NEAR TERM [Today and Tonight]...
Expect a generally hot and dry day to unfold across across the region this afternoon, with lighter low level easterly flow and even lower PWATs expected than yesterday (around 1.5"). Therefore kept PoPs limited to the 20 to 30 percent range, with about 70% of the CWA around 20%. This is supported well by the bulk of the numerical,
CAM, and confidence guidance, with the only caveat being potential
MCS redevelopment to our north. However, should this occur, it could
likely be a a post 00 UTC event, which would require upward PoP
adjustments for tonight.
SHORT TERM [Friday through Saturday]...
The short story for Friday and Saturday is that we expect a fairly high coverage of rain, and that the increased cloud cover and rain will keep the diurnal temperature range a bit more restricted than normal. However, depending on how the details pan out, we could end up with a variety of different QPF scenarios.
The main change to the forecast was to bump PoPs up slightly into the 50-60% range both days, and this may need to be increased further in subsequent forecasts. High temperatures were also nudged down a couple degrees.
Regardless of how exact mesoscale details pan out, the 1000-700mb
flow will shift to a southerly direction with deeper moisture arriving by Friday morning. This sort of pattern favors greater coverage of rain - usually at least in the "likely" (>55%) range.
A few of the WRF-based models, such as the NAM and our locally-run
WRF-ARW both want to develop a non-tropical low over the eastern
Gulf of Mexico and then track it toward coastal MS/AL. This low is
projected to develop out of a more concentrated area of convection
on the east side of a mid-upper level low centered along roughly
86W in the eastern Gulf of Mexico this morning.
Such a low could help focus heavier rain bands to its east - or roughly over south Alabama and the Florida Panhandle. While this scenario can`t be discounted, it is also not the most likely possibility. Therefore,
we will continue to carry a forecast of increased PoPs, but there
is a small (perhaps ~20%) chance of locally heavy rainfall
particularly in the western part of our area.
LONG TERM [Saturday Night through Wednesday]...
Through the extended period the previously mentioned mid/upper low
will move away from the Gulf to the west, with a ridge building in
behind, and a trough eventually sliding into the southeast from
the north. At the surface, flow will transition from southerly to
more of a west, southwest direction by Tuesday.
Rain chances will remain near to above average for the extended period due in part to an extended period of upper level diffluent flow from the shifting pattern. With plentiful moisture in the lower and middle levels of the atmosphere, the upper level diffluence will likely
be assisted by some sort of disturbed sea breeze influence each
VFR conditions will prevail at the terminals through the TAF Cycle,
with the exception of periods of MVFR to IFR conditions at VLD
(based on persistence), and DHN due to some rainfall after 00 UTC.
Expect convective coverage to be at a minimum today with easterly
flow and low PWATS, so will not include any convective tempos or
Prob30s at this time.
Winds will gradually veer to the south and southwest this weekend,
and to the west early next week, but will generally stay in the 10
to 15 knot range. Seas of 2 to 3 feet will gradually subside to 1
to 2 feet later in the weekend. SCEC or Advisory conditions are
not expected at this time.
Red flag conditions are not expected for the next several days.
A few area river points remain in flood early this morning - most
notably, the Choctawhatchee near Bruce which is forecast to remain
in moderate flood stage into the weekend. However, all area rivers
and streams are seeing decreasing flows and falling river stages.
Average rainfall amounts through Saturday should be on the order
of 0.50 to 1.00 inches.
This would not be sufficient to cause significant rises on rivers. However, there is a small chance for localized heavy rainfall on Friday and into the weekend. If that is focused in a particular basin, it could cause a few river points to see some rises this weekend given flows higher than climatological normals in July.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 94 73 88 73 89 / 20 20 60 30 60
Panama City 88 76 87 75 87 / 20 20 50 30 60
Dothan 92 73 89 73 90 / 30 20 50 30 50
Albany 93 74 91 72 90 / 30 20 50 30 50
Valdosta 96 74 89 72 90 / 20 20 60 30 50
Cross City 90 73 87 73 89 / 30 30 60 40 50
Apalachicola 87 76 85 76 86 / 20 20 50 30 50