Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
403 am EST Friday Feb 12 2016
Short term (today-saturday)...
a broad upper-level trough will remain over the eastern half of
the U.S. Today with a shortwave dropping into the southeast this
afternoon and exiting off the East Coast by this evening. At the
surface...high pressure will become suppressed as an area of low
pressure forms off the Carolina coast...with a weak frontal
boundary nearing the Florida Panhandle by the end of the day. This
set-up will give US southwesterly winds through the day which will
allow temperatures to warm by several degrees compared to
yesterday and highs will top out in the 70s under mostly sunny
As the shortwave and area of low pressure pull away to the
northeast tonight into Saturday...the weak cold front will be
pushed southward through the peninsula. Plenty of dry air will
remain in place with no rain chances in the forecast for its
passage...just a few extra clouds. Most of the area should then
be sunny by the afternoon. We will be in for a slight cool down
for Saturday afternoon after the front moves through the forecast
area and a cooler and drier air mass filters into the region on
northerly winds. Highs will be more in the 60s and lower 70s.
Long term (saturday night-friday)...
the coldest night of the middle/long term period continues to be
Saturday night into early Sunday as northerly winds behind a cold
front provide a reinforcing shot of cool/dry low level air. We
still never get a really good position of the surface ridge to
support efficient radiational cooling...as it remains centered
well to our north. So...the resulting gradient should be enough to
slow the nocturnal decoupling process...and keep temperatures from
dropping significantly. Current forecast calls for widespread 40s
to the south of the I-4 corridor...with 30s further north through
the Nature Coast. Coldest temperatures will be in Levy County where a few
normally colder spots may briefly drop down to freezing toward
sunrise. With a light but steady northerly wind through the
night...it will feel colder for most...with late night wind chills
dropping into the 30s as far south as interior
Sunday begins a moderating trend as the surface ridge moves off
the middle-Atlantic coast and allows the cold air advection behind the front to end.
Winds come around to the east and southeast and begin a slow
transport of moisture back over the peninsula from the Atlantic.
Generally looking for high temperatures in the 60s Sunday afternoon with
abundant sunshine. Low temperatures Sunday night will be up considerably
from Saturday nights cold temperatures...with temperatures ranging from the
low/middle 40s far north to upper 40s and 50s elsewhere.
The next amplification to the longwave pattern takes place quickly
Monday/Monday night as troughing once again digs into the
southeastern Continental U.S./Northern Gulf of Mexico. Global guidance members
are in better agreement in the evolution of this system tonight
compared to 24 hours ago...and have trended toward a more amplified
and stronger shortwave trough moving along the northern Gulf Coast.
Current global model solutions are a bit more concerning with
respect to some potential for stronger storms. It is still too early
to get caught up in the details...but this looks like a typical cool
season setup for our region. High shear/Low Cape scenario. The
kinematics look decent...with plenty of deep layer shear to support
storm organization and impressive height falls. But...the
instability...especially surface based instability is marginal.
Sometimes marginal is enough...sometimes it is not. We will have a
better handle on the potential in the days to come when some of the
higher resolution convective models begin to simulate the system and
we can see how the updrafts react to the particular shear/cape
Either way...the synoptic forcing for ascent is very strong...and
will show increasing rain chances as we head into Monday night.
Forecast will show at least likely probability of precipitation for all zones...with
categorical 80%+ probability of precipitation to the north of the I-4 corridor in closer
proximity to the best height falls/qg forcing. Looks as through this
will be a fast moving system...and with all global members in good
agreement with the timing...dry things out quickly Tuesday morning
with the passage of the associated cold front.
An extended period of dry weather will then be highlighted for the
middle/later portion of next week as high pressure quickly builds
overhead in the wake of the early week system. Generally speaking
the airmass behind this system is cool but not cold...and moderates
quickly. Therefore... temperatures look to be seasonable for Wednesday...
and then begin a climb toward slightly above normal temperatures for
the end of next week.
mainly VFR conditions prevail this morning...although a few sites
continue to briefly drop to IFR/LIFR in fog. All sites are
expected to return to VFR by 14z and continue through the rest of
the forecast period.
no headlines for today and tonight but winds will then near
exercise caution levels on Saturday as they turn north and
increase behind a cold front. Winds will quickly become easterly
Saturday night and continue through Sunday night...with a surge
to exercise caution levels possible both nights. Winds become
southwesterly for early next week ahead of a storm system and
cold front...which will pass through the region Monday night into
Tuesday and likely bring a round of showers and thunderstorms
along with increasing winds and seas across the waters.
several hours of critical relative humidity values can be
expected this afternoon generally south of the I-4 corridor...but
neither wind nor erc value criteria are expected to be met...so
no red flag conditions are anticipated. For Saturday...a cold
front moving through the region will bring some drier air over
the area...and some spots across the interior and over the Nature
Coast can expect a few hours of low relative humidity values. But
similar to today...red flag conditions are not expected.
Preliminary point temps/pops...
tpa 69 56 66 44 / 0 10 0 0
fmy 73 53 73 49 / 0 0 0 0
gif 74 54 69 44 / 0 10 0 0
srq 66 56 67 45 / 0 10 10 0
bkv 71 51 65 37 / 0 10 0 0
spg 69 57 65 49 / 0 10 10 0
Florida...Beach hazards statement through Saturday evening for
coastal Charlotte-coastal Lee-coastal Manatee-coastal
Short term/aviation/marine/fire weather...05/Carlisle