Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Miami Florida
1021 am EDT Monday Sep 1 2014
The latest water vapor imagery indicates the middle to upper level
trough continues to retrograde to the southwest and is entering
the northwest Bahamas. This is bringing in some drier middle to upper
level air into South Florida and adjacent waters this morning.
Recent radar returns indicate isolated shower activity mainly
across the Atlantic waters. Minor updates were done to the short
term forecast to reflect the current conditions. But as the
aforementioned trough continues to move to the southwest and into
the regional Atlantic waters...that will likely allow for some
potential for convection. There is currently active convection in
the northwest Bahamas Islands. So the forecast reflects scattered
shower/thunderstorm activity possible over the Atlantic waters
and East Coast metropolitan areas later this afternoon with greater
coverage expected across the western peninsula late this afternoon
where the surface convergence will be most dominant. So overall no
significant changes from previous forecast or synoptic reasoning
except for the very short term.
Previous discussion... /issued 728 am EDT Monday Sep 1 2014/
mostly VFR conditions are expected through the forecast with a
moderate east wind flow. Anticipated thunderstorms and rain development will be over
the interior with a westward propagation. At this time, placed a
thunderstorms in the vicinity in the kapf taf after 19z and they could have a brief MVFR or
even IFR ceiling/visibility through the afternoon. East flow will prevent a
sea breeze along the southwest coast but wind is likely to veer to
the south-southeast as it tries to form.
Previous discussion... /issued 329 am EDT Monday Sep 1 2014/
* moderate risk of rip currents Atlantic beaches
* slight tstorm chance East Coast, better chance Gulf Coast today
* stormier pattern middle-late week; strong storms possible
the weather pattern on this Labor Day will remain
mostly unchanged from yesterday. Ridge axis will remain over North
Florida, maintaining an easterly wind flow locally with convective
focus along the Gulf Coast in the afternoon. Low level winds will
be strong enough to disallow a full Gulf sea breeze from
developing, but some veering of the wind field is expectedthere
which again will lead to enough convergence to spark some tstorm
development. Across the East Coast, hrrr shows a scenario similar
to yesterday with quick passing showers developing. Cannot rule
out thunderstorms East Coast but convergence will be lacking so coverage
would be isolated at best.
Like yesterday, a limiting factor for more active thunderstorms is the
lack of a full fledged onshore Gulf sea breeze. However, cannot
rule out a strong tstorm or two given some convergence along with
the instability and continued dry air aloft. Wind gusts of 40-50
miles per hour is the primary threat.
A deep layered trough east of the Bahamas is shown by the global
models to move west and across South Florida Wednesday night-Thu. This
will be associated with cooling aloft along with increasing
moisture, spelling a stormier period middle week and even into late
week as higher instability remains. Probability of precipitation accordingly show an
upward trend middle-late week. Could see some strong storms anywhere
beginning Wednesday through late week due to the cold air aloft and
trough passage, though more cloudiness would be a limiting factor.
high pressure will slowly weaken over the southeastern United
States today which in turn will keep a easterly wind flow of
around 5 knots through early this morning at all of the taf sites.
The wind direction will remain easterly after 14z today but
increase to around 10 knots over all of the taf sites.
The weather should remain dry through the early morning hours before
some showers works into the East Coast taf sites after 14z.
So will put in vcsh after 14z for the East Coast taf sites. For
kapf taf site...the weather will also remain dry through most of
this Labor Day. However...a late West Coast sea breeze could
develop and push into the kapf taf site after 21z today. So will
put in thunderstorms in the vicinity between 21z and 00z today.
The ceiling and visible will also remain in the VFR conditions at all
of the taf sites for this Labor Day.
Marine...east southeast winds less than 15 knots will prevail as
the Atlantic ridge remains north of the local waters. Seas will be
correspondingly low. A trough will move across the waters late
Wednesday- Thu, bringing an increasing chance of thunderstorms
especially across the Atlantic waters.
Preliminary point temps/pops...
West Palm Beach 90 79 90 77 / 30 20 40 20
Fort Lauderdale 91 80 90 80 / 30 20 50 20
Miami 90 80 89 78 / 30 20 50 20
Naples 91 76 91 76 / 60 30 60 20