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Area Forecast Discussion

725
FXUS62 KJAX 160857
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
457 AM EDT WED APR 16 2014

...WINDY CONDITIONS IN THE COASTAL COUNTIES TODAY...
...HEAVY RAINFALL EXPECTED ON FRIDAY AND FRIDAY NIGHT THROUGHOUT
NORTHEAST FLORIDA AND COASTAL SOUTHEAST GEORGIA...

.SHORT TERM (TODAY THROUGH FRIDAY NIGHT)...

TODAY...STRONG HIGH PRESSURE BEGINS TO BUILD TO THE NORTH OF THE
AREA BEHIND THE DEPARTING COLD FRONT. AN UNUSUALLY COOL AIR MASS
MOVES INTO THE AREA TODAY ON BREEZY NORTH TO NORTHEAST WINDS
INLAND AND A WINDY NE WINDS ALONG THE COAST WHERE A LAKE WIND
ADVISORY IS IN EFFECT THRU EARLY EVE. THE STRONG NE FLOW IS
EXPECTED TO BRING IN COASTAL CLOUDS...WITH A FEW SHOWERS ALONG THE
COAST AND COASTAL WATERS LATE THIS AFTERNOON. HIGHS ONLY IN THE
MID 60S FOR SE GA AND COASTAL SE GA AND UPPER 60S TO LOWER 70S
ELSEWHERE WHERE THERE WILL BE MORE SUN.

TONIGHT...STRONG HIGH PRESSURE ACROSS NORTHERN NEW ENGLAND
WEDGES SOUTH INTO THE AREA WHILE A COASTAL TROUGH BEGINS
TO DEVELOP AND MOVE TOWARDS THE FL EAST COAST. RAIN CHANCES
INCREASE FROM SE TO NW DURING THE NIGHT AS AN APPROACHING
SHORT WAVE FROM THE GULF INCREASES ISENTROPIC LIFT AND
COMBINES WITH THE COASTAL TROUGH. WILL HAVE A LARGE RANGE
IN TEMPS RANGING FROM THE MID/UPPER 40S ACROSS FAR INLAND
SE GA TO THE LOWER 60S ALONG THE NE FL COAST WHERE THERE
WILL BE MORE CLOUD COVER AND BREEZY NE WINDS.

THURS AND THURS NIGHT...A TIGHT PRESSURE GRADIENT WILL PERSIST
OVER OUR REGION AS IMPRESSIVE SURFACE RIDGING OVER NEW ENGLAND
WEDGES DOWN THE EASTERN SEABOARD. COASTAL TROUGHING AND SPEED
CONVERGENCE WILL ADVECT AT LEAST WIDELY SCATTERED SHOWERS INTO THE
COASTAL COUNTIES DURING THE MORNING HOURS. WILL NEED TO MONITOR
THE THREAT FOR HEAVY SURF AND MINOR COASTAL FLOODING DURING TIMES
OF HIGH TIDE AS A DEEP FETCH OF NORTHEAST WINDS REMAINS IN PLACE.
MEANWHILE...SOUTHWEST FLOW ALOFT STRENGTHENS THROUGHOUT THE DAY AS
TROUGHING ALOFT OVER THE PLAINS STATES PROGRESSES
EASTWARD...INITIATING WEAK ISENTROPIC LIFT INITIALLY OVER NORTH
CENTRAL FLORIDA. THIS LIFT WILL GRADUALLY STRENGTHEN FROM SOUTH TO
NORTH BY THE EVENING HOURS...WITH CHANCE POPS FOR ALL BUT INTERIOR
SOUTHEAST GA BY SUNSET. ONSHORE FLOW AND INCREASING CLOUDS SHOULD
KEEP HIGHS IN THE UPPER 60S OVER MUCH OF SOUTHEAST GA AND COASTAL
NORTHEAST FL...WITH LOWER 70S EXPECTED IN NORTH CENTRAL FL. THESE
READINGS ARE ABOUT 10 DEGREES BELOW CLIMO. DYNAMICS ALOFT MOVING
INTO THE EASTERN U.S. WILL RESULT IN CYCLOGENESIS OVER THE EASTERN
GULF OF MEXICO ON THURS NIGHT...WITH MODEL SOUNDINGS DEPICTING
STRENGTHENING LOW-LEVEL CONVERGENCE DEVELOPING OVER COASTAL
NORTHEAST FL. LIKELY POPS WERE USED FOR OUR FL COUNTIES...WITH
CHANCE POPS FOR MOST OF SOUTHEAST GA. LOWS WILL RANGE FROM 55-60
IN SOUTHEAST GA...AND 60-65 IN NORTHEAST FL.

FRI AND FRI NIGHT...00Z OPERATIONAL NAM/ECMWF/CMC DEPICT A
STRONGER AND SLOWER EVOLUTION OF THE SURFACE LOW IN THE GULF OF
MEXICO...AS UPPER LEVEL TROUGHING CUTS OFF OVER THE SOUTHEASTERN
STATES. THE 00Z OPERATIONAL GFS DEPICTS A MORE PROGRESSIVE
SOLUTION...BUT STILL BRINGS A SUBSTANTIAL WAVE OF LOW PRESSURE AND
SLUG OF DEEP MOISTURE OVER OUR REGION. THE WEATHER PREDICTION
CENTER HAS INCLUDED MUCH OF OUR AREA IN A SLIGHT RISK FOR
EXCESSIVE RAINFALL DURING THIS TIME PERIOD...WITH WIDESPREAD
ADDITIONAL RAINFALL AMOUNTS OF 2-3 INCHES OVER NEARLY ALL OF OUR
FL COUNTIES AS WELL AS COASTAL SOUTHEAST GA. DEPENDING ON THE
STRENGTH AND MOVEMENT OF THE SURFACE LOW IN THE EASTERN
GULF/FL...EMBEDDED THUNDERSTORM DEVELOPMENT COULD BECOME A CONCERN
OVER NORTH CENTRAL FL AS A WARM SECTOR POTENTIALLY PUSHES
NORTHWARD. STRONG COASTAL CONVERGENCE MAY ALSO ENHANCE BANDS OF
CONVECTION THAT MAY POTENTIALLY TRAIN INTO THE COASTAL COUNTIES
DURING THIS TIME PERIOD. GIVEN SATURATED CONDITIONS...THE THREAT
FOR FLOODING ON FRI AND ESPECIALLY FRI NIGHT IS INCREASING FOR OUR
FL COUNTIES AND COASTAL SOUTHEAST GA. IF THE WARM SECTOR ADVECTS
INTO NORTH CENTRAL FL...HIGHS WILL PUSH INTO THE MID 70S. A FEW
STRONG THUNDERSTORMS MAY DEVELOP LATE IN THE DAY OR THE EVENING
HOURS AS DEEP-LAYER SOUTHWESTERLY FLOW STRENGTHENS AND EAST TO
SOUTHEAST SURFACE FLOW PREVAILS. ELSEWHERE...WIDESPREAD RAINFALL
AND PERSISTENT ONSHORE FLOW SHOULD KEEP HIGHS IN THE 65-70 RANGE.
LOWS FRI NIGHT WILL RANGE FROM THE MID 50S OVER INTERIOR SOUTHEAST
GA...WHERE RAINS MAY GRADUALLY END OVERNIGHT...TO THE LOW/MID 60S
ELSEWHERE.

.LONG TERM (SATURDAY THROUGH TUESDAY)...
SIGNIFICANT DISAGREEMENT PREVAILS IN THE LONG-RANGE GUIDANCE...AS
00Z CMC/ECWMF DEPICT A SIGNIFICANT CUTOFF CYCLONE MIGRATING THROUGH
OUR REGION ON SAT/SAT NIGHT...WHILE THE 00Z OPERATIONAL GFS
MAINTAINS A PROGRESSIVE PATTERN THAT ENDS RAINFALL OVER OUR REGION
BY EARLY SAT. SIDED WITH THE CUTOFF SOLUTION FOR NOW...WHICH
MAINTAINS STRONGER NORTH TO NORTHEAST LOW-LEVEL FLOW THROUGHOUT
THE WEEKEND AS STACKED LOW PRESSURE ONLY GRADUALLY PUSHES
OFFSHORE. LEFT CHANCE POPS IN FOR MOST AREAS ON SAT MORNING...AND
MAINTAINED CHANCE POPS IN COASTAL LOCATIONS THROUGH SAT NIGHT. MAY
NEED TO RAISE RAINFALL CHANCES FOR SAT REGION-WIDE IN FUTURE
FORECASTS IF SLOWER LONG-TERM MODEL SOLUTIONS PREVAIL. FLOODING
AND HIGH SURF/BEACH EROSION MAY BE EXTENDED INTO SATURDAY FOR
COASTAL LOCATIONS. RAINFALL CHANCES DIMINISH FOR EASTER SUN...BUT
PREVAILING N-NE FLOW SHOULD KEEP HIGHS BELOW CLIMO THIS
WEEKEND...GENERALLY 70-75 (UPPER 60S COAST) SAT AND MID 70S SUN
(LOW 70S COAST). LOWS WILL FALL INTO THE 50S INLAND...RANGING TO
LOWER 60S AT THE COAST. DRY CONDITIONS EXPECTED MON AS STACKED LOW
MOVES FURTHER AWAY FROM OUR REGION. HIGHS SHOULD REBOUND TO NEAR
80 INLAND AND LOW/MID 70S AT THE COAST. TROUGHING ALOFT MAY DIG
BACK INTO THE SOUTHEASTERN STATES BY TUES...SPARKING ISOLATED TO
WIDELY SCATTERED MAINLY DIURNAL CONVECTION WITH NEAR CLIMO TEMPS
EXPECTED.

&&

.AVIATION...
THE WINDS WILL QUICKLY VEER TO THE NE THIS MORNING WITH WINDY
CONDITIONS EXPECTED AFT 13Z-14Z. THE ONSHORE FLOW IS EXPECTED TO
ADVECT IN COASTAL CLOUDS WITH MVFR CEILINGS ARE EXPECTED AT MOST
TERMINALS AFT 13Z-14Z. THE EXCEPTION WAS HAVING VFR CIGS AT GNV.

&&

.MARINE...
STRONG HIGH PRESSURE WILL BUILD TO THE NORTH OF THE WATERS THROUGH
MUCH OF THE REMAINING WEEK WHILE A BROAD COASTAL TROUGH FORMS
OFFSHORE AND MOVES TO THE WEST. THE TIGHT GRADIENT RESULTS IN SCA
CONDITIONS FOR ALL LEGS AT LEAST THRU THU NIGHT. BROAD LOW
PRESSURE IS FORECAST TO MOVE ACROSS THE FL PENINSULA ON FRIDAY
BRINGING WIDESPREAD SHOWERS SCATTERED STORMS. THE LOW IS THEN
FORECAST TO GRADUALLY MOVE OFFSHORE THE COAST OVER THE WEEKEND.
SCA CONDITIONS MAY LINGER INTO THE WEEKEND AS A RESULT.

RIP CURRENTS: MODERATE RISK FOR MUCH OF THE REMAINING WEEK DUE TO
A STRONG ONSHORE FLOW AND BUILDING SWELLS.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  65  45  68  55 /   0  20  20  60
SSI  59  55  66  61 /  10  30  40  60
JAX  64  55  69  62 /  20  30  40  70
SGJ  65  62  71  65 /  20  40  50  60
GNV  69  54  72  61 /  10  30  40  70
OCF  73  57  72  62 /  10  30  50  60

&&

.JAX WATCHES/WARNINGS/ADVISORIES...
FL...LAKE WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR DUVAL-FLAGLER-
     NASSAU-ST JOHNS.

GA...LAKE WIND ADVISORY UNTIL 7 PM EDT THIS EVENING FOR COASTAL
     CAMDEN-COASTAL GLYNN.

AM...SMALL CRAFT ADVISORY UNTIL 3 AM EDT SATURDAY FOR ALTAMAHA SOUND
     GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-
     FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-
     ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.

     SMALL CRAFT ADVISORY UNTIL 9 PM EDT THURSDAY FOR ALTAMAHA SOUND
     GA TO FERNANDINA BEACH FL OUT 20 NM-FERNANDINA BEACH TO ST
     AUGUSTINE FL OUT 20 NM-ST AUGUSTINE TO FLAGLER BEACH FL OUT
     20 NM.

&&

$$

PETERSON/NELSON







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