Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 231308
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
808 AM CDT WED APR 23 2014

.UPDATE...THE DENSE FOG ADVISORY WAS CANCELED AND WEATHER GRIDS WERE
UPDATED TO REFLECT LATEST FOG DISTRIBUTION AND LATEST TEMPERATURE
TRENDS.

SOME FOG REMAINS ACROSS THE MISSISSIPPI RIVER VALLEY AND NE
LOUISIANA PARISHES THIS MORNING THAT AT TIMES HAS BEEN DENSE BUT THE
TEMPORAL SCOPE OF DENSE FOG OBSERVATIONS WILL NOT NECESSITATE AN
ADVISORY IN THIS AREA. CONVERSELY...THE DENSE FOG ADVISORY THAT WAS
IN EFFECT FOR SE MS HAS BEEN CANCELED AS RECENT OBSERVATIONS SHOWN
THE ONCE DENSE FOG DISSIPATING QUICKLY. HOURLY TEMP AND DEWPOINT
TRENDS WERE UPDATED SLIGHTLY WITH GOING TRENDS. ALL UPDATES ARE OUT.
/ALLEN/


&&

.PREV DISCUSSION... /ISSUED 430 AM CDT WED APR 23 2014/

SHORT TERM...TODAY THROUGH THURSDAY NIGHT...IT WILL BE A FOGGY
START TO THE DAY IN MANY PLACES ACROSS THE REGION...ESPECIALLY
ACROSS SOUTHEASTERN PORTIONS OF MS. THE WEAK FRONT WHICH MOVED
THROUGH YESTERDAY FAILED TO MAKE A BIG PUSH TOWARD THE COAST AND THE
STALLING AND WASHING OUT OF THE FEATURE IN SOUTHERN ZONES IS
PRODUCING AN ENVIRONMENT OF LIGHT WINDS AND SUBTLE MOISTURE
CONVERGENCE CONDUCIVE FOR FOG. WE HAVE HOISTED A DENSE FOG ADVISORY
IN EFFECT THROUGH 9 AM FOR AREAS ROUGHLY ALONG AND SOUTHEAST OF A
BROOKHAVEN TO MERIDIAN LINE WHERE FOG SHOULD BE THICKEST AND LESS
PATCHY. IN OTHER AREAS WHERE PATCHY DENSE FOG WILL STILL BE POSSIBLE
WE WILL ALLOW THE HWO AND GRAPHICS TO COVER RISKS.

AFTER MORNING FOG AND LOW CLOUDS BURN OFF IN THE SOUTHERN HALF OF
ZONES ANTICIPATE A NICE AND WARM DAY WITH WINDS GENERALLY 10 MPH OR
LESS AROUND HIGHS AROUND 80. WEAK HIGH PRESSURE PARTLY RESPONSIBLE
FOR THE GOOD WEATHER TODAY WILL BE TRANSITIONING OFF TO THE EAST
TONIGHT WHICH WILL TURN FLOW BACK TO THE SOUTH...ALTHOUGH THESE
WINDS SHOULD REMAIN RATHER LIGHT AS WELL. DECENT MOISTURE NOT TOO
FAR TO OUR SOUTH WILL BE IMPORTED BACK NORTH INTO SOUTHERN ZONES
LATE TONIGHT INTO EARLY THURSDAY MORNING IN THE FORM OF LOW STRATUS
CLOUDS AND PERHAPS A LITTLE FOG. LOW TEMPERATURES WILL BE SLIGHTLY
ABOVE AVERAGE.

TOMORROW THE BOTTOM END OF AN FAST-MOVING DISTURBANCE WILL BE HEADED
AT THE REGION...INCREASING CLOUD COVER AND SOUTHERLY WINDS. WIND
SPEEDS AND GUSTS WILL DEFINITELY BE HIGHEST ACROSS THE ARKLAMISS
DELTA ALTHOUGH NOT TO THE LEVEL WHERE A WIND ADVISORY WOULD BE
NECESSARY. DESPITE SCATTERED CLOUDS TEMPS SHOULD BE ABLE TO TOP OUT
IN THE VERY WARM MID 80S IN SOME SPOTS. A PACIFIC FRONTAL SYSTEM
COINCIDENT WITH THE INCOMING TROUGH AXIS SHOULD BE KICKING UP
SHOWERS AND THUNDERSTORMS TO OUR WEST IN THE AFTERNOON AS MOISTURE
TRIES TO QUICKLY RECOVER UP THE AXIS OF THE MS RIVER AHEAD OF THE
SYSTEM. THE BEST FORCING WITH THE SYSTEM SHOULD BE WELL TO OUR NORTH
AND THERMAL MID LEVEL CAPPING PUSHING NORTH FROM THE COAST LIKELY
PROHIBITIVE OF STORMS SOUTH OF I-20. MODELS HAVE SLOWED DOWN A
LITTLE WITH BRINGING THE CONVECTION INTO THE REGION...WHICH IS A
POSITIVE DEVELOPMENT IF WE ARE TRYING TO MINIMIZE THE SEVERE WEATHER
RISK. BUT CONSENSUS STILL SUGGESTS 1000-1500 ML CAPE AND SUFFICIENT
SHEAR FOR A BROKEN SQUALL LINE OR MAYBE EVEN A SUPERCELL OR TWO IN
AREAS MAINLY ALONG AND NORTHWEST OF A WINNSBORO LA...TO YAZOO
CITY...TO EUPORA MS LINE IN THE LATE AFTERNOON THROUGH MID EVENING
HOURS. THE MAIN RISKS SHOULD BE HAIL AND DAMAGING WIND GUSTS.
ACTIVITY SHOULD WANE IN INTENSITY FURTHER EAST YOU GO IN THE
FORECAST AREA WITH PRECIP EXITING WELL BEFORE DAYBREAK FRIDAY. /BB/

LONG TERM...FRIDAY THROUGH WEDNESDAY...BROAD RIDGING WILL BE IN
PLACE BY FRIDAY MORNING FOLLOWING THE PASSAGE OF A COLD FRONT TO THE
NORTH THURSDAY. AS THE END OF THE WEEK PROGRESSES...THIS RIDGING
WILL BECOME A LITTLE GREATER OVER THE AREA WHICH SHOULD RESULT IN
HIGHS IN THE 80S...LOWS IN THE 60S AND GENERALLY DRY WEATHER.

OUR NEXT BIG SYSTEM WILL AFFECT THE REGION FOR THE END OF THE
WEEKEND INTO EARLY NEXT WEEK. EARLY SUNDAY MORNING...A LARGE UPPER
LEVEL LOW DEVELOPING ACROSS THE SOUTHWESTERN UNITED STATES WILL
EJECT NORTHEASTWARD AND TAKE ON A BIT OF A NEGATIVE TILT. AS THIS
OCCURS...A SFC LOW WILL ALSO DEVELOP ON THE LEESIDE OF THE ROCKIES
AND TRACK WITH THIS UPPER LOW ACROSS THE SOUTH CENTRAL PLAINS AND
INTO MISSOURI BY MONDAY. THE ECMWF IS A LITTLE MORE INTENSE WITH
THIS SFC LOW THAN THE GFS ON THE 00Z RUN...BUT BOTH KEEP IT
SUB-1000MB. AHEAD OF THIS...MOISTURE WILL INCREASE ACROSS THE REGION
WITH MODEL PW VALUES AROUND 1.6-1.8 INCHES DEPICTED THROUGH MONDAY.
THIS WILL FALL AROUND THE 99TH PERCENTILE WITH REGARDS TO
CLIMATOLOGY FOR THIS TIME OF YEAR...MEANING THIS SHOULD LEAD TO
EFFICIENT HEAVY RAINFALL. IT APPEARS THAT SOME LOCATIONS COULD SEE
ANYWHERE FROM 1-3 INCHES OF RAIN(LOCALLY HIGHER AMOUNTS) DURING THE
SUNDAY THROUGH TUESDAY TIME PERIOD. IN ADDITION...MODELS SHOW THE
POTENTIAL FOR MULTIPLE ROUNDS OF STORMS FROM ABOUT SUNDAY
AFTERNOON/NIGHT THROUGH MONDAY BEFORE TAPERING OFF LATE MONDAY NIGHT
INTO EARLY TUESDAY AS THE FRONT PASSES THROUGH. WHILE THE DETAILS
WILL CERTAINLY CHANGE OVER THE COURSE OF THE NEXT SEVERAL
DAYS...PARAMETERS LOOK GOOD FOR ALL TYPES OF SEVERE WEATHER DURING
THIS TIME. VERTICAL TOTALS INCREASE TO AROUND 29-30C BY SUNDAY
AFTERNOON AND INSTABILITY WONT BE AN ISSUE AS MODELS BRING MID 60S
DEWPOINTS INTO THE REGION...WITH EVEN SOME 70 DEGREE DEWPOINTS. IT
LOOKS LIKE THE BETTER INSTABILITY/IN TERMS OF MOST UNSTABLE AND
SBCAPE/ WILL COME ON MONDAY ACROSS THE ENTIRE AREA WITH VALUES
AROUND 2500-3000J/KG. PLENTY OF SHEAR WILL BE AVAILABLE AS LOW LEVEL
VALUES WILL BE AROUND 30-40KTS AND DEEPER LAYER SHEAR WILL BE AROUND
40-50KTS. WILL KEEP MONITORING THIS OVER THE NEXT SEVERAL DAYS AND
WILL REMAIN MENTIONING THIS IN THE HWO/GRAPHICS.

THE RAIN WILL EXIT THE REGION DURING THE MORNING HOURS TUESDAY BUT
THE LARGE UPPER LOW AND SFC LOW WILL CONTINUE TO SPIN ACROSS THE
MID-MISSISSIPPI RIVER VALLEY REGION THROUGH AT LEAST THE END OF THE
PERIOD. BOTH THE GFS AND ECMWF MOVE IT VERY SLOWLY TO THE EAST
THROUGH THE END OF THE WEEK...LEAVING THE SOUTHEASTERN UNITED STATES
UNDER LARGE SCALE TROUGHING. THIS WILL LEAD TO COOLER...BELOW
NORMAL...TEMPERATURES INTO THE EARLY DAYS OF MAY. /28/

&&

.AVIATION...
MVFR TO IFR FLIGHT CATS EXPECTED ALONG AND SOUTH OF I-20
THIS MORNING DUE TO FOG AND LOW CLOUDS. ANTICIPATE IMPROVEMENT TO
VFR CONDITIONS PROBABLY LATEST THIS MORNING IN SOUTHEASTERN MS...BUT
AT LEAST BY 10 AM ALL AREAS SHOULD BE VFR. WINDS WILL BE FROM THE
NORTHEAST TO EAST AND GENERALLY LESS THAN 10 KTS. SUB VFR CONDITIONS
WILL AGAIN BE POSSIBLE LATE TONIGHT INTO THURSDAY IN SOUTHERN ZONES
THANKS TO LOW CLOUDS AND STRATUS. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       82  55  84  63 /   0   1   8  23
MERIDIAN      82  51  84  60 /   0   1   8  26
VICKSBURG     82  57  84  61 /   0   3  12  23
HATTIESBURG   84  56  84  63 /   0   3   8  10
NATCHEZ       83  59  82  63 /   0   5   8  11
GREENVILLE    79  57  84  59 /   0   1  26  47
GREENWOOD     79  54  84  59 /   0   1  16  51

&&

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

$$








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