Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tallahassee Florida
1029 am EDT Tuesday Jul 28 2015
Near term [through today]...
From 12-14z, dewpoints have been tracking above most model
guidance across the area, particularly near the Gulf Coast and in
central parts of our forecast area - roughly bounded by a line
from ecp-bge-mgr-vld-40j. The morning sounding from Tallahassee
revealed slightly more moisture in the boundary layer as compared
to 24 hours ago, and significantly less dry air in the 1000-3000ft
above ground level layer. This should make the higher surface dewpoints (mid-
upper 70s) more resilient today as compared to yesterday, even
with slightly hotter temperatures (and a well-mixed boundary
layer) expected. The surface dewpoints mixed down closer to 70
degrees by 16z yesterday, but even an extra hour or two of higher
dewpoints should be sufficient to produce some areas of heat index
readings around 110 degrees in the early afternoon. A heat
advisory was issued for those areas, largely described by the
aforementioned bounded region (ecp-bge-mgr-vld-40j). We did not
include Bay or Gulf counties in the advisory at this time, as
visible satellite indicated some more dense cloud cover in that
area that may persist for another few hours.
By the hottest time of day for interior portions of the area,
approximately 19-21z, dewpoints should finally mix down into at
least the lower 70s as deeper mixing occurs. However, near the
coast, higher dewpoints may linger, so heat index readings may
remain around 110 degrees in those areas into the late afternoon.
Very few changes were made to the rest of the forecast. We still
expect highs in the 95-100 degree range in most areas. Isolated to
scattered storms will be possible - mainly in the northwest and
southeast parts of our area, with convection fairly suppressed in
between (parts of SW Georgia and the c/east Florida panhandle).
Prev discussion [419 am edt]...
Short term [tonight through thursday]...
The local region will remain under the eastern periphery of the
mid/upper level ridge centered over the Southern Plains. Both the
GFS and latest European model (ecmwf) show a possible mesoscale convective system diving down from the top
of the ridge into our area Wednesday/Wednesday night. At the
surface, a weak area of low pressure will linger over the tri-
state region. Additionally, deep layer moisture will be increasing
with forecast precipitable water values at or above 2.0" by Wednesday. Look for
a return of scattered to possibly numerous showers and
thunderstorms mainly late afternoon/early evening. It will be hot
with temperatures most inland areas in the mid to upper 90s. A few
spots may reach 100 degrees on Wednesday. With the increasing low
level moisture, Max heat indices may reach heat advisory criteria
in some areas.
Long term [thursday night through tuesday]...
The mid/upper level pattern across the Continental U.S. Become more amplified
as the aforementioned ridge builds and retrogrades to The Four
Corners region and a trough deepens over the east. A frontal
boundary will drop down and stall over the County Warning Area on Friday. The
front will gradually dissipate over the weekend but the weak area
of low pressure may persist into early next week. Also, a ribbon
of deep layer moisture will extend down from the mid-Atlantic
states through the northern Gulf for most of the extended period.
All this will lead to what should be a very active period for
diurnal convection. Afternoon temperatures will generally remain
below average due to all of the clouds and rain.
[through 16z wednesday] mainly VFR conditions are expected to
prevail through the period, although a brief period of MVFR-IFR
conditions is possible at vld around dawn. Isolated convection is
possible this afternoon, but the chances appear too low to mention
at any of the individual taf sites at this time.
The aforementioned low pressure system in the Gulf will remain
weak enough to allow winds and seas to remain below headline
levels through the week. By this weekend, it's possible that
cautionary conditions will overspread the northeast Gulf. Rain
chances will drastically increase beginning on Thursday.
Red flag conditions will not occur for the next several days.
Rain chances will steadily increase as the week progresses. Five day
rain totals are estimated to be 2 to 3 inches near the Florida
coast, particularly The Big Bend. Elsewhere, 1 to 2 inches is
likely. Area rivers are still below action stage. With the heaviest
rainfall expected near the coast, river flooding is not expected.
Preliminary point temps/pops...
Tallahassee 99 75 99 77 95 / 20 20 40 30 50
Panama City 92 79 94 79 93 / 20 20 40 30 40
Dothan 98 75 98 75 98 / 30 20 40 30 40
Albany 97 75 99 75 95 / 20 20 40 30 40
Valdosta 95 74 98 76 96 / 20 20 40 30 40
Cross City 93 75 94 77 91 / 40 40 50 40 50
Apalachicola 94 79 93 80 93 / 20 20 40 40 50
Florida...heat advisory until 7 PM EDT /6 PM CDT/ this evening for Calhoun-
coastal Franklin-coastal Jefferson-coastal Taylor-coastal
Wakulla-Gadsden-inland Franklin-inland Jefferson-inland
Georgia...heat advisory until 7 PM EDT this evening for Baker-Brooks-