Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
313 am EDT Sat Aug 1 2015
..Flood Watch in effect for Levy...Citrus...and Hernando
counties today through Sunday...
..very heavy rainfall and the potential for flooding possible
across portions of the Nature Coast today through Sunday...
Short term (today - sunday)...
little change in the overall forecast philosophy is expected
during the short term period. A strong middle/upper level ridge
will remain in place over the western U.S. While short wave
energy moving around the large ridge will maintain a positive
tilted upper level trough over the eastern U.S. With the southern
extension of the this trough remaining in place across the
southeastern states and Florida through Sunday. At the surface a
frontal trough with weak areas of low pressure on it will also
remain stationary across the southeastern states and northern Gulf
region...while surface high pressure remains parked across the
southern peninsula with a moderate to strong low and middle level
southwest wind flow continuing over the forecast area.
Similar to yesterday at this time models show deep tropical
moisture (pw's at or above 2 inches) remaining over the forecast area.
This deep moisture combined with the troughing...a diffluent
flow aloft...and a strong onshore flow off the Gulf will support
widespread showers and scattered storms across the forecast area
today and again on Sunday...with the potential for some
significant heavy rainfall and possible flooding problems
developing across the Florida Big Bend region and along coastal
locations of the Nature Coast from Hernando Beach north to Cedar
Key where the deepest moisture axis and best low level coastal
convergence will reside. Hi-res models are in fairly good
agreement with this scenario...but differ some with the exact
placement of the heaviest rain potential. Despite these
differences though very saturated grounds from recent heavy
rainfall along with the potential for more heavy rain warrants
hoisting a Flood Watch from Hernando County north to Levy County
today through Sunday.
Across the remainder of the forecast area scattered to numerous
showers and isolated storms will continue to be the rule within
the very moist and unstable air mass...with the threat of some
locally heavy rainfall in some locations along with gusty winds
and occasional lightning strikes.
Daytime temperatures will continue to run a few degrees below
normal through Sunday due to considerable cloud cover and high
rain chances with highs in the middle to upper 80s...while overnight
lows will remain above normal along the coast where readings in
the upper 70s to around 80 can be expected with lower to middle 70s
degree readings inland.
Middle/long term (sunday night - friday)...
models are finally hinting at a break in the pattern. The
lingering upper level trough hanging over the East Coast is
expected to nudge north as a broad area of weak ridging builds
in. At the surface...the quasi stationary boundary near the
Panhandle is expected to wash out by middle week as high pressure
strengthens from the central Atlantic. Both GFS and Euro show
this pattern developing which will bring a return to south to
southeasterly flow by Tuesday. However...models are indicating
an area of low pressure tracking eastward towards the middle
Atlantic which is forecast to drop another boundary into the
southeast US. This would force the ridge axis further south and
bring a return to a wet westerly flow by the end of the period.
Probability of precipitation for the middle term will continue to run high and favor the
northern half of the County Warning Area through Monday. With S-southeast flow setting
up by Tuesday...the moist airmass will moderate helping to
decrease rain chances through Thursday...mainly favoring inland
areas along the afternoon sea breezes. Higher rain chances are
expected to return by Friday with westerly flow developing south
of the surface boundary.
Temperatures will run within a degree or two of normal early August
abundant moisture combined with a trough of low pressure over the
area will support numerous showers and scattered storms over the
region during the next 24 hours. Rain showers/thunderstorms and rain that move over the
terminal sites will produce brief MVFR/IFR conditions...otherwise
VFR will prevail. Southwest winds in the 7 to 10 knot range early
this morning will increase to 12 to 18 knots after 15z...with
gusts up to 35 knots possible in vicinity of thunderstorms and rain.
a stationary frontal trough with weak areas of low pressure on
it across the southeastern states and northern Gulf region
combined with surface high pressure over the southern Florida
Peninsula will maintain a moderate south to southwest wind flow
over the Gulf waters today through Monday with wind speeds at
cautionary levels at times through the period. The strong onshore
flow will continue to favor a high risk of rip currents along area
beaches from Pinellas County south to Lee County today...so will
keep inherited rip current statement in place through tonight.
As the surface high to the south builds north to the Central
Peninsula during Tuesday and Wednesday a lighter southeast to
southwest wind flow can be expected from south to north each
day...with an enhanced onshore sea breeze component developing
along the coast each afternoon. Numerous showers and scattered
thunderstorms will be possible each day into early next
week...with the best chances over the near and offshore waters
from Tarpon Springs north to the Suwannee River.
abundant tropical moisture and high rain chances will keep
humidity values well above critical levels the next several
days. Increasing 20 foot winds and transport winds will support
high dispersion indices across the region today and again on
Sunday...otherwise no other fire weather issues expected.
river flood warnings continue in effect for the Myakka River at
Myakka River State Park...the Little Manatee River at Wimauma...
and Cypress Creek at Worthington Gardens through the weekend.
Any additional heavy rain today and again on Sunday will keep
water levels along these rivers elevated and in minor flood
through the period. All rivers will continue to be closely
monitored for any significant rises in waters levels through the
weekend and updates to the ongoing warnings will be issued
immediately if conditions warrant. All residents living along
rivers or faster flowing streams should keep alert to any rapid
rises in water levels and be ready to move to higher ground if
flooding is observed.
Preliminary point temps/pops...
tpa 87 77 88 78 / 70 40 60 40
fmy 90 76 90 76 / 50 30 50 20
gif 89 75 89 75 / 70 40 60 30
srq 88 78 88 78 / 60 30 60 30
bkv 87 75 87 74 / 80 40 70 40
spg 87 79 87 79 / 70 40 60 40
Florida...high rip current risk through this evening for coastal
Charlotte-coastal Hillsborough-coastal Lee-coastal
Flood Watch from 8 am EDT this morning through Sunday
evening for coastal Citrus-coastal Hernando-coastal
Levy-inland Citrus-inland Hernando-inland Levy.
Short term/aviation/marine/fire weather...57/McMichael
long term/decision support...20/Barron