Scientific Forecaster Discussion
fxus62 ktbw 241338
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
938 am EDT Wed may 24 2017
..severe storms possible this afternoon and tonight...
..Minor coastal flooding possible through early tonight...
a large and potent upper level trough and closed low over the mid
Mississippi Valley early this morning will continue to sink
southeast into the lower Mississippi Valley this afternoon
and across the southeastern states tonight, before lifting
out to the northeast on Thursday, as an attendant surface
low over the Tennessee/Ohio valleys deepens and lifts north into the
eastern Great Lakes region. As the surface low lifts out a
trailing cold front will move across the southeastern states
the remainder of today, then south through the forecast
area tonight and Thursday.
Ample low level moisture (pw's increasing toward 2 inches) within
the deep layered southwest wind flow ahead of the front combined
with sufficient instability, embedded vort maxes rotating through
the base of the upper trough, and decent upper level divergence
will support increasing chances for showers and thunderstorms
over the forecast area the remainder of today and continuing
into tonight. Strengthening wind fields ahead of the upper
trough and front (850mb winds increasing into the 45-55 knot
range during the afternoon) will support increasing shear
within the atmosphere which will be supportive of organized
convection and supercells with a favorable environment for
severe storms to develop with damaging winds the primary
hazard, with a potential for a tornado or two as well.
At the present time hi-res guidance suggests that there will be
an increasing threat for multiple rounds of severe convection moving
in from the Gulf and affecting the region during the afternoon and
evening hours with the latest hrrr depicting the greatest chances
across central and northern portions of the forecast area through the
In addition to the severe threat locally heavy rainfall will be
possible which may produce some minor flooding of low lying and poor
drainage areas, as well as the ponding of water on roadways.
Frequent deadly lightning will also accompany the storms.
Strong and gusty south to southwest winds ahead of the front will
continue to support increasing seas over the adjacent Gulf waters
with hazardous surf conditions developing along area beaches along
with a high risk of rip currents. The strong onshore flow will also
likely cause tides to run some 2 to 3 feet above normal at times of
high tide along the Levy and Citrus County coasts where a coastal
Flood Warning remains in effect until 5 PM EDT this evening, with
1 to 2 feet above normal tides expected further to the south.
Residents living along the coast should monitor water levels
and be ready to move to higher ground if flooding is observed.
The strong and gusty winds will also produce very hazardous boating
conditions on area lakes and a lake Wind Advisory will remain
in effect for the entire area until 10 PM EDT tonight. All residents
and visitors to west central and southwest Florida should
continue to monitor the latest forecast through tonight.
As for a morning update have already adjusted rain chances down
across central and southern portions of the forecast area for the
remainder of the morning hours based on latest radar trends, and
have added severe wording for the afternoon and evening time
frame given the the severe threat being upgraded to an enhanced
risk via the Storm Prediction Center latest convective outlook.
Will update the zones shortly to reflect these minor changes.
prevailing MVFR cigs and vsby with brief IFR conditions associated
with rain and embedded thunderstorms that will be moving in from
the Gulf associated with an approaching cold front will begin
to impact the northern terminals after 15z, with these conditions
then spreading south to the southern terminals after 20z. Southwest
winds in the 12 to 15 knot range with gusts up to 20 knots this
morning will increase to 18 to 20 knots with frequent gusts above
25 knots expected after 17z.
hazardous marine conditions are expected across the Gulf waters the
remainder of today through early Thursday as a cold front approaches
and moves south through the waters. South to southwest winds around
20 knots this morning are expected to increase to 20 to 25 knots
with frequent gusts up to gale force likely this afternoon through
tonight. These winds along with building seas will create very rough
boating conditions for small craft operators, and small craft
headlines will remain in place for all of the waters through early
Thursday morning. Ongoing forecast is on track with only some
cosmetic wording cleanup is expected in the next forecast issuance
around 10 am.
Florida...high rip current risk through this evening for coastal
Charlotte-coastal Hillsborough-coastal Lee-coastal
Lake Wind Advisory until 10 PM EDT this evening for
coastal Charlotte-coastal Citrus-coastal Hernando-
coastal Hillsborough-coastal Lee-coastal Levy-coastal
Manatee-coastal Pasco-coastal Sarasota-DeSoto-Hardee-
Highlands-inland Charlotte-inland Citrus-inland
Hernando-inland Hillsborough-inland Lee-inland Levy-
inland Manatee-inland Pasco-inland Sarasota-Pinellas-
Coastal Flood Warning until 5 PM EDT this afternoon for
coastal Citrus-coastal Levy.
Gulf waters...Small Craft Advisory until 5 am EDT Thursday for Charlotte
Harbor and Pine Island Sound-coastal waters from
Bonita Beach to Englewood Florida out 20 nm-coastal waters
from Englewood to Tarpon Springs Florida out 20 nm-coastal
waters from Tarpon Springs to Suwannee River Florida out
20 nm-Tampa Bay waters-waters from Bonita Beach to
Englewood Florida out 20 to 60 nm-waters from Englewood to
Tarpon Springs Florida out 20 to 60 nm-waters from Tarpon
Springs to Suwannee River Florida out 20 to 60 nm.