AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
1005 AM EDT Fri Jul 6 2012
DISCUSSION...
The MCS that moved across our western zones overnight was exiting
to the southwest this morning. There are currently only a FEW
thunderstorms remaining over Walton county and the westernmost
panhandle waters. For later this morning and afternoon, the CURRENT
POP distribution looks good. See previous discussion for reasoning.
The only concern is how much CONVECTION we will see west of the
river in the WAKE of the MCS. Visible satellite imagery does show
the skies already clearing over our SE AL zones so there will be
plenty of INSOLATION. The 12z KTAE SOUNDING has a PW of 1.90" and is
more unstable than yesterdays. The steering FLOW is once again very
light so storms will be slow movers.

&&

.AVIATION [through 12z Saturday]...
Overall, VFR is expected to be the predominant condition for the
bulk of the 24-HR period. MVFR in storms, with gusty winds to 20 or
30 knots possible in the strongest ones This afternoon. For now the
TAFs reflect a VFR forecast with VCTS group at the time we think
storms are most LIKELY.

&&

.PREVIOUS DISCUSSION (524 AM EDT Fri Jul 6 2012)...

.SYNOPSIS...
The 03 UTC regional surface analysis showed a typically weak
summertime PRESSURE pattern, with a lot of contamination from
MESOSCALE convective systems (i.e. MESO highs and OUTFLOW
boundaries). The main nearby synoptic features were the Piedmont
TROUGH extending through central GA, and the West Atlantic RIDGE
in the southern Gulf of Mexico. Although it is 0521 EDT,
thunderstorms were still ongoing over our forecast area, which is
unusual (except for this season). Vapor imagery and upper AIR data
showed a maximum in the 500 MB HEIGHT field over MO, and a trough
along the U.S. east coast.

&&

.SHORT TERM...
(Today through Sunday) Since none of the 00 UTC NWP guidance did
an especially good job at initializing the late NIGHT/early
morning thunderstorms, our forecast confidence for today isn`t all
that strong. We`ll assume that the current storms and clouds will
mostly dissipate by late morning, allowing plenty of time for
daytime heating and sea breeze development. The combination of this
sea breeze, the trough to our north, and any outflow boundaries or
small scale MCVs from the current convection will contribute to
convective initiation this afternoon and evening. Our PoP is an
average of the GFS/NAM/EU MOS and local CAM PoP, and is generally
around 40%. It`s not higher than that because there is some CHANCE
that this morning`s clouds and storms could actually suppress
later convection, and that the highest deep layer MOISTURE may
begin transitioning west later this afternoon. It`s not lower
than 40% because it`s still pretty moist and there should be a lot
of mesoscale boundaries around today. While the weak winds aloft
will prevent significant STORM organization (and WIDESPREAD severe
storms), there could still be some strong to severe storms that
are either PULSE type, or loosely- organized multi CELL type.
Marginally severe HAIL and WIND gusts are the main threats, with
the highest chances being this afternoon and evening. The global
models show gradual drying from west to east in the MID
TROPOSPHERE this weekend, which will allow for a gradual decrease in
the PoP Saturday and Sunday from east to west. Highs will be in the
mid 90s (inland) each day, and it will be humid. However, it doesn`t
appear that heat index values will REACH" onClick="return popup(this, 'notes')">REACH ADVISORY levels through
this weekend.


.LONG TERM [Sunday Night through next Friday]...
Not a lot has changed with the thinking in the extended forecast
from this time last night. Large upper level ANTICYCLONE centered
over the Upper Midwest in the short term period will be slowly
retrograding by Monday into the Intermountain West. The accompanying
large upper level ridge axis will get split by an amplifying trough
in the eastern CONUS such that two highs emerge - the Bermuda HIGH
to the east and the aforementioned one over the west. The digging
SHORTWAVE that will be carving out the east coast trough should be
embedded in the northern branch of the JET stream, and thus should
be fairly progressive. Therefore, a broad mid-upper level trough is
likely to become somewhat CUTOFF from steering flow and linger over
the lower Mississippi River Valley. This is likely to allow a deep
favorable FETCH of moisture to evolve from the deep TROPICS and
Caribbean, with EASTERLIES over the Caribbean Sea rounding the
western edge of the Bermuda High and generally southerly flow over
the eastern Gulf of Mexico. Meanwhile, HPC forecasts and global
model consensus place a stalling FRONT somewhere in the vicinity of
the Gulf Coast states by later in the week. The combination of all
these factors should lead to increasingly UNSETTLED weather,
especially once the western edge of the Bermuda High begins to
erode. Best RAIN chances look to be Wednesday to Friday and they
were nudged more into the 40-50% RANGE in the afternoons based on
the latest guidance. Increased cloudiness and rain should lead to
cooler temperatures on average, so high temperatures were gradually
trended down closer to 90 by the end of the work week.

&&

.MARINE...
Typically LOW summertime values of winds and SEAS are expected
at least into early next week.

&&

.FIRE WEATHER...
No fire weather concerns for the next week AS relative HUMIDITY
should remain at or above 40 percent.