Area Forecast Discussion
Issued by NWS Jacksonville, FL

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FXUS62 KJAX 050819
AFDJAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
410 AM EDT SUN JUL 5 2015

...SCATTERED TO NUMEROUS THUNDERSTORMS TODAY...

.NEAR TERM...
TODAY...WATER VAPOR IMAGERY AND MODEL GUIDANCE SHOW BROAD MID
AND UPPER LEVEL LOW OVER TN WITH TROUGHING EXTENDING INTO THE ERN
GULF OF MEXICO. THIS SYSTEM WILL TRANSLATE SLOWLY E TO NE TODAY
AND TONIGHT HELPING TO AID CONVECTIVE DEVELOPMENT AS SHORTWAVE
TROUGHS ROTATE THROUGH THE TROUGH. OVER THE FORECAST AREA TEMPS
ALOFT REMAIN RELATIVELY COOL ABOUT -9.5C AND MID LEVEL LAPSE RATES
ARE NEAR 6.5C/KM. SATELLITE DATA ALSO SHOWING PWAT NEAR 1.77
INCHES...VERY CLOSE TO NORMAL FOR EARLY JULY. INITIAL CONVECTION
TODAY WILL LIKELY FORM ALONG THE W COAST SEA BREEZE AND BROAD
CONFLUENT LOW LEVEL FLOW OVER SE AL AND SW GA. ANTICIPATE ISOLD TO
WIDELY SCT CONVECTION IN THE MORNING OVER THE WRN ZONES...TRANSLATING
EWD AND MEETING WITH E COAST SEA BREEZE BOUNDARY W OF INTERSTATE 95.
OTHERWISE...AIRMASS SCT/NRMS STORMS WILL FORM FROM DAYTIME HEATING
AND OUTFLOWS. BASED ON MESOSCALE MODELS AND YESTERDAY`S CONVECTION
WILL CONTINUE WITH MAINLY NMRS SHOWERS AND STORM COVERAGE IN THE
FCST GRIDS. ATLC BEACHES MAY SEE A BIT LESS OF A CHANCE OWING TO
INLAND PROGRESS OF E COAST SEA BREEZE. ESTIMATED AFTN INSTABILITY
PEGGED AT ABOUT 3100 J/KG AND DOWNDRAFT CAPE OF 800 WILL RESULT IN A
LOCALLY STRONG TO LOCALLY SEVERE DOWNBURSTS AND PERHAPS SOME
MARGINALLY SEVERE HAIL. MOVEMENT OF ACTIVITY WILL BE A LITTLE
STRONGER...EWD AT NEAR 15-20 KT.

SCT CONVECTION LOOKS LIKE A GOOD BET THIS EVENING WITH SOMEWHAT LESS
ACTIVITY W OF I-75 AS AIRMASS THERE WILL LIKELY GET WORKED OVER
EARLIER IN THE DAY. LOWS TONIGHT MAINLY IN THE 70-75 DEG RANGE.
MOST CONVECTION WILL WIND DOWN BY MIDNIGHT...THOUGH ISOLD LINGERING
WEAK CONVECTION IS POSSIBLE IN THE EARLY MORNING HOURS DUE TO
AFFECTS OF MID LEVEL TROUGHING AND VORT ADVECTION. SOME SHALLOW
PATCHY LATE NIGHT FOG IS POSSIBLE OVER SE GA.

.SHORT TERM (MONDAY THROUGH TUESDAY NIGHT)...
MID/UPPER LEVEL LOW CENTERED OVER THE OHIO VALLEY ON MON WILL DRIFT
EASTWARD WHILE WEAKENING...WITH ITS AXIS EXTENDING SOUTHWARD TO THE
FL PANHANDLE. SHORTWAVE ENERGY WILL PROGRESS NORTHEASTWARD ACROSS
SOUTHEAST GA ON MONDAY AFTERNOON...WHICH WILL ENHANCE CONVECTIVE
DEVELOPMENT ALONG THE GULF AND ATLANTIC SEA BREEZE BOUNDARIES THAT
WILL PROGRESS INLAND. NUMEROUS THUNDERSTORMS ARE EXPECTED BY THE
EARLY AFTERNOON HOURS FROM EAST OF INTERSTATE 75 TO U.S. HIGHWAY
301...WITH A SEA BREEZE COLLISION EXPECTED ALONG THE I-95 CORRIDOR
BY THE LATE AFTERNOON. SHORTWAVE ACTIVITY ROTATING ACROSS SOUTHEAST
GA SHOULD SPARK AT LEAST SCATTERED AFTERNOON COVERAGE. PULSE STRONG
TO SEVERE THUNDERSTORMS ARE EXPECTED DUE TO PERSISTENT COOL MID-
LEVEL TEMPS...WITH WET MICROBURSTS AND FREQUENT LIGHTNING STRIKES
ACCOMPANYING STRONGER ACTIVITY. S/SW STEERING FLOW AROUND 10 KNOTS
WILL ALSO RESULT IN SLOW MOVING STORMS...WITH LOCALLY HEAVY RAINFALL
AMOUNTS POSSIBLE. HIGHS WILL CLIMB INTO THE LOWER 90S INLAND BEFORE
CONVECTION ERUPTS...WITH UPPER 80S IN COASTAL LOCATIONS. SCATTERED
CONVECTION MAY LINGER INTO THE EARLY EVENING HOURS...DIMINISHING
TOWARDS MIDNIGHT. LOWS AGAIN FALL TO THE 70-75 RANGE.

TUES WILL BE A TRANSITION DAY AS REMNANT TROUGHING ALONG THE U.S.
EASTERN SEABOARD FILLS...ALLOWING LOW-LEVEL ATLANTIC RIDGING TO
BUILD NORTHWARD FROM THE FL PENINSULA. PLENTIFUL MOISTURE AND
LINGERING COOL MID-LEVEL TEMPS WILL CREATE ANOTHER CONVECTIVELY
ACTIVE AFTERNOON/EARLY EVENING ON TUES OVER NORTHEAST AND NORTH
CENTRAL FL...WITH NUMEROUS COVERAGE EXPECTED BETWEEN I-75 AND I-95
DUE TO SEA BREEZE AND OTHER MESOSCALE BOUNDARY INTERACTIONS.
OUTFLOWS PUSHING NORTHWARD WILL TRIGGER SCATTERED LATE AFTERNOON
ACTIVITY OVER SOUTHEAST GA...WITH SLIGHTLY LOWER RAIN CHANCES
EXPECTED THAN MON. A LATER START TO THUNDERSTORM ACTIVITY WILL ALLOW
HIGHS TO REACH THE MID 90S OVER INLAND SOUTHEAST GA AND THE SUWANNEE
VALLEY...WITH LOWER 90S ELSEWHERE AND UPPER 80S AT THE BEACHES.
STORMS MAY PULSE TO STRONG LEVELS...WITH SLOW STORM MOTION AGAIN
RESULTING IN LOCALLY HEAVY RAINFALL TOTALS. CONVECTION WILL RETURN
TO A DIURNAL PATTERN...WITH ACTIVITY ENDING SHORTLY AFTER SUNSET.
LOWS WILL FALL TO THE 70-75 RANGE.

.LONG TERM (WEDNESDAY THROUGH SUNDAY)...
DEEP-LAYERED RIDGING WILL EXPAND EASTWARD FROM TEXAS INTO OUR
REGION. THE AXIS OF ATLANTIC RIDGING WILL LIFT NORTHWARD TO A
POSITION ALONG THE FL/GA BORDER...PLACING MUCH OF OUR AREA IN
DEEPENING SOUTHEAST FLOW BY LATE WEEK. THIS WEATHER PATTERN WILL
ADVECT A DRIER AIR MASS INTO OUR REGION FROM THE WESTERN
ATLANTIC...WITH INCREASING SUBSIDENCE RESULTING IN DECREASING RAIN
CHANCES. LEFTOVER LOW-LEVEL MOISTURE AND A WEAK PRESSURE
GRADIENT ON WED SHOULD STILL PROMOTE SCATTERED DIURNAL CONVECTIVE
DEVELOPMENT...PARTICULARLY INLAND WHERE THE ATLANTIC AND GULF COAST
SEA BREEZES WILL COLLIDE DURING THE LATE AFTERNOON HOURS. LESS
ACTIVITY IS EXPECTED BY MID/LATE AFTERNOON ALONG THE COAST AS THE
SEA BREEZE PUSHES INLAND. HIGHS WILL CLIMB INTO THE LOW/MID 90S
INLAND...WITH UPPER 80S FOR COASTAL LOCATIONS.

BELOW CLIMO POPS ARE FORECAST THURS-SUN AS DEEP-LAYERED RIDGING
TAKES HOLD OF OUR AREA...AND PRECIPITABLE WATER VAPOR (PWAT) VALUES
POTENTIALLY FALL BACK TO THE 1.25-1.5 INCH RANGE. ISOLATED TO WIDELY
SCATTERED DIURNAL ACTIVITY IS EXPECTED INLAND DURING THIS PERIOD
EACH DAY...WITH COASTAL LOCATIONS REMAINING MOSTLY DRY. LESS
CONVECTION WILL ALLOW HIGHS INLAND TO CLIMB INTO THE MID/UPPER
90S...WITH LOWS GENERALLY IN THE MID 70S.

&&

.AVIATION...PERIODS OF MVFR TO IFR VSBY AT JAX METRO TAFS BUT 6SM OR
MORE REST OF TAFS THROUGH 12Z THIS MORNING. A FEW SHOWERS AND STORMS
EXPECTED TO DEVELOP INITIALLY BETWEEN 15Z-16Z AND THEN BLOSSOM...
BECOMING SCT-NMRS IN COVERAGE THROUGH THE DAY. GUSTY WINDS TO AT
LEAST 30-35 KT AND IFR TO POSSIBLY ANTICIPATED IN STRONGER STORM
ACTIVITY. AVERAGE STORM MOTION IS ENE TO NE ABOUT 15-20 KT. SCT
SHOWERS AND STORMS EXPECTED IN THE EVENING HOURS...WITH HIGHER
PROBABILITIES FOR COASTAL TAF SITES.

&&

.MARINE...NO HEADLINES. WINDS MAINLY SOUTH 10 TO 15 KNOTS...EXCEPT
SLIGHTLY STRONGER AT NIGHT AND SOUTHEAST ALONG THE COAST IN THE
AFTERNOON. SEAS 2 TO 4 FEET. SCATTERED SHOWERS AND STORMS NEAR THE
COAST MAINLY IN THE AFTERNOON AND EVENING HOURS. A LOWER THREAT OF
STORMS WED AND THU. LITTLE OVERALL CHANGE IN SEA STATE OVER THE NEXT
FEW DAYS WITH PREVAILING ESE SWELLS AOB 2 FT OR LESS AROUND 8-9
SECONDS AND WIND WAVES 1-3 FT.

RIP CURRENTS: A MARGINAL MODERATE RISK ALONG THE NE FL COAST
TODAY DUE TO AN EASTERLY GROUNDSWELL AROUND 9 SECONDS.
SIMILAR OR LOWER CONDITIONS FCST ON MONDAY.

&&

.PRELIMINARY POINT TEMPS/POPS...
AMG  92  70  91  71 /  60  30  50  30
SSI  88  75  88  75 /  40  40  50  30
JAX  91  72  90  72 /  60  40  60  40
SGJ  89  74  89  74 /  50  30  50  40
GNV  92  71  92  71 /  60  30  60  30
OCF  92  72  93  72 /  60  30  60  30

&&

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

$$

SHASHY/NELSON


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