NEAR TERM UPDATED [Into this Eve]...
The large scale longwave pattern is highlighted by broad cyclonic
flow in the form of a mid/upper trough that dominates all but western and eastern most states. 552dm closed low over South Dakota
with axis SWD into TX. Another trough was noted from off Carolina
coast south through the Bahamas with assocd moisture spreading NWWD into our region.
As initial trough deepens EWD, the weak ridge will push gradually ewd with axis shifting east of I-75 thru the day resulting in a modest weakening in local gradients. At the surface, high pressure over the Atlantic coast will continue to ridge WSW thru the Carolinas across the SE region and into the NRN Gulf. This reflected in 24 hr temp/dew point comparison which show almost no change.
All this places local region in a persistent warm, moist SE flow as reflected in TAE 12Z RAOBs which shows PWATs above 1.50 inches and onshore flow to H5.
Highs will warm to the low 90s, mid 80s along the immediate coast. Similar to yesterday, the afternoon may see scattered showers and thunderstorms from the sea breeze, with most of the convection occurring between 2 PM and 8 PM and dissipating through the evening.
SHORT TERM UPDATED [Tonight through Monday]...
The broad 500mb trough currently over the Central Plains will
translate slowly eastward this weekend. The largest height falls
will be to our north, and wind speeds will weaken dramatically by
the time the trough axis nears our forecast area late Sunday.
Thus we do not expect the widespread, strong-severe thunderstorms that have been affecting the central CONUS in association with this
However, deep layer moisture will gradually increase across much of our area, resulting in higher rain chances Sunday afternoon through Monday. On Saturday the aforementioned trough will still be too far away to affect our local weather, so any convective forcing will have to come through mesoscale systems like the sea breeze front(s) and/or outflow boundary interactions.
Our PoP is in the 30-40% range for Saturday afternoon, which is a
blend of the various NWP MOS. On Sunday and Monday,the PoP is 50% and 50-60% respectively across most of our forecast area, as
forcing could come from the sea breeze front and/or outflow from
convective systems to our north and northwest (in association with
the approaching trough).
Since we expect most showers and thunderstorms to occur during
the mid afternoon through early evening hours, there probably won`t be enough cloud cover to hold high temperatures down, so we expect highs in the lower 90s (away from the slightly cooler beaches).
With only weak Q-G forcing and light winds aloft, it`s unlikely there will be much thunderstorm organization this weekend, which should limit the overall threat of severe storms.
On Sunday, SBCAPE values may approach 2,000 J/KG in southeast AL. This airmass could be unstable enough to support isolated strong updrafts, with a low risk of a pulse strong/severe storm or two.
An even better chance for strong to severe storms is expected on
LONG TERM...[Monday Night through Friday]...
The large scale longwave pattern commences with a trough over Wrn
states, ridging over Cntrl states EWD to Appalachians and a trough
from Ern seaboard into Wrn Atlc with axis just off Ern seaboard. At
the surface, low over Quebec with front SWD down extreme Wrn Atlc
then bisecting local area. This has pushed persistent area ridge
into Wrn Atlc.
Looking SWD, models in decent agreement with the development of an area of low pressure over the SRN Gulf of Mex likely over the Bay of Campeche.
During the rest of the period, Ern trough moves offshore while cold front slow, stalls and washes out near the coast on Tues. In its wake, upstream ridge shifts EWD with steering flow shifting to NW as drier air overspreads the Gulf region with a return to limited afternoon and evening shallow seabreeze convection.
However, at the same time, ample tropical moisture from SRN Gulf flow begins to spread newd towards FL. There remains models differences on low development and in how fast and how far north moisture will spread. For example, GFS faster than ECMWF in bringing up moisture.
For now, its unlikely that local area will feel any impact (likely heavy
rain) until Fri. With model differences and this far out, will not
bite on very high POPs.
Local area will show 20-40% Mon night and Tues, 20-30% Tues night
and Wed, then 30-40% Thurs and Fri.
With weak deep layer shear and departing upper dynamics should limit any severe weather.
Seasonable temperatures should occur throughout the period, with highs generally in the low 90s and lows in the mid- upper 60s.
AVIATION UPDATED [Through 12Z Saturday]...
Persistent pattern continues.
VFR conditions later this afternoon, vicinity showers are possible with the afternoon seabreeze.
Winds will be from the SE around 10 kts.
After 08z MVFR cigs with possible IFR CIGS near sunrise mainly KTLH and KVLD.
Borderline exercise caution conditions were occurring across much
of our marine area this morning, and will continue until early this
Another easterly "surge" is likely late tonight and early Saturday, though not quite as strong as the current one.
The pressure gradient will diminish considerably Saturday night and
Sunday as a cold front slowly approaches from the west.
This front will stall and dissipate early next week, and have little impact on winds and seas.
Southeasterly and later southerly flow will bring Gulf moisture into
the forecast area through early next week, keeping relative humidity
values well above red flag criteria.
With all of the local rivers currently below action stage, it appears unlikely that the expected rainfall through Monday will be heavy and concentrated enough to produce river flooding or widespread flash flooding.
PRELIMINARY POINT TEMPS/POPS...
Tallahassee 90 73 90 72 90 / 30 20 30 20 50
Panama City 87 74 85 74 84 / 30 20 30 20 40
Dothan 91 71 91 72 91 / 20 20 30 20 50
Albany 91 71 90 72 91 / 20 10 30 20 50
Valdosta 90 70 93 70 92 / 20 10 30 20 50
Cross City 91 71 88 69 89 / 40 20 40 20 40
Apalachicola 86 75 83 73 84 / 30 20 30 20 30
High risk of rip currents Franklin, Bay, Gulf, and Walton Counties through 03 UTC tonight.
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