Area Forecast Discussion
Issued by NWS Miami, FL

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FXUS62 KMFL 011255
AFDMFL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
855 AM EDT TUE SEP 1 2015

.UPDATE...
PREVAILING WIND FLOW ON THE MORNING MIAMI SOUNDING IS OUT OF THE
SOUTHEAST WITH MEAN STEERING WINDS AROUND 8 KT. THE FORECAST WAS
UPDATED EARLIER TO INCREASE THE SHOWER COVERAGE ALONG THE PALM
BEACH COAST. HOWEVER, THE FOCUS WILL SHIFT TO THE INTERIOR THIS
AFTERNOON AS SEA BREEZES DEVELOP ALONG BOTH COAST. SO THE HIGHEST
POPS OVER THE RURAL INTERIOR STILL LOOK GOOD AND NO SIGNIFICANT
CHANGES WILL BE MADE TO THE FORECAST THIS MORNING. /GREGORIA

&&

.PREV DISCUSSION... /ISSUED 720 AM EDT TUE SEP 1 2015/

AVIATION...
VFR WILL PREVAIL. A FEW SHOWERS WILL BE IN THE VICINITY OF THE
EAST COAST TERMINALS, ESPECIALLY DURING THE MORNING. THUNDERSTORMS
DEVELOPING THIS AFTERNOON WILL FOCUS OVER THE INTERIOR AWAY FROM
THE TERMINALS. LIGHT WINDS WILL BECOME SE NEAR 10 KT EAST COAST
AND SW NEAR 10 KT AT KAPF THIS AFTERNOON. /GREGORIA

PREV DISCUSSION... /ISSUED 410 AM EDT TUE SEP 1 2015/

DISCUSSION...
A GENERALLY UNREMARKABLE PATTERN OVER THE FORECAST PERIOD, WITH
HIGH PRESSURE TO THE NORTH AND THE WESTERN EDGE OF AN UPPER LEVEL
RIDGE. THIS WILL KEEP THE LOW LEVEL FLOW OUT OF THE EAST TO
SOUTHEAST FOR THE NEXT SEVERAL DAYS. THE FLOW LOOKS TO BE LIGHT
ENOUGH FOR THE SEA BREEZE TO FORM ON BOTH COASTS, THE LOOK TO
COLLIDE IN DIFFERENT LOCATIONS EACH DAY. OF COURSE, THIS WILL BE
THE LOCATIONS FOR THE BEST CHANCES OF SHOWERS AND THUNDERSTORMS
OVER THE NEXT SEVERAL DAYS.

BY FRIDAY, THE FLOW DOES TURN MORE TO THE SOUTH TO SOUTHEAST AS A
WEAK SFC LOW DEVELOPS OVER NORTH FLORIDA AND A WEAK UPPER LEVEL
TROUGH MOVES ACROSS THE SOUTHEAST UNITED STATES. THE WEAK LOW WILL
MEANDER AROUND THE REGION INTO THE EARLY PART OF NEXT WEEK THIS
WILL CAUSE THE LOW LEVEL WINDS TO FLUCTUATE EACH DAY. THIS WILL
HELP TO ENHANCE THE CHANCES FOR SHOWERS AND THUNDERSTORMS FROM
THIS WEEKEND AND THE BEGINNING OF NEXT WEEK.

AS FOR TODAY, THE MAIN AREA OF THUNDERSTORM DEVELOPMENT LOOKS TO
BE IN THE INTERIOR COLLIER COUNT AND MAINLAND MONROE WHERE THE
MODELS SHOW THE SEA BREEZES COMING TOGETHER. THE GFS AND THE SHORT
RANGE MODELS GENERALLY AGREE WITH THIS, WITH SOME DISAGREEMENT
WITH THE COVERAGE. HOWEVER, THIS IS REFLECTED IN THE POPS TO
ACCOMMODATE THE VARIOUS MODELS. THE ECMWF IS THE OUTLIER WITH
ALMOST NOTHING DEVELOPING TODAY.

AS FOR DYNAMICS BESIDES THE SEA BREEZE, THE 500MB TEMPS ARE ON
THE WARM SIDE, WITH BETWEEN -6C AND -6.5C PER THE GFS. THE NAM
MODEL SOUNDINGS SHOW THE 700MB-500MB LAPSE RATES TO BE AROUND
6-6.5 C/KM. THE FREEZING LEVEL LOOKS TO AROUND 4.7 KM, OR 15000
FT. THIS PUTS THE DBZ CORE OF 50DBZ REACHING OVER 39000FT FOR
LARGE HAIL, WHICH IS UNLIKELY TODAY. THE NCAPE IS OVER .2, WHICH
IS INDICATIVE OF SOME LONGER LAST STORM WITH STRONGER VERTICAL VELOCITY.
GIVEN THAT, WOULD NOT RULE OUT SOME SMALL HAIL TODAY. PWATS DO
LOOK SOMEWHAT LOWER TODAY, SITTING AROUND 1.75 INCHES ALONG THE
COAST, BUT AROUND 2 INCHES IN THE INTERIOR. REGARDLESS, BEING
SOUTH FLORIDA IN THE SUMMER, HEAVY RAIN WILL BE POSSIBLE ACROSS
THE AREA. THE MBE VELOCITY IS LOW OVER THE ATLANTIC COAST, AT
LESS THAN 10KTS. FOR THE INTERIOR AND GULF COAST THEY ARE BETTER
AT 20 KTS. THERE IS THE POSSIBILITY OF SOME BACK BUILDING AND/OR
TRAINING OVER THE EAST AREAS. LOOKING AT LAST NIGHTS SOUNDING, THE
DCAPE WAS AROUND 800 J/KG. WHILE THIS MORNINGS SOUNDING WILL
INDICATE A BETTER ESTIMATE, THIS WOULD INDICATE MAXIMUM DOWNBURSTS
OF POSSIBLY 35-45 KTS, GIVE OR TAKE A FEW KTS.

AVIATION...
A LIGHT SOUTHEAST STEERING WIND WILL PREVAIL ACROSS SOUTH FLORIDA
TODAY WITH A MOIST AND UNSTABLE AIR MASS. SEA BREEZES WILL
DEVELOP ALONG BOTH COASTS AND SCATTERED CONVECTION WILL FORM ALONG
THE BOUNDARIES AND PUSH INLAND AWAY FROM THE COASTS. THUS, HAVE
ONLY PLACED VCSH IN THE TAFS AS THUNDER SHOULD BE WELL INLAND FROM
ANY OF THE TERMINALS.

MARINE...
HIGH TO THE NORTHEAST WILL KEEP A SURFACE FLOW OF 5-10 KTS ACROSS
THE SOUTH FLORIDA WATERS. THIS WILL RESULT IN WAVE HEIGHTS
GENERALLY AROUND 1 FT, WITH OCCASIONAL WAVES TO 3 FT. THERE IS A
CHANCES OF NOCTURNAL SHOWERS AND THUNDERSTORMS EACH NIGHT. BY THE
WEEKEND, THE WIND WILL TURN MORE TO THE SOUTH TO SOUTHWEST, STILL
AROUND THE SAME SPEED. THE ARE NO SIGNIFICANT FORECASTED SWELLS
THROUGH THE WEEKEND.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH  92  78  92  79 /  20  10  20  10
FORT LAUDERDALE  91  80  91  79 /  20  10  30  10
MIAMI            91  80  92  79 /  30  10  40  10
NAPLES           91  78  90  78 /  40  30  30  30

&&

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

$$


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