River Flood Warning 61, NWS Tallahassee, FL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TALLAHASSEE FL
340 PM EDT Wed Jul 10 2013

.NEAR TERM [Through Tonight]...
A disturbed pattern is laid across the area today. A Tropical
Upper-Tropospheric Trough (TUTT) hangs to our SE over SoFla and a
weakness in the UL pressure pattern lies over the SErn half of the
CONUS. At the lower levels...convergence zones over SE AL and the
Ern FL Big Bend helped initialize convection this morning. With
PWATs around 2" still and MLCAPE around 2600 J/kg shown on the 12Z
sounding this morning, a higher coverage of small showers and
thunderstorms has already kicked off. These 'spotty' storms will
continue through the afternoon and begin to dissipate around
sunset. With high CAPE values, some of these storms may become
strong to severe. WMSI values indicate the potential for wet
microbursts. Looking at the lapse rates in the hail growth zone in
this morning's sounding, there is also some potential for small
hail. Highs today will be in the low 90s and lows tonight will be
in the low to mid 70s.

&&

.SHORT TERM [Thursday through Friday night]...
Unsettled conditions are expected through the short term as weak
upper level troughing and deep moisture remain across the area. A
weak surface trough will slide south into the area and stall
around Friday, which will likely keep rain chances elevated above
climatology. With precipitable water values greater than 2 inches,
some pockets of locally heavy rain will probably also occur. We
will have to monitor for localized flooding by the end of the
short term and into the long term in this wet pattern, but at this
time it is tough to pick out any one day or specific area to focus
on for any potential flooding.

&&

.LONG TERM [Saturday through Wednesday]...
Unsettled conditions will continue through a large portion of the
long term with near to above climo PoPs. The forecast pattern is
rather unusual with both the 10/00z ECMWF and 10/12z GFS showing
an upper level low retrograding southwestward from the northeast
states down to the Gulf coast. There are some detail differences
in the models, but both models signal an overall wet pattern
continuing. Near to slightly below average high temperatures are
forecast given the expected cloud cover.

&&

.AVIATION...
[Through 18z Thursday] Mostly VFR conditions expected today with
exceptions coming with the widespread storms today. Visibilities
may decrease when afternoon showers and thunderstorms are over the
airports and gusts of around 30kts have already been seen today
and may happen again with stronger storms. After the storms
dissipate around 00Z, guidance is suggesting lower visibilities
over ABY, DHN, and VLD.

&&

.MARINE...
Winds and seas will remain low as the marine area remains at the
western periphery of the subtropical Atlantic ridge. This portion
of the ridge will erode at the end of the week as a weakening
cold front approaches and stalls just north of the waters on
Friday and dissipates over the weekend.

&&

.FIRE WEATHER...
Humid conditions are expected for the foreseeable future with
scattered to numerous showers and thunderstorms increasing over
the weekend as a cold front reaches the area. Relative humidities
will remain high and there are no fire weather concerns.

&&

.HYDROLOGY...
We appear to be headed into another stretch of wet weather over
the next 7-10 days based on the latest model guidance. Unlike the
round of heavy rainfall in early July, there is not much agreement
yet on a particular area where the heaviest rain totals may be
focused. Therefore, the outlook (in terms of hydrology) is just
for heavy rainfall and the possibility of some flooding issues
again. The 7-day WPC QPF calls for widespread 2-3 inch totals over
our entire area, which is very close to model ensemble mean
values. Of course, there are likely to be localized values well in
excess of that.

Even taking the 2-3 inch rain forecast literally (which is pretty
close to the majority of the NAEFS members) and applying it to
MMEFS forecasts for river points in our area does produce some
chance of flooding on a few of the rivers.

Rivers Most At-Risk For Continued / Developing Flooding July 10-20
------------------------------------------------------------------
Aucilla River, St. Marks River, Withlacoochee River near Valdosta,
the Choctawhatchee River (particularly lower portions), and the
Apalachicola River.

Of course, given high flows on many rivers due to recent rainfall,
it would be impossible to totally rule out rises and/or flooding on
any of our area rivers. Where localized heavy rainfall sets up will
be the main concern - as it will have the potential to produce
flash flooding, as well as more considerable rises on rivers.
After several days of rain, the more at-risk areas may be easier
to pinpoint. The bottom line is that those with interests along
area rivers, streams, and creeks, and in flood-prone areas should
keep a close eye on forecasts over the next 7-10 days.

&&

.PRELIMINARY POINT TEMPS/POPS...
Tallahassee   72  89  72  88  71 / 30  70  50  70  50
Panama City   74  88  74  86  74 / 30  70  60  70  50
Dothan        73  89  72  89  72 / 40  70  50  60  30
Albany        74  90  72  89  71 / 40  70  50  70  40
Valdosta      71  90  71  88  70 / 30  70  50  70  40
Cross City    71  89  71  89  71 / 30  60  40  70  50
Apalachicola  74  87  74  85  74 / 30  60  50  70  50

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.

&&

Near Term/Aviation...Moore
Short Term/Long Term/Marine...DVD
Fire Weather...Block
Hydrology...Lamers