Special Weather Statement, NWS Miami, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
217 PM EDT SAT APR 20 2013

.DISCUSSION...

SATURDAY THROUGH MONDAY...

IN THE SHORT TERM FOR THIS AFTERNOON AND EVENING THERE IS NOT MUCH
CHANGE FROM THE PREVIOUS THINKING. THE SHOWERS AND THUNDERSTORMS
OVER THE ATLANTIC WATERS HAVE DIMINISHED IN COVERAGE BUT A FEW
SHOWERS ARE BEGINNING TO DEVELOP ALONG THE SEA BREEZE EXTENDING FROM
SOUTH MIAMI-DADE TO COASTAL PALM BEACH COUNTY AS WELL AS WEST OF
LAKE OKEECHOBEE ASSOCIATED WITH THE FRONT ITSELF. THIS PATTERN IS
CONSISTENT WITH THE FORECAST OF HIGH RESOLUTION MODELS FOR THIS
AFTERNOON AND EVENING. FAVORING FACTORS FOR THE FORMATION OF SHOWERS
AND THUNDERSTORMS ALONG THE EAST COAST ARE: THE WEAK SOUTHWESTERLY
FLOW AND THE TROUGH OF LOW PRESSURE NEAR THE FLORIDA EAST COAST. THE
LIMITING FACTORS ARE THE WARM 500 MB TEMPERATURES AND THE CAP AROUND
15KFT. IT IS POSSIBLE THAT ONCE THE ACTIVITY ALONG THE SEA BREEZE
REACHES THE CAP IT COULD DIMINISH IN INTENSITY BUT STILL PRODUCE
HEAVY RAINS, GUSTY WINDS, AND LIGHTNING. IN OTHER WORDS, IT COULD
START ACTIVE IN THE NEXT FEW HOURS AND THEN WEAKEN A BIT AS THE
STORMS START REACHING THE CAP. THE ADVANCE OF THE FRONT IS ALSO A
FAVORABLE FACTOR THAT IT COULD BECOME MORE IMPORTANT AS THE DAY
PROGRESSES. THE STEERING FLOW WILL MOVE STORMS GENERALLY FROM WEST
TO EAST. THIS WILL INCREASE THE POTENTIAL FOR THUNDERSTORMS FOR
THE EAST COAST.

THE CURRENT 500 MB PATTERN SHOWS A TROUGH OF LOW PRESSURE OVER THE
EASTERN AND CENTRAL US AND A STRONG BLOCKING RIDGE OF HIGH PRESSURE
OVER THE WESTERN ATLANTIC. AS THE HIGH CONTINUES TO MOVE FURTHER
EAST COOLER 500 MB TEMPERATURES WILL SPREAD OVER SOUTH FLORIDA ON
SUNDAY. THIS IS EXPECTED TO INCREASE THE POTENTIAL FOR STRONG OR
EVEN SEVERE STORMS ON SUNDAY IF HEATING IS FAVORABLE.

LONG TERM /TUESDAY THROUGH FRIDAY/...
BEHIND THE SURFACE TROUGH...A MORE TYPICAL SPRING WEATHER REGIME
WILL TAKE HOLD OVER FLORIDA...WITH EASTERLY LOW-LEVEL FLOW AND
HIGH PRESSURE BUILDING BOTH NEAR SURFACE AND ALOFT. ISOLATED
MAINLY DIURNAL SHOWERS ARE EXPECTED...WITH PARTLY TO MOSTLY SUNNY
SKIES AND TEMPERATURES REMAINING SLIGHTLY ABOVE AVERAGE.

&&

.AVIATION...ISSUED AT 147 PM EDT SAT APR 20 2013...
SHOWERS AND THUNDERSTORMS ARE BEGINNING TO SAG INTO THE NORTHWEST
INTERIOR AREAS. WITH AN ESTABLISHED GULF COAST SEA BREEZE...THIS
ACTIVITY SHOULD CONTINUE TO PUSH TO THE EAST. ADDITIONAL
CONVECTION WILL ALSO BE POSSIBLE ACROSS THE EAST COAST TERMINALS
OVER THE NEXT FEW HOURS OF PEAK HEATING. KEPT TEMPO GROUPS AT ALL
EAST COAST SITES FROM 20Z-23Z. WILL AMEND IF NECESSARY.

&&

MARINE...
LONG-FUSED ADVISORIES AND WARNINGS ARE NOT EXPECTED THIS WEEKEND
OR NEXT WEEK OVER THE WATERS. LOCALLY HIGH WAVES AND WINDS CAN BE
EXPECTED IN SCATTERED TO NUMEROUS THUNDERSTORMS TODAY THROUGH
MONDAY...AND SPECIAL MARINE WARNINGS MAY BE ISSUED FROM TIME TO
TIME.

&&

FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES WILL BE ABOVE 50 PERCENT THIS
WEEKEND AND EARLY NEXT WEEK...AS MOIST ATMOSPHERE CONTRIBUTES TO
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. WINDS WILL MAINLY
SOUTH TODAY...BUT TRANSITION TO THE NORTHEAST TONIGHT AS COLD FRONT
MOVES IN. LOW WIND SPEEDS ARE EXPECTED OUTSIDE OF SHOWERS AND
THUNDERSTORMS.

&&

.PREV DISCUSSION... /ISSUED 947 AM EDT SAT APR 20 2013/

UPDATE...

SHOWERS AND THUNDERSTORMS OVER THE ATLANTIC WATERS HAVE DEVELOPED
THIS MORNING DUE TO THE CONVERGENCE OF SE FLOW OVER THE BAHAMAS
AND MORE SOUTHERLY FLOW OVER SOUTH FLORIDA. THE 12Z SOUNDING FROM
THIS MORNING SHOWS A CAP AROUND 650 MB ASSOCIATED WITH THE
SUBTROPICAL HIGH PRESSURE OVER THE ATLANTIC AND THE GULF. 500 MB
TEMPERATURES ARE AROUND -6C AND ARE NOT EXPECTED TO COOL BEYOND
-7C THIS AFTERNOON. HOWEVER, THE INFLUENCE OF A COLD FRONT MOVING
SOUTHWARD IS EXPECTED TO INTERACT WITH A WEAK EAST COAST SEA
BREEZE TO TRIGGER SHOWERS AND THUNDERSTORMS, ESPECIALLY IN PALM
BEACH AND BROWARD COUNTIES. SOME STORMS CAN ALSO EXTEND INTO
MIAMI-DADE. FOR THE WEST COAST THERE IS ONLY A SMALL CHANCE OF
THUNDERSTORMS, SINCE MOST OF THE SURFACE TROUGH IS ALIGNED FROM
NORTHEAST TO SOUTHWEST OVER THE ATLANTIC WATERS.

AS MENTIONED IN THE PREVIOUS DISCUSSION THE UPPER LEVEL
TEMPERATURES ARE FORECAST TO COOL ON SUNDAY ALLOWING FOR A GREATER
CHANCE OF THUNDERSTORMS THAN TODAY.

FOR TODAY THE HIGHEST POPS ARE STILL INCLUDED FOR PALM BEACH AND
BROWARD.

PREV DISCUSSION... /ISSUED 725 AM EDT SAT APR 20 2013/

AVIATION...
MOSTLY VFR CONDITIONS WILL OCCUR EARLY IN THE FORECAST ALTHOUGH
THERE COULD BE A BRIEF MVFR CIG AS A FEW SHOWERS MOVE ACROSS SOUTH
FLORIDA. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO DEVELOP BY THIS AFTERNOON AHEAD OF A WEAKENING COLD
FRONT THAT WILL SAG ACROSS THE REGION. THE HRRR INDICATES
CONVECTION TO BEGIN DEVELOPING IN EARNEST BETWEEN 18-20Z WITH THE
STEERING FLOW TAKING THE STORMS TO THE EAST COAST. THEREFORE, HAVE
LEFT TEMPO 18-22Z FOR ALL EAST TERMINALS WITH SOME OF THE ACTIVITY
POSSIBLY PERSISTING BEYOND THIS TIME FRAME. SURFACE WINDS ARE
QUESTIONABLE WITH A SLOW MOVING FRONTAL BOUNDARY BUT GENERALLY
SSW-SSE AHEAD OF THE FRONT AND NE BEHIND THE FRONT.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  73  84  70  83 / 40 60 40 60
FORT LAUDERDALE  74  85  72  84 / 30 60 40 60
MIAMI            75  86  73  85 / 30 50 40 60
NAPLES           69  86  70  84 / 20 40 40 50

&&

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

DISCUSSION/MARINE/FIRE...71/JE
AVIATION/RADAR...10/CD

HAZARDOUS WEATHER OUTLOOK FOR SOUTH FLORIDA
NATIONAL WEATHER SERVICE MIAMI FL
418 AM EDT SAT APR 20 2013

AMZ610-630-650-651-670-671-FLZ063-066>075-168-172>174-GMZ656-657-676-
202330-
LAKE OKEECHOBEE-BISCAYNE BAY-
COASTAL WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL OUT 20 NM-
COASTAL WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL OUT 20 NM-
WATERS FROM JUPITER INLET TO DEERFIELD BEACH, FL EXTENDING FROM
20 NM TO 60 NM-
WATERS FROM DEERFIELD BEACH TO OCEAN REEF, FL EXTENDING FROM 20 NM
TO THE TERRITORIAL WATERS OF THE BAHAMAS-GLADES-HENDRY-
INLAND PALM BEACH-METRO PALM BEACH-COASTAL COLLIER-INLAND COLLIER-
INLAND BROWARD-METRO BROWARD-INLAND MIAMI DADE-METRO MIAMI DADE-
MAINLAND MONROE-COASTAL PALM BEACH-COASTAL BROWARD-
COASTAL MIAMI DADE-FAR SOUTH MIAMI DADE-
COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-
GULF WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL EXTENDING FROM
20 TO 60 NM-
418 AM EDT SAT APR 20 2013

...SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS THIS AFTERNOON...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH FLORIDA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS: SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS
ARE EXPECTED BY THIS AFTERNOON. THE BEST CHANCE WILL BE NORTH OF
TAMIAMI TRAIL WITH THE STRONGEST STORMS CAPABLE OF PRODUCING
FREQUENT LIGHTNING STRIKES ALONG WITH BRIEF HEAVY DOWNPOURS AND
GUSTY WINDS.

WIND: SOME OF THE STORMS MAY PRODUCE WIND GUSTS OF 40-50 MPH.

FLOODING: THE STORMS WILL CONTAIN BRIEF HEAVY DOWNPOURS AND THIS
COULD LEAD TO SOME MINOR URBAN STREET FLOODING MAINLY ACROSS THE
EAST COAST METROPOLITAN REGION.

RIP CURRENTS: A SOUTH TO SOUTHEAST WIND OF AROUND 10 MPH ALONG THE
ATLANTIC COAST AND A SOUTHWEST WIND OF 5 TO 10 MPH ALONG THE GULF
COAST WILL RESULT IN A SLIGHT RISK OF RIP CURRENTS AT THE BEACHES.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

STRONG THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH SUNDAY AND
MONDAY AS A WEAKENING STATIONARY FRONT REMAINS OVER THE AREA. THE MAIN
IMPACTS WITH ANY STORM THAT DOES DEVELOP WILL BE LIGHTNING...HAIL
AND STRONG WIND GUSTS. ADDITIONALLY, ANY ACTIVITY THAT BECOMES
CONCENTRATED IN ONE AREA COULD LEAD TO LOCALIZED FLOODING.

.SPOTTER INFORMATION STATEMENT...

WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED, HOWEVER
INDIVIDUAL SPOTTERS ARE ENCOURAGED TO REPORT HIGH WIND, HAIL AND
FLOODING TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
MIAMI.

FOR MORE INFORMATION...VISIT THE NATIONAL WEATHER SERVICE IN
MIAMI WEBSITE AT WWW.WEATHER.GOV/MIAMI.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
416 PM EDT SAT APR 20 2013

FLZ071-072-202045-
INLAND BROWARD COUNTY FL METRO BROWARD COUNTY FL
416 PM EDT SAT APR 20 2013

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR CENTRAL BROWARD
COUNTY...FOR GUSTY WINDS OF 45 TO 55 MPH...

* UNTIL 445 PM EDT

* AT 414 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
  STRONG THUNDERSTORM NEAR MILE MARKER 30 ON ALLIGATOR ALLEY...AND
  MOVING SOUTHEAST AT 25 MPH.

* THE STORM WILL AFFECT...
  MILE MARKER 30 ON ALLIGATOR ALLEY...
  EAST TOLL GATE ON ALLIGATOR ALLEY...
  INTERSECTION I-75 AND U.S. 27...
  WESTON...
  AND SURROUNDING COMMUNITIES.

FREQUENT TO EXCESSIVE LIGHTNING...GUSTY WINDS FROM 45 TO 55 MPH...UP
TO NICKEL-SIZED HAIL...TORRENTIAL DOWNPOURS...OR A COMBINATION OF
THESE ARE POSSIBLE. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION. THESE
WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING UNTIL THE
STORM PASSES.

LAT...LON 2618 8020 2597 8041 2613 8062 2625 8054
TIME...MOT...LOC 2016Z 295DEG 20KT 2616 8052

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
436 PM EDT SAT APR 20 2013

FLZ063-202100-
GLADES FL
436 PM EDT SAT APR 20 2013

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR NORTHEASTERN
GLADES COUNTY...FOR FREQUENT TO EXCESSIVE LIGHTNING...GUSTY WINDS
FROM 45 TO 55 MPH...UP TO NICKEL-SIZED HAIL...

* UNTIL 500 PM EDT

* AT 430 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
  STRONG THUNDERSTORM NEAR BRIGHTON SEMINOLE INDIAN...AND MOVING
  NORTHEAST AT 15 MPH.

* THE STORM WILL AFFECT...
  RURAL NORTHEASTERN GLADES COUNTY
  AND SURROUNDING COMMUNITIES.

FREQUENT TO EXCESSIVE LIGHTNING...GUSTY WINDS FROM 45 TO 55 MPH...UP
TO NICKEL-SIZED HAIL...TORRENTIAL DOWNPOURS...OR A COMBINATION OF
THESE ARE POSSIBLE. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION. THESE
WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING UNTIL THE
STORM PASSES.

LAT...LON 2720 8094 2719 8091 2701 8103 2709 8122
      2713 8120 2713 8117 2718 8117 2722 8116
      2722 8095
TIME...MOT...LOC 2036Z 207DEG 12KT 2713 8108

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
449 PM EDT SAT APR 20 2013

FLZ071-072-168-172-202130-
COASTAL BROWARD COUNTY FL COASTAL PALM BEACH COUNTY FL INLAND BROWARD
COUNTY FL METRO BROWARD COUNTY FL
449 PM EDT SAT APR 20 2013

...A SIGNIFICANT WEATHER ADVISORY IS IN EFFECT FOR EASTERN BROWARD
COUNTY...SOUTHEASTERN PALM BEACH COUNTY...FOR FREQUENT TO EXCESSIVE
LIGHTNING...GUSTY WINDS FROM 45 TO 55 MPH...UP TO NICKEL-SIZED
HAIL...

* UNTIL 530 PM EDT

* AT 447 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
  STRONG THUNDERSTORM NEAR DAVIE...AND MOVING EAST AT 10 MPH.

* THE STORM WILL AFFECT...
  SUNRISE...
  PLANTATION...
  NOVA SOUTHEASTERN UNIVERSITY...
  DOWNTOWN-DAVIE...
  NORTH PERRY AIRPORT...
  AND SURROUNDING COMMUNITIES.

FREQUENT TO EXCESSIVE LIGHTNING...GUSTY WINDS FROM 45 TO 55 MPH...UP
TO NICKEL-SIZED HAIL...TORRENTIAL DOWNPOURS...OR A COMBINATION OF
THESE ARE POSSIBLE. LIGHTNING IS THE NUMBER ONE WEATHER RELATED
KILLER IN FLORIDA. TREES AND OPEN SHELTERS OFFER NO PROTECTION. THESE
WINDS CAN DOWN SMALL TREE LIMBS AND BRANCHES...AND BLOW AROUND
UNSECURED SMALL OBJECTS. SEEK SHELTER IN A SAFE BUILDING UNTIL THE
STORM PASSES.

LAT...LON 2626 8007 2615 8010 2613 8009 2598 8012
      2597 8049 2633 8044 2633 8007
TIME...MOT...LOC 2049Z 283DEG 8KT 2611 8030

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