Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
099
FXUS62 KTBW 240531
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
1230 AM EST Fri Nov 24 2017


.AVIATION (24/06Z THROUGH 25/06Z)...
Weak cold from from KPGD to the Space Coast with IFR CIGS behind it.
Front will slowly move south today. Radar showed showers moving into
southwest Florida and patchy drizzle in KTPA area. Visibility
forecast to be tricky through 15Z, then conditions improve to VFR
around 17-19Z. Clear skies and patchy fog expected later Friday
night.

&&

.Previous Discussion /Issued at 657 PM Thu Nov 23 2017/...

.UPDATE (Overnight and Friday)...
00Z water vapor and H4 RAP analysis shows amplified deep
layer troughing digging through the central and eastern Gulf
of Mexico...with a large plume of mid/upper level
subtropical moisture streaming northward over the Florida
peninsula ahead of the trough axis. As the trough continues
to approach the area...the weak associated surface low is
coming ashore near Tampa Bay. Most of the favorable synoptic
lift has actually now shifted to our east and
northeast...resulting in most of the area seeing just a few
lighter scattered showers. More concentrated shower activity
continues to move ashore into the Fort Myers area as of
7PM...associated with WAA/lift along a lower level theta-e
ridge extending across the SE Gulf of Mexico to the SW
Florida coast. Latest RAP progs are for this feature to
shift south with time tonight...and this should shift the
better rain chances south of Fort Myers eventually as well.

Elsewhere...as mentioned above...the best forcing is gone,
but weak large scale synoptic forcing ahead of the trough
axis along with abundant moisture will still support
isolated to widely scattered showers/sprinkles...but QPF
amounts will be very low.

As the surface low shifts slowly southeast through the rest
of the evening...good agreement that lower level winds from
the north/NE across the Nature Coast will expand down into
the Tampa Bay Area. This flow will support the development
of lower stratus across the area...initially from Tampa Bay
area northward...but eventually further south as well. This
stratus will mainly be a concern for the aviation community,
but will likely make for a dreary start to the daylight
hours of Friday. BUFKIT profiles from the NAM/RAP and local
hires models are all showing very favorable thermodynamic
profiles for the stratus...and support only a slow
improvement during Friday morning.

Can not rule out a few isolated showers Friday
morning...however...drier air will be arriving aloft...even
in the morning...and this should really end this potential
pretty quickly. Most NWP guidance has trended faster with
the exit of shower potential during the day Friday. By
afternoon...looking like fairly decent weather region-wide
as the deep and even lower level moisture really becomes
scoured out from W to E.

Pleasant weather then dominates the forecast for the rest of
the holiday weekend.

&&

.Prev Discussion... /issued 204 PM EST Thu Nov 23 2017/

SHORT TERM (Tonight - Friday)...
A closed upper low sits over the southern portion of the Hudson Bay
with deep troughing extending south along the east coast into the
central Gulf of Mexico. This trough is lending support to an area of
low pressure over the eastern Gulf of Mexico and associated frontal
boundary that is sweeping across Florida today. The upper trough
will slowly drift eastward through the period as the surface low and
frontal boundary moves east of Florida on Friday. High pressure will
build into the Gulf of Mexico late Friday bringing clearing
conditions into the weekend.

There are two separate bands of showers and storms making their way
ashore along the west coast of Florida this afternoon. The northern
one is located along the Nature Coast just north of Tampa Bay and
the southern one is streaming onshore from Sarasota southward to
Fort Myers. 60-90% POPs can be expected through the evening hours in
these bands. Rain chances decrease overnight but will still remain
around 30-50% through Friday afternoon. Temperatures will be
slightly below average over the next couple of days as the high
pressure filters in cooler air in the wake of the low pressure and
frontal boundary.

LONG TERM (Friday Night through Thursday)...
As we enter the medium range timeframe, the pattern will begin to
change as surface low pressure departs into the Atlantic Ocean, and
surface high pressure builds southward. This will usher in a rather
prolonged period of relatively cool and dry conditions with a series
of reinforcing cold fronts and dry/stable post-frontal airmasses.

For the upcoming weekend, weak surface high pressure will build
southward to the northern Gulf Coast. A subtle inverted trough
feature may yield increased cloudiness and a shower or two over the
southern/eastern Gulf of Mexico Saturday into Sunday, but this
feature will be ushered quickly southward by a secondary cold front
set to move through early next week. This front will allow for the
dry and seasonal weather to persist through the end of next week.

Daytime highs will rise into the low to mid 70s each day with lows
ranging from the upper 40s to lower 50s north to the middle 50s and
lower 60s south. As usual, warmer conditions will reside along the
immediate coast due to water temperatures in the upper 60s and low
70s.

MARINE...
An area of low pressure moves across the Nature Coast with a frontal
boundary extending across the coastal waters. Showers and storms
will continue through the evening hours, then diminishing in
coverage by early Friday morning. High pressure builds into the Gulf
of Mexico on Friday and into the weekend. Interaction between the
high pressure and the front east of Florida will produce gusty winds
near cautionary level late tonight through early Friday. As the high
settles over northern Florida by Saturday, the winds decrease to 10
knots or less through the weekend. No other marine issues are
expected.

FIRE WEATHER...
High rain chances and humidity levels will preclude any fire weather
concerns through the period.

&&

.Preliminary Point Temps/PoPs...
TPA  63  72  59  74 /  30  30   0   0
FMY  67  77  60  78 /  70  30  10   0
GIF  62  72  56  76 /  30  30  10   0
SRQ  64  72  58  75 /  30  30  10   0
BKV  60  70  50  74 /  30  30  10   0
SPG  62  71  60  73 /  30  30  10   0

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.