Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 290943
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
445 AM CDT FRI APR 29 2016

...SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAIN WILL BE AN
INCREASING THREAT IN THE SHORT TERM...

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...A STALLED BOUNDARY
RUNNING FROM WEST TO EAST ACROSS THE NORTHERN PORTION OF THE AREA
THIS MORNING EXTENDS WAY BACK WEST THROUGH THE RED RIVER
VALLEY...WHERE AN INCOMING DISTURBANCE IS CURRENTLY USING THE
BOUNDARY TO HELP SPARK VIGOROUS THUNDERSTORM DEVELOPMENT OUT THAT
DIRECTION. THIS DISTURBANCE WILL GLANCE ACROSS NORTHWEST PORTIONS OF
OUR REGION TODAY AND SHOULD TRIGGER THUNDERSTORMS FURTHER EAST (IN
THE VICINITY OF THE PINE BLUFF AR TO CLARKSDALE MS TO GREENVILLE MS
AREA) LATE MORNING TO EARLY AFTERNOON. BY THAT TIME HIGH ATMOSPHERIC
LAPSE RATES AND PLENTY OF LOW LEVEL MOISTURE AND SURFACE WARMTH WILL
CONTRIBUTE TO IMPRESSIVE INSTABILITY OF AT LEAST 1500-2000 J/KG
MLCAPE. HIRES MODELS SUGGEST MOST LIKELY ONE OR TWO POTENT TSTORM
LINE SEGMENTS INITIATING IN THIS VICINITY WILL ADVANCE
EAST/SOUTHEAST ACROSS AREAS MAINLY NORTH OF I-20 THROUGH THE
AFTERNOON AND INTO THE EARLY EVENING. SHEAR LEVELS COULD BE HIGH
ENOUGH FOR SUPERCELL OR TWO AND...GIVEN THE BOUNDARY IN THE
VICINITY...LOW LEVEL HELICITY COULD BE LOCALLY ENHANCED HIGH ENOUGH
TO MAKE A TORNADO A NON-NEGLIGIBLE THREAT. BUT THE MAIN RISKS WILL
BE DAMAGING WIND GUSTS AND LARGE HAIL ON THIS WILL BE THE FOCUS FOR
THE HWO/GRAPHICS. ALONG AND SOUTH OF THE I-20 CORRIDOR CONDITIONS
WILL MOSTLY LIKELY REMAIN DRY THROUGH THE DAY ALTHOUGH ANY ISOLATED
STORMS WILL STILL BE TROUBLING CONSIDERING HIGH INSTABILITY WILL
DEVELOP BY AFTERNOON OWING TO MAX TEMPS FLIRTING WITH THE 90 DEGREE
MARK.

AFTER THIS EVENING ATTENTION WILL BE TURNING BACK TO THE WEST AS THE
MAIN UPPER DISTURBANCE (WHICH SENT THE EARLIER PIECE OF ENERGY OUR
WAY) BEGINS SWINGING INTO THE ARKLATEX. EXPECTING THIS SYSTEM TO GET
MORE VIGOROUS THUNDERSTORMS GOING OUT TO OUR WEST OVERNIGHT WITH
SOME HIRES AND SHORT TERM MODEL MEMBERS SUGGESTING THIS ACTIVITY
COULD IMPINGE ON AREAS ALONG AND WEST OF THE MS RIVER...MAINLY AFTER
MIDNIGHT. WE WILL HAVE TO MONITOR CLOSELY TRENDS OF MODEL SOLUTIONS
REGARDING LATE TONIGHT...BUT CONFIDENCE IS PRETTY HIGH THE STRONGEST
STORMS WILL REMAIN OUTSIDE OF THE FORECAST AREA THROUGH
DAYBREAK.

BUT THE SITUATION FOR SATURDAY INTO SATURDAY NIGHT WILL LIKELY BRING
SOME WEATHER TROUBLES FOR THE REGION AS THE DISTURBANCE GRADUALLY
SHEARING OUT JUST TO OUR NORTH SLOWLY PUSHES A FRONT TOWARD THE
REGION. AS THIS OCCURS IMPRESSIVE AND PROLONGED GULF MOISTURE
TRANSPORT WILL SET UP INTO OUR REGION WITH THE GFS ADVERTISING
SEVERAL BATCHES OF THUNDERSTORMS IN AN AIR MASS OF 1.75 TO 2.00 INCH
PRECIPITABLE WATER VALUES. WIND SHEAR WILL REMAIN SUFFICIENT FOR AT
LEAST SOME SEVERE CONCERN...ESPECIALLY MIDDAY AND AFTERNOON
SATURDAY...BUT BY SATURDAY NIGHT I THINK THE HEAVY RAIN POTENTIAL
WILL BE THE LARGER WORRY AND LOCALIZED TOTAL RAIN AMOUNTS IN EXCESS
OF SEVERAL INCHES COULD DEFINITELY CAUSE AT LEAST MINOR FLOODING
ISSUES. THE HWO/GRAPHICS WILL BE UPDATED TO REFLECT THIS LATEST
THINKING. /BB/

.LONG TERM...SATURDAY THROUGH WEDNESDAY)...THE EXTENDED WILL FEATURE
EPISODIC SHOWERS AND THUNDERSTORMS INTO EARLY NEXT WEEK, FOLLOWED BY
IMPROVING CONDITIONS MIDWEEK. THE GOOD NEWS IN THE LONG TERM IS THAT
MODEL GUIDANCE IS BEGINNING TO COME INTO SOMEWHAT BETTER AGREEMENT,
AT LEAST ON THE PROSPECTS OF RAIN CHANCES CONTINUING INTO THE EARLY
PART OF NEXT WEEK. THERE ARE STILL SOME DIFFERENCES ON THE SPECIFICS
OF FRONTAL PLACEMENT, WHICH WILL HAVE AN IMPACT ON THE TEMP
FORECAST.

TO START OFF THE PERIOD, BROAD TROUGHING IN THE NORTHERN STREAM OF
THE JET WILL BE SITUATED OVER THE WEST, WITH A SERIES OF MID LEVEL
SHORTWAVES FROM THE FOUR CORNERS THROUGH THE GREAT LAKES REGION. THE
SUBTROPICAL JET WILL ALSO BE IN PLAY, EXTENDING ACROSS NORTHERN
MEXICO INTO THE NORTHERN GULF. AT THE SURFACE, A COLD FRONT WILL BE
ORIENTED SSW/NNE NEAR OR ALONG THE NW BORDER OF THE CWA.

HEADING INTO EARLY NEXT WEEK, UPPER FLOW WILL BECOME MORE ZONAL OVER
OUR REGION WITH THE NORTHERN STREAM OF THE JET REMAINING NORTH OF
THE AREA, GIVING THE SURFACE FRONT LITTLE IMPETUS TO MAKE
SUBSTANTIAL SOUTHWARD PROGRESS. AS A RESULT, THE FRONT WILL STALL/
WAFFLE/WAVER OVER THE CWA THROUGH TUESDAY RESULTING IN MULTIPLE
CHANCES FOR RAIN THROUGH THAT TIME AS MAINLY WEAK MID LEVEL
DISTURBANCES TRAVERSE THE REGION. THOUGH SUBSTANTIAL INSTABILITY
WILL BE POSSIBLE IN THE WARM SECTOR DURING THIS TIME FRAME, A LACK
OF FORCING AND WEAK SHEAR PRECLUDE BEING ABLE TO PICK OUT ANY
NOTABLE THREAT FOR STRONG STORMS DURING THIS TIME FRAME. HOWEVER,
FLOODING COULD BECOME MORE OF A CONCERN GIVEN MULTIPLE RAIN CHANCES
OVER THE NEXT SEVERAL DAYS.

BY MIDWEEK, UPPER TROUGHING WILL DEEPEN OVER THE ATLANTIC COAST,
SENDING A MORE POTENT SHORTWAVE THROUGH THE REGION. THIS WILL THRUST
THE COLD FRONT SOUTH OF THE AREA BY WEDNESDAY, MAKING FOR DRY
CONDITIONS MID TO LATE WEEK. /DL/

&&

.AVIATION...MVFR TO IFR FLIGHT CATS ARE EXPECTED IN MOST AREAS EARLY
THIS MORNING THROUGH 9 OR 10 AM DUE TO A COMBINATION OF LOW CEILINGS
AND REDUCED VISIBILITIES. EXPECT FLIGHT CATS TO IMPROVE TO VFR IN
MOST AREAS BY MIDDAY ALTHOUGH SCATTERED TO NUMEROUS THUNDERSTORMS
EXPECTED IN THE AFTERNOON OVER THE GLH/GWO/CBM/GTR CORRIDOR COULD
CAUSE MAJOR ISSUES AND BRIEF IFR CONDITIONS AND GUSTY WINDS. WINDS
WILL BE MAINLY FROM THE SOUTH AND SOUTHEAST AND A LITTLE GUSTY IN
THE MIDDAY TO AFTERNOON...BUT MAY HAVE A TENDENCY TO BE A LITTLE
MORE ERRATIC NORTH OF I-20 AROUND THUNDERSTORM ACTIVITY. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       89  67  84  66 /  29  21  52  74
MERIDIAN      88  66  86  67 /  34  17  26  55
VICKSBURG     88  70  83  66 /  29  46  71  75
HATTIESBURG   89  69  87  70 /  14   6  24  46
NATCHEZ       88  71  82  67 /  15  35  65  73
GREENVILLE    81  68  81  65 /  74  63  66  66
GREENWOOD     82  66  82  66 /  74  48  56  70

&&

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

$$

BB/DL



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