Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 171145
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
645 AM EST Wed Jan 17 2018

.AVIATION...
Primarily VFR conditions expected with light and variable
winds for the morning hours. Seeing some patchy ground fog
in the center part of the state that will start to diminish
by 13z. Fog may result in visibility restrictions at more
fog prone terminals. A strong cold front will bring gusty
northwest winds by 18z to 21z which will decrease slightly
after 00z.

&&

.Prev Discussion... /issued 358 AM EST Wed Jan 17 2018/

..Widespread freezing temperatures and dangerous wind
chills tonight into early Thursday...

SHORT TERM (Today and Thursday)...
A strong positive tilt upper trough continues to dive
southeastward across the Mississippi Valley region. This in
conjunction with an Arctic cold front is making for a wintry
mess along the northern Gulf Coast this morning. This front
will continue to slip southeastward, eventually pushing
through the Florida peninsula by this evening, bringing
another shot of very cold air into the region for the end of
the week.

For today, as the cold front works into the Florida
panhandle and northern peninsular areas by late
morning/early afternoon, expect a rather substantial
temperature gradient north to south. Highs along the Nature
Coast will be in the upper 40s and lower 50s, while areas
along the I-4 corridor and points south should rise into
the 60s to near 70 degrees before frontal passage. This
frontal passage will be a dry one as northerly flow has
persisted over the last several days. A sharp increase in
winds will occur in the wake of the front, with a sort of
slap you in the face feel. This will especially hold true
for coastal areas, where 25 to 30 mph wind gusts will be
common this afternoon into tonight.

For tonight, substantial cold air advection will continue
with widespread freezing temperatures appearing likely over
a good part of the peninsula. Freeze watches of the hard and
soft variety remain in effect for the overnight hours, and
will likely be upgraded to warnings later this afternoon as
confidence in areal extent and duration increase. Elevated
winds in concert with falling temperatures should lead to
some fairly impressive wind chills with teens expected north
of I-4, and low to mid 20s elsewhere. Wind chill advisories
have been issued for this potential. Marine conditions will
also become quite dangerous this evening and overnight with
building waves and strong north winds.

For Thursday, as high pressure gradually slips closer to
the region, winds should slowly decrease. However, as the
airmass in place will remain quite cold, highs are only
expected to top out in the 40s and 50s most areas.
Temperatures will fall quite rapidly again after sunset with
another night of freezing temperatures possible, especially
north of I-4.

Mid/Long Term (Thursday Night through Tuesday)...
The mid term period will begin with another cold start to
the day on Friday with temps expected in the 20s and 30s by
daybreak. A warming trend will begin on Friday however as a
surface high will gradually shift into the Atlantic allowing
the airmass to begin to moderate. Afternoon highs Friday
will top out in the upper 50s to upper 60s which is still
well below normal but is some 7-10 degrees higher than what
our highs will be on Thursday. The more noticeable warmup
really gets going during the weekend as easterly flow will
continue to moderate temps across the area, with readings
expected to return to the 70s for the southern half of the
forecast area Saturday and by Sunday everyone will be back
in 70s for highs with noticeably higher dewpoints as well.

The next frontal system looks to approach the area late
Monday and out ahead of it winds will become more southerly
allowing temps to push 80 in spots. Increased moisture will
allow for some isolated showers as well out ahead of this
system. Front looks to push through on Tuesday, although it
will lose much of its upper level support as it does so, so
the boundary looks to be decaying as it moves through thus
limiting any potential rain chances. For now, have PoPs
capped at 30 percent for this FROPA. Not a lot of cold air
behind this system either so no major cooldown is expected-
just a few degrees perhaps.


MARINE...
Light winds will remain over the waters through the
remainder of the morning. Marine conditions will rapidly
deteriorate however this afternoon through tonight. A strong
cold front will bring solid advisory level winds and seas
beginning this afternoon and continuing into the day
Thursday. Gale force wind gusts will also be possible over
the offshore waters with seas building up to 8 feet. High
pressure will slowly move toward the region late tomorrow
into the weekend, with improving winds and seas. Modest
easterly wind surges may yield cautionary winds at times. A
cold front will approach the waters early next week, this
may allow for patchy sea fog development as moisture rides
up over the cooler Gulf waters. Winds may also increase in
response to the frontal passage mid week.

FIRE WEATHER...
A strong cold front will bring breezy north winds and very
dry air into the region, along with much colder
temperatures. While humidities will fall well below critical
levels Thursday, ERCs and winds will generally remain low.
Moisture will return rather quickly from Friday into the
weekend as easterly flow allows Atlantic moisture to return.
This will allow humidities to remain well above critical
levels from the weekend into next week.

&&

.Preliminary Point Temps/PoPs...
TPA  59  31  53  38 /   0   0   0   0
FMY  69  35  58  41 /   0   0   0   0
GIF  65  31  54  36 /   0   0   0   0
SRQ  62  33  54  39 /   0   0   0   0
BKV  57  27  52  30 /   0   0   0   0
SPG  60  33  52  40 /   0   0   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk from 1 PM EST this afternoon through
     Thursday morning for Coastal Charlotte-Coastal
     Hillsborough-Coastal Lee-Coastal Manatee-Coastal
     Sarasota-Pinellas.

     Wind Chill Advisory from 11 PM this evening to 10 AM EST
     Thursday for Coastal Charlotte-Coastal Hillsborough-
     Coastal Lee-Coastal Manatee-Coastal Sarasota-DeSoto-
     Hardee-Highlands-Inland Charlotte-Inland Hillsborough-
     Inland Lee-Inland Manatee-Inland Sarasota-Pinellas-
     Polk.

     Freeze Watch from this evening through Thursday morning
     for Coastal Hernando-Coastal Hillsborough-Coastal
     Pasco-DeSoto-Hardee-Highlands-Inland Charlotte-Inland
     Hillsborough-Inland Manatee-Inland Sarasota-Polk.

     Hard Freeze Watch from this evening through Thursday
     morning for Coastal Citrus-Coastal Levy-Inland Citrus-
     Inland Hernando-Inland Levy-Inland Pasco-Sumter.

     Wind Chill Advisory from 7 PM this evening to 10 AM EST
     Thursday for Coastal Citrus-Coastal Hernando-Coastal
     Levy-Coastal Pasco-Inland Citrus-Inland Hernando-
     Inland Levy-Inland Pasco-Sumter.

Gulf waters...Small Craft Advisory from 10 AM this morning to 6 AM EST
     Thursday for Coastal waters from Tarpon Springs to
     Suwannee River FL out 20 NM-Waters from Tarpon
     Springs to Suwannee River FL out 20 to 60 NM.

     Small Craft Advisory from 10 AM this morning to 1 PM EST
     Thursday for Waters from Englewood to Tarpon Springs
     FL out 20 to 60 NM.

     Small Craft Advisory from 2 PM this afternoon to 1 PM EST
     Thursday for Waters from Bonita Beach to Englewood FL
     out 20 to 60 NM.

     Small Craft Advisory from 10 AM this morning to 10 AM EST
     Thursday for Coastal waters from Englewood to Tarpon
     Springs FL out 20 NM.

     Small Craft Advisory from 2 PM this afternoon to 10 AM EST
     Thursday for Coastal waters from Bonita Beach to
     Englewood FL out 20 NM.

     Small Craft Advisory from 2 PM this afternoon to 6 AM EST
     Thursday for Charlotte Harbor and Pine Island Sound-
     Tampa Bay waters.

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...27/Shiveley
MID TERM/LONG TERM/DECISION SUPPORT...05/Carlisle



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