Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL
FXUS62 KTBW 211324
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
924 AM EDT Fri Oct 21 2016
...Much Cooler And Drier Conditions For The Weekend...
...Hazardous Boating Conditions Late Today Through Saturday...
Well advertised cold front now moving through NW FL this morning.
Amplifying upper longwave trough stretches from Hudson Bay
southward into the Gulf Coast region. Vort max ahead of trough
only generating thin cloud band associated with the front in dry
atmosphere. 12Z TBW sounding showing pwats below 1 inch in stable
environment with NW-W flow through the atmosphere so expect dry
fropa through the area later today. Upstream dewpoints in the 40s
with gusty NW-N winds to advect into the local area late today and
tonight. Latest grids and forecast on track.
VFR conditions all sites today into tonight with increasing and
gusty NW winds.
.Prev Discussion... /issued 300 AM EDT Fri Oct 21 2016/
SHORT TERM (Today - Saturday)...
An amplifying upper level trough will move across the Southeastern
states today becoming negatively tilted as it moves offshore the
eastern seaboard on Saturday. As the upper trough moves eastward an
attendant cold front now approaching the western Florida Panhandle
this morning will move south through forecast area later today and
then south of the region tonight and Saturday. Lack of moisture
accompanying this front will support a dry frontal passage with
winds backing and increasing from the northwest and north in its
wake. Temperatures will remain above normal for one more day today
with highs climbing into the mid 80s
Tonight the cold front will exit to the south of the forecast area.
A breezy northerly wind flow in the wake of the front will usher in
a much drier and cooler airmass with temperatures falling to below
seasonal norms, with lows falling into upper 40s to around 50 across
the Nature Coast, lower to mid 50s central interior, and upper 50s
to lower 60s south and along the coast by early Saturday morning.
On Saturday a dry northwest flow aloft and surface high pressure
building in over the lower Mississippi valley will support ample
sunshine with much lower humidity across the entire forecast area.
Despite the ample sunshine though cool air advection will will keep
temperatures below normal with highs in the lower 70s north, and
mid to upper 70s central and south.
MID/LONG TERM (Saturday Night - Thursday)...
An upper ridge over the western Gulf of Mexico extends north over
the plains states while surface high pressure centered over LA/MS
sprawls across the Gulf region. A deep low over New England has an
upper trough south over the Atlantic and trails a cold front
arcing south then southwest to Cuba.
The center of the upper ridge moves to the Central Gulf Mon then
weakens and flattens...as a long wave slides into the Great Lakes
to Gulf of mexico region by Thu. The LA/MS high pressure builds
east over the southeastern states...gets reinforced by a Canadain
airmass Mon...then continues east. The high stretches along the
eastern seaboard Tue-Wed and slips offshore Thu.
Deep northerly flow at the beginning of the period will provide a
cool dry and stable airmass. The flow becomes northeasterly by the
start of the work week...allowing for a gradual increase in
moisture and temperatures. A secondary surge comes through Tue
night or early Wed with a brief increase in winds. During Wed-Thu
the flow becomes east-northeast with temperatures warming to
around normal and enough moisture for low odds of showers...mainly
streaming in from the Fl east coast.
MARINE... Northeast winds of late are already backing to the
northwest and north early this morning ahead of a cold front now
approaching the western Florida panhandle. As the day continues
expect winds to increase into the small craft range across the
northern Gulf waters during mid to late afternoon with these
increasing winds and seas spreading south to the central and
southern waters by evening as the cold front moves south through
the region with hazardous boating conditions developing.
Given these expected trends will hoist small craft headlines for
the northern Gulf waters beginning by mid afternoon and across
the central and southern waters by evening. In addition, will
headline the Tampa Bay and Charlotte Harbor waters with exercise
caution headlines beginning by early this evening with these
hazardous boating conditions continuing through mid day on
Winds and seas will gradually diminish and subside Saturday night
into Sunday as winds shift to the northeast and east as surface
high pressure settles in over the region through early next week.
Humidity values will remain above 35 percent today. A much
cooler and drier airmass will overspread the region tonight and
into the upcoming weekend in the wake of a cold front. This drier
airmass will support humidity values falling into the lower 30
percent range for 3 to 4 hours across Levy county, and mid to
upper 30 percent range across the remainder of the forecast area.
Despite these lower humidity values sustained winds below 15 mph
combined with low ERC values will preclude red flag conditions
with no fire weather issues expected.
.Preliminary Point Temps/PoPs...
TPA 85 59 75 56 / 0 0 0 0
FMY 85 62 79 57 / 0 0 0 0
GIF 86 57 76 53 / 0 0 0 0
SRQ 83 61 75 55 / 0 0 0 0
BKV 85 51 74 45 / 0 0 0 0
SPG 84 63 75 62 / 0 0 0 0
FL...Beach Hazards Statement through Monday evening for Coastal
Gulf waters...Small Craft Advisory from 8 PM this evening to 11 AM EDT
Saturday for Coastal waters from Bonita Beach to
Englewood FL out 20 NM-Coastal waters from Englewood
to Tarpon Springs 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.
Small Craft Advisory from 5 PM this afternoon to 11 AM EDT
Saturday 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.