Dothan Area Weather Forecast Aug 18

NEAR TERM [through Rest of Tonight]...

The large scale pattern marked by amplified trough with axis down
MS River Valley and broad high pressure over Wrn Atlc. At surface,
subtropical ridge north of CWA with stationary front parked across
FL/GA border.

During the aftn, radar and satellite showed Ewd moving outflow
boundaries intersecting with Nwd moving lines of convection over
Gulf of Mex. These lines of moderate to heavy storms moved over
Panhandle and Wrn most Big Bend. Additional storms develop inland
aided by diurnal heating along a stalled frontal boundary. The
result has been abundant cell mergers and some echo training over N FL/SE AL/SW GA. Generally 1-2 inches per hour estimated with
isolated 2-3 inches past 2 hours. Significant heavy rain threat
expected to continue until around sundown with 1-3 additional inches
estimated from Walton to Franklin County. Locally heavier rainfall
also expected over SE AL and SW GA as cells move NEWD from front.
Additional storms assocd with east coast seabreeze will also be
monitored. Thus the flash flood threat continues and is being
closely monitored.

Numerous showers and thunderstorms have developed across the area early this afternoon along a warm front that extends eastward
along the Gulf coast from a mesoscale area of low pressure near
coastal Mississippi. With precipitable water values around 2.10"
(according to GOES Blended TPW), some of the rain bands and storms have been very efficient rain producers. Model guidance shows most of the convection peaking prior to 22-00 UTC, with a diminishing trend around that time and into the evening hours. One exception may be in the eastern part of our area where storms that have developed along the Atlantic sea breeze will approach late this
afternoon. These could potentially linger longer into the evening, but after 06 UTC most of the convection should shift over the coastal waters.

With respect to the Flash Flood Watch, we expanded the watch to
cover the entire forecast area and extended the valid time through
tomorrow (Monday). This was due to several factors, including: (1)
multiple reports of existing high water levels in low-lying areas
and near bodies of water, (2) high soil moisture even in areas
that don`t currently have standing water, (3) moist environment
with PWATs in excess of 2 inches, AND (4) expected high coverage
of showers and thunderstorms. Any additional rainfall would likely
exacerbate existing flooding, and the environment is generally
supportive of localized heavy rainfall and flash flooding anyway.
More on the flash flooding threat in the short term section below.

SHORT TERM [Monday through Tuesday Night]...

The Flash Flood Watch was extended through Monday afternoon as
there should be a high coverage of rain and thunderstorms. Also
the wind field will get weaker over the next 24 hours, with storm
motions on BUFKIT forecast soundings falling to 5 knots or less
(both the NAM and GFS), and PWATs around 2.2 to 2.3 inches.
Therefore, it`s possible that thunderstorms tomorrow will be even
more slow-moving than today - the heavy rainfall could be more
localized but this will likely contribute to the threat of flash
flooding continuing into tomorrow. High temperatures were lowered
slightly as well. Tuesday looks like it could be another high
coverage day for rain with light southeast flow and continued
PWATs over 2 inches. However, confidence is not high enough in any
particular scenario to warrant a Flash Flood Watch into that
period.

After Tuesday, an upper level ridge should build into the area and suppress convection more than in recent days.

LONG TERM [Wednesday through Sunday]...

The extended period will herald a shift from an enormously wet
pattern to a more typical summertime pattern.

The large scale pattern commences with Ern trough lifting NEWD to be progressively replaced by Atlc ridge retrograding WWD to FL/GA and remains dominant feature over SE region thru period. At surface, weak SW-NE frontal boundary bisecting our area with upstream high anchored over wrn KY.

By Thurs eve, ridge builds WWD into our area allowing front to largely wash out as PWATS drop to below 2 inches. All this means SE low level flow will back to ELY. So any convection will largely be seabreeze aftn/eve driven and any seabreeze/mesoscale boundaries could ignite strong to isold pulse severe storms. Expect a mix of clouds and sun. Temperatures will be closer to normal, perhaps warming to slightly above normal by later in the week. With grounds likely to be at or near saturated from rains earlier in week, any cells mergers can produce locally heavy rain and localized flooding especially in low terrain and poorly drained areas.

AVIATION [through 18 UTC Monday]...

Showers and thunderstorms this evening will have associated MVFR or lower cigs and vsbys. Gusts to 20-25 kts may be possible with these storms.

Low cigs expected to develop again overnight at TLH, DHN, ABY, and VLD similar to what was seen early this morning.

MARINE...

Winds and seas should continue to diminish through tonight.

For the remainder of the forecast, winds should be around 10 knots with seas 2 feet or less.

FIRE WEATHER...

There are currently no fire weather concerns with moist conditions
in place.

HYDROLOGY...

Heavy rain has affected much of the area over the past several days, with most of the rivers, streams, and creeks seeing increased flows and levels now.

Flooding will be most likely along portions of the Choctawhatchee, Shoal, Chipola, and Apalachicola Rivers, although problems along certain sections of other river systems will also be possible.

Through Tuesday afternoon, we are forecasting a widespread average of 1.5 to 2.5 inches of rain. Localized amounts are likely to be at least double that, so the rainfall over the next couple days will determine whether or not flooding can develop on any additional area rivers.

Based on reports from some of our counties - especially in the
western Florida Panhandle which received substantial amounts of
rain in July - there is already quite a bit of high water with flooding affecting some roads and infrastructure. In some places this may be due to streams and creeks, but in others it could just be due to a high water table affecting low-lying spots, ditches, and small ponds. Either way any additional rainfall would only worsen flooding conditions in these areas. This means that sections of Walton, Holmes, Washington, Bay, and Jackson Counties would be particularly susceptible to flash flooding.

The most up to date, specific river forecast information can be
found on the AHPS web page at:

http:/water.weather.gov/ahps2/index.php?wfo=tae.

PRELIMINARY POINT TEMPS/POPS...

Tallahassee 74 87 73 90 73 / 40 70 30 50 20
Panama City 76 87 76 87 76 / 40 60 30 50 30
Dothan 72 86 72 89 72 / 50 60 30 60 30
Albany 73 87 73 90 73 / 40 60 30 60 30
Valdosta 73 88 72 90 72 / 60 60 30 50 20
Cross City 73 88 72 91 72 / 60 60 30 50 20
Apalachicola 77 87 77 86 77 / 40 50 30 50 20

TAE WATCHES/WARNINGS/ADVISORIES...

FL...
FLASH FLOOD WATCH through Monday evening for Calhoun-Central
Walton-Coastal Bay-Coastal Dixie-Coastal Franklin-Coastal
Gulf-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-
Gadsden-Holmes-Inland Bay-Inland Dixie-Inland Franklin-
Inland Gulf-Inland Jefferson-Inland Taylor-Inland Wakulla-
Inland Walton-Jackson-Lafayette-Leon-Liberty-Madison-
South Walton-Washington.

HIGH RISK RIP CURRENTS Walton...Bay and Gulf until 00z.

GA...
FLASH FLOOD WATCH through Monday evening for Baker-Ben Hill-
Berrien- Brooks-Calhoun-Clay-Colquitt-Cook-Decatur- Dougherty-
Early-Grady- Irwin-Lanier-Lee-Lowndes-Miller- Mitchell-Quitman-
Randolph- Seminole-Terrell-Thomas-Tift- Turner-Worth.

AL...
FLASH FLOOD WATCH through Monday evening for Coffee-Dale-Geneva-Henry-Houston.

GM...None.


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