Area Forecast Discussion
Issued by NWS Mobile, AL

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000
FXUS64 KMOB 080546
AFDMOB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
1146 PM CST SUN FEB 7 2016

.DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.

&&

.AVIATION...
06Z ISSUANCE...VFR FORECAST TO CONTINUE THROUGH THE FORECAST PERIOD.
CLEAR SKIES AND LIGHT W/SW PREVAIL TONIGHT. A COLD FRONT IS EXPECTED
TO MOVE ACROSS THE AREA MONDAY MORNING. WINDS WILL BECOME NORTHWEST
AND INCREASE TO 15-20 KNOTS WITH GUSTS TO AROUND 30 KNOTS ESPECIALLY
AFTER 18Z MONDAY. SCATTERED LOWER CLOUD DECKS AROUND 4-6 KFT AGL ARE
POSSIBLE MONDAY. /21

&&

.PREV DISCUSSION... /ISSUED 943 PM CST SUN FEB 7 2016/

DISCUSSION...SEE UPDATED INFORMATION FOR LAND AREAS BELOW.

UPDATE...THE FORECAST IS ON TRACK AND ONLY MADE SLIGHT ADJUSTMENTS
TO TEMPERATURES AND DEWPOINTS BASED ON THE LATEST TRENDS. MAINLY
CLEAR SKIES WITH LIGHT W/SW WINDS WILL OTHERWISE PERSIST TONIGHT.

WATER VAPOR IMAGERY AND RAP 500 MB ANALYSIS SHOW AN UPPER LEVEL LOW
IN THE VICINITY OF NORTHERN WI AND THE UPPER PENINSULA OF MICHIGAN
THIS EVENING. A STRONG 90-110 KT 500 MB JET WAS DIVING SOUTHWARD
ACROSS THE PLAINS STATES TO THE WEST OF THE TROUGH AXIS WITH AN
ASSOCIATED SURFACE COLD FRONT PUSHING ACROSS THE SOUTHERN PLAINS
STATES AND APPROACHING THE MID MISSISSIPPI VALLEY REGION. THE COLD
FRONT IS STILL ON TRACK TO QUICKLY MOVE THROUGH OUR REGION MONDAY
MORNING...WITH INCREASING NORTHWEST WINDS EXPECTED IN THE WAKE OF
FRONTAL PASSAGE LATE MONDAY MORNING INTO MONDAY AFTERNOON. A WIND
ADVISORY REMAINS IN EFFECT ACROSS INLAND AREAS MONDAY AFTERNOON...
AND ALONG THE IMMEDIATE COAST MONDAY AFTERNOON THROUGH MONDAY NIGHT
FOR EXPECTED FREQUENT GUSTS AROUND OR IN EXCESS OF 30 MPH. /21

PREV DISCUSSION... /ISSUED 426 PM CST SUN FEB 7 2016/

NEAR TERM /NOW THROUGH MONDAY/...FORECAST AREA IS POSITIONED
BETWEEN TWO WEATHER SYSTEMS. THE FIRST BEING A LOW PRESSURE SYSTEM
OFF THE COASTAL CAROLINA`S...LIFTING NORTH NORTHEAST AND THE SECOND
BEING A STRONG COLD FRONT SURGING SOUTHEAST ACROSS THE
CENTRAL/SOUTHERN PLAINS. THERE IS A STRONG PUSH BEHIND THE PLAINS
FRONT WITH SURFACE OBSERVATIONS SHOWING VERY STRONG NORTHWEST FLOW
FROM NEBRASKA...NORTHWARD ACROSS THE DAKOTAS...WHERE FORECASTERS
NOTE GUSTS RANGING FROM 35 TO 45 KNOTS. A FEW LOCALES IN THESE
STATES ARE SHOWING BETWEEN 50 AND 55 KNOTS AND THIS HAS BEEN THE
CASE FOR SEVERAL HOURS. A VERY STRONG SYSTEM INDEED. GIVEN THE
TRENDS SEEN UPSTREAM AND LATEST FORECAST LOW LEVEL WIND PROFILES IN
FORECAST SOUNDING DATA...FORECASTERS HAVE ISSUED A WIND ADVISORY FOR
MONDAY AFTERNOON AREA-WIDE. WILL MAINTAIN THIS ADVISORY INTO MONDAY
NIGHT ALONG THE IMMEDIATE COAST AS THE STRONG THERMAL GRADIENT/COLD
ADVECTION PATTERN BETWEEN THE LAND/SEA INTERFACE KEEPS WINDS HIGHER
THERE. WINDS WILL BE THE MAIN IMPACT FOR MONDAY.

THE ENSEMBLES ARE TIGHTLY CLUSTERED WITH AN ANOMALOUSLY LOW BASE TO
THE LONGWAVE TROF SETTING UP FROM ACROSS THE NORTHERN FLORIDA
PENINSULA TO THE SOUTHERN HALF OF MISSISSIPPI MONDAY AFTERNOON.
HEIGHTS ALOFT LOWER THROUGH THE DAY...SOME 3 TO 4 STANDARD
DEVIATIONS BELOW THE MEAN FROM GEORGIA TO MISSISSIPPI BY THE CLOSE
OF MONDAY AFTERNOON. GIVEN THE LOWERING 1000-850 MILLIBAR THICKNESS
VALUES MONDAY AFTERNOON...A NON-DIURNAL TEMPERATURE CURVE IS
ANTICIPATED...PROGRESSIVELY LOWERING THROUGH THE AFTERNOON IN THE
WAKE OF THE FRONTAL PASSAGE. AN INCREASE IN CLOUDS IS FORECAST FROM
NORTH TO SOUTH DURING THE DAY MONDAY...BUT THE DEPTH OF THE MOISTURE
ALOFT IS SHALLOW DENOTED BY CROSS-SECTION ANALYSES. THUS...ALTHOUGH
UPPER LEVEL STORM/DYNAMICS IS AN ANOMALY FOR THIS TIME OF YEAR...NOT
ANTICIPATING ANY MEASURABLE RAIN GIVEN THE SHALLOW RH STRATA ALOFT.
/10

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...CONTINUED WINDY
ALONG THE ESPECIALLY ALONG THE COAST AS GFS AND ECMWF DEPICT THE
TROPOSPHERIC FOLD STILL OVER THE AREA COURTESY OF THE POTENT UPPER
LEVEL TROUGH PROPAGATING OVER THE AREA. WINDS THOUGH MAY TAPER BACK
TO BREEZY IN OUR MORE PROTECTED INLAND WITH A MIXTURE OF SPOTTY WINDY
CONDITIONS IN MORE EXPOSED AREAS AND EVEN LIGHT WINDS MIXED IN WHERE
ENOUGH COOLING CAN OCCUR IN SHELTERED AREAS TO SET UP A SHALLOW
INVERSION. BUT IN GENERAL COLD AIR ADVECTION (CAA) CONTINUES
OVERNIGHT KEEPING LOWER AIRMASS WELL MIXED AND ALLOWING HIGHER WINDS
ALOFT TO MIX DOWN TO THE SURFACE. GFS HAS TEMPERATURES AT THE 850 MB
LEVEL BOTTOMING OUT AT BETWEEN -8 TO -10C ACROSS THE AREA. OVERNIGHT
LOWS THOUGH WON`T PLUMMET TOO FAR DUE TO THE EFFICIENT
MIXING...GENERALLY MID 20S TO NEAR 30 NORTHWEST OF THE I-65 CORRIDOR
AND NEAR 30 TO MID 30S SOUTHEAST.

WINDS WILL GRADUALLY DIMINISH TUESDAY AS THE UPPER LEVEL DISTURBANCE
DEPARTS THE AREA. DAYTIME HIGHS WILL PROBABLY TOP OFF IN THE 40S AND
PERHAPS LOW 50S CLOSER TO THE COAST. DRY...COOL WEATHER PERSISTS THEN
THROUGH WEDNESDAY NIGHT AS REGION REMAINS UNDER THE INFLUENCE OF THE
UPPER LEVEL LONGWAVE TROUGH...A REINFORCING SHOT OF COOLER AIR IS
PROGGED TO PUSH THROUGH WEDNESDAY. THE ECMWF AND GFS DIVERGE
SIGNIFICANTLY ON THE IMPACTS TO SENSIBLE WEATHER E.G., GFS FORECASTS
OVERNIGHT LOWS IN SOME LOCATIONS AS MUCH AS 6 TO 11 DEGREES COLDER
THAN THE ECMWF. THE CAA DOESN`T APPEAR THAT STRONG AT THIS TIME BUT
RADIATIONAL COOLING AND LIGHT WINDS WEDNESDAY NIGHT SHOULD PROVIDE
EFFICIENT COOLING SO TRENDED TEMPERATURES A LITTLE COOLER THAN THE
LAST FORECAST PACKAGE BUT NOT AS COOL AS THE GFS. /08

LONG TERM /THURSDAY THROUGH SUNDAY/...BY THURSDAY HEIGHTS START TO
RISE ALOFT AS THE SHORTWAVE TROUGH EJECTS TO THE NORTHEAST...FLOW
ALOFT GENERALLY BECOMES ZONAL BUT WE REMAIN MORE UNDER THE INFLUENCE
OF THE LONGWAVE TROUGH MORE THAN THE UPSTREAM RIDGE. ANOTHER COLD
FRONT APPROACHES THE AREA FRIDAY NIGHT. FAIRLY STRONG UPPER LEVEL
SHORTWAVE IN ADVANCE OF THE FRIDAY NIGHT FRONT COULD RESULT IN A
SLIGHT CHANCE OF RAIN THEN...BUT MORE LIKE A SPRINKLE. TEMPERATURE
SHOULD WARM INTO THE 60S FRIDAY...UPPER 50S AND LOW 60S SATURDAY AND
MAINLY 50S ON SUNDAY. WHILE LOWS WILL TREND UPWARD FROM THE MID 30S
TO LOW 40S FRIDAY MORNING TO 40S TO LOW 50S SATURDAY MORNING AND THEN
DOWNWARD INTO THE 30S AND LOW 40S ON SUNDAY MORNING. /08

MARINE...HAZARDOUS CONDITIONS FOR SMALL MARINE CRAFT TO DEVELOP
MONDAY AND CONTINUE INTO TUESDAY. A STRONG COLD FRONTAL PASSAGE
MONDAY MORNING IS LIKELY TO BRING GALE CONDITIONS AND HIGH SEAS IN
ITS WAKE MONDAY AFTERNOON...CONTINUING INTO EARLY TUESDAY. GALE
WATCHES HAVE BEEN UPGRADED TO WARNINGS ON THIS PACKAGE. DUE TO THE
STRONG NORTHWEST FETCH...SEAS WILL BE HIGHEST MONDAY NIGHT INTO
TUESDAY. SEAS BUILDING TO 5 TO 8 FEET NEAR SHORE BY MONDAY AFTERNOON
THEN 7 TO 10 FEET MONDAY NIGHT. WELL OFFSHORE...SEAS BUILD TO 8 TO
10 FEET BY MONDAY AFTERNOON AND 10 TO 13 FEET MONDAY NIGHT.
/10

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...WIND ADVISORY FROM NOON TO 6 PM CST MONDAY FOR ALZ051>060-
     261>264.

     WIND ADVISORY FROM NOON MONDAY TO 6 AM CST TUESDAY FOR ALZ265-
     266.

FL...WIND ADVISORY FROM NOON TO 6 PM CST MONDAY FOR FLZ201-203-205.

     WIND ADVISORY FROM NOON MONDAY TO 6 AM CST TUESDAY FOR FLZ202-
     204-206.

MS...WIND ADVISORY FROM NOON TO 6 PM CST MONDAY FOR MSZ067-075-076-
     078-079.

GM...SMALL CRAFT ADVISORY UNTIL NOON CST MONDAY FOR GMZ650-655-670-
     675.

     SMALL CRAFT ADVISORY FROM 1 PM TUESDAY TO 6 AM CST WEDNESDAY FOR
     GMZ630>635-650-655-670-675.

     GALE WARNING FROM NOON MONDAY TO 1 PM CST TUESDAY FOR GMZ630>635-
     650-655-670-675.

     SMALL CRAFT ADVISORY FROM 6 AM TO NOON CST MONDAY FOR GMZ630>635.

&&

$$

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