Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
433 am EDT Monday Oct 20 2014
Short term (today-tuesday)...
surface high pressure is centered across the eastern Seaboard early
this morning with a weak front still hanging on across central
Florida. With a fairly dry air mass still in place...the only rain
noted overnight has been a convergent band over on the East Coast
associated with the boundary. For today...an upper-level trough over
the Great Lakes region will amplify while at the surface...the high
will shift eastward with a dry front moving into the southeast.
Moisture will increase for today...though still not enough for any
rain so the forecast will remain dry. The previously mentioned
trough will close off near the northeast on Tuesday with the frontal
boundary shifting southward into the forecast area. Again...not a
whole lot of moisture associated with this boundary...so no rain is
expected with it but there will be some drier air behind it over our
northern zones. The other player in our sensible weather for Tuesday
will be a broad area of low pressure located over the southwestern
Gulf...with deep moisture extending eastward over the southern part
of the state. For now...will keep rain in the forecast south of
Tampa Bay and dry conditions elsewhere.
Long term (tuesday night-monday)...
medium range guidance is coming into better agreement with respect
to the synoptic pattern evolution through the long term periods.
That said...given the run to run continuity issues and lack of
a strong model consensus over the past couple of days...confidence
remains below average particularly in the latter portion of the long
Model solutions are in good agreement showing a deep upper level
trough closing off an upper low over the Middle-Atlantic States Tuesday
night and Wednesday...with this feature then lifting into the New
England states by Friday evening. As this occurs upper level
troughing over the Florida Peninsula Tuesday night and Wednesday
will give way to weak upper level ridging Thursday through Friday.
Another shortwave trough will dig into the lower Mississippi Valley
and northern Gulf of Mexico on Friday...with this positive tilted
upper trough shifting east-southeastward and into the peninsula on
Saturday and into the western Atlantic for Sunday and Monday. This
secondary shortwave trough is the one that the models have struggled
capturing over the past couple of days...but the 00z GFS and 00z
European model (ecmwf) have trended very closely together with their handling of
this feature...leading to higher albeit still below average
At the surface...a trough of low pressure extending from Bay of
Campeche into the Florida straights will will move very little
through Friday evening. The main feature the models are latching
onto along this trough...is the broad area of low pressure over the
Bay of Campeche which will shift slowly eastward into the southeast
Gulf of Mexico and northwest Carribean by Friday evening. This
feature will then shift east-northeastward through the Florida
straights into the vicinity of the Bahamas by Saturday evening. High
pressure is then expected to slowly build from the north Saturday
night through early next week.
As for forecast details...will continue to advertise slight
chance/low chance probability of precipitation in the forecast primarily south of Tampa Bay
Tuesday night through Saturday. It certainly doesn/T appear to be a
big rain maker for this portion of the state as the deepest moisture
will remain across the Florida straights. By Saturday night...the
deepest moisture will have shifted over the Bahamas if the 00z
GFS/European model (ecmwf) solutions have trended in the right direction...so will
keep the forecast optimistic and rain free for the end of the
weekend through early next week.
VFR conditions are expected for the next 24 hours. Generally light
southeasterly winds will be in place for today but will turn onshore
this afternoon at coastal sites as the sea breeze circulation forms.
winds will remain generally southeast through today...though will
become lighter in the afternoon and turn onshore as the sea breeze
circulation forms. Winds with speeds of 15 knots or less will
continue into Wednesday then will increase for the later part of the
week. The forecast will remain dry through today but rain chances
increase for the southern waters starting tonight and continuing
through mid-week. Seas will remain 3 feet or less through much of
no fire weather issues for the next several days as relative
humidity values will remain above critical levels.
Preliminary point temps/pops...
tpa 86 70 85 69 / 0 0 10 10
fmy 88 70 84 71 / 0 10 40 30
gif 86 69 85 68 / 0 0 20 10
srq 85 67 83 68 / 0 10 20 20
bkv 87 59 85 59 / 0 0 10 10
spg 85 72 84 72 / 0 0 10 10
Short term/aviation/marine/fire weather...05/Carlisle
long term/decision support...21/jelsema