Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 280051
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
851 PM EDT Thu Apr 27 2017

.UPDATE...
00Z water vapor and H4 RAP analysis shows the beginning
stages of upper ridge building over the eastern Gulf of
Mexico and FL peninsula have commenced. This upper ridge
will be the dominant player in our weather through the
upcoming weekend, as it protects the forecast area from any
real inclement weather attempting to move eastward from
upstream.

This ridge will be complimented by a surface ridge axis
extending from the Atlantic, across the peninsula and into
the Gulf of Mexico. Overall, we are looking at a very
summer-like synoptic pattern, and will be certainly seeing
summer-like temperatures. The sea-surface temperatures are
still generally in the 70s, so unlike the pure summer,
dewpoints will not be as high, and it will not feel overly
oppressive.

On the flip side of the coin, the lack of low level moisture
and strong subsidence aloft will likely almost completely
prevent any chances for sea-breeze showers/storms. The
chances will not be zero, but just very low at any one
location to see a passing storms. One lone thunderstorm was
able to break through the hostile air aloft this evening as
sea-breezes collided over Highlands County. A renegade
similar type storm is possible again late Friday, however,
it will be fighting even greater thermodynamic hostility
aloft as the upper ridge continues to strengthen.

So...the main thing to take from the forecast the next few
days, so that it will be hot. Even the beaches will get
pretty toasty by early afternoon, and then settle back down
through the 80s as the sea-breeze kicks in and turns winds
off the relatively cooler shelf waters.

Those shelf waters are continuing to warm, and it will not
be too long before they cross a crucial threshold, and add
yet one more ingredient to the start of the summer storm
season.

&&

.AVIATION (28/00Z through 29/00Z)...
The synoptic situation has not changed significantly since
early Thursday morning, and therefore areas of shallow
field fog are possible once again between roughly 07-11Z at
KLAL/KPGD/KFMY/KRSW. Have included MVFR vis, but a period of
IFR is not out of the question given what occurred last
night. Although some guidance has been bullish with fog near
the coast later tonight, have disregarded this as unlikely
and kept restrictions out of KTPA/KPIE/KSRQ. Any fog is gone
very early Friday morning...followed by prevailing VFR the
remainder of the day. Just a slight chance of an isolated
shower along the sea-breeze after 21Z, but potential low
enough to leave mention out of the TAFs at this point.

&&

.Prev Discussion... /issued 247 PM EDT Thu Apr 27 2017/

SHORT TERM (Tonight - Friday)...
An upper level low sits over southwestern Ontario with broad
troughing extending over the central U.S. Upper level ridging
continues to hold over the Florida peninsula and will further build
through the short term period. On the surface, an area of low
pressure just north of the Great Lakes extends a cold front over the
eastern Great Lakes region and further southward along the
Appalachian mountain chain. The trailing edge of this front
dissipates over southern Georgia/northern Florida as high pressure
continues to ridge across the peninsula through the end of the week
and into the weekend. This will keep a southeast through southwest
wind flow over the area which will result in above average
temperatures. The coastal counties will top out in the upper 80`s,
while the inland counties will see daytime highs in the 90`s. Rain
free conditions will continue through the end of the week.

MID/LONG TERM...
Strong mid-level ridge will keep us hot and dry into the weekend.
H5 heights of 591+ DM will support high temps soaring well
above normal Saturday and again on Sunday with widespread
90s expected with some mid 90s possible across interior
zones. Some record high temperatures will certainly be
possible. The location of the Atlantic surface ridge will
keep a SE wind flow in place through the weekend.

The ridge will break down at the start of next week as a low
pressure system develops across the central U.S. This
system will gradually move towards the Great Lakes region
while an associated frontal boundary approaches the area
Monday. Upper-level support looks to diminish as the front
moves towards the area. GFS continues to show the front
moving through at least the Bay area while the ECMWF keeps
it draped across the Nature Coast. Forecast continues to
lean more towards the Euro solution for now but either way,
low end PoPs continue in the forecast for Monday and Tuesday
with warm temperatures continuing.

Late in the forecast period, and just beyond, models continue
to show a major pattern change across the CONUS with deep
upper-level troughing developing across the eastern U.S.
Will see how this plays out over time as it is still over a
week from now and much can change between now and then. Stay
tuned.

AVIATION...
The stratus/fog from this morning has dissipated and a CU/SC cloud
deck has developed over the region. Even with the CU/SC clouds,
conditions are expected to remain VFR through late tonight. Some
patchy fog and low clouds will be possible once again tonight that
may bring some MVFR/IFR conditions to the terminals early Friday
morning. Predominant wind flow will be out of the southwest this
afternoon/evening, then becoming more southeast overnight. No other
aviation impacts expected.

MARINE...
High pressure will continue to ridge from the Atlantic into the
eastern Gulf of Mexico through the weekend. A weak front washing out
over the northern Gulf today will produce a tight pressure gradient,
with cautionary headlines needed for the Gulf waters north of Tarpon
Springs for the remainder of the day. Winds will increase again to
around exercise caution levels Sunday and Monday as another front
moves into the region.

FIRE WEATHER...
Dry and rain free conditions continue across west central and
southwest Florida into the weekend. Relative humidity values may
briefly drop below 35 percent over the inland counties today, but
should not be below 35 percent for more than a couple of hours, so
no Red Flag Warning will be needed. With that being said, drought
conditions continue across the region and county burn bans remain in
place for many counties. Humidity values will be on the rise into
the weekend and a chance of rain will occur on Monday and Tuesday
next week which will briefly reduce the risk of wildfires.

&&

.Preliminary Point Temps/PoPs...
TPA  73  91  74  91 /  10  20  10   0
FMY  72  92  73  91 /   0  20   0   0
GIF  71  96  72  93 /   0  10  10   0
SRQ  71  87  72  86 /  10  20  10   0
BKV  67  95  69  93 /   0  20  10   0
SPG  73  90  75  90 /  10  10  10   0

&&

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

$$

UPDATE/AVIATION/MARINE...14/Mroczka
UPPER AIR...99
DECISION SUPPORT...99


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