Scientific Forecaster Discussion
fxus62 kmfl 232013
Area forecast discussion
National Weather Service Miami Florida
413 PM EDT Tue may 23 2017
..strong to even severe storms possible late Wednesday into
a trough of low pressure located over the central United States
will move east this week and be over the eastern United States by
late in the week. The trough will also strengthen while moving
eastward, pushing a stationary front over the southeastern United
States southward into the Florida Peninsula. The front is forecast
to enter the South Florida area by late Thursday as it weakens and
dissipates across the region. Main concern this forecast cycle is
the potential for strong storms with a few severe possible late
Wednesday into Thursday morning.
Wednesday through Thursday...the wind flow will become southwesterly
on Wednesday and Wednesday night ahead of the cold front bringing in
deep tropical moisture to the area. Showers and thunderstorms are
forecast to develop over South Florida Wednesday afternoon through
Thursday with the best coverage Wednesday evening into Thursday.
The latest short range models continue to show a mid to upper
level jet of 100 to 130 knots moving around the base of the trough
Wednesday night through Georgia/north/central Florida along with a low
level jet of 40 to 50 knots. European model (ecmwf) and NAM bring this low level yet
as far south as the lake Okee region. This will allow for a possible
squall line to develop on Wednesday over northern Florida and move
southward into South Florida Wednesday night into Thursday morning.
At this time, give or take a few hours, the best timing looks to be
the evening hours toward midnight SW coast and lake Okee region and
Southeast Florida overnight towards Thursday morning. Discrete strong
storms could also develop well ahead of this main activity across
South Florida Wednesday afternoon. The low level front weakens
considerably on Thursday lagging well behind main upper level
forcing resulting in cloudiness and wet conditions lingering through
much of the day before conditions begin to dry out overnight.
Winds gusting in excess of 40 to 50 kts will be the main concern
primarily with the main activity laid out above. Hail is a concern
but to a lesser extent and the best chance will be tomorrow
afternoon into early evening. NAM continues to show 0-1 km helicity
values in the 200-300 m2/s2 range across SW Florida and lake Okee
regions overnight tomorrow night with the main activity. Therefore a
tornado or two cannot be ruled out.
All of that certainly justifies the slight risk of severe weather
for the northern areas Storm Prediction Center currently has in place for tomorrow
and tomorrow night with a marginal risk elsewhere.
The pwat values will also be increasing from around 1.5 inches
Wednesday morning to around 2 inches Wednesday night and Thursday
which is well above normal for this time of year. This will allow
for some heavy rainfall to occur over the area. However, the
grounds are dry to very dry over South Florida, and the western
areas of South Florida are also in a severe to extreme drought
conditions. Therefore, flooding concerns with this activity are
limited at this time but will continue to monitor.
Extended forecast... the trough of low pressure will continue to
move east into the western Atlantic waters this weekend. This will
allow for high pressure to build into South Florida this weekend
into early next week, and allow for both sea breezes to develop and
push inland. Therefore, a more typical Summer pattern with a slight
chance to a chance of showers and thunderstorms are possible each
afternoon this weekend into early next week mainly over the interior
areas of South Florida.
wind speeds will increase 20 knots for Wednesday and Wednesday night.
The winds will then remain southwesterly on Thursday, as the
speeds decrease through the day. Small craft advisories will
likely be needed starting tomorrow.
the threat of rip currents will continue to be low for the East Coast
beaches through end of the week, but the Gulf Coast beaches will
likely increase to a high risk on Wednesday and Thursday due to
the southwest breezy conditions.
the East Coast Metro areas could see near record highs for
Wednesday, due to the breezy southwest wind flow. Here are the
record highs and forecast highs for the East Coast areas for
forecast highs record highs
mia 93 94 - 2013
fll 93 94 - 1951
pbi 94 96 - 1917
Preliminary point temps/pops...
West Palm Beach 77 92 75 87 / 10 50 60 70
Fort Lauderdale 77 91 76 90 / 20 50 60 70
Miami 77 91 76 89 / 20 50 60 70
Naples 77 87 78 85 / 10 70 80 70