Area Forecast Discussion
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000
FXUS62 KTAE 180906
AFDTAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
506 AM EDT SAT APR 18 2015

.NEAR TERM [REST OF TODAY]...

A FEW LINGERING SHOWERS AND STORMS ASSOCIATED WITH A PASSING
SHORTWAVE SHOULD EXIT OUR EASTERN ZONES BY DAYBREAK. MODEL
GUIDANCE SHOWS A BRIEF PERIOD OF MID-LEVEL DRYING FOR OUR CWA IN
THE WAKE OF THIS FEATURE BEFORE DEEP LAYER MOISTURE RETURNS AS A
LARGE MESOSCALE COMPLEX CURRENTLY OVER SOUTHERN LA APPROACHES THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS WILL SPREAD INTO
THE WESTERN ZONES THIS AFTERNOON WHERE POPS ARE HIGHEST (40-60%).
POPS FOR THE EASTERN ZONES HAVE BEEN TRIMMED BACK INTO THE LOWER
CHANCE CATEGORY (30%). ENHANCED UPPER RIDGING OVER THE REGION
AHEAD OF A DEEP TROUGH ALONG WITH SOME BREAKS IN THE CLOUD COVER
WILL PUSH TEMPS INTO THE MID TO UPPER 80S FOR MOST OF THE CWA.


.SHORT TERM [TONIGHT THROUGH MONDAY]...

BY LATE TONIGHT OR EARLY SUNDAY A LOBE OF MID-UPPER LEVEL
VORTICITY, ASSOCIATED WITH A SUBTLE SHORTWAVE, IS EXPECTED TO
REACH ALABAMA AND THE WESTERN FLORIDA PANHANDLE. COINCIDING WITH
THIS WILL BE THE RAPID DEVELOPMENT AND STRENGTHENING OF A 100-120
KNOT UPPER LEVEL (250MB) JET STREAK FROM ALABAMA INTO EASTERN
KENTUCKY. THIS WOULD PLACE OUR FORECAST AREA IN A REGION OF
POSITIVE DCVA AND THE RIGHT FRONT QUADRANT OF AN UPPER LEVEL JET
STREAK. IN OTHER WORDS, THE STAGE WILL BE SET FOR VERTICAL MOTION
BY SUNDAY MORNING, AND WE SHOULD SEE SHOWERS AND STORMS EITHER
PERSIST IN A NORTHEASTWARD TRAJECTORY FROM THE GULF OF MEXICO, OR
DEVELOP ACROSS PORTIONS OF ALABAMA, GEORGIA, AND NORTH FLORIDA.

MODELS ARE ACTUALLY IN EXCELLENT AGREEMENT WITH THE MAJORITY OF
THE CONVECTIVE DEVELOPMENT TAKING PLACE BETWEEN AROUND 09 UTC AND
15 UTC SUNDAY MORNING. HI-RES MODELS INDICATE THAT WHILE INITIAL
CONVECTIVE MODES MAY BE MORE CELLULAR, GROWTH INTO A LINEAR SYSTEM
IS EXPECTED WITH TIME WITH STORMS EVENTUALLY PUSHING EAST THROUGH
MUCH OF THE AREA. GIVEN THE AGREEMENT, POPS WERE BUMPED UP TO
AROUND 80 PERCENT FOR MUCH OF THE AREA. ALTHOUGH IT SHOULDN`T RAIN
FOR MORE THAN A FEW HOURS AT A GIVEN LOCATION IT SEEMS QUITE
LIKELY THAT MUCH OF THE AREA WILL SEE RAIN. MODEL FORECAST
SOUNDINGS INDICATE A FAVORABLE OVERLAP OF AROUND 40-50 KNOTS OF
DEEP LAYER SHEAR AND 1000-1500 J/KG OF SBCAPE, EVEN IN THE EARLY
MORNING HOURS, ACROSS THE AREA. GIVEN THE FAVORABLE ENVIRONMENT,
WE INCLUDED SEVERE THUNDERSTORM WORDING IN THE FORECAST. HOWEVER,
SOME UNCERTAINTIES REMAIN, LARGELY CENTERED AROUND WHETHER OR NOT
THIS INITIAL ROUND OF STORMS WILL BE ABLE TO ROOT QUICKLY IN THE
BOUNDARY LAYER OR WILL ACTUALLY BE REALIZING LESS INSTABILITY THAN
WHAT MODELS ARE PROJECTING. PRECIPITABLE WATER VALUES SHOULD BE
AROUND THE 99TH PERCENTILE FOR THIS TIME OF YEAR, SO HEAVY RAIN
WILL ALSO BE POSSIBLE.

ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE IN THE SHORT
TERM PERIOD, LIKELY EITHER LATER SUNDAY NIGHT OR MONDAY.
SUBSIDENCE IN THE WAKE OF THE MORNING MCS COULD LEAD TO A LULL IN
THE LATE AFTERNOON AND EVENING BEFORE A SURFACE COLD FRONT AND
ANOTHER UPPER LEVEL SHORTWAVE BEGIN TO APPROACH. FORCING WILL NOT
BE AS STRONG OR FOCUSED FROM SUNDAY NIGHT INTO MONDAY, SO RAIN
CHANCES ARE NOT AS HIGH. HOWEVER, INSTABILITY IS LIKELY TO BE
HIGHER WITH CONTINUED MODERATE-STRONG DEEP LAYER SHEAR AND STEEPER
MID LEVEL LAPSE RATES AS AN EML PLUME ARRIVES RELATIVELY IN TACT
FROM THE HIGH PLAINS. THEREFORE, ADDITIONAL STRONG TO SEVERE
STORMS WILL BE POSSIBLE. GIVEN LOWER OVERALL LIKELIHOOD OF STORMS,
SEVERE WORDING WAS NOT INCLUDED IN THE FORECAST AT THIS TIME.


.LONG TERM [MONDAY NIGHT THROUGH SATURDAY]...

THE SURFACE COLD FRONT SHOULD PUSH THROUGH THE AREA ON MONDAY
NIGHT WITH HIGH PRESSURE SETTLING INTO THE GULF COAST REGION
THROUGH WEDNESDAY MORNING. ALTHOUGH THE FRONT SHOULD NOT MAKE HIGH
TEMPERATURES SIGNIFICANTLY COOLER, IT SHOULD BRING IN A SLIGHTLY
DRIER AIR MASS THEREBY ALSO LEADING TO SLIGHTLY COOLER OVERNIGHT
LOWS. SOME SMALL RAIN CHANCES ENTER THE FORECAST AGAIN ON THURSDAY
AS THE SURFACE HIGH ERODES.

&&

.AVIATION...

[THROUGH 12Z SUNDAY] CEILINGS WILL FALL TO IFR/LIFR LEVELS AT ALL
TERMINALS BY DAYBREAK. THE POTENTIAL EXISTS FOR LIFR
VISIBILITIES AS WELL, BUT CONFIDENCE REMAINS LOWER WRT FOG. FOR
NOW, IFR VISIBILITIES ARE ADVERTISED. CEILINGS WILL BE SLOW TO
SCATTER TOMORROW MORNING. SCATTERED CONVECTION WILL DEVELOP AND
SPREAD FROM WEST TO EAST LATER TODAY BECOMING WIDESPREAD LATE
TONIGHT THROUGH SUNDAY MORNING.

&&

.MARINE...

SOUTHERLY WINDS WILL SLOWLY INCREASE THIS WEEKEND AND COULD REACH
SCEC LEVELS OF 15-20 KNOTS OVER PARTS OF THE COASTAL WATERS LATE
TONIGHT OR EARLY SUNDAY. LIGHTER WINDS WILL RETURN BEHIND THE COLD
FRONT ON TUESDAY AND WEDNESDAY. SHOWERS AND STORMS WILL BE
POSSIBLE AHEAD OF THE FRONT FROM TODAY THROUGH MONDAY. SOME STORMS
ON SUNDAY COULD BE SEVERE WITH STRONG WINDS.

&&

.FIRE WEATHER...

NO RED FLAG CONDITIONS ARE EXPECTED AT LEAST THROUGH THE MIDDLE OF
NEXT WEEK.

&&

.HYDROLOGY...

RECENT HEAVY RAINS HAVE RESULTED THE FOLLOWING RIVERS REACHING
ACTION OR BANK FULL STAGES: OCHLOCKONEE RIVER AT THOMASVILLE,
APALACHICOLA RIVER AT BLOUNTSTOWN, AND CHOCTAWHATCHEE RIVER.
HOWEVER, NONE OF THESE RIVERS ARE FORECAST TO REACH FLOOD STAGE
IN THE NEXT SEVERAL DAYS. WE EXPECT ADDITIONAL RAINFALL AMOUNTS
THROUGH THE WEEKEND TO RANGE FROM 1 TO 2 INCHES. FORTUNATELY MANY
OF THE RIVER STAGES IN SOUTHEAST AL AND THE FL PANHANDLE WERE
BELOW NORMAL BEFORE THIS WEEK. HOWEVER, THE RAINS FROM THIS WEEK
HAVE BROUGHT MANY OF THESE RIVERS TO ABOVE-NORMAL FLOWS. DEPENDING
ON WHERE THE HEAVIEST RAIN SETS UP OVER THE NEXT SEVERAL DAYS,
MORE OF THESE RIVERS COULD REACH LOCAL ACTION STAGE NEXT WEEK.

&&

.PRELIMINARY POINT TEMPS/POPS...

TALLAHASSEE   88  70  81  68  84 /  30  30  80  20  30
PANAMA CITY   83  73  78  72  79 /  40  50  80  20  30
DOTHAN        82  68  80  67  82 /  40  70  80  20  30
ALBANY        83  69  81  67  82 /  30  70  80  20  30
VALDOSTA      87  69  84  67  83 /  30  30  80  20  30
CROSS CITY    86  69  84  68  83 /  30  20  70  20  40
APALACHICOLA  84  73  78  73  80 /  40  30  80  20  30

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AL...NONE.
GM...NONE.

&&

$$

NEAR TERM...BARRY
SHORT TERM...LAMERS
LONG TERM...LAMERS
AVIATION...BARRY
MARINE...LAMERS
FIRE WEATHER...BARRY
HYDROLOGY...WESTON


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