Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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FXUS62 KTBW 281138

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
738 AM EDT Fri Apr 28 2017

Some patches of fog will continue for the next couple of hours
causing periods of MVFR or potentially IFR/LIFR conditions.
After 15Z, VFR conditions will take control again. A few showers
cannot be ruled out along the sea breezes this afternoon, mostly
around KRSW and KFMY.


.Prev Discussion... /issued 403 AM EDT Fri Apr 28 2017/

SHORT TERM (Today - Saturday)...
A mid-level ridge will build into the Florida Peninsula today and
Saturday, as the surface high pressure centered over the Atlantic
continues to ridge across the area. Under the effects of this
ridging, very warm and stable conditions will continue, with record
temperatures possible. Highs today will top out in the low to mid 90s
inland and in the mid to upper 80s along the coast. Building low
level moisture will allow for the possibility of a few sea breeze
showers this afternoon, mainly over southwest Florida along the
Interstate 75 corridor. On Saturday, temperatures will still be hot,
but are forecast to be a couple degrees milder than today`s marks.
The strengthening ridge will also suppress any rain chances, despite
the intense surface heating.

LONG TERM (Saturday night-Thursday)...
Period will begin with a deep U/L trough over the southern Plains
inducing a strong U/L ridge over the western Atlantic and Florida. A
strong U/L disturbance over the southern plains Sunday will lift
northeast across the mid Missouri valley Sunday night to the western
Great Lakes late Monday and Monday night.

As the U/L trough pushes east Monday and Tuesday with decreasing
amplitude, the trough will suppress the U/L ridge over Florida with
quasi-zonal flow developing from the southern Plains across the
northern Gulf of Mexico and Florida.  A cold front associated with
the system over the Great Lakes will approach the northern forecast
area late Monday and Monday night with an increasing chance of
showers and possible thunderstorms.  Front will begin to stall as it
becomes parallel with the U/L flow.  Decreasing U/L support and
weakening L/L convergence will allow shower activity to decrease in
areal coverage as the front approaches west central Florida.  GFS
not as aggressive as previous runs now stalling the front across
south central Florida Tuesday.  Still leaning toward ECMWF solution
stalling the boundary across north Florida...which would also mean
slightly lower pops except over the northern nature coast.

More uncertainty in the long term as GFS has a strong northern
stream disturbance digging over the Mid Missouri Valley and Lower
Mississippi Valley late Wednesday with a sharp trough developing
from the Great Lakes to the Gulf of Mexico Thursday with the main
U/L energy over the Great Lakes/Ohio River Valley.  ECMWF is much
slower with a positively tilted trough developing Thursday from the
Great Lakes to the southern Plains. These varying solutions create
significant sensible weather differences across west central and
southwest Florida with GFS bringing in higher pops on Thursday...and
ECMWF delaying pops until Friday.  Given stark differences, low
confidence with developing system at end of the period.

Temperatures are expected to run above climatic normals through the
period...with the exception of Tuesday where temps will be near
climo to a few degrees above climo due to cloud cover, possible
shower activity, and flow off the Gulf of Mexico.

Some patches of fog have started to develop early this morning, and
will continue to expand in coverage through sunrise, causing periods
of MVFR or potentially IFR/LIFR conditions. After sunrise, VFR
conditions will take control again by around 14z. A few showers
cannot be ruled out along the sea breezes this afternoon, mostly
around KRSW and KFMY.

High pressure will continue to build across the eastern Gulf of
Mexico into the weekend, with generally easterly/southeasterly
winds, turning onshore each afternoon with the sea breeze. Nocturnal
surges could bring winds up to cautionary levels during the late
night/early morning hours. An approaching cold front will cause a
longer period of cautionary or possibly low end advisory level winds
Saturday night through Sunday. Winds will then relax during the
early part of the week as the front washes out across the area.

Relative humidity percentages will drop into the upper 30s each
afternoon through the upper weekend, and a few sites could
potentially drop to below 35 percent for a couple of hours. However,
widespread Red Flag conditions are not expected.


.Preliminary Point Temps/PoPs...
TPA  91  74  90  73 /  10  10   0   0
FMY  92  73  91  71 /  20  10   0   0
GIF  95  73  93  71 /  10  10   0   0
SRQ  87  73  87  72 /  10  10   0   0
BKV  94  68  93  68 /  10  10  10   0
SPG  90  75  89  74 /  10  10  10   0


Gulf waters...None.


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