Scientific Forecaster Discussion
fxus64 kmob 240103
Area forecast discussion
National Weather Service Mobile Alabama
803 PM CDT Tue may 23 2017
Discussion...see updated information below.
Update...thunderstorms continue to train east-northeast along a
stalled frontal boundary just inland from the coast. Radar
estimates that some locations across western Escambia County
Alabama have received 3 to 4 inches of rainfall over the past
several hours, and a Flash Flood Warning is in effect for that
area this evening as another inch or so of rainfall is possible.
A few of the storms have briefly become strong as well, likely
producing winds of 40 to 45 mph. We expect that the intensity, as
well as the coverage, of the thunderstorms to diminish as we go
through the evening hours.
No changes to forecast at this time.
Marine...we did make some adjustments to the coastal waters
forecast. Observations indicate that winds over the bays and
inland waterways occasionally continue to be in the 20 to 25
knot range early this evening, so we extended the Small Craft
Advisory for those waterways until midnight. Offshore over the
Gulf, the Small Craft Advisory continues through late Wednesday
night. Already updated coastal waters forecast product, will issue updated mww shortly.
24/00z issuance...removed convection from most of the taf
locations for tonight, although thunderstorms in the vicinity. With the frontal boundary
still in the area, could see some isolated to scattered convection
Wednesday morning, but that should be ending by late morning into
the afternoon tomorrow as the front finally moves offshore and
drier air filters into the region from the northwest. Prior to
frontal passage at taf locations, ocnl MVFR ceilings and possible IFR vsbys
in isolated/scattered showers and storms. The low ceilings could
persist into the afternoon, but will gradually be improving late
in the day. General southwesterly winds overnight, becoming
northwesterly behind the front Wednesday. 12/ds
Previous discussion... /issued 306 PM CDT Tue may 23 2017/
Near term /now through Wednesday/...a greater coverage of
storms has failed to develop along the residual boundary across
the coastal counties. This is likely due to lack of upper level
forcing and the loss of low level convergence as winds north of
the boundary have also switched back to south and southwest.
Therefore, the risk of flash flooding has diminished and we have
cancelled the remainder of the Flash Flood Watch. However,
isolated to scattered storms are still expected over southern
portions of the area through early this evening with MLCAPES of
1500-2000 j/kg. Isolated lighter showers possible further inland.
The heavier storms could result in a few localized minor flooding
issues. This convection should diminish by mid to late evening
with the next round of precipitation moving in overnight in
association with the main upper level trough and cold front. Rain
chances becoming likely in the northwest zones after midnight with
better rain chances spreading east through the early morning
hours. Instability will be limited over land, so only a few
thunderstorms are expected with the potential for additional heavy
The best rain chances will be found across the far eastern zones
Wednesday morning after sunrise where there will be an opportunity
for the atmosphere to destabilize and be supportive of scattered to
numerous showers and thunderstorms. Rain chances diminish from west
to east as the day progresses with the advection of drier air into
Lows tonight will be fairly mild in the mid to upper 60s with highs
tomorrow in the upper 70s to lower 80s. Did not deviate from
Short term /Wednesday night through Friday night/...a cooler and
drier airmass moves into the region Wednesday night into Thursday
as an upper trough moves toward the East Coast. This will place
the central Gulf Coast in a northwest flow aloft with building
high pressure at the sfc. The result will be clear skies with
below normal temps Wed night and Thursday. The sfc high quickly
moves east Thursday night into Friday with a return flow setting
up, resulting in warmer temps and increasing moisture late in the
Long term /Saturday through Tuesday/...moisture will continue to
increase across the region through the weekend as another weak
front begins to make slow progress southward toward the Gulf
Coast. Much of the area remains dry on Saturday with scattered
showers and thunderstorms returning by Sunday and continuing
through Tuesday as the weak boundary stalls across the region.
The coverage of showers and storms will be most numerous during
peak heating hours, before decreasing at night. Highs will
generally be in the mid and upper 80s away from the coast with
overnight lows in the low to mid 70s. /13
Marine...southwest winds have been very strong today over the
coastal waters, measured between 20 to 30 kt. Winds are expected to
gradually diminish tonight, especially over the bays. Will continue
the Small Craft Advisory for the bays until 7pm. Expect winds to
diminish below advisory levels after this, but we will have to
carefully monitor observations. Over the Gulf waters, winds will
likely diminish below 20 kt at times late tonight, but given winds
will pick back up on Wednesday, will continue to advisory through
the night. Speaking of Wednesday, west to northwest winds will
increase through the day as the cold front passes through. Boaters
will need to exercise caution on the bays as winds increase to 15-20
kt with 20-25 kt expected over the Gulf waters.
An onshore flow becomes reestablished by Friday as high pressure
moves east across the Florida Peninsula and another storm system develops
over the plains. Southerly winds will become moderate at times.
Alabama...high rip current risk through Wednesday evening for alz265-266.
Florida...high rip current risk through Wednesday evening for flz202-204-
GM...Small Craft Advisory until midnight CDT tonight for gmz630>635.
Small Craft Advisory until 1 am CDT Thursday for gmz650-655-670-