Area Forecast Discussion
Issued by NWS Miami, FL

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000
FXUS62 KMFL 301846
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
246 PM EDT SAT AUG 30 2014

.SHORT TERM (THROUGH MONDAY NIGHT)...

FOCUS THIS AFTERNOON AND EARLY EVENING WILL BE ACROSS THE WEST
COAST WITH A GUSTY AT TIMES EASTERLY BREEZE ACROSS THE PENINSULA.
ALTHOUGH WINDS MAY NEVER TURN OFFSHORE AT NAPLES, ENOUGH UPPER
LEVEL DIVERGENCE WILL EXIST FOR SHOWERS AND THUNDERSTORMS, SOME OF
WHICH HAVE POPPED UP OVER COLLIER AND HENDRY. HOWEVER, ANY
ACTIVITY TODAY IS FIGHTING DRY AIR IN THE MIDLEVELS AND SAL CLOSER
TO THE GROUND. BECAUSE OF A RELATIVELY LOW FREEZING LEVEL AND
DECENT LAPSE RATES, THERE WILL BE AN OPPORTUNITY FOR GUSTY
WINDS/HAIL AS A STRONGER STORM OR TWO MAY DEVELOP NAPLES/WESTERN
HENDRY/COLLIER OR THE LAKE REGION.

ALTHOUGH THE SAL IS GONE INTO SUNDAY, AIRMASS REMAINS DRY WITH
SUBSIDENCE THANKS TO AN UPPER LEVEL RIDGE PARKED OVER THE
SOUTHEASTERN US. NOT EXPECTING MUCH CHANGE TO THE FORECAST THROUGH
THE SHORT TERM, UNTIL THE CENTER OF THE UPPER HIGH SHIFTS TO THE
CENTRAL/WESTERN GULF COAST INTO TUESDAY. A TUTT/UPPER LEVEL
DISTURBANCE WILL THEN BE ABLE TO MOVE INTO THE BAHAMAS INCREASING
PRECIP CHANCES FOR THE WHOLE REGION BY THE MIDDLE OF THE WEEK.
BOTH SUNDAY AND MONDAY, PWATS NEVER RISE ABOVE 1.75" PER MODEL
SOUNDINGS WITH DEEP EASTERLY FLOW CONTINUING. THIS SHOULD KEEP
NAPLES/WESTERN CWA/INTERIOR WITH THE HIGHER POPS, WITH ONLY
ISOLATED TO SCATTERED STORMS EAST COAST BOTH DAYS. MONDAY WILL
FEATURE THE BEST CHANCE FOR ACTIVITY ALONG THE EAST COAST. DESPITE
THE MEAGER MOISTURE IN THE MIDLEVELS, STILL CAN`T RULE OUT SOME
SHOWERS DURING THE EARLY MORNING HOURS ACROSS THE NEARSHORE
WATERS, POSSIBLY CROSSING THE BEACHES MONDAY MORNING, AS THE GFS
IS RATHER BULLISH, IN CONTRAST WITH THE REST OF THE MODEL SUITE.
WITH NOT MUCH COVERAGE EXPECTED, THE HOLIDAY WEEKEND SHOULD END
HOT, BUT WITH A PERSISTENT EASTERLY SEA BREEZE TO PROVIDE A TOUCH
OF RELIEF.

.PREV DISCUSSION... /ISSUED 151 PM EDT SAT AUG 30 2014/

AVIATION...

THE THREAT OF ANY THUNDERSTORMS FOR ANY OF THE EAST COAST
TERMINALS APPEARS TO HAVE DIMINISHED THIS AFTERNOON WITH NO
MENTION IN THE TAF`S AND MAINLY VFR CONDITIONS EXPECTED TO
PREVAIL. FOR TERMINAL KAPF...LATEST GUIDANCE CONTINUES TO SUGGEST
THAT SHOWERS/THUNDERSTORMS POSSIBLE LATER THIS AFTERNOON AND
ASSIGNED VCTS AT 20Z AND BRIEF PERIODS OF IFR CONDITIONS MAY BE
POSSIBLE WITH OCCURRENCE OF ANY SHOWERS/THUNDERSTORMS.

60

PREV DISCUSSION... /ISSUED 1036 AM EDT SAT AUG 30 2014/

UPDATE...

SAL CHARACTERISTICS IN THE LOWEST LEVELS OF THE SOUNDING THIS
MORNING EVIDENT WITH SOME HAZY SKIES ALSO OBSERVED TODAY. LAPSE
RATES AND H5 TEMP ARE VERY FAVORABLE FOR STORMS, HOWEVER 12Z MFL
PWAT WAS 1.49". CONSIDERING THE LAPSE RATES AND H5 TEMPS WERE
SIMILAR YESTERDAY AND ACTIVITY WAS SCATTERED AT BEST ALONG THE
EAST COAST, EXPECTING THE SAME OR LESS TODAY THROUGH THE CITIES.
MODELS AGGRESSIVE WITH STORMS FIRING THIS AFTERNOON NEAR NAPLES
AND MUCH OF WESTERN COLLIER AND HENDRY COUNTIES, CUSTOMARY WITH
DEEP EASTERLY FLOW. BASED ON THE HEIGHT OF THE FREEZING LEVEL AND
LAPSE RATES, THERE IS A CHANCE OF A FEW STRONG STORMS WITH HAIL
THIS AFTERNOON INTERIOR AND WEST COAST. ONLY CHANGE TO CURRENT
FORECAST WAS TO INCREASE POPS NAPLES/WESTERN HENDRY/WESTERN
COLLIER.

PREV DISCUSSION... /ISSUED 801 AM EDT SAT AUG 30 2014/

AVIATION...

FOR THE EAST COAST TERMINALS...THERE IS AN AREA OF
SHOWERS/THUNDERSTORMS IN THE NORTHWEST BAHAMAS WITH DEEP MOISTURE
AND SOME SHOWERS EXTENDING WESTWARD TOWARDS SOUTH FLORIDA.
TERMINAL KPBI COULD EXPERIENCE LIGHT TO MODERATE SHOWERS THIS
MORNING ALTHOUGH MAINLY VFR CONDITIONS EXPECTED TO PREVAIL. WITH
THE INFLUX OF DEEP MOISTURE...VCTS ASSIGNED TO ALL EAST COAST
TERMINALS AT 16Z. WITH ANY SHOWER/THUNDERSTORM ACTIVITY VERY BRIEF
IFR CONDITIONS MAY BE POSSIBLE.

FOR TERMINAL KAPF...WITH HIGH PRESSURE PREVAILING ACROSS THE
REGION AND RESULTANT MODERATE EASTERLY WINDS...THE WEST COAST SEA
BREEZE MAY NOT DEVELOP WITH THE KAPF TAF WIND FORECAST INDICATING
SOUTHEASTERLY WINDS IN AFTERNOON. AS THE AFTERNOON PROGRESSES
SHOWER/THUNDERSTORM ACTIVITY IS EXPECTED TO INCREASE ACROSS THE
WESTERN PENINSULA WITH VCTS ASSIGNED AT 18Z.

60

PREV DISCUSSION... /ISSUED 349 AM EDT SAT AUG 30 2014/

HIGHLIGHTS...

* MAX HEAT INDICES HITTING 102-108 TODAY
* MODERATE RISK OF RIP CURRENTS ATLANTIC BEACHES
* STRONG TSTORM POTENTIAL WESTERN INTERIOR/GULF COAST THIS
  AFTERNOON

DISCUSSION...
HEAT INDICES ARE STILL IN THE 90S AT THIS EARLY MORNING HOUR
ACROSS THE EAST COAST METROPOLITAN AREAS WHERE IT HAS NOT RAINED.
A SAHARAN AIR LAYER IS OVER SOUTH FLORIDA AND WILL REMAIN OVERHEAD
TODAY. LIDAR AND SOUNDING DATA SHOW THAT THIS SAL IS RATHER
LOW...MAXED AT 1 KM. FORECAST SOUNDINGS SHOW THIS LAYER WITH A CAP
AND STEEP LAPSE RATES/DRY AIR ABOVE IT. HOWEVER, THIS IS NOT A
STRONG SAL SO IT WON`T LIMIT CONVECTION AS WOULD A STRONG EPISODE.
AS SUCH, MOISTURE WILL BE SUFFICIENT AND WITH THE PRESENCE OF THE
SAL (STEEPER LAPSE RATES ABOVE AN INVERSION) AND H5 TEMPS COOLING
TO NEAR -8C...WE COULD AGAIN HAVE STRONG THUNDERSTORMS THIS
AFTERNOON ACROSS THE WESTERN INTERIOR/GULF COAST REGION WHERE
CONVERGENCE WILL BE BEST...THOUGH NOT OPTIMAL. THAT`S ONE NEGATING
FACTOR FOR ROBUST CONVECTION...THE LOW LEVEL WIND FLOW WILL BE
EASTERLY AT NEAR 15 KT WHICH LIKELY WILL PREVENT A FULL BLOWN GULF
SEA BREEZE FROM DEVELOPING. HOWEVER, THERE STILL WILL BE SOME
CONVERGENCE WITH WIND FLOW VEERING ALONG THE GULF COAST. WILL
ORIENT POPS FROM ISOLATED EAST COAST TO SCATTERED CATEGORY GULF
COAST...WHERE FREQUENT LIGHTNING/STRONG WIND GUSTS WILL BE
POSSIBLE.

MAX HEAT INDICES ARE FORECAST TO BE IN THE 102-108F RANGE ACROSS
SOUTH FLORIDA TODAY...DUE TO LOWER TO MID 90S MAX TEMPS AND
DEWPOINTS WELL INTO THE 70S.

ONSHORE WINDS WILL RESULT IN A MODERATE RISK OF RIP CURRENTS ALONG
THE ATLANTIC BEACHES TODAY.

THE SAL WILL DEPART THE AREA ON SUNDAY AS RIDGING ACROSS NORTH
FLORIDA MOVES THIS AREA WESTWARD ON THE EASTERLY WIND FLOW. A DEEP
LAYERED RIDGE WILL REMAIN OVER NORTH FLORIDA WITH DEEP EASTERLY
FLOW ACROSS SOUTH FLORIDA NEXT WEEK. A TUTT/UPPER LEVEL TROUGH
EAST OF THE BAHAMAS WILL CONTINUE TO MOVE WESTWARD. MODEL
CONSENSUS TAKES THIS TO THE BAHAMAS DURING THE MIDDLE PART OF NEXT
WEEK WHILE OPENING UP. GFS/ECMWF SHOW A LOW LEVEL TROUGH MOVING NW
AND ACROSS THE AREA MID WEEK....LEADING TO AN INCREASING CHANCE OF
SHOWERS AND THUNDERSTORMS THEN. GUIDANCE INDICATES INCREASING POPS
BEGINNING TOMORROW AS WELL. NO SIGNIFICANT WEATHER FEATURES...BUT
IT LOOKS UNSTABLE AND SUFFICIENTLY MOIST AND AS SUCH FOLLOWED THE
POP TRENDS IN THE GUIDANCE THROUGH NEXT WEEK. /GREGORIA

MARINE...A LIGHT TO MODERATE EAST TO SOUTHEAST WIND WILL PREVAIL
ACROSS THE LOCAL WATERS AS THE ATLANTIC RIDGE REMAINS ACROSS NORTH
FLORIDA. SEAS WILL PREVAIL LESS THAN 4 FEET THROUGH NEXT WEEK.
WINDS/SEAS WILL BE HIGHER IN AND NEAR AN INCREASING CHANCE OF
THUNDERSTORMS EARLY NEXT WEEK.

AVIATION...
ISOLATED SHOWERS WILL CONTINUE TO DEVELOP AND MOVE NORTHWEST OVER
THE ATLANTIC WATERS EARLY THIS MORNING...BEFORE DRIER AIR WORKS
INTO THE AREA FROM THE BAHAMA ISLANDS. A FEW OF THE SHOWERS COULD
EVEN WORK INTO THE EAST COAST TAF SITES. THEREFORE...A VCSH WILL
BE PUT IN FOR THE EAST COAST TAF SITES THROUGH 14Z TODAY BEFORE
GOING DRY FOR REST OF TODAY.

THE WINDS OVER THE EAST COAST TAF SITES WILL REMAIN EAST TO
SOUTHEAST AT 5 TO 10 KNOTS INCREASING TO AROUND 12 KNOTS AFTER
14Z. THE WINDS AT KAPF TAF SITE WILL BE EASTERLY AT 5 TO 10 KNOTS
THROUGH MOST OF TODAY...BUT COULD BECOME MORE SOUTHERLY LATE THIS
AFTERNOON AFTER 20Z WHEN THE WEST COAST SEA BREEZE TRIES TO
DEVELOP. SO WILL ALSO PUT IN VCTS FOR KAPF TAF SITES BETWEEN 21Z
AND 00Z TODAY.

THE CEILING AND VIS WILL ALSO REMAIN IN THE VFR CONDITIONS TODAY
AT ALL OF THE TAF SITES. /BNB

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  79  90  79  90 /  20  30  10  40
FORT LAUDERDALE  81  91  80  90 /  20  20  10  40
MIAMI            80  90  80  90 /  20  20  10  40
NAPLES           77  92  77  91 /  20  60  20  60

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&

$$

SHORT TERM...21/KM
LONG TERM....57/DG



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