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Area forecast discussion 
National Weather Service Miami Florida
627 PM EDT Sat Apr 25 2015

afternoon convection has waned with just isolated showers along
the Palm Beach coast. Still an isolated tstorm possible off the
Palm beaches this evening. Otherwise, a tranquil, muggy night is
expected. /Gregoria


Previous discussion... /issued 406 PM EDT Sat Apr 25 2015/

quick update to account for the activity across Miami-Dade and
Broward and the expectation of more activity developing/focusing
further north into the West Palm Beach metropolitan area. Also, some of
the activity is developing in an east-west fashion with Doppler radar
showing near 1.5 inches of rain having fallen in downtown Miami.
So there is a risk for isolated street flooding in poorly drained
locales in metropolitan Southeast Florida with the activity this afternoon. A
strong wind gust cannot be ruled out as well before the
convection wanes early this evening. /Gregoria

Previous discussion... /issued 235 PM EDT Sat Apr 25 2015/

Short term (tonight-Monday night)...
currently, the middle to upper flow is nearly zonal with 500mb
temperatures at -6.5c which is warmer than typically seen in late
April. A surface ridge extends from the Atlantic to just south of
Lake Okeechobee and into the southeast Gulf of Mexico. This is
yielding a low level light southeast to south flow of air with
westerly flow aloft. Surface temperatures have not quite climbed to
90f and this is needed to break the low level cap with its base at
800mb. Still will expect some late afternoon boomers to develop with
the greatest concentration over the interior and towards the East
Coast metropolitan region. Middle level lapse rates are running near average
for this time of the year at 6.5c/km. This combined with the above
mentioned parameters and precipitable water at over 1.5" would suggest a few
storms could become strong with wind gusts to around 50 miles per hour.

On Sunday, while the upper flow does not change much the surface
ridge will shift south to the Florida Straits placing South Florida
under deep southwest to west flow and also forecast soundings show
some middle level drying with precipitable water dropping to around 1.5". This will
yield plenty of sunshine so that along with the westerly flow East
Coast temperatures will approach the middle 90s and will be flirting
with record maximums for the date. That kind of heating will
certainly cause vertical motion and even with some middle level
drying this will lead to a few possible afternoon thunderstorms
near the East Coast.

The surface ridge will remain suppressed to the south on Monday but
there will be some increase in middle level moisture once again as
developing low pressure aloft occurs over the Southern Plains
states. So again, increased moisture along with marginal middle level
lapse rates and deep westerly flow there will be higher chances for
afternoon thunderstorm activity across the interior and East Coast

Long term (tuesday-saturday)...
the European model (ecmwf) and GFS are having difficulty in the evolution of the
upstream trough and have differing solutions on how this will affect
South Florida weather from the middle into the end of next week.
They both show a southern stream trough cutting off over the
southern states and then slowly drift it towards the east. The
European model (ecmwf) depicts this low getting picked up by a northern stream
trough on Wednesday with a surface low moving across North Florida
with its associated late season cool front moving through South
Florida on Thursday. This would decrease rain chances then for
late Thursday and Friday with much less humid conditions. The GFS
however shows the cut off low getting left behind and not getting
kicked out to the east becoming an elongated trough across the
southern states late into the week. This scenario would stall the
associated cool front near South Florida keeping high rain chances
for the entire forecast. That being said, both models show an
unsettled period for South Florida next week with possible strong
thunderstorms towards the middle of the week. Rain chances will be
much higher than typical for late April and possibly persisting
through the end of the week.

winds across the regional waters will be transitioning to a south
to southwest direction tonight and Sunday at speeds of 10-15 knots
diminishing on Monday as the gradient slackens. A southerly wind
of around 15 knots will develop once again towards the middle of
next week as low pressure moves across the northern Gulf of
Mexico. With a mostly southerly wind direction, seas are expected
to be 4 feet or less through the period.


Preliminary point temps/pops...
West Palm Beach 74 93 75 89 / 20 10 10 50
Fort Lauderdale 77 93 78 89 / 20 10 0 50
Miami 76 94 77 90 / 20 10 0 40
Naples 78 88 76 86 / 0 10 10 30


Mfl watches/warnings/advisories...


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