Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 221940
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
240 PM EST Sun Jan 22 2017

...TORNADO WATCH for Levy County...
...HIGH RISK of Severe Thunderstorms Today...
...Gale Warning for Dangerous Coastal Marine Conditions today
through Monday...
...Hazardous Lake Conditions Today through Tuesday...
...Minor Coastal Flooding possible today around high tide...

.SHORT TERM (Tonight - Monday)...
A significant upper low sits over Mississippi and will continue
tracking east through Monday morning. Associated deep troughing
associated with this low will track across the Florida peninsula
later this evening and track into the Western Atlantic by Monday
afternoon. On the surface a complex weather system is developing
over northern Louisiana along an existing frontal boundary and
boundary. This parent low will drift to the northeast as another low
forms along the triple point along the southern Louisiana border.
This low will track east-northeast and drag a cold front across the
Florida peninsula later this afternoon/evening. A squall line ahead
of this front will produce a widespread severe outbreak across the
entire Florida peninsula through the early morning hours on Monday.

With the above mentioned synoptic pattern, things are lining up to
be a very active weather day in west central and southwest Florida.
SPC has upgraded the risk for severe storms to HIGH RISK for Citrus
County northward, MODERATE RISK for Tampa Bay northward through
Citrus County and ENHANCED RISK for Lee County northward through
Tampa Bay. The upper low is very evident on WV imagery this
afternoon and continues to spin over Louisiana. A 110 kt jet max is
streaming across the gulf coast just south of Louisiana and will
progress eastward through the day just adding fuel to the fire for
the possibility of severe weather across the region. Another
ingredient adding to the potential for severe weather, including
downburst straight line winds, will be a 50-60 knot low level 925 mb
jet coming in off the eastern gulf this afternoon. Sfc-3km Helicity
value of 500 m2/s2 and shear values of 50+ knots will add to the
threat of a significant tornado outbreak. The timing for the
strongest storms will be around 18Z for the nature coast, 21Z for
the Tampa Bay area and 00Z for the inland counties and southwest
Florida. This is a very dangerous storm system moving through today,
so everyone should stay weather aware and be prepared to take
shelter in case of severe storms or tornadoes.

&&

.LONG TERM (Monday Night - Sunday)...
At the start of the period a deep closed upper level low and an
attendant deepening surface low will be lifting northeastward up
along the mid Atlantic coast, as mid and surface level ridging
builds in from the west. A breezy northwest wind flow will continue
to usher in cooler and drier air with rain free conditions expected
across the entire forecast area through Wednesday as the surface and
mid level ridging builds in over the region.

By late Wednesday the high will shift east into the Atlantic as
another upper level trough and cold front approach from the west.
Sufficient moisture return ahead of this next front should support a
slight chance of showers (Pops 20 percent) across the Nature Coast
Wednesday night, with the showers then spreading south into the
central and southern portions of the forecast area during Thursday
and Thursday night as the front moves south through the region.

During Friday and into the first part of the upcoming weekend cooler
and drier air will advect into the region in the wake of the front
with cool dry weather with below normal temperatures expected as
high pressure noses in from the northwest. During the latter part of
the weekend (Saturday night into Sunday) weak embedded shortwaves
moving east across the Gulf within a very strong (160+ knot) jet
aloft aligned west to east across the northern Gulf coast combined
with sufficient low level moisture and another frontal trough
sinking south through the region will likely support a good deal of
clouds and a slight chance of some showers (Pops 20 percent) as
these features affect the region.

Near seasonal level temperatures on Tuesday will climb back to above
normal Wednesday through early Thursday before falling back to below
normal Friday and into the weekend as cooler drier air overspreads
the region in the wake of the cold front.

&&

.AVIATION...
Southerly sustained winds near 25 knots with gusts near 40 knots are
already being reported this afternoon with some MVFR CIGS for the
coastal terminals to increase in coverage through the day. SW wind
flow will remain gusty at all sites through the day with mainly
MVFR/IFR CIGS well ahead of an approaching squall line. Expect
VCTS/TSRA and TEMPO +TSRA starting from 21-00Z around the Tampa Bay
sites (TPA/PIE/LAL/SRQ), and starting from 00Z-03Z for the southern
sites (PGD/FMY/RSW). Winds will remain gusty on Monday as they shift
to the west.

&&

.MARINE...

...Mariners should remain in port until conditions improve...

A strong frontal boundary is moving toward the eastern gulf coast
waters and will create dangerous marine conditions for mariners. The
squall line ahead of this front will move through the waters late
this afternoon through the evening hours. Winds in the 25-30 knot
range are already being reported and will steadily increase through
the night with 35-45 knot winds possible. Off shore buoys are
reporting seas up to 6-8 feet currently and will quickly build to 10-
15 feet by later tonight into Monday morning. As the front passes,
the winds will shift to the west southwest remaining gusty at Gale
force. Residual strong winds and elevated seas continue into
Tuesday. These are dangerous and life threatening marine conditions
for the Gulf of Mexico. Winds and seas finally decrease by mid week
as high pressure builds into the region.

&&

.FIRE WEATHER...
No fire weather hazards are expected through the week as relative
humidity values will remain above 35 percent each day.

&&

.Preliminary Point Temps/PoPs...
TPA  64  71  55  71 /  80  50   0   0
FMY  67  74  57  76 /  80  50   0   0
GIF  61  72  51  74 /  90  30   0   0
SRQ  67  71  58  72 /  80  50   0   0
BKV  61  71  48  71 /  70  40   0   0
SPG  64  71  58  70 /  70  50   0   0

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Monday evening for Coastal
     Manatee-Coastal Sarasota.

     Lake Wind Advisory until 7 PM EST Monday 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-
     Polk-Sumter.

     High Surf Advisory until 1 PM EST Tuesday for Coastal
     Charlotte-Coastal Hillsborough-Coastal Lee-Coastal
     Manatee-Coastal Sarasota-Pinellas.

     High Rip Current Risk through Tuesday evening for Coastal
     Charlotte-Coastal Hillsborough-Coastal Lee-Coastal
     Manatee-Coastal Sarasota-Pinellas.

Gulf waters...Gale Warning until 7 PM EST Monday for Coastal waters from
     Bonita Beach to Englewood FL out 20 NM-Coastal waters
     from Englewood to Tarpon Springs FL out 20 NM-Coastal
     waters from Tarpon Springs to Suwannee River FL out
     20 NM-Waters from Bonita Beach to Englewood FL out 20
     to 60 NM-Waters from Englewood to Tarpon Springs FL
     out 20 to 60 NM-Waters from Tarpon Springs to
     Suwannee River FL out 20 to 60 NM.

     Small Craft Advisory until 7 PM EST Monday for Charlotte
     Harbor and Pine Island Sound-Tampa Bay waters.

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...74/Wynn
MID TERM/LONG TERM/DECISION SUPPORT...57/McMichael



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