Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 180047
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
747 PM EST Wed Jan 17 2018

.AVIATION (18/00Z through 19/00Z)...
Cold front has exited south of the area this evening. A band
of post-frontal MVFR CIGS has dropped south of
KTPA/KPIE/KLAL/KSRQ...and prevailing VFR conditions can be
expected for these terminals the rest of the forecast
period. The clouds are dissipating as they head south...so
just a chance of a brief MVFR CIG for KPGD/KFMY/KRSW through
04Z...but chances seem to be decreasing with time. After
04Z...VFR for all through the period. Gusty NW winds will
become more northerly and less gusty later tonight...and
generally stay at or less than 10 knots for the daylight
hours Thursday.

&&

.Prev Discussion... /issued 502 PM EST Wed Jan 17 2018/

..Freeze Warning Expanded...

UPDATE (Overnight through Early Thursday Morning)...
Late afternoon high resolution guidance members are adding
increased confidence in a full swing of the winds to a more
northerly or even slightly northeasterly direction during
the second of tonight. If this verifies, there is little
reason to believe that in an advection event such as this,
and given the nearby downstream temperatures already in the
forecast, that colder temperatures (dropping to around
freezing or slightly below) will not eventually make their
way into portions of northern Pinellas, coastal Manattee,
Coastal Sarasota, Coastal Charlotte, and interior Lee
Counties. Obviously every location in these zones will not
reach freezing...especially some immediate shore locations,
and much of southern Pinellas county, where at least some
fetch of flow off the waters is unavoidable. However,
confidence is now high enough in sufficient areal coverage
of freeze criteria to add these zones to the current freeze
warning. Hazard Statement (NPWTBW) has been issued, forecast
grids have been updated, and ZFP will be issued shortly.

Although some colder temperatures have been added to these
areas above, and wind chills later tonight are now a couple
of degrees colder, Wind Chill Advisories were already in
effect and these areas, and the changes do not impact or
change this hazard.

In addition...Although Thursday night will not be quite as
cold as tonight...it will still be well below normal. The
area of potential freezing temperatures will shrink
considerably from what is in place tonight, but portions of
the Nature Coast will not escape one additional night of
freezing temps. Have gone ahead and issued a freeze watch
for Levy/Citrus/Sumter/Hernando/and inland Pasco county from
12AM Friday through 9 AM Friday.

Once this potential freeze is over...temperatures really
begin to moderate. Temperatures warm very quickly this
weekend...and a lot of the region is expected to see
temperatures back up into the upper 60s to middle 70s by
Sunday.

Prev Discussion... /issued 233 PM EST Wed Jan 17 2018/

SHORT TERM (Through Thursday)...
A cold front will work its way through Florida as we go
into the afternoon and evening hours. A few clouds will be
associated with the front but no rain is expected. Clouds
will clear a few hours after frontal passage and then most
models agree we will see plummeting dew point
temperatures...strong northwesterly winds....clear
skies...and an arctic airmass settling into the area. All
these ingredients together will result in a very cold night
for western Florida.

We will see temperatures in the mid 20`s for areas
north of I-4. As we move south of I-4 the farther away from the
coast you go the colder you will get. Along the coast temperatures
could stay just above freezing...but once you get east of I-75
temperatures will be upper 20`s to low 30`s. Factoring in the winds
(which will be around 10-13 mph) and wind chill values will be the
20`s for almost everyone. Some spots in Levy county could even see
temperatures in the upper teens.

The arctic airmass will help to keep us clear and cool
through the day on Thursday. We will get plenty of sunshine
but temperatures will struggle to get into the 50`s through
the afternoon.

LONG TERM(Thursday Night-Wednesday)...
Surface high pressure will remain over the region for
Friday and much of the weekend, with a general warming trend
poised to take place. Friday morning will be the last of
the cooler starts for the next week or so, with low
temperatures in the mid to upper 20s across the Nature Coast
and then 30s and 40s elsewhere. Another freeze for Nature
Coast seems likely at this point. Highs Friday afternoon
will be in the upper 50s to upper 60s and then warming each
day through the weekend. By the time we get to Sunday
afternoon, portions of the southwest Florida region will
approach 80 degrees for highs.

For early next week, another mid/upper-level trough will move into
the eastern part of the country, with an associated cold front
approaching the southeast on Monday. This approaching boundary will
turn our winds more to the southwest and south, allowing
temperatures and dew points to rise even more for Monday. The front
tries to move through on Tuesday, but most of the support aloft
passes well to our north, so the boundary will likely be decaying as
it moves through the peninsula. Even still, there will be about a 20-
30 percent chance for a few showers Monday and Monday night ahead of
it. High pressure then moves in quickly over the southeast for
Wednesday, with just a slight cool-down.

MARINE...
A strong cold front will bring gusty winds through the rest
of today and into parts of the overnight hours. Gale force
wind gusts and seas building up to 8 feet can`t be ruled
out. 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
plummeting dew points overnight. Humidity will easily get
below critical levels tomorrow. However, the ERCs and winds
will remain low. This will keeps us above red flag
conditions for Thursday. Moisture will quickly return Friday
and into the weekend with easterly flow allowing us to stay
above critical levels for the rest of the forecast period.

&&

.Preliminary Point Temps/PoPs...
TPA  31  52  38  61 /   0   0   0   0
FMY  32  57  41  67 /   0   0   0   0
GIF  28  52  36  64 /   0   0   0   0
SRQ  34  53  39  62 /   0   0   0   0
BKV  25  50  30  61 /   0   0   0   0
SPG  34  51  40  61 /   0   0   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk until 7 AM EST Thursday for Coastal
     Charlotte-Coastal Hillsborough-Coastal Lee-Coastal
     Manatee-Coastal Sarasota-Pinellas.

     Freeze Warning from 11 PM this evening to 9 AM EST
     Thursday for Coastal Charlotte-Coastal Hernando-
     Coastal Hillsborough-Coastal Manatee-Coastal Pasco-
     Coastal Sarasota-DeSoto-Hardee-Highlands-Inland
     Charlotte-Inland Hillsborough-Inland Lee-Inland
     Manatee-Inland Sarasota-Pinellas-Polk.

     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.

     Hard Freeze Warning from 11 PM this evening to 9 AM EST
     Thursday for Coastal Citrus-Coastal Levy-Inland
     Citrus-Inland Hernando-Inland Levy-Inland Pasco-
     Sumter.

     Freeze Watch from late Thursday night through Friday
     morning for Coastal Citrus-Coastal Hernando-Coastal
     Levy-Inland Citrus-Inland Hernando-Inland Levy-Inland
     Pasco-Sumter.

     Wind Chill Advisory until 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 until 6 AM EST Thursday for Charlotte
     Harbor and Pine Island Sound-Coastal waters from
     Tarpon Springs to Suwannee River FL out 20 NM-Tampa
     Bay waters-Waters from Tarpon Springs to Suwannee
     River FL out 20 to 60 NM.

     Small Craft Advisory until 1 PM EST Thursday for Waters
     from Bonita Beach to Englewood FL out 20 to 60 NM-
     Waters from Englewood to Tarpon Springs FL out 20 to
     60 NM.

     Small Craft Advisory until 10 AM EST Thursday for Coastal
     waters from Bonita Beach to Englewood FL out 20 NM-
     Coastal waters from Englewood to Tarpon Springs FL
     out 20 NM.

&&

$$

UPDATE/AVIATION/MARINE...99
UPPER AIR...99
DECISION SUPPORT...99


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