Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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760
FXUS62 KTBW 210733
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
333 AM EDT Mon May 21 2018

.SHORT TERM (Today - Tuesday)...
Very little change in the short term period. An U/L trough
persists over the Gulf of Mexico and western
Caribbean...with an U/L ridge centered northeast of the
Bahamas. Broad flow around these two systems has created
atmospheric river pulling deep tropical moisture from the
ITCZ north across the Caribbean and Cuba...funneling this
moisture along the east side of the trough and west side of
the ridge over the Florida peninsula under unusually deep
south to southeast flow which 22/00Z TBW sounding shows
from the surface to about 45K feet. U/L diffluence will aid
shower/thunderstorm development across west central and
southwest Florida today and Tuesday. W/V imagery also shows
significant dry air aloft over the eastern Gulf of Mexico
and moisture convergence boundary over the western peninsula
will also increase convective instability over the region.
PCPW values will remain near 2 inches which will continue
threat for locally heavy rain. Conditionally unstable
atmosphere persists and weak surface heating today and
Tuesday will allow areal coverage of showers/thunderstorms
to increase as the afternoon progresses...with numerous
showers and isolated thunderstorms developing across west
central and southwest Florida each day.

Due to the heavy rain over the past several days, there
have been significant rises on rivers across west central
Florida. The Alafia river, Manatee river, and Horse Creek
have risen above flood stage. The Little Manatee river is
expected to crest near flood stage...and any additional rain
today will likely cause the river to rise above flood
stage.

.LONG TERM (Tuesday night - Saturday)...
Throughout the extended forecast period, much of Florida
will remain in a tropical airmass with ample moisture in
place each day setting the stage for daily showers and
thunderstorms. Placement of surface high pressure across the
western Atlantic will keep a moist S/SE in place in the
lower-levels through mid-week. As we get later into the
week, models continue to indicate a weak area of low
pressure developing in the western Caribbean Sea/Yucatan
Peninsula. There continues to be a wide range of scenarios
with the GFS still weaker and slower moving the system north
northeast across south Florida Saturday night and then
north to off the Carolinas Sunday. Meanwhile, the ECMWF
drifts the system north northwest into the central Gulf of
Mexico and then stalls it along the north central gulf coast
next weekend. Either way, with moist south to southwest
flow in place aloft and sufficient lift it looks like we`ll
continue to see numerous showers and thunderstorms across
the area into the upcoming holiday weekend. Temperatures
will generally run a few degrees below normal through the
period with ample rain chances and widespread cloud cover
expected for much of the period. Highs in the mid to upper
80s expected with lower 70s expected during the overnight.

&&

.AVIATION...
VFR CIGS this morning 060-080 with LCL MVFR CIGS 010-020
possible toward sunrise mainly over the interior vcnty LAL.
Numerous showers and isolated thunderstorms will develop
today with LCL MVFR CIGS and IFR VSBYS. Areas of marginal
MVFR CIGS will develop this afternoon 025-035.

&&

.MARINE...
Winds and seas are expected to remain below advisory levels
through the period. Main hazard will be showers and
thunderstorms which will be possible over the waters through
the remainder of the week. The stronger storms will be
capable of producing strong gusty winds, locally rough seas,
and heavy rain.

&&

.FIRE WEATHER...
No fire weather hazards are expected for the next several
days as relative humidity values are expected to remain well
above critical levels.

&&

.Preliminary Point Temps/PoPs...
TPA  81  71  85  72 /  70  30  60  30
FMY  81  71  85  72 /  70  30  70  30
GIF  80  71  84  70 /  70  30  60  30
SRQ  80  71  84  72 /  60  30  60  30
BKV  82  70  85  69 /  70  30  60  30
SPG  82  74  85  75 /  70  30  60  30

&&

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

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...13/Oglesby
MID TERM/LONG TERM/DECISION SUPPORT...11/McKaughan



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