Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 241147
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
342 AM EDT Sat Jun 24 2017

.AVIATION (UPDATE)...
Still seeing some lingering light showers mainly around Tampa and
areas north. Also seeing some more steadier showers this morning
about 30 miles out in the gulf. By afternoon, scattered showers and
thunderstorm will develop with the greatest coverage expected across
the interior peninsula.

&&

.SHORT TERM (Today - Sunday Night)...
Still seeing a few lingering showers around Tampa Bay this
morning with this activity likely to continue slowly pushing
northwest for a few more hours this morning. The surface
ridge axis placement will keep a light flow in place over
central FL with winds southeasterly across our southern
zones with a more southwesterly flow expected across the
Nature Coast. This SW flow combined with ample atmospheric
moisture should support some morning showers moving into the
areas north of Tampa Bay in the mid to late morning.
Elsewhere, terrestrial heating will allow a seabreeze to
develop by early afternoon turning winds onshore near the
coast. Sufficient moisture will be in place across the area
to support shra/tstm development with afternoon seabreeze
collision. Looks like the greatest coverage will be along
and east of I-75 today in the late afternoon to early
evening. Temperatures will be warm again today with low to
mid 90s expected.

Fairly similar weather pattern expected for Sunday although
models are showing a slightly more moist atmosphere compared
to Saturday. This should lead to a bit better coverage of
afternoon showers and storms with the interior peninsula
most likely to see greatest coverage.

.LONG TERM (Monday - Friday)...
The upcoming work week is shaping up to be an active summer
convection period as several factors work together in order
to keep late afternoon and evening thunderstorms coverage
rather high. Monday begins the long term period with the
Florida peninsula residing at or just below the base of
longwave troughing over the eastern CONUS. Associated with
this trough, we will find a weak frontal boundary that will
have sagged to near the I-10 corridor by morning. This
feature will have a big impact on the Monday forecast,
especially just how far south this boundary sags by the
afternoon hours. This aspect is not 100% agreed upon among
the ensemble members, with the GFS showing the most
southward solution. Using LI as a proxy for surface boundary
position, the front will lie somewhere between Gainesville,
and the I-4 corridor. Other guidance members are slightly
shifted northward back closer to I-10. The main impact of
this difference would be just how much drier the forecast
will be for the northern zones (Levy/Citrus). Being behind
the boundary would certainly decrease rain chances, however,
with the GFS being the most aggressive in movement, will
keep a forecast that gives some weight to the more numerous
northern solutions. Things can be adjusted should a trend
toward the current GFS solution appear in later guidance
packages. For everyone else, this combination of synoptic
focus, sea-breeze focus, and a highly moist column south of
the boundary will no doubt support development of numerous
diurnal showers/storms. Monday will see the weakest low
level flow of the extended period, and hence the west-coast
sea- breeze will have the best potential to move inland
during the day. Of course, convection may alter some of this
evolution, but feel Monday is the best chance to see
convection consolidate during the evening hours across our
inland areas (similar to the current NAM).

The frontal boundary will certainly become stationary by
Monday night, and then decay quickly during the day
Tuesday. The frontal decay will allow continental high
pressure along the eastern seaboard to take control of our
synoptic low level flow. 100-700mb flow will become increasingly
easterly through Tuesday, and become defined by Tuesday
night. The ridge then shifts offshore of the Carolinas for
the remainder of the week, with our low level winds veering
slightly out of the southeast.

This E/SE flow is an active sea-breeze convection setup for
the Florida west coast, as it focuses the greatest low level
focus/convergence along the west-coast seabreeze / I-75
corridor of the state. This already favorable convection
setup will be enhanced by a very moist and thermodynamically
friendly atmospheric column (PW values at or over 2").

Therefore, the forecasts for the middle and end of the week
will remain similar from day to day. Nocturnal scattered
storms are likely over the eastern Gulf of Mexico
(especially late along land-breeze boundaries). The landmass
will should see mostly dry conditions during the overnight
and through the morning/midday hours. Sct showers and storms
will migrate east to west across the state during the afternoon
hours, and then consolidate in coverage during the late
afternoon/early evening hours along the FL west coast. The
synoptic flow will then favor this activity migrating offshore
into the Gulf and weakening during the later evening hours.


Temperatures throughout this period look to be near climo,
with no significant synoptic influences to suggest anything
different. Local convective clusters on Monday and Tuesday
may be enough to keep certain areas in the 80s, but to early
to try and get all that detailed at this stage, nor is it
going to change many plans whether high temps are say 90 vs
85.


&&



.MARINE...
No major marine hazards are expected through early next
week. High pressure will continue to dominate our area
producing a south to southeast flow with winds taking on a
southwest and west component during the afternoon/evening
hours as the sea breeze forms and pushes inland. While
greatest rain chances will remain inland, typical summertime
boating precautions should still be exercised as any
thunderstorm can produce gusty winds and locally higher
waves.

&&

.FIRE WEATHER...
With moist southeasterly flow continuing into next week,
moisture content and relative humidity values will remain
well above critical levels. This combined with chances for
rain each day will prevent any fire weather concerns.

&&

.Preliminary Point Temps/PoPs...
TPA  91  77  90  76 /  30  20  40  30
FMY  93  76  92  75 /  40  30  30  30
GIF  94  76  93  74 /  40  40  50  40
SRQ  90  76  88  76 /  20  20  20  20
BKV  92  74  91  73 /  30  20  40  30
SPG  91  78  90  77 /  30  10  30  20

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...27/Shiveley
MID TERM/LONG TERM/DECISION SUPPORT...03/Paxton



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