Severe Thunderstorm Warning 591, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
155 PM CDT SAT JUL 21 2001

ON WATER VAPOR IMAGERY FLAT UPPER RIDGE CONTINUED OVER THE LOWER
MISSISSIPPI VALLEY. A SERIES OF SHORT WAVES WERE MOVING SOUTHWARD
OVER THE REGION FROM THE NORTH...WHICH WAS TRIGGERING CONVECTION
OVER THE EASTERN HALF OF THE REGION. IN THE LOW LEVELS AN 850
MB EAST-WEST TROF EXTENDED OVER THE REGION. A SURFACE INVERTED TROF
WAS NOTED OVER THE EASTERN SECTION...FROM YESTERDAYS CONVECTIVE
ACTIVITY OVER ALABAMA. PRECIPITABLE WATER WAS RUNNING AROUND 1.75 TO
2.75 INCHES WITH DEWPOINTS IN THE MIDDLE 70S.

LOOKING AT THE SHORT TERM....SCATTERED AFTERNOON CONVECTION WILL END
BEFORE MIDNIGHT WITH LOSS OF DAYTIME HEATING AND DIMINISHING SURFACE
BOUNDARY. MID/UPPER RIDGE WILL GRADUALLY REBUILD ACROSS THE REGION
ON SUNDAY...EPECIALLY ON MONDAY...MOVING THE STRONGER SHORT WAVES
EAST OF THE REGION. THE AVN MODEL SEEMED TO BE A LITTLE SLOW IN THE
REBUILDING OF THE UPPER RIDGE AND THUS BRINGS IN HIGHER QPF AMOUNTS
OVER THE WEST HALF ON SUNDAY AND MONDAY...WHICH WAS DISCARDED.

WARMER DRYER AIR ALOFT WILL MOVE BACK INTO THE REGION FOR SUNDAY AND
MONDAY...AS LAPSE RATES WILL DECREASE...ALLOWING FOR ONLY ISOLATED
TO WIDELY SCATTERED CONVECTIVE ACTIVITY. EASTERLY SURFACE WINDS FOR
SUNDAY AND MONDAY WILL CUT OFF SEABREEZE POTENTIAL FROM THE SOUTH
AND DRY OUT THE AIRMASS SOME. PRECIPITABLE WATER WILL GO FROM AROUND
2 INCHES TO AROUND 1.5 INCHES BY MONDAY.

GUIDANCE LOOKS TO BE A LITTLE COOL FOR DAYTIME TEMPS IN SOME
AREAS...BUT WILL FAVOR MIDDLE 90S OVER THE WEST HALF AND LOW TO
MIDDLE 90S EAST FOR SUNDAY. ON MONDAY MIDDLE TO UPPER 90S WEST HALF AND
MIDDLE 90S EAST HALF AS THE MID/UPPER RIDGE ANCHORS ONTO THE REGION.
NIGHTTIME LOWS APPEAR TO BE ON TRACK. WILL PUT IN SUNDAY HEAT
INDICES OF 105 TO 110 IN NORTHEAST LOUISIANA...SOUTHEAST ARKANSAS
AND THE NORTHWEST DELTA AND AROUND 105 ELSEWHERE.

EXTENDED FORECAST...TUESDAY THROUGH SATURDAY...
MEDIUM RANGE MODELS SHOW THE RIDGE PULSING UP AND DOWN DURING THE
PERIOD...WHILE MAINTAINING IT PRESENCE. MRF DOES SHOW A CYCLONIC
SHEAR AXIS AFFECTING THE REGION FOR MIDWEEK AND A SHORT WAVE COMING
INTO THE REGION BY FRIDAY AND SATURDAY. THIS WILL OCCUR BEFORE THE
UPPER RIDGE WEAKENS AND A TROF DEEPENS OVER THE MISSISSIPPI VALLEY.
SO WITH SOUTHERLY INFLOW OVER THE REGION THROUGH THE PERIOD WILL
CONTINUE CHANCES OF AFTERNOON CONVECTION. POP WISE THE AVN MODEL
IS TOO HIGH FOR SUNDAY IN THE SOUTHWEST AND PORTIONS OF THE WEST. WILL
GO WITH LOW POPS FOR THE REGION.

PRELIM NUMBERS:
JAN 74/96/73/96/74 3211
MEI 72/94/72/96/73 3211

.JAN...
MS...NONE.
LA...NONE.
AR...NONE.
17

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
221200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
314 PM CDT SAT JUL 21 2001

...THUNDERSTORMS...
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THROUGH MID EVENING
GENERALLY ALONG AND SOUTHWEST OF A GREENWOOD, TO PICKENS,TO
JACKSON,TO LAUREL AND HATTIESBURG LINE. THIS INCLUDES MOST OF
WEST-CENTRAL AND SOUTHERN MISSISSIPPI AS WELL AS EXTREME
SOUTHEAST ARKANSAS AND NORTHEAST LOUISIANA. THE MAIN THREAT WILL
BE STRAIGHTLINE WINDS UPWARDS TO 60 MPH.
NORTHEAST OF THIS OF THIS LINE, WIDELY SCATTERED THUNDERSTORMS
ARE STILL POSSIBLE. HOWEVER, PREVIOUS STORMS HAVE STABILIZED THE
ATMOSPHERE SOMEWHAT AND ANY ADDITIONAL STORMS THROUGH THIS
EVENING ARE NOT EXPECTED TO BE SEVERE.

A SURFACE, OUTFLOW BOUNDARY WILL CONTINUE TO SLOWLY EAST
SOUTHWESTWARD ACROSS PORTIONS OF CENTRAL AND SOUTHERN MISSISSIPPI
THROUGH THIS EVENING. THE AIRMASS AHEAD OF THIS BOUNDARY IS VERY
MOIST AND UNSTABLE. SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE ALONG THIS BOUNDARY UNTIL AFTER SUNSET, AT WHICH TIME
THE LOSS OF DAYTIME HEATING SHOULD RESULT IN A DIMINISHING TREND
OF ANY STORMS.

EMERGENCY MANAGEMENT PERSONNEL AND SPOTTERS SHOULD NOT BE
REQUIRED THE REMAINDER OF THIS AFTERNOON OR THIS EVENING.

...FLOODING...
LOCALIZED HEAVY RAINFALL AMOUNTS OF 1 TO 2 INCHES IS POSSIBLE
FROM NEAR GREENWOOD, TO JACKSON, TO COLUMBIA AND HATTIESBURG.
SCATTERED STORMS THROUGH THIS EVENING WILL HAVE THE POTENTIAL TO
PRODUCE BRIEF, VERY HEAVY RAINFALL WHICH COULD RESULT IN
LOCALIZED URBAN STREET OR SMALL STREAM FLOODING.

...SEASONAL THREATS...
AFTERNOON TEMPERATURES IN THE 90S CONTINUE THROUGH THE LATER HALF
OF THIS AFTERNOON INTO EARLY THIS EVENING WITH HEAT INDICES OF
AROUND 105 DEGREES EXPECTED. HEAT INDICES IN THE MISSISSIPPI
DELTA REGION WILL CONTINE TO BE CLOSE TO 110 DEGREES THE
REMAINDER OF THIS AFTERNOON.

THOSE THAT WILL BE OUTSIDE DURING THESE CONDITIONS ARE ENCOURAGED
TO TAKE FREQUENT BREAKS IN THE SHADE OR INDOORS AND DRINK PLENTY
OF WATER.

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
323 PM CDT SAT JUL 21 2001

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ...COUNTY LOCATION....

0230 PM    POLKVILLE                 MS   WIND DAMAGE
07/21/01   SMITH                          S.O. REPORTED TREES
                                          DOWN.

0255 PM    1 S RALEIGH               MS   WIND DAMAGE
07/21/01   SMITH                          S.O. REPORTED TREES
                                          DOWN.

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
221200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
327 PM CDT SAT JUL 21 2001

...THUNDERSTORMS...
ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THROUGH MID EVENING
GENERALLY ALONG AND SOUTHWEST OF A GREENWOOD, TO PICKENS,TO
JACKSON,TO LAUREL AND HATTIESBURG LINE. THIS INCLUDES MOST OF
WEST-CENTRAL AND SOUTHERN MISSISSIPPI AS WELL AS EXTREME
SOUTHEAST ARKANSAS AND NORTHEAST LOUISIANA. THE MAIN THREAT WILL
BE STRAIGHTLINE WINDS UPWARDS TO 60 MPH.
NORTHEAST OF THIS OF THIS LINE, WIDELY SCATTERED THUNDERSTORMS
ARE STILL POSSIBLE. HOWEVER, PREVIOUS STORMS HAVE STABILIZED THE
ATMOSPHERE SOMEWHAT AND ANY ADDITIONAL STORMS THROUGH THIS
EVENING ARE NOT EXPECTED TO BE SEVERE.

A SURFACE, OUTFLOW BOUNDARY WILL CONTINUE TO MOVE SLOWLY
SOUTHWESTWARD ACROSS PORTIONS OF CENTRAL AND SOUTHERN MISSISSIPPI
TOWARDS NORTHEAST LOUSIIANA AND EXTREME SOUTHEAST ARKANASAS
THROUGH THIS EVENING. THE AIRMASS AHEAD OF THIS BOUNDARY IS VERY
MOIST AND UNSTABLE. SCATTERED SHOWERS AND THUNDERSTORMS WILL
CONTINUE ALONG THIS BOUNDARY UNTIL AFTER SUNSET, AT WHICH TIME
THE LOSS OF DAYTIME HEATING SHOULD RESULT IN A DIMINISHING TREND
OF ANY STORMS.

EMERGENCY MANAGEMENT PERSONNEL AND SPOTTERS SHOULD NOT BE
REQUIRED THE REMAINDER OF THIS AFTERNOON OR THIS EVENING.

...FLOODING...
LOCALIZED HEAVY RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE
FROM NEAR GREENWOOD, TO JACKSON, TO COLUMBIA AND HATTIESBURG.
SCATTERED STORMS THROUGH THIS EVENING WILL HAVE THE POTENTIAL TO
PRODUCE BRIEF, VERY HEAVY RAINFALL WHICH COULD RESULT IN
LOCALIZED URBAN STREET AND SMALL STREAM FLOODING.

...SEASONAL THREATS...
AFTERNOON TEMPERATURES IN THE 90S WILL CONTINUE THROUGH THE LATER
HALF OF THIS AFTERNOON INTO EARLY THIS EVENING WITH HEAT INDICES
OF AROUND 105 DEGREES EXPECTED. HEAT INDICES IN THE MISSISSIPPI
DELTA REGION WILL CONTINUE TO BE CLOSE TO 110 DEGREES THE
REMAINDER OF THIS AFTERNOON.

THOSE THAT WILL BE OUTSIDE DURING THESE CONDITIONS ARE ENCOURAGED
TO TAKE FREQUENT BREAKS IN THE SHADE OR INDOORS AND DRINK PLENTY
OF WATER.

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