Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 251140
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
740 AM EDT Sun Jun 25 2017

.AVIATION (UPDATE)...

Expect VFR conditions for much of the day today. Only
exception will be after 17Z as shra/tsra develop over the
region which could bring brief MVFR/IFR conditions. Winds
will stay light and variable this morning shifting to a
southwest to west direction around 5 to 10 this afternoon.

&&

.SHORT TERM...
Our weather pattern for today is very similar to what we
saw yesterday with a few subtle changes. Surface ridge axis
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. Could see a few light showers develop over the
Gulf and move ashore north of Tampa Bay during the mid/late
morning. By early afternoon, the seabreeze will begin to
push inland shifting winds to the west across the area.
Similar to yesterday, seabreeze collision will be across
the interior portions of the forecast area and this is where
the highest rain chances are depicted in the forecast.
Models are showing slightly cooler temps aloft and a bit
more moisture so looks like we should have a bit more storm
coverage compared to Saturday. Temps once again will be
warm, it is June in Florida after all, with highs in the low
to mid 90s with heat indices near 100.

On Monday, a frontal boundary encroaching on north Florida
should help lead to an increase in moisture and cooling
aloft. This should lead to more widespread coverage of
showers and storms across the area. Current forecast has
likely POPs (60-70%) along and east of I- 75 where the
highest moisture and lift will be with 30-40 percent near
the Gulf Coast. Temps again will be in the lower 90s.

&&

.LONG TERM...
Good agreement among the guidance members that a weak
diffuse low-level boundary will still be place across the
central to north- central Florida Peninsula Tuesday morning.
The apparent position of this boundary can be determined by
the confluence zone and evolution of the 0-500M ML CAPE
evolution through the day. The fact that this subtle
boundary remains in place, however, weak will keep the
convective evolution highly uncertain in pattern/timing, but
almost certainly active...as sea-breeze and frontal
interaction within a moist column gives little reason to
assume otherwise. One possible wildcard would be the
evolution of the sea-breeze. Does the weak gradient and
resulting weak low level synoptic flow allow a defined sea-
breeze to move inland and concentrate the convection during
the late day/evening over the interior, or are there enough
clouds/early showers along the boundary to prevent that kind
of defined sea- breeze. These type of details will become
more clear as Tuesday gets closer, however, are difficult to
lean one way or another due to how subtle these differences
can be. For now will go with chance PoPs near the coast,
and likely PoPs inland, since either solution would suggest
active storms inland from I-75.

The real transition in our weather pattern to the one that
will define the forecast through the remainder of the week
occurs Tuesday night. Continental high pressure will emerge
off the Carolina coast during the night, shifting a tighter
gradient down into our region and finally washing out the
diffuse boundary. By Wednesday morning, the low level
1000-850mb synoptic flow will have shifting out of the east.
This easterly flow will favor the strongest and most
numerous convection along the I75 corridor during the late
afternoon and evening hours. GFS/ECMWF both show a tight
moisture gradient near headed northward toward the I-10
corridor, but both would suggest no significant negative
factors from this drying until beyond our northern borders.

Thursday and Friday look to hold this diurnal convective
pattern  with a continued veering of the low level synoptic
flow to a ESE direction as the surface ridge continue to
shift eastward into the Atlantic. If anything, ESE/SE flow
is even more favorable for west coast convection during the
late day period than easterly flow, as it usually brings
high levels of low level moisture. Either way, with a
favorable flow pattern and little hostility in the
moisture/thermodynamic profiles, we can expect a lot of late
day storm activity during all of these days.

By next weekend, the surface ridge axis begins to move
southward  over the peninsula, and this will begin a
transition back toward a neutral flow pattern for convective
evolution. Saturday, although the flow is weaker, will
still primarily be out of the SE, and favor west coast
storms late in the day. By, Sunday though, it is appearing
as though storms will initiate near the coast early
afternoon and then consolidate inland with time.

No significant departures form normal in temperature are
anticipated  through the long term forecast period.



&&


.MARINE...

Surface high pressure will remain over the area bringing us
a  southeast to southwest flow for the next few days. With
a weak pressure pattern supporting a typical summer
afternoon for boaters with most showers occurring over land
with heating of the day. However boaters should still watch
out for a few storms in the gulf that could 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  78  90  77 /  40  10  50  30
FMY  93  76  92  75 /  30  30  40  30
GIF  94  76  92  74 /  50  40  70  50
SRQ  89  76  89  76 /  20  10  30  20
BKV  92  74  91  73 /  50  10  60  30
SPG  90  79  90  77 /  30  10  40  20

&&

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

$$

UPDATE/AVIATION/MARINE/FIRE WEATHER...27/Shiveley
UPPER AIR...10/LaMarre
DECISION SUPPORT...03/Paxton



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