AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
823 PM EDT SAT Aug 18 2012

.SHORT TERM…
[Sunday through Monday NIGHT] Looks like a very UNSETTLED period
with the broad trough over the eastern CONUS DEEPENING as
several impulses drop southeastward from the plains into the base
of the trough. The axis of the trough will remain west of the
local region which will tap into the tropical MOISTURE associated
with Helene or its remnants in the deep layer southwest FLOW. The
GFS continues to show the upper JET dipping well into the
southeastern states Sunday into Monday placing the Tri-State area
within the right entrance region. SPC`s day 2 discussion currently
mentions this put no highlighted area for a severe risk at this
time. This will need to be monitored closely. At the surface, a
cold FRONT will approach from the northwest pushing into our
western zones Monday possibly becoming QUASI-STATIONARY late
Monday or Tuesday. As mentioned in an earlier discussion, this
could SET the STAGE for a heavy rain event with localized
flooding. Understandably PoPs will be rather HIGH during this
period and will generally go above numerical guidance. MAX TEMPS
will be held down a few degrees with the extensive CLOUD cover and
convective activity.

&&

.LONG TERM…
[Tuesday through Saturday] With the MEAN upper level trough
expected to remain quite persistent across the eastern half of the
U.S. through much (if not all) of the upcoming week, impulses of
energy rounding the base of the trough over the Southeast will
combine with plenty of deep layer moisture to keep above NORMAL
PoPs in the FCST throughout much of the extended period.
Additionally, the likely remnants of Tropical STORM Helene (which
is still PROGGED to move into southern Mexico, well away from our
region), may still play an important role in our fcst before the
week is over. While there are still plenty of discrepancies
between the global models (and run to run differences within each
model) over timing and potential moisture influx, the simple
presence of the steep upper level trough, will likely pull in some
deep layer tropical moisture into our region from the SW by MID to
late next week. Now, the latest runs of the GFS (00 UTC) and ECMWF
(12 UTC Thu), are back to showing some potential for a “break” in
the organized CONVECTION later on Tue. and possibly lasting into
Thu., but am not ready to buy into this solution just yet, given
the NUMEROUS changes and uncertainty surrounding Helene. Should
this become a trend that all of the global models begin embracing,
then PoPs can be adjusted downward at a later time. Also, with the
increased cloud cover which is still expected during the day, the
effects of the more typical afternoon sea breeze will be somewhat
limited (except for possibly Tue AFTN THRU Thu.), so high temps
should average a bit below CLIMO values through much of the
period. While this does NOT appear to be the best stretch of
“beach weather” by any means, the potential of a good stretch of
WIDESPREAD RAINFALL will certainly help many areas to continue to
chip away at our long term ongoing DROUGHT. Please stay tuned to
the latest fcsts from the National Weather Service, as this
pattern may need some fine tuning once the global models come into
better agreement with each other, and maintain more run to run
consistency.

&&

.AVIATION…
[Through 00z Monday] Latest RADAR trends show a large area of
showers and thunderstorms stretching from central Alabama into
the northern Gulf of Mexico, pushing steadily to the east. This
activity will begin to impact the western terminals (KDHN and
KECP) over the next few hours with SHRA and TSRA. Terminals
farther east may be impacted later tonight. Given these trends,
have increased mention of rain and THUNDER in the TAF`s throughout
the forecast period at all terminals.

&&

.MARINE…
Winds will be from the southwest at least through mid-week with
winds and SEAS gradually increasing to cautionary levels by Tuesday
as the PRESSURE GRADIENT tightens ahead of a cold front. This front
will also bring numerous showers and thunderstorms to the coastal
waters. Winds and seas may subside below headline criteria on
Wednesday.

&&

.FIRE WEATHER…
Typical of this wet SUMMER pattern, afternoon relative humidities
will remain well above critical levels over the next several days
and, and therefore, conditions will continue to remain safely
above red flag levels.