Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL

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000
FXUS62 KTBW 271834
AFDTBW

Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
234 PM EDT Sat May 27 2017

.SYNOPSIS...
18Z water vapor and H4 RAP analysis shows a pattern already
set up to support a benign weekend forecast for the entire
area. Harmless upper level shortwave is exiting our region
this morning...followed by mid/upper level high pressure
building/expanding east/NE overhead from the Gulf of Mexico.
This upper level ridging will be in control of our weather
through the duration of the holiday weekend. Very dry
representation on WV imagery was confirmed by the 12Z RAOB.
Once again a very dry troposphere was sampled through the
entire column. The measured PW this morning was only 0.62".
To put that into perspective for the 27th of May in central
Florida, the 10th percentile value for today is 1.01" and
the lowest value every sampled for today is 0.57". This puts
today`s PW well below the 5th percentile of values.
Basically...the atmosphere over our heads is dry. With the
lack of moisture and no synoptic forcing to speak of, it is
no wonder our skies are clear this morning. Other than some
passing thin cirrus tonight or Sunday, the pattern will
continue to suggest mostly clear skies right through the
weekend.

At the surface...The subtropical ridge axis lies directly
across the central or south-central FL peninsula and into
the eastern Gulf of Mexico. This ridge axis will not move
much through the weekend. The ridge axis in the vicinity
means winds and gradient flow are weak...and will be
dominated by sea and land breeze circulations during the day
and night respectively.

&&

.SHORT TERM (Rest of Today through Sunday)...
Rest of Today/Tonight...As mentioned above, generally
benign weather conditions with warm seasonable temperatures
and near 0% chance of rainfall. Only concern with the
current weather has to do with the forestry/fire weather
community, as relative humidity values will be and are
already rather low this afternoon away from the moderating
influence of the sea- breeze. Based on our morning RAOB,
once we mixed the boundary layer to between 900-950mb, we
would mix down some very dry air from just above the
surface. This has seemed to occur as we have several
stations across the Highlands/Polk counties with RH values
down into the upper teens/lower 20s. Therefore, an extended
period of sub-critical level relative humidity will be
ongoing into early this evening for inland
areas...particularly Polk/Highlands/DeSoto/Hardee Counties.

Low temperatures tonight looks seasonable also, with middle
to upper 60s common inland and lower to middle 70s at the
beaches. Some potential with the upper ridge building
overhead to see patchy and shallow field fog late tonight,
but this should not be of significant impact to travel.

Sunday...More of the same, under plenty of sunshine.
High temperatures are likely to be a degree or two warmer,
but so will dewpoints. Therefore, it will begin to feel a
bit more humid for those with outdoor activities planned.

Have a fun and safe holiday weekend everyone!

&&

.Long Term (Sunday Night - Saturday)...
Mid level high pressure centered over the eastern Gulf of Mexico to
start the week will gradually strengthen and shift east across the
state and into the western Atlantic through midweek. Meanwhile, the
low level high will continue to ridge across the southern and
central Florida Peninsula, with generally light winds. Strong sea
breeze pushes will collide over the interior each afternoon.
Although subsidence and a relatively dry airmass will prevent
mentionable rain chances on Monday, atmospheric moisture will
gradually increase through the week, leading to building chances of
afternoon thunderstorms, with the highest chances over the interior.

During the second half of the week and into next weekend, the mid
level ridge will move east of the region as a broad trough fills
into the Great Lakes and northeastern US, while the surface ridge
centered over the Atlantic continues to ridge into the Florida
Peninsula. Atmospheric moisture will continue to build, allowing for
increasing rain chances.

Temperatures will run slightly above normal for late May and early
June, with highs in the upper 80s and low 90s along the coast, and
mid 90s inland. Lows will generally run in the low to mid
70s.

&&

.AVIATION (27/18Z through 28/18Z)...
Benign aviation forecast through the TAF period for all
terminals. Continued dry atmosphere will keep skies mostly
clear...with only a few passing cirrus at times later in the
forecast period. Onshore sea-breese winds will diminish and
become light and variable once again a few hours after
sunset. Some slight potential for shallow MVFR type ground
fog toward dawn Sunday for KLAL/KPGD, however, confidence
still low enough to exclude mention with current TAFs.
Onshore winds around 10 knots again develop and spread
inland Sunday afternoon.

&&

.MARINE...
High pressure will be the dominant player in our weather
across the eastern Gulf of Mexico through the next several
days. The pattern will keep winds and seas generally low.
Only gusty conditions will occur near the coast each
afternoon as the daily sea-breeze develops and migrates
onshore.

&&

.FIRE WEATHER...
High pressure remains over the region through the holiday
weekend, keeping our weather dry and warm. The lowest
relative humidity values should be today, with a slow
increase in low level moisture Sunday and then further
Monday. Even still, a few areas well inland from the coast
may see a brief period of sub-35% relative humidity Sunday
afternoon, however, due to lower confidence in extended
durations will hold off any any additional red flag
warnings.

Fog Potential...Patchy and shallow field fog is possible
late tonight in the hour or two surrounding dawn. No
significant visibility issues are anticipated.

&&

.Preliminary Point Temps/PoPs...
TPA  72  89  75  90 /   0   0   0  10
FMY  70  93  73  93 /   0   0   0  10
GIF  66  95  73  96 /   0   0   0  10
SRQ  73  88  73  87 /   0   0   0  10
BKV  66  90  69  92 /   0   0  10  10
SPG  73  88  76  90 /   0   0   0  10

&&

.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Red Flag Warning until 7 PM EDT this evening for Highlands-
     Polk.

Gulf waters...None.

&&

$$

SHORT TERM/AVIATION/MARINE/FIRE WEATHER...Mroczka
MID TERM/LONG TERM/DECISION SUPPORT...Fleming


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