Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 301343
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
943 AM EDT SUN AUG 30 2015

.UPDATE...

DEEP TROPICAL MOISTURE IN PLACE WITH 12Z RAOB PWAT AT 2.4". HVY
RAINFALL THREAT CONTINUES WITH TRAINING LINES OF SHOWERS AND
STORMS APPROACHING THE EAST COAST FROM THE SOUTHEAST. SOLID 2 TO 3
INCHES FELL OVERNIGHT, SO ANY ADDITIONAL STORMS WHICH CONTAIN
INTENSE RAINFALL RATES CAN QUICKLY LEAD TO URBAN STREET FLOODING
IN THE METRO AREAS THIS MORNING AND THIS AFTERNOON.

SOUNDING ALSO SHOWED FAVORABLE H7-H5 LAPSE RATES OF 6.8C/KM AND
FAIR H5 TEMPS AROUND -7C. KEY TO ADDITIONAL DEVELOPMENT THIS
AFTERNOON, WITH PERHAPS SOME STRONG STORMS, ESPECIALLY INTERIOR
AND WEST, WILL BE BASED UPON HEATING LATER TODAY. LLVL
SHR/HELICITY AND WIND PROFILES SUGGEST STRONG WIND GUSTS AND
POSSIBLY ISOLATED TORNADOES INTERIOR AND WEST COAST. BY 0Z MONDAY,
SURFACE LOW PRESSURE IS JUST OFFSHORE OF NAPLES, WHICH SHOULD ALSO
PLACE VERY HEAVY RAINFALL ALONG THE WEST COAST INTO THIS EVENING.

&&

.PREV DISCUSSION... /ISSUED 745 AM EDT SUN AUG 30 2015/

AVIATION...

NUMEROUS SHOWERS AND STORMS ARE EXPECTED TO MOVE ONSHORE FROM THE
OFFSHORE MIAMI-DADE WATERS THROUGH THIS MORNING. CURRENT LINE OF
HVY RAIN AND CONVECTION MAY TRAIN RIGHT OVER MIA/OPF OVER THE
NEXT HR OR SO. MVFR/IFR CONDS POSSIBLE IF THIS OCCURS. AFTERNOON
CONVECTION MAY BE STUNTED BY CLOUDS AND ACTIVITY THIS AM, SO WILL
NOT ADD ANY TEMPO GROUPS AT THIS TIME EXCEPT FOR APF. BASED ON
CURRENT RADAR TRENDS, MOST ACTIVITY MAY BE SOUTH OF PBI THROUGH
THIS MORNING. NUMEROUS SHWS/STORMS MAY ONCE AGAIN AFFECT EAST
COAST TERMINALS INTO THIS EVENING AND TONIGHT.

PREV DISCUSSION... /ISSUED 406 AM EDT SUN AUG 30 2015/

SHORT TERM (TODAY-TUESDAY)...
THE CURRENT ANALYSIS IN THE MID AND UPPER LEVELS SHOWS A CLOSED LOW
PRESSURE AREA CENTERED OVER THE FLORIDA PANHANDLE WITH A RIDGE AXIS
FROM THE SOUTHERN TIP OF THE PENINSULA INTO THE WESTERN ATLANTIC. AT
THE SURFACE, A TROUGH WHICH IS THE REMNANTS OF ERIKA EXTENDS FROM
THE FLORIDA STRAITS AND ACROSS THE WESTERN BAHAMAS. THE MID LEVEL
TROUGH WILL LIFT TO THE NORTHEAST THROUGH MONDAY WITH THE ATLANTIC
RIDGE BUILDING BACK TO THE WEST WHILE THE SURFACE TROUGH MOVES
ACROSS SOUTH FLORIDA TODAY AND INTO THE SOUTHEAST GULF OF MEXICO
TONIGHT AND MONDAY. THIS TROUGH WILL DISSIPATE BY TUESDAY AS WEAK
HIGH PRESSURE BUILDS BACK TO THE WEST.

GIVEN THE ABOVE SCENARIO, PWAT IS FORECAST TO JUMP TO NEAR 2.25"
THIS MORNING AND REMAIN AT THAT LEVEL THROUGH MONDAY WITH A DEEP
SOUTH TO SOUTHEAST FLOW OF TROPICAL AIR. THE FIRST BAND FROM THE
REMNANTS OF ERIKA MOVED ONTO THE SOUTHEAST COAST AROUND MIDNIGHT
WITH MULTIPLE BANDS SINCE THAT TIME. THIS WILL ONLY CONTINUE FOR THE
NEXT 24 TO 36 HOURS WITH 2-4" OVERALL RAINFALL TOTALS WITH THE
HIGHEST AMOUNTS LIKELY TO BE OVER THE SOUTHERN HALF OF THE AREA.
EVEN HIGHER TOTALS MAY OCCUR WHEREVER CONVERGENT BOUNDARIES SET UP
WITH MULTIPLE BANDS TRAINING ACROSS THE SAME AREA. THEREFORE, THE
FLOOD WATCH WILL CONTINUE ACROSS ALL OF SOUTH FLORIDA THROUGH EARLY
MONDAY AND MAY NEED TO BE EXTENDED IF THIS WET TREND CONTINUES INTO
MONDAY EVENING AS SOME OF THE MODELS ARE SUGGESTING. BY TUESDAY,
SLIGHT DRYING ALOFT WILL OCCUR AS THE MID LEVEL RIDGE BUILDS IN.
HOWEVER, PWATS ARE FORECAST TO LOWER BELOW 2" BUT STILL REMAIN AT
CLIMATOLOGICAL LEVELS FOR EARLY SEPTEMBER SO POPS WILL CONTINUE ON
THE HIGH END ALTHOUGH THE THREAT FOR FLOODING SHOULD END.

LONG TERM (WEDNESDAY-SATURDAY)...
A DEEP LAYER RIDGE WILL RETURN TO THE AREA IN THE EXTENDED PERIOD
WITH EASTERLY FLOW EXPECTED. THE FORECAST SOUNDINGS FROM BOTH THE
GFS AND ECMWF SHOW THE GRADIENT FLOW BECOMING EXTREMELY WEEK BY THE
END OF THE WEEK INTO NEXT WEEKEND AS THE HIGH PRESSURE WEAKENS. THIS
PATTERN WILL ALLOW FOR THE GREATEST CHANCES FOR RAIN TO BE OVER THE
INTERIOR AND SOUTHWEST COAST AT MIDWEEK AND THEN MOSTLY INTERIOR
TOWARDS THE END OF THE WEEK INTO THE WEEKEND WITH MOSTLY SEA BREEZE
INTERACTION.

MARINE...
EAST TO SOUTHEAST WIND WILL BE ON THE INCREASE ACROSS THE SOUTH
FLORIDA WATERS TODAY AS A SURFACE TROUGH MOVES THROUGH THE AREA. A
SCA WILL REMAIN IN EFFECT THROUGH TODAY AS THE WIND BECOMES 20-25
KNOTS OVER THE ATLANTIC AND CLOSE TO 20 KNOTS ELSEWHERE. THE WIND
WILL BEGIN TO SUBSIDE SOMEWHAT TONIGHT AND MONDAY AS THE TROUGH
WEAKENS AND MOVES INTO THE EASTERN GULF OF MEXICO BUT A SCEC
STATEMENT WILL LIKELY BE NEEDED FOR AT LEAST SOME OF THE AREA.
HIGH PRESSURE WILL BUILD BACK INTO THE LOCAL WATERS BY THE END OF
THE WEEK.

HYDROLOGY...
LOCALLY RAINS ARE LIKELY TO OCCUR THROUGH AT LEAST TONIGHT AND
POSSIBLY INTO MONDAY AS THE REMNANTS OF ERIKA MOVE THROUGH.
RAINFALL TOTALS OF 3-6" ARE LIKELY BY MONDAY NIGHT WITH EVEN
ISOLATED MUCH HIGHER AMOUNTS IF CONVERGENT BOUNDARIES SET UP AND
STRONGER CELLS TRAIN ACROSS THE SAME AREA.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  84  78  91  78 /  90  70  60  40
FORT LAUDERDALE  84  78  90  79 /  90  70  60  30
MIAMI            85  78  90  79 /  90  70  60  30
NAPLES           88  77  90  77 /  80  80  70  40

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...FLOOD WATCH THROUGH MONDAY MORNING FOR FLZ063-066>075-168-
     172>174.

     HIGH RIP CURRENT RISK UNTIL 8 PM EDT THIS EVENING FOR FLZ168-172-
     173.

AM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR AMZ630-650-
     651-670-671.

GM...NONE.
&&

$$

SHORT TERM...21/KM
LONG TERM....21/KM


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