Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 191840
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
240 PM EDT FRI SEP 19 2014

...UNSETTLED WET PATTERN WITH COOLER TEMPS THROUGH SAT...

.SHORT TERM...THIS AFTN THROUGH TONIGHT...

RADAR LOOP DEPICTED THE DYNAMIC WEATHER PATTERN WELL WITH LOW LEVEL
ONSHORE FLOW PUSHING SFC BASED CONVECTION FROM THE ATLANTIC
WESTWARD...WHILE A STREAM OF MID LEVEL MOISTURE FROM THE WEST WAS
BRINGING LIGHT TO MODERATE STRATIFORM RAINFALL FROM GNV TO PALM
COAST SOUTHWARD. UPPER LEVEL DIVERGENCE WAS INCREASING AS AN UPPER
TROUGH CONTINUE TO DIG OVER THE CENTRAL GULF COAST STATES...WHILE
SHALLOW ENE LOW LEVEL FLOW WAS BRINGING LOW LEVEL ISENTROPIC LIFT
OVER OUR SOUTHERN FL ZONES. SHALLOW AND MID LEVEL MOISTURE WAS
GRADUALLY INCREASING FROM THE ESE AS LOW PRESSURE DEEPENED OVER THE
EASTERN GULF.

UPDATED THE FORECAST TO REFLECT LATEST HRRR MODEL GUIDANCE WHICH
INDICATED ADDITIONAL CONVECTIVE DEVELOPMENT GENERALLY FROM
GAINESVILLE NORTHWARD WITH ISOLATED TSTORMS POSSIBLY BECOMING STRONG
DUE TO INCREASING SHEAR AHEAD OF STRONG DEEPENING UPPER TROUGH OVER
THE GULF COAST REGION. STRONG STORMS WOULD BE CAPABLE OF GUSTY
WINDS...FREQUENT LIGHTNING AND EVEN HAIL. FARTHER SOUTH...A LIGHT TO
MODERATE STRATIFORM RAINFALL WILL CONTINUE WITH EMBEDDED TSTORMS
POSSIBLE.

THIS EVENING PRECIP WILL GRADUALLY DECREASE FROM NW TO SE AS THE
UPPER LEVEL TROUGH DIGS FURTHER AND INDUCES SFC LOW PRESSURE TO
DEEPEN OVER S FL AND THEN OFFSHORE OF THE SE FL ATLANTIC COAST. THIS
WILL OCCUR AS A SFC RIDGE AXIS BEGINS TO NUDGED FARTHER SOUTHWARD
DOWN THE LEE OF THE APPALACHIANS AND OVER N GA. THIS SCENARIO WILL
INCREASE ENE FLOW AND COASTAL CONVERGENCE ALONG OUR LOCAL
COASTLINE...ESPECIALLY AFTER MIDNIGHT...WHICH COULD BRING WAVES OF
LOCALLY HEAVY RAINFALL TO THE LOCAL COASTLINE EARLY SAT MORNING.
ADVERTISED 60% ALONG THE COAST TONIGHT...FALLING TO LESS THAN 10%
WEST OF TRAIL RIDGE. TEMPS WILL BE MILD IN THE LOW TO MID 70S
COAST...TO UPPER 60S INLAND UNDER MOSTLY CLOUDY SKIES.

SATURDAY THROUGH MONDAY...UPPER TROUGH MOVING OVER THE AREA WILL
DEVELOP A SURFACE LOW OFF THE EAST CENTRAL FL COAST EARLY SATURDAY.
UPPER DIVERGENCE AND ISENTROPIC LIFT WILL CONTINUE THE RAIN ACROSS
MOST OF THE AREA ON SATURDAY. RAIN WILL TAPER OFF SATURDAY NIGHT AS
UPPER TROUGH AND SURFACE LOW LIFT NE TO THE CAROLINA COAST. DRIER
AIR WILL ADVECT INTO SE GA SUNDAY WITH MOIST AXIS AND CHANCE OF
SHOWERS PERSISTING OVER NE FL. ON MONDAY A COLD FRONT WILL DROP
SOUTH INTO S GA BRINGING A CHANCE OF MAINLY AFTERNOON AND EVENING
SHOWERS/THUNDERSTORMS TO THE AREA.

.LONG TERM...TUESDAY THROUGH FRIDAY...MODERATE ONSHORE WINDS ARE
EXPECTED FOR MUCH OF NEXT WEEK. SURFACE HIGH PRESSURE TO THE NORTH
WILL BE REINFORCED ON WEDNESDAY AS A 1035 MB HIGH DROPS SE FROM
CANADA INTO NEW ENGLAND. WEAK CYCLONIC FLOW ALOFT ASSOCIATED WITH
UPPER TROUGHING COMBINED WITH DEEP MOISTURE WILL CONTINUE RAIN
CHANCES THROUGH THE PERIOD. POPS WILL BE ABOVE NORMAL WITH
TEMPERATURES NEAR NORMAL THROUGH THE PERIOD.

&&

.AVIATION...
RAIN ALONG A DEVELOPING FRONTAL BOUNDARY WILL CONTINUE TO IMPACT GNV
THROUGH THE NIGHT. TERMINALS NORTH OF THE BOUNDARY WILL SEE IMPACTS
FROM SCATTERED SHOWERS AND THUNDERSTORMS BETWEEN 18Z AND 00Z. EXPECT
BRIEF BOUTS OF GUSTY WINDS AND IFR/MVFR VIS AND CEILINGS. SOME LOW
CEILINGS MAY BE POSSIBLE HEADING INTO TOMORROW MORNING BUT WE WILL
WAIT TO ADDRESS THOSE IN THE NEXT PACKAGE WHEN THERE IS MORE
CONFIDENCE.

&&

.MARINE...EAST WINDS 10-15 KTS PREVAILED THIS AFTN WITH SEAS 3 FT OR
LESS. AS LOW PRESSURE DEEPENS OVER S FL AND JUST OFFSHORE OF THE FL
ATLANTIC COAST TONIGHT...ENE FLOW WILL INCREASE OVER THE GA WATERS.
THERE WAS STILL MODEL DISCREPANCY WITH THE STRENGTH OF THE LOW AND
RESULTANT NE SURGE DOWN THE LOCAL COASTLINE...WITH THE NAM12 MUCH
STRONGER COMPARED TO THE GFS. THUS USED A MODEL BLEND WHICH YIELDED
PREVAILING SPEEDS INCREASING TO 15-20 KTS LATE TONIGHT INTO SAT N OF
ST AUGUSTINE. PLAN TO RAISE A SMALL CRAFT EXERCISE CAUTION FOR THE
WATERS N OF ST AUGUSTINE DIVISION FOR WINDS 15-20 KTS. IF NAM12 PANS
OUT AND THE LOW DEEPENS FURTHER...A LAST MINUTE ADVISORY MAY BE
NEEDED FOR OFFSHORE WINDS FOR WINDS 20-25 KTS. SEAS WILL BUILD FROM
2-4 FT TONIGHT TO 4-6 FT OFFSHORE LEGS LATE SAT INTO SAT NIGHT.
ONSHORE FLOW WILL CONTINUE INTO SUN WHILE WEAKENING AS THE SFC LOW
EJECTS NE OF THE LOCAL WATERS AND HIGH PRESSURE BUILDS IN FROM THE
WEST. WINDS AND SEAS WILL SUBSIDE INTO EARLY NEXT WEEK.

.RIP CURRENTS...ONSHORE FLOW WILL CONTINUE AN ELEVATED RISK OF RIP
CURRENTS TODAY AND SATURDAY WITH A MODERATE RISK EXPECTED.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  69  83  66  86 /  20  50  40  10
SSI  73  80  71  82 /  60  70  70  30
JAX  70  82  68  84 /  50  70  60  20
SGJ  73  81  71  81 /  60  70  60  40
GNV  67  83  66  85 /  40  50  50  40
OCF  68  83  67  86 /  70  40  40  40

&&

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

$$

ENYEDI/ZIBURA/WALSH










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