Area Forecast Discussion
Issued by NWS Mobile, AL

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FXUS64 KMOB 190412
AFDMOB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
1012 PM CST THU DEC 18 2014

.UPDATE...THE AREA OF LIGHT RAINFALL THAT WAS OVER SOUTHEAST
MISSISSIPPI MUCH OF THE AFTERNOON HAS NOW NEARLY DISSIPATED...
ALTHOUGH THERE MAY BE A FEW SPRINKLES LEFT OVER IN SOME AREAS OF
SOUTHEAST MISSISSIPPI AND SOUTHWEST ALABAMA THIS EVENING.
GENERALLY...NO PCPN IS EXPECTED OVERNIGHT...BUT TOWARD DAYBREAK AND
ESPECIALLY INTO FRIDAY MORNING AS WEAK SFC LOW PRESSURE DEVELOPS OVER
THE GULF TO OUR SOUTH AND A WEAK UPPER LEVEL SHORTWAVE PASSES TO THE
NORTH. THIS WILL RESULT IN INCREASING ISTENTROPIC LIFT AND WIDESPREAD
RAINFALL ACROSS THE REGION FRIDAY AND FRIDAY NIGHT. WITH THE SFC LOW
BEING WELL TO THE SOUTH...NOT EXPECTING ANY THUNDERSTORMS WITH THE
PASSAGE OF THIS SYSTEM AS MENTIONED BY PREVIOUS SHIFT.
OTHERWISE...FOR THE REST OF TONIGHT MOSTLY CLOUDY TO CLOUDY
SKIES...LIGHT NORTHEAST WINDS AND TEMPS FALLING INTO THE LOW 40S
NORTHERN COUNTIES TO MID TO UPPER 40S SOUTHERN COUNTIES (AROUND 50
IMMEDIATE COAST). NO CHANGES/AMENDMENTS REQUIRED. 12/DS

&&

.AVIATION...
19.00Z TAF CYCLE...CLOUD COVER HAS LOWERED AS EXPECTED THIS
EVENING...WITH CEILINGS AROUND 5000 KFT ATTM. DO NOT REALLY EXPECT
THAT BASES WILL LOWER MUCH MORE...AND IF THEY DO ARE EXPECTED TO
REMAIN AT VFR CRITERIA. AREA OF RAIN TO THE WEST OF THE TAF SITES
EARLY THIS EVENING HAS GENERALLY DISSIPATED...ALTHOUGH A LIGHT
SPRINKLE IS POSSIBLE OVER PARTS OF INTERIOR SOUTHEAST MISSISSIPPI AND
SOUTHWEST ALABAMA THIS EVENING. VFR CONDITIONS ARE EXPECTED TO
PERSIST TONIGHT. RAIN IS FORECAST TO DEVELOP ACROSS COASTAL AREAS BY
EARLY FRIDAY MORNING AND CONTINUE THROUGH MIDDAY. PERIODS OF MODERATE
TO HEAVY RAIN MAY RESULT IN TEMPORARY MVFR VSBYS/CIGS THROUGH THE
MORNING. 12/DS

&&

.PREV DISCUSSION... /ISSUED 334 PM CST THU DEC 18 2014/

SHORT TERM [TONIGHT THROUGH FRIDAY AFTERNOON]...A SMALL AREA OF
RAIN HAS HELD TOGETHER FAIRLY WELL THIS AFTERNOON ACROSS SOUTH
CENTRAL MS. THIS ACTIVITY CONTINUES TO MOVE EAST AND WILL AFFECT
PORTIONS OF INLAND SE MS/SW AL THIS AFTERNOON AND EARLY EVENING.
GUIDANCE CONTINUES TO SHOW THIS ACTIVITY DIMINISHING THIS
EVENING...BUT BASED ON RADAR TRENDS HAVE INCREASED THE RAIN CHANCES
OVER THE FAR WESTERN ZONES FOR THE REST OF THE AFTERNOON AND WILL
KEEP A 30% CHANCE FOR THIS EVENING AS WELL. AS THIS AREA OF RAIN
DIMINISHES THIS EVENING...WE WILL LIKELY SEE A BREAK IN THE PRECIP.
HOWEVER...IT WILL BE SHORT LIVED AS THE MORE SIGNIFICANT SHORTWAVE
NOW OVER THE SOUTHWEST STATES/NORTHERN MEXICO QUICKLY MOVES EAST.
THIS SHORTWAVE IS NOW FORECAST TO DEAMPLIFY AS IT BECOMES EMBEDDED
IN THE FAST WSW FLOW ALOFT. DUE TO THE WEAKER NATURE OF THE UPPER
SYSTEM...THE WELL ADVERTISED SFC LOW/TROUGH THAT DEVELOPS OFF THE TX
COAST TONIGHT INTO FRIDAY MORNING IS NOW FORECAST TO BE MUCH WEAKER
AS IT MOVES EAST ACROSS THE NW GULF. NEVERTHELESS...INCREASING UPPER
LEVEL DIVERGENCE ASSOCIATED WITH A 125-135 KT UPPER LEVEL JET TO OUR
NORTH COMBINED WITH INCREASING ISENTROPIC LIFT IN THE 300-310K LAYER
WILL RESULT IN RAIN DEVELOPING ACROSS THE REGION FRIDAY
MORNING...LIKELY OVER SOUTHERN AND WESTERN PORTIONS OF THE FORECAST
AREA...WITH THE RAIN SPREADING NORTH AND EAST THROUGH THE DAY.
REMOVED ALL MENTION OF THUNDER GIVEN THAT WE NOW STAY IN THE COOL
SECTOR AND WE NO LONGER ANTICIPATE ANY STRONG THUNDERSTORM ACTIVITY.
THE COMBINATION OF THE CLOUDS AND RAIN WILL RESULT IN A CHILLY DAY
WITH HIGHS NOT EXPECTED TO CLIMB OUT OF THE LOW TO MID 50S IN THE
WESTERN HALF OF THE AREA...WITH UPPER 50S FURTHER EAST. IT IS
POSSIBLE THAT SOME LOCATIONS ACROSS SW AL/SE MS MAY NOT CLIMB OUT OF
THE UPPER 40S. THIS FORECAST LEANED TOWARD THE COLDER MET GUIDANCE
WHICH IS COOLER THAN THE GFS BASED MAV GUIDANCE. LOWS TONIGHT WILL
BE IN THE 40S. 34/JFB

[FRIDAY NIGHT THROUGH SATURDAY]...THE WEAK UPPER LEVEL SHORTWAVE
APPROACHING THE MISSISSIPPI RIVER VALLEY FROM THE WEST FRIDAY
EVENING WILL CONTINUE TO MOVE EAST AND DEAMPLIFY FURTHER ACROSS THE
EASTERN CONUS. AN AREA OF SURFACE LOW PRESSURE FORMING OVER THE
NORTHEAST GULF OF MEXICO FRIDAY EVENING WILL ALSO MOVE EAST...
REACHING THE NORTH CENTRAL GULF WATERS SATURDAY MORNING. THE LOW
WILL THEN STALL AND WEAKEN INTO AN INVERTED SURFACE TROUGH FOR THE
REMAINDER OF THE SHORT TERM. THE FORECAST AREA WILL REMAIN WEDGE
BETWEEN THE APPROACHING SURFACE LOW AND A LARGE SURFACE HIGH
PRESSURE ACROSS THE EASTERN CONUS...MAINTAINING A LIGHT AND CHILLY
NORTHEASTERLY WIND FLOW.

EXPECT LIKELY TO DEFINITE RAIN CHANCES TO CONTINUE THROUGH FRIDAY
NIGHT...FOLLOWED BY ISOLATED TO SCATTERED PRECIP SATURDAY MORNING.
THE PRECIP WILL TAPER OFF WEST OF THE TOMBIGBEE RIVER IN THE
AFTERNOON...BUT FEW REMAINING VERY LIGHT RAIN SHOWERS OR SPRINKLES
WILL PERSIST THROUGH SATURDAY NIGHT AS THE INVERTED SURFACE TROUGH
REMAINS OVER THE GULF.

LOWS BOTH FRIDAY AND SATURDAY NIGHTS WILL FALL INTO THE LOW TO MID
40S INLAND AREAS...WITH UPPER 40S TO LOWER 50S ALONG THE IMMEDIATE
COASTAL SECTIONS. HIGHS ON SATURDAY WILL RANGE FROM 56 TO 61
DEGREES. /22

LONG TERM [SUNDAY THROUGH THURSDAY]...THE PLAINS UPPER TROF
AMPLIFIES INTO A LONGWAVE TROF THROUGH TUESDAY THEN TAKES ON A
NEGATIVE TILT TUESDAY NIGHT INTO WEDNESDAY WHILE ADVANCING INTO THE
EASTERN STATES. A SURFACE LOW ASSOCIATED WITH THIS SYSTEM PASSES
WELL TO THE NORTH AND BRINGS A COLD FRONT THROUGH THE AREA MAINLY
TUESDAY NIGHT. WHILE THE SHEAR IS NOT ALL THAT IMPRESSIVE
CURRENTLY...THERE IS THE POTENTIAL FOR 0-3 KM MUCAPES AROUND 500
J/KG OVER THE COASTAL COUNTIES AND GIVEN THE STRUCTURE OF THE SYSTEM
MENTIONED SOME STRONG STORMS POSSIBLE MAINLY ON TUESDAY IN THE
HAZARDOUS WEATHER OUTLOOK. WILL HAVE MAINLY SMALL POPS ON SUNDAY
INCREASING TO CHANCE POPS BY TUESDAY THEN DRY CONDITIONS FOLLOW FOR
WEDNESDAY. /29

AVIATION...
18.18Z KMOB/KBFM AND KPNS TAF CYCLE
WHILE CLOUD COVER WILL GRADUALLY TRANSITION FROM HIGH LEVEL BASES
THIS AFTERNOON TO LOWER CIGS TONIGHT...VFR CONDITIONS ARE EXPECTED TO
PERSIST WITH CIGS OF AROUND 5000 FT EXPECTED TONIGHT. RAIN IS
FORECAST TO DEVELOP ACROSS COASTAL AREAS BY EARLY FRIDAY MORNING AND
CONTINUE THROUGH MIDDAY. PERIODS OF MODERATE TO HEAVY RAIN MAY RESULT
IN TEMPORARY MVFR VSBYS/CIGS THROUGH THE MORNING. 34/JFB

MARINE...A WEAK SURFACE LOW IS FORECAST TO MOVE ACROSS THE NORTHERN
GULF FRIDAY INTO EARLY SATURDAY...BUT WILL NOW LIKELY STAY SOUTH OF
THE MARINE AREA. THIS RESULTS IN NORTHEAST TO EAST WINDS INCREASING
ACROSS THE COASTAL WATERS WITH A SLIGHT BUILD IN SEAS. THE LOW IS
FORECAST TO WEAKEN WITH A SURFACE TROUGH LINGERING SOUTH OF THE
MARINE AREA OVER THE WEEKEND. THIS RESULTS IN WINDS BECOMING LIGHT
AND VARIABLE BY SUNDAY NIGHT INTO MONDAY. A SOUTHERLY FLOW DEVELOPS
MONDAY NIGHT INTO TUESDAY AHEAD OF ANOTHER APPROACHING COLD FRONT.
THE FRONT IS CURRENTLY PROJECTED TO MOVE THROUGH THE MARINE AREA ON
TUESDAY...WITH A STRONG OFFSHORE FLOW DEVELOPING TUESDAY NIGHT INTO
WEDNESDAY. 34/JFB

&&

.PRELIMINARY POINT TEMPS/POPS...
MOBILE      46  53  46  60  48 /  20  80  80  30  20
PENSACOLA   47  55  50  61  50 /  05  70  70  40  20
DESTIN      50  59  49  60  50 /  05  50  50  50  20
EVERGREEN   41  56  44  59  44 /  10  60  80  40  20
WAYNESBORO  43  52  40  58  42 /  30  80  80  20  05
CAMDEN      40  55  41  57  41 /  10  60  90  30  20
CRESTVIEW   43  58  44  62  45 /  05  50  60  50  20

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
FL...NONE.
MS...NONE.
GM...NONE.
&&

$$







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