Severe Thunderstorm Warning 366, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
400 PM CDT FRI JUL 20 2007

.SHORT TERM...
THE LARGE ANTICYCLONIC RIDGING THAT HAS BEEN AFFECTING OUR WEATHER
FOR THE PAST COUPLE OF DAYS IS CONTINUING TO BREAK DOWN AND MOVE
FURTHER SOUTH AS A LARGE TROUGH IS BUILDING IN OVER THE EASTERN
CONUS.  A COLD FRONT CURRENTLY OVER TENNESSEE IS THE LEADING EDGE OF
THIS TROUGH...WHICH WILL SLIGHTLY CHANGE OUR WEATHER PATTERN AROUND
HERE FOR THE WEEKEND.  THIS FRONT IS FIRING UP A LINE OF
THUNDERSTORMS OVER NORTHERN MISSISSIPPI AND IS FORECAST TO MOVE
SOUTHBOUND.  INSTABILITY AHEAD OF THE FRONT REMAINS FAIRLY HIGH WITH
MLCAPE VALUES AT OR ABOVE 2000 J/KG.  SURFACE TEMPERATURES NEAR 90
DEGREES AND HIGH DEWPOINTS WILL ALSO HELP IN THE DEVELOPMENT OF
THESE STORMS.

FOR TONIGHT...MOST OF THE NORTHERN COUNTIES IN THE JAN CWA WILL HAVE
SEEN RAINFALL.  HOWEVER...THE DRIER AIR BEHIND THE COLD FRONT WILL
BE SLOWER TO ARRIVE AS THE MAJORITY OF THE RAINFALL IS WELL AHEAD OF
THE ACTUAL FRONT.  THE HUMIDITY WILL REMAIN HIGH TONIGHT THROUGH
MOST OF MISSISSIPPI...THEN BEGIN TO DECREASE OVER NORTHERN ZONES
AROUND MIDDAY ON SATURDAY.  THUNDERSTORMS WILL BE MOST PREVALENT
OVER CENTRAL AND SOUTHERN ZONES ON SATURDAY SINCE THAT WILL BE THE
BEST AREA FOR FORCING.  ALTHOUGH WIDESPREAD SEVERE WEATHER IS NOT
ANTICIPATED AT THIS TIME...SOME OF THESE STORMS MAY BRIEFLY BECOME
SEVERE WITH DAMAGING WIND GUSTS BEIG THE MAIN THREAT.  TEMPERATURES
SHOULD GENERALLY BE IN THE UPPER 80S IN NORTHERN ZONES TO LOWER 90S
IN SOUTHERN ZONES.  POPS WERE RAISED FOR AREAS SOUTH OF INTERSTATE
20 ON SATURDAY TO ACCOUNT FOR THE PASSAGE OF THIS FRONT. /DH/

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY...
THERE SEEMS TO BE SOME DIFFERENCE IN OPINION OF THE UPPER FLOW FOR
THE LONG TERM. THE LATEST 12Z GFS HAS THE UPPER PATTERN WILL BE
CHANGING FROM A NORTHERLY FLOW TO A SOUTHWESTERLY FLOW...WHICH WILL
BE UNDER THE INFLUENCE OF A CLOSED UPPER LOW OVER THE MIDDLE
MISSISSIPPI VALLEY. THE POSITION OF THE CLOSED LOW NEARLY MATCHES THE
EUROPEAN MODEL. THE EUROPEAN TRANSITIONS FROM A NORTHERLY FLOW TO A
LIGHT FLOW WITH A CLOSED LOW OVER THE MID TO UPPER MISSISSIPPI
VALLEY. THE ENSEMBLES TRANSITIONED FROM A NORTHERLY FLOW TO A FLAT
UPPER RIDGE OVER THE REGION FOR NEXT WEEK. WILL GO CLOSER TO A
COMPROMISE WITH THE EUROPEAN AND GFS MODELS FOR THE LONG TERM.

FOR SATURDAY NIGHT THE FRONT WILL PUSH SOUTH TO THE COAST BY EARLY
SUNDAY. THE RAINS WILL END FROM THE NORTH. THE UPPER FLOW WILL CHANGE
FROM A NORTHERLY FLOW TO A LIGHT AND VARIABLE FLOW WITH A WEAKNESS
IN THE HEIGHT FIELDS OVERHEAD. DRYER NORTHERLY FLOW WILL PUSH INTO
THE REGION FOR SUNDAY INTO MONDAY WITH VERY LITTLE CHANCE FOR RAIN
EXPECTED. THIS SEEMED TO BE THE CONSENSUS AMONG THE
MODELS...INCLUDING THE UKMET.  WITH THE DRIER AIR FOR BOTH SUNDAY
AND MONDAY TEMPS SHOULD DIP MAINLY INTO THE LOWER AND MIDDLE
60S...WHICH WILL BE AROUND 5 TO 10 DEGREES BELOW NORMAL FOR THIS
TIME OF YEAR. HIGHS FROM SUNDAY AND MONDAY WILL BE IN THE UPPER 80S
TO LOWER 90S.

FOR TUESDAY THROUGH FRIDAY MODELS START TO STRAY FROM EACH OTHER ON
SOLUTIONS...EXCEPT FOR THE GFS AND EUROPEAN...WHICH BRINGS SOME
LOWER CONFIDENCE IN THE FORECAST...ESPECIALLY WHEN THE GFS SUDDENLY
PUSHES UPPER LOW TO THE MIDDLE MISSISSIPPI VALLEY.

NOW THE 12Z GFS RETROGRADES THE CLOSED UPPER LOW FROM THE EASTERN
SEABOARD TO THE MIDDLE MISSISSIPPI VALLEY ON A TUESDAY TO FRIDAY
TIME PERIOD. THIS WILL RESULT IN BETTER RETURN MOISTURE COMING EARLIER TO
THE REGION ON WEDNESDAY NIGHT AS SOUTHWEST FLOW BEGINS TO DEVELOP
OVER THE REGION. THE GFS SHOWS SOME CONVECTIVE FEED BACK ON THURSDAY
ACROSS THE REGION. OUR CHANCES OF RAIN WILL CONTINUE THROUGH FRIDAY
AS SHORT WAVES ROTATE AROUND THE UPPER CLOSED LOW ACROSS THE REGION.
THE GFS STARTS TO BRING IN SOME RETURN MOISTURE ACROSS THE REGION
FOR LATE TUESDAY THROUGH FRIDAY. THE BEST PRECIPITABLE WATER WILL
COME IN FOR LATE THURSDAY INTO FRIDAY...WHEN PWATS WILL BE AROUND 2
INCHES. UPPER RIDGING WILL RETROGRADE BACK TO THE ROCKIES. SO AS THE UPPER
LOW MOVES TOWARD THE MIDDLE MISSISSIPPI VALLEY...THIS WILL OPEN THE GULF
UP AND GRADUALLY INCREASE OUR RAIN CHANCES DURING THE SECOND HALF OF
THE WORK WEEK. MODELS SEEM TO BE TRENDING BACK AND FORTH WITH THE
CLOSED UPPER LOW...SO DO NOT HAVE VERY HIGH CONFIDENCE WITH THIS SOLUTION
EVEN THOUGH THE GFS IS TRENDING TOWARD THE EUROPEAN.

AS FAR AS GUIDANCE GOES...WENT WITH THE COOLER GUIDANCE TEMPS WITH
LOWS IN THE LOWER TO MIDDLE 60S FOR SUNDAY THROUGH TUESDAY MORNINGS
WITH THE DRYER AIRMASS IN PLACE. MORNING LOWS WILL BEGIN TO MODERATE
AS LOW LEVEL MOISTURE INCREASES ACROSS THE REGION AS THE UPPER LOW
RETROGRADES TOWARD THE MIDDLE MISSISSIPPI VALLEY. MADE ONLY A SLIGHT
ADJUSTMENT AS LOWS RISE TO THE UPPER 60S AND LOWER 70S.

AS FAR AS GUIDANCE IS CONCERNED...FOR HIGHS WENT WITH THE SLIGHTLY
COOLER ROUND OF THE 12Z MEX RUN. LOW LEVEL 850 MB TEMPS WILL BE
AROUND 13-14C...WHICH CORRESPONDS TO HIGHS GENERALLY IN THE UPPER 80S
TO LOWER 90S. THERE WAS SOME MIDDLE 80S FROM MODEL OUTPUT...WHICH
SEEMED TO BE A LITTLE ON THE COOL SIDE. SO MADE SLIGHT ADJUSTMENT TO
MEX AND ENSEMBLE GUIDANCE. AS FAR AS POPS ARE CONCERN WITH CONFIDENCE
NOT REAL HIGH CUT DOWN POPS AROUND 20 PERCENT DURING THE WEEK. /17/

&&

.AVIATION...
WIDESPREAD IFR CONDITIONS HAVE BEEN PRESENT IN NORTHERN MISSISSIPPI
LATE THIS AFTERNOON AS WIDESPREAD CONVECTION HAS DEVELOPED.
VISIBILITIES MAY BE REDUCED TO HALF A MILE OR LESS AS THUNDERSTORMS
MOVE THROUGH...AND ABOUT 2 TO 4 MILES IN AREAS THAT ARE RECEIVING
MODERATE RAIN. FOR AREAS SOUTH OF GREENWOOD...MAINLY VFR CONDITIONS
SHOULD PREVAIL UNTIL CONDITIONS DETERIORATE LATER THIS EVENING. GUSTY
WINDS UP TO 35 KNOTS WILL BE POSSIBLE AT THE LEADING EDGE OF
THUNDERSTORMS...BUT SHOULD BE VERY BRIEF.

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       70  89  64  92 /  48  47   7   4
MERIDIAN      70  90  63  92 /  52  41   7   3
VICKSBURG     71  89  66  92 /  47  52   6   4
HATTIESBURG   72  90  67  93 /  41  69  21   3
NATCHEZ       72  88  67  88 /  42  69  21   6
GREENVILLE    69  89  63  91 /  55  27   4   3
GREENWOOD     67  90  63  90 /  57  23   6   3

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

DH/17

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
320 PM CDT FRI JUL 20 2007

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
212030-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-RICHLAND-
MADISON-FRANKLIN-CATAHOULA-TENSAS-CONCORDIA-BOLIVAR-SUNFLOWER-
LEFLORE-GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-LOWNDES-CHOCTAW-
OKTIBBEHA-WASHINGTON-HUMPHREYS-HOLMES-ATTALA-WINSTON-NOXUBEE-
ISSAQUENA-SHARKEY-YAZOO-LEAKE-NESHOBA-KEMPER-WARREN-HINDS-RANKIN-
SCOTT-NEWTON-LAUDERDALE-CLAIBORNE-COPIAH-SIMPSON-SMITH-JASPER-
CLARKE-JEFFERSON-ADAMS-LINCOLN-LAWRENCE-JEFFERSON DAVIS-COVINGTON-
JONES-MARION-LAMAR-FORREST-
320 PM CDT FRI JUL 20 2007

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

.DAY ONE...TONIGHT AND SATURDAY

DEEP GULF MOISTURE WILL COMBINE WITH AFTERNOON HEATING AND A
DEEPENING UPPER LEVEL TROUGH TO DEVELOP SCATTERED THUNDERSTORMS OVER
THE OUTLOOK AREA THIS EVENING AND INTO THE OVERNIGHT HOURS. A COLD
FRONT WILL DROP INTO THE NORTHERN COUNTIES OF THE OUTLOOK AREA AFTER
MIDNIGHT TONIGHT AND SHOULD HELP DEVELOP ADDITIONAL THUNDERSTORMS. A
FEW THUNDERSTORMS MAY BECOME STRONG AND PRODUCE WIND GUSTS TO 45 MPH
AND LOCALLY HEAVY DOWNPOURS...ALONG WITH FREQUENT LIGHTNING. A FEW OF
THESE STORMS MAY BECOME SEVERE WITH WINDS GUSTS OF 60 MPH OR GREATER.

ADDITIONAL THUNDERSTORM ACTIVITY CAN BE EXPECTED ON SATURDAY AS WELL
AS THE COLD FRONT MOVES FURTHER SOUTH. THE MAJORITY OF THE ACTIVITY
SHOULD BE ALONG AND SOUTH OF INTERSTATE 20...AND THE MAIN THREATS
WOULD LIKELY BE GUSTY WINDS OF 50 MPH...SMALL HAIL...AND FREQUENT
LIGHTNING STRIKES...ALONG WITH HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...SATURDAY NIGHT THROUGH THURSDAY

NO SIGNIFICANT HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.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 NEEDED THIS EVENING OR SATURDAY AFTERNOON...BUT
SHOULD NOT OTHERWISE BE NEEDED THROUGH NEXT FRIDAY...JULY 27.

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

DFH/MRM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
334 PM CDT FRI JUL 20 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0228 PM     TSTM WND DMG     5 W WEST POINT          33.61N 88.73W
07/20/2007                   CLAY               MS   LAW ENFORCEMENT

            S.O. REPORTED TREE DOWN

&&

BURSE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
341 PM CDT FRI JUL 20 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0249 PM     TSTM WND DMG     COLUMBUS                33.51N 88.40W
07/20/2007                   LOWNDES            MS   EMERGENCY MNGR

            CD REPORTED TREE DOWN...ALSO TWO HOMES STRUCK BY
            LIGHTNING

&&

BURSE