Area Forecast Discussion
Issued by NWS Tampa Bay Area, FL
FXUS62 KTBW 270701
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
301 AM EDT Mon Mar 27 2017
07Z water vapor and H4 RAP analysis shows a negatively tilted lead
trough/shortwave pivoting through the eastern states early this
morning...with a trough extension down off the Carolina coast. A
secondary and currently potent shortwave is ejecting out of the
central/southern plains over the MS Valley. Between these
features...over our region we find synoptic mid/upper level ridging
in place. This ridging will hold in control of the forecast
today...and providing our region with benign, generally dry, and
Far upstream we find a large synoptic trough moving ashore along the
Pacific coast. This energy will take much of the rest of the week to
evolve eastward past the MS valley...and is unlikely to have much
impact on our local weather anytime soon.
At the surface...high pressure centered over the western Atlantic
continues to ridge back to the southwest along the Carolina/GA
coast...and then over the FL peninsula and eastern Gulf of Mexico.
This ridge axis will only slowly settle southward through the next
several days...and will remain the dominant feature of our boundary
.Short Term (Today through Tuesday)...
To sum up the short term forecast period with a few words...quiet,
generally dry, and warm.
Ok...now more details than that. Stacked ridging will control our
weather today. Synoptic flow will provide an easterly to
southeasterly wind this morning...but boundary layer flow will again
be quite weak...and terrestrial heating will be plenty enough to
force a well-defined sea-breeze to develop and slowly move inland
toward the I-75 corridor. The east-coast sea-breeze will be much
more progressive with the east-SE synoptic flow, resulting in an
early evening boundary collision near the I-75 corridor. A few
months from now...this would be a good setup for robust deep
convection along the FL west coast, but not today. We did see a few
showers along this collision Sunday evening, but the upper ridging
overhead has since suppressed the moisture layer and increased the
depth of the very hostile air aloft. It would appear that there is
no longer enough depth to the moisture to support any showers for
almost the entire region...and will cap PoPs at a silent 10%. Only
exception will be up across western Levy county. The late day
approach of shortwave energy into the SE states may provide just
enough synoptic support down into northern Florida to aid a few
updrafts where the sea-breezes collide along the I-10 corridor
(mainly after 5 PM EDT). 00Z GFS/NAM both show a weak swath of mid-
level Qvector convergence over northern Florida early this
evening...with a somewhat favorable upper jet position to enhance
divergence aloft. Even with all this...will still be battling a
rather hostile thermodynamic environment for deep convection...but
will add a 20% PoP to inland Levy out of respect for a few of the
explicit convection guidance members that are supporting a few brief
showers in this region. Although...all of these factors stated above
are "maximized" farther to the north. Will not be surprised if we do
not see any showers as far south as Levy County. High temperatures
today will be in the 80s away from the immediate coast. At the
beaches...temps will behave similar to Sunday and briefly reach
within a degree or two of 80 before sea-breeze flow drops them back
into the mid/upper 70s for the later afternoon hours.
Weak shortwave makes it pass to our north tonight...and is east of
the GA/NE Florida coast by early Tuesday morning. Good agreement in
the ensemble guidance that large scale mid/upper level ridging
quickly builds back overhead during the daylight hours.
Therefore...the forecast remains rather unchanged. Another sea-breeze
in the afternoon, warm temperatures, and likely not enough available
moisture to support any isolated sea-breeze showers.
Mostly dry with above normal temps more or less sums up much of the
extended forecast period. Mid/upper level ridging will be in place
across the area through Thursday keeping us warm and dry across the
peninsula. Temps will remain warm and above normal reaching into the
80s area wide on Wednesday with some upper 80s possible across the
interior. Temps will continue to warm into Thursday with upper 80s
to even some 90 degree temps possible across interior zones.
Certainly the month of March will be ending on a warm note across
west-central and SW Florida.
As we get into Thursday, a shortwave trough across the Arklatex will
pivot into the Tennessee Valley by Friday bringing the potential for
increased rain chances across our area. Models continue to vary on
the overall coverage of rain chances so for now will continue the 20
to 30 PoPs mention from the Bay area north into Saturday morning and
a 20 PoP for our southern zones Saturday afternoon. Temperatures
into the weekend will continue above normal with some readings again
approaching 90 over the interior.
.Aviation (27/06Z through 28/06Z)...
Generally benign aviation conditions will continue for the duration
of the current TAF period. The forecast will essential be on related
to wind direction...with an afternoon sea-breeze moving inland to
the I-75 corridor by early evening. May see a brief period of MVFR
fog around dawn at KLAL/KPGD...however no significant problems are
anticipated. VFR conditions prevail for the daylight and evening
hours of Monday. Unlikely that we will see a repeat of the isolated
showers from Sunday evening...and will not mention VCSH at any site.
E-SE winds this morning will shift SW-W for coastal terminals during
the afternoon and then W-NW in the evening. As is often the case
with light flow...KPIE will likely see winds go NE for a short time
during midday, with the sea-breeze off the bay, before the Gulf sea-
breeze shifts winds westerly after 19Z.
Seasonable conditions with no significant marine concerns through the
next several days, as surface high pressure continues to ridge
westward from the Atlantic over the Florida peninsula and eastern
Gulf. Light east to southeast wind overnight and during the morning
hours will shift onshore with sea-breeze development near the coast
each afternoon. Winds offshore are likely to become light and
variable each afternoon before finally going west-NW in the evening
Dry and seasonably warm weather will be the forecast for the next
several days as high pressure controls the region. Fire weather
activities along and inside the I-75 corridor should expect a wind
shift to westerly each afternoon with the development of sea-
breezes...although timing of this wind shift will depend on
location. Relative humidity will briefly approach 35% away from the
coast the next couple of afternoons, however, extended durations of
low relative humidity are not expected and winds will be generally
light, preventing red flag conditions from being achieved.
Fog potential...Patchy fog is expected away from the coast late
Monday Night into early tuesday morning...although widespread or
dense fog is not expected.
.Preliminary Point Temps/PoPs...
TPA 84 64 82 65 / 0 0 0 0
FMY 85 62 84 63 / 0 0 0 0
GIF 85 60 85 63 / 0 0 0 0
SRQ 79 64 77 62 / 0 0 10 0
BKV 84 58 84 56 / 0 0 0 0
SPG 84 65 81 67 / 0 0 10 0
SYNOPSIS/SHORT TERM/AVIATION/MARINE/FIRE WX...Mroczka
MID TERM/LONG TERM/DECISION SUPPORT...McKaughan