Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 011544
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
1044 AM CDT TUE SEP 1 2015

.UPDATE...

THE FORECAST IS GENERALLY ON TRACK WITH LITTLE ADJUSTMENT NEEDED FOR
THE NEAR TERM OTHER THAN TO NUDGE HIGH TEMPERATURES DOWN SLIGHTLY
OVER NE LA WHERE HIGHER LEVEL CLOUDINESS IS MORE PREVALENT. THE MID
LEVEL CAP DISCUSSED PREVIOUSLY WAS REVEALED BY THE 12Z JAN RAOB AND
WILL HELP TO LIMIT CONVECTIVE DEVELOPMENT THIS AFTERNOON...BUT
GREATER MID LEVEL MOISTURE INDICATED BY THE SHV RAOB SUPPORTS HIGHER
THUNDERSTORM CHANCES OVER NE LA/SE AR AND HAVE NOT ADJUSTED POPS.
THE MICROBURST CHECKLIST THIS MORNING SUGGESTS A LOW RISK FOR STRONG
WIND GUSTS WITH ANY STORMS...WITH LOW LEVEL LAPSE RATES BEING THE
BIGGEST CONTRIBUTOR TO THIS POTENTIAL. /EC/

&&

.AVIATION...THE MID AND HIGH LEVEL CLOUDS STREAMING UP FROM THE
SOUTHWEST WAS BROKEN ENOUGH TO ALLOW FOR BRIEF PATCHY FOG MVFR
VSBYS THIS MORNING BUT CONDITIONS HAVE IMPROVED AND VFR CONDS WERE
BEING REPORTED AREAWIDE AT 14Z. VFR CONDS WL PREVAIL AT MOST TAF
SITES THROUGH TONIGHT BUT PATCHY FOG DEVELOPMENT LEADING TO MVFR
VSBYS WL BE PSBL AGAIN 09Z-13Z. VERY ISOLD AFTN/EARLY EVNG SHRA/TSRA
DEVELOPMENT WL BE PSBL MAINLY WEST OF I-55 TODAY. THESE SHOULD NOT
IMPACT TAF SITES. LIGHT/VARIABLE WINDS WILL CONTINUE THROUGH TONIGHT.
/22/

&&

.PREV DISCUSSION... /ISSUED 331 AM CDT TUE SEP 1 2015/

SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT... LATEST SATELLITE
VAPOR IMAGERY A WEAK SHEAR AXIS WHICH EXTENDED FROM THE SOUTHERN
PLAINS TO THE OHIO VALLEY. ALONG THE SHEAR AXIS A WEAK CLOSED LOW
WAS NOTED OVER SOUTHERN TEXAS...WESTERN ARKANSAS AND IN THE OHIO
VALLEY. AREA RADARS WERE PICKING UP SOME NORTHWARD MOVING ISOLATED
CONVECTION OVER SOUTH CENTRAL LOUISIANA. HIGH DEBRIS CLOUDS WERE
MOVING OVER THE CWA FROM CONVECTION OFF THE NORTHWEST GULF. THE
REGION WAS UNDER LARGE AMPLITUDE RIDGING OVER THE EASTERN CONUS WITH
594 DKM HIGH EAST OF FLORIDA. SURFACE HIGH PRESSURE WAS CENTERED THE
NORTHERN GULF.

925 MB TEMPS WILL BE FROM 25-26C FOR DAILY HIGHS IN THE LOWER TO
MIDDLE 90S. OVERALL LIGHT FLOW AT THE SURFACE AND ALOFT WILL KEEP
MOISTURE LEVELS ABOUT THE SAME EACH DAY WITH DEWPOINTS MIXING INTO
THE 60S EACH AFTERNOON. NIGHTLY LOWS WILL BE MAINLY IN THE LOWER 70S.

PWATS WILL HOLD STEADY ACROSS THE REGION RANGING FROM THE 1.7 EAST
TO NEAR 2 INCHES WEST NEAR THE SHEAR AXIS. THE WEAK SHEAR AXIS WILL
BE CLOSE ENOUGH TO THE CWA TO TRIGGER SOME ISOLATED DIURNAL
CONVECTION IN THE WEST FOR TODAY AND FOR MOST OF THE CWA ON
WEDNESDAY. SO COVERAGE WILL BE LIMITED BY MIDLEVEL CAPPING AND HIGH
PRESSURE CENTERED OVER THE NORTHERN GULF. THIS IS CONFIRMED BY THE
LACK OF ACTIVITY IN MOST OF THE HI-RES MODELS./17/

LONG TERM...THURSDAY THROUGH NEXT MONDAY...A WEAK UPPER LOW
MEANDERING NEAR THE REGION LATE IN THE WORK WEEK WILL ESSENTIALLY
BECOME ABSORBED BY ANOTHER UPPER LEVEL LOW DROPPING SOUTH ALONG THE
EAST COAST OF THE UNITED STATES OVER THE WEEKEND.  THE RESULT WILL
BE THE FORECAST AREA BECOMING WEDGED BETWEEN SAID UPPER LOW NOW
RESIDING ALONG THE SOUTHEAST COAST OF THE U.S. AND AN AMPLIFYING
UPPER RIDGE OVER THE SOUTHERN PLAINS AND MID-MISSISSIPPI RIVER
VALLEY.  MEANWHILE AT THE SURFACE...WEAK HIGH PRESSURE WILL BE IN
PLACE...PREDOMINATELY RESULTING IN EASTERLY FLOW ACROSS THE REGION
THROUGH MUCH OF THE PERIOD.

ALL OF THIS EQUATES TO TYPICAL LATE SUMMER HOT AND HUMID CONDITIONS
EXISTING ACROSS THE CWA DURING THE LONG TERM PORTION OF THE
FORECAST.  HIGHS EACH AFTERNOON WILL CLIMB INTO THE 90S...WITH LOWS
FALLING DOWN AROUND 70 EACH NIGHT.  ISOLATED TO SCATTERED SHOWERS
AND STORMS WILL DEVELOP DURING THE HEAT OF THE AFTERNOON...BUT WILL
QUICKLY DISSIPATE AROUND SUNSET EACH EVENING AS DAYTIME HEATING IS
LOST. /19/

&&

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

&&

$$


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