO
MERIDIAN. ANY SEVERE STORMS THAT DEVELOP WILL BE CAPABLE OF
PRODUCING QUARTER TO DIME SIZE HAIL AND DAMAGING WIND GUSTS TO 60
MPH. ISOLATED TORNADOES CANNOT BE RULED OUT EITHER...MAINLY OVER
EXTREME SOUTHERN SECTIONS OF THE OUTLOOK AREA.

THIS THUNDERSTORM ACTIVITY IS IN RESPONSE TO A COLD FRONT THAT
WILL MOVE ACROSS THE AREA THIS AFTERNOON AND EVENING. COLD
TEMPERATURES ALOFT AND A VERY STRONG JET STREAM WILL COMBINE WITH
THE SURFACE COLD FRONT TO PRODUCE THUNDERSTORMS THIS AFTERNOON.
THIS INTENSIFYING SYSTEM WILL BE EAST OF THE AREA LATER THIS
EVENING PUTTING A END TO OUR THUNDERSTORM CHANCES.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS...MAY BE REQUIRED THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...
A MUCH COLDER AIRMASS WILL SETTLE OVER THE LOWER MISSISSIPPI
RIVER VALLEY SATURDAY IN THE WAKE OF THE COLD FRONT. MUCH OF THE
AREA COULD EXPERIENCE A FREEZE SUNDAY AND MONDAY MORNINGS.
TEMPERATURES FROM THE MIDDLE 20S TO LOWER 30S SHOULD BE
EXPECTED...WITH THE COLDEST READINGS ON MONDAY MORNING.

IN ADDITION...COLDER TEMPERATURES AND WINDS OF 15 TO 25 MPH ON
SATURDAY WILL PRODUCE BLUSTERY CONDITIONS OVER THE ENTIRE WATCH
AREA.

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