Area Forecast Discussion
Issued by NWS Jacksonville, FL

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000
FXUS62 KJAX 190120
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
920 PM EDT SAT APR 18 2015

.NEAR TERM...THROUGH MID MORNING SUNDAY... SOME RESIDUAL CONVECTION
HAS LIFTED NORTH OF THE ALTAMAHA RIVER THIS EVENING AS OUTFLOW
BOUNDARY PRODUCING THIS STRONG CONVECTION PUSHED NORTHWARD.
OTHERWISE THE REMAINING CONVECTION HAS MOVED WELL OFFSHORE WITH
PREVAILING WESTERLIES ALOFT. THE CONVECTION WILL BE DIURNAL IN
NATURE AND REMAIN NEAR NIL ACROSS THE REMAINDER OF THE CWA THE
REST OF THE EVENING. THE HI-RES ARW HAS HANDLED THIS SCENARIO VERY
WELL AND WILL CONTINUE TO UTILIZE THE MODEL FOR THE TIMING AND
MOVEMENT OF SHOWERS AND THUNDERSTORMS FOR THE NEXT 24 HOURS.
SHOWERS WILL BE QUITE LIMITED DURING THE OVERNIGHT HOURS WITH THE
STRONGEST KINEMATICS AND ISENTROPIC LIFT WELL WEST OF THE REGION
THROUGH THE NOCTURNAL HOURS AND THROUGH MOST OF THE MORNING HOURS
SUNDAY. HENCE...LOWERED POPS CONSIDERABLY BRINGING SOME
PRECIPITION AND COMMENCEMENT OF CONVECTION ACROSS INTERIOR SE GA
BETWEEN 15Z AND 18Z.

SUNDAY...THE ARW DOES SHOW THE AFORMENTIONED LIMITED PRECIPITATION
COVERAGE THROUGH MID TO LATE MORNING. THE NORTHERN SUWANNEE
VALLEY AND INTERIOR SE GA WILL BE ON THE EASTERN PRECIPICE OF THE
UPSTREAM UPPER LEVEL TROUGH...DIFFLUENT FLOW AND A BAND OF FORCING
IN CONCERT WITH MOISTURE LADEN SOUTHWEST FLOW BRINING A LINE OF
SHOWER AND TSTM ACTIVITY ON THE WESTERN CWA DOORSTEP DURING THE
LATE MORNING AND EARLY AFTERNOON SUNDAY. THIS BAND IS ANTICIPATED
TO TRANSLATE TO THE EAST INTO THE CWA DURING THE AFTERNOON HOURS
BRING NUMEROUS TO CATEGORICAL SHOWERS AND THUNDERSTORMS ACROSS THE
SE GA AND NE FL REGION. THE BEST INSTABILITY...SHEERED
ENVIRONMENT...FORCING AND INSTABILITY WILL RESIDE OVER THE
SUWANNEE VALLEY AND INTERIOR SE GA DURING THE AFTERNOON. THIS WILL
PRODUCE A THREAT OF SEVERE WEATHER...PARTICULARLY ACROSS THE
WESTERN CWA...WHERE HIGH WIND GUSTS WILL BE PRIMARY THREAT. THE
FORCING DECREASES FURTHER TO THE EAST AND SOUTH IN NE FL AND NORTH
CENTRAL FLORIDA. WITH THE MOISTURE LADEN ATMOSHERE AND POTENTIAL
TRAINING ACROSS THE WESTERN CWA...RAINFALL WILL BE ENHANCED WITH
SOME POCKETS OF 1 TO 3 INCHES WITH LOCALLY HIGHER AMOUNTS
POSSIBLE...MAINLY WEST OF STATE ROUTE 1 IN SE GA.

SUNDAY NIGHT AND MONDAY...ACTIVITY DIMINISHES AS MID-LEVEL DRY
SLOT SPREADS OVER FORECAST AREA. FOR MONDAY...SYSTEM CONTINUES
TRACKING NORTH AND EAST...COLD FRONT APPROACHES THE AREA FROM THE
NORTHWEST. MODEL GUIDANCE INDICATES DRIER CONDITIONS ALOFT AND
BETTER DYNAMICS PASSING WELL NORTH OF OUR FORECAST AREA...THUS
CONSIDERABLY LESS PRECIP COVERAGE MON COMPARED TO SUN. DESPITE
LESSER COVERAGE...MODEL GUIDNCE SUGGESTS A FEW STRONG OR SEVERE
STORMS WILL BE POSSIBLE IN AN ENVIRONMENT WITH 2000 J/KG CAPE AND
150-200 0-3KM SR-HELICITY. SPC HAS A MARGINAL/SLIGHT RISK AREA
OVER SE GA MON.

&&

.AVIATION...MVFR VISIBILITIES ARE EXPECTED AT SGJ AND SSI
THROUGH 02Z.VFR CONDITIONS WILL PREVAIL ELSEWHERE THROUGH AT
LEAST 06Z. MVFR VISIBILITIES MAY DEVELOP AT VQQ AFTER 06Z. LOW
STRATUS CIGS OF 1000-1500 FT ARE POSSIBLE AT GNV AND SGJ TOWARDS
10Z-11Z...BUT CONFIDENCE WAS TOO LOW TO INCLUDE SUB-VFR CIGS IN
THE 00Z TAFS. VFR CONDITIONS WILL PREVAIL AT THE REGIONAL
TERMINALS BY 13Z. SOUTH TO SOUTHWEST SURFACE WINDS WILL INCREASE
TO NEAR 10 KTS AFTER 13Z. NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO MOVE INTO OUR REGION FROM THE WEST ON SUNDAY
AFTERNOON. PLACED PROB30 GROUPS FOR GUSTY WINDS AND SUB-VFR
CONDITIONS AFTER 19Z...AND A FEW STRONG THUNDERSTORMS WILL BE
POSSIBLE BY LATE AFTERNOON.

&&

.MARINE...SOUTH TO SOUTHWEST WINDS 10-15KTS AND 2-4FT SEAS EXPECTED
THRU MONDAY AHEAD OF NEXT COLD FRONT. AFTER FRONT PASSES...WINDS
WILL BECOME NORTH AND THEN NORTHEAST WITH HIGH PRESSURE BUILDING
JUST NORTH OF THE AREA. THE HIGH IS EXPECTED TO BE WEAK...RESULTING
IN FAIRLY WEAK WINDS AND LOW SEAS TUE/WED. BEFORE THE FRONT PASSES
MON NIGHT...WINDS COULD APPROACH SMALL CRAFT ADVISORY LEVELS
ACROSS THE OFFSHORE COMPONENT.

RIP CURRENTS: MODERATE RISK THROUGH SUNDAY DUE TO A LINGERING
SWELL.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  67  82  67  83 /  20  80  20  30
SSI  68  80  69  82 /  20  70  40  30
JAX  69  85  69  85 /  50  60  30  30
SGJ  69  82  69  83 /  40  60  30  30
GNV  68  85  68  85 /  10  60  20  30
OCF  68  85  69  85 /   0  60  20  40

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...NONE.
&&

$$

CORDERO/NELSON/GUILLET


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