Area Forecast Discussion
Issued by NWS Mobile, AL

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476
FXUS64 KMOB 261150
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
650 AM CDT Sat May 26 2018

.DISCUSSION...Updated for latest aviation discussion below.

&&

.AVIATION...
12Z issuance...
A few widely scattered showers near the coast will persist through
mid morning. After which expect afternoon showers and
thunderstorms to form beginning near the coastline before moving
inland throughout the day. Winds will be generally out of the
southeast during the day before becoming light and variable
overnight. DJ/17


&&

.PREV DISCUSSION... /issued 429 AM CDT Sat May 26 2018/

..Sub-Tropical Storm Alberto Brings a Multitude of Impacts Over
the Central Gulf Coast Into The Memorial Day Holiday Weekend...

NEAR TERM /Now Through Saturday night/...26.00Z upper air analysis
shows a long wave trof positioned from the MS River Valley southward
to off the LA coast. Within the trof axis, a deep layer moist
airmass remains unchanged with PWATs remaining unseasonably high
for the late part of May (resting between 1 and 2 standard
deviations above the climatological mean). That being said and
with the region on the favored east side of the high level trof
axis where a series of subtle mid level impulses eject northeast
atop the local area, an unsettled weather pattern is maintained in
the near term. With daily instability and presence of weak
mesoscale boundaries to help provide for a focus, scattered to
numerous showers and storms are forecast to develop thru the
course of the day. In addition to frequent lightning activity and
brief strong wind gusts, some of the storms will be quite
efficient in dropping locally heavy rains in a short period of
time. This could lead to some isolated cases of mainly nuisance
type flooding over areas subject to poor drainage during heavier
rain occurrences. Forecasters taper off the PoPs going into this
evening.

In the meantime, Alberto over the northwest Caribbean, is
forecast by the National Hurricane Center to begin lifting slowly
northward thru the Yucatan Channel today and emerge into the
southern Gulf tonight. Well north of Alberto, there are
indications that rain bands will begin to spread north and west up
across the coastal waters late tonight. considering this, an
increase in PoPs is aligned along the western Florida Gulf coast
late.

SHORT TERM /Sunday Through Monday night/...Sub-Topical Storm
Alberto will be the big impact player during the short term as it
lifts northward over the southeast Gulf Sunday. The track bends
more to the northwest by Monday. There will be a multitude of
impacts related to Alberto. For specific information on all of
these, including the latest thinking from the National Hurricane
Center on track, please refer to the National weather Service
Mobile AL web site at www.weather.gov/mob.

LONG TERM /Tuesday Through Friday/...Sub-Topical Storm
Alberto continues to be the big impact player early in the long
term as it comes ashore somewhere along the central Gulf coast
early Tuesday morning. The center of Alberto is progged to be
positioned over west central AL Tuesday night, then begin lifting
northeast across the TN River Valley on Wednesday. As the effects
of Alberto begin to move away by mid and late week, chances of
showers and storms taper back to more seasonable then. /10

The following is a breakdown of impacts and confidence levels for
each:

- Flash Flood Threat - Confidence: HIGH. Timing: This evening
  through Tuesday evening. Significant rainfall amounts of 6 to 12
  inches remain unchanged through this time period, especially
  closer to the coast and over our southeastern counties. 5 to 8
  inches over portions of the interior. Note: Some areas could see
  localized double these amounts. The Flash Flood Watch has been
  extended northward as the threat of excessive rain has increased
  in latest excessive rain outlooks by the weather prediction
  center.

- Storm Surge - Confidence: HIGH. Timing: This evening through
  Tuesday. A Storm Surge Watch is in effect for all local coastal
  zones, where 2 to 4 feet above ground level (or inundation) is
  expected. The timing of maximum coastal water rises looks to be
  Sunday night into Monday night.

- High Surf - Confidence: HIGH. Timing: This evening through
  Tuesday. Surf heights of 5 to 9 feet will result in pounding
  waves and resultant beach erosion. Surf heights could build
  upwards of 8 to 12 feet with higher sets possible by Monday. A
  High Surf Advisory will likely be required on later forecasts.

- Rip Currents - Confidence: HIGH. A high risk of dangerous to
  potentially deadly rip currents remains in effect through the
  period.

- Wind - Confidence: HIGH. Timing: Sunday through Tuesday. Given
  current track and forecast strength. A Tropical Storm Watch
  remains in effect for the entire coast line.

- Severe Storm Potential - Confidence: Low. Timing: Beginning as
  early as this evening then increasing potential through Sunday
  night into Memorial Day.

MARINE...Sub-tropical Storm Alberto will bring impacts to the
marine area by way of strong winds, high seas over the open Gulf
waters and building waves over area bays and sounds. /10

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Flash Flood Watch from this evening through Tuesday evening for
     ALZ052-053-055-056-059-060-261>266.

     Tropical Storm Watch for ALZ263>266.

     High Rip Current Risk through Tuesday morning for ALZ265-266.

     High Surf Advisory from 1 PM this afternoon to 7 PM CDT Tuesday
     for ALZ263>266.

FL...Flash Flood Watch from this evening through Tuesday evening for
     FLZ201>206.

     Tropical Storm Watch for FLZ202-204-206.

     High Rip Current Risk through Tuesday morning for FLZ202-204-206.

     High Surf Advisory from 1 PM this afternoon to 7 PM CDT Tuesday
     for FLZ202-204-206.

MS...Flash Flood Watch from this evening through Tuesday evening for
     MSZ076-078-079.

GM...Tropical Storm Watch for GMZ630>636-650-655-670-675.

&&

$$

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