Area Forecast Discussion
Issued by NWS Mobile, AL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS64 KMOB 270844

Area Forecast Discussion
National Weather Service Mobile AL
344 AM CDT Tue Jul 27 2021

.NEAR TERM UPDATE /Now Through Wednesday/...Current temperatures are
in the mid to upper 70s with a few spots at the immediate coast
around 80 degrees. Temperatures are still on track to fall a couple
more degrees through early morning, with upper 70s at the beaches
and mid 70s elsewhere. The showers and storms that flared up over
south-central Alabama and over northern Choctaw County and southern
Escambia (FL) and Baldwin counties have decreased in the past half
hour or so. Expecting this activity to continue to dwindle, with
little to no activity anticipated through the morning hours.

An expansive mid and upper level ridge continues to amplify over the
western and central portions of the CONUS as a trough digs across
the Mid Atlantic region through mid-week. This ridge remained
loosely draped through the Southeast and western Atlantic earlier
tonight, but will begin to split today as the ridge amplifies
further west and another ridge amplifies over the western Atlantic.
The ridge to the west will then begin to build back into the Deep
South through the day on Wednesday. Meanwhile, a weak inverted
trough in the upper levels will continue to cruise west across the
northern Gulf through day today. Winds aloft will remain weak today
and Wednesday as the local area remains sandwiched between all these
features aloft in a col. Down in the lower levels, the surface ridge
over the western Atlantic will continue to nudge into parts of the
Southeast and Gulf waters. Drier air will then also linger into this
morning across southeast Mississippi, coastal Alabama, and the Gulf
waters. However, moisture is expected to begin to stream back into
the region by this afternoon as PWATs quickly increase to 2.0+
inches and even further to 2.0-2.2 inches by Wednesday.

Tapered back PoPs for today to account for the residual dry air,
especially during the early morning hours. Introduced isolated
showers into the forecast by 15Z across southern Alabama and the
western Florida Panhandle; although, that might be too early based
on some of the recent CAM guidance. Coverage begins to ramp up by
early afternoon with the highest coverage of showers and storms
generally north of the I-10 corridor. As is typical in the
summertime, cannot rule out a strong storm or two as there will be
plenty of instability for storms to tap into by late afternoon.
Scattered showers and a few storms will then linger through the
evening and perhaps until at least midnight over land areas. Some
model guidance (including a few CAMs) is beginning to trend downward
somewhat in terms of the coverage of precipitation Wednesday
afternoon with the highest coverage noted across the southern half
of the area. Not confident enough in these model solutions to
decrease PoPs quite yet, but this trend will need to be monitored.
For now, left mention of numerous showers and storms across much of
the area for Wednesday afternoon given plentiful moisture and the
lingering upper dynamics in the region. Given the light flow aloft
and plenty of moisture, storms will be capable of producing 1-2
inches of rain in a short period of time as they drift across the
area on both afternoons. Wet antecedent conditions combined with
storms capable of producing heavy rainfall could lead to minor
flooding issues (especially where storms repeatedly move across the
same locations).

Temperatures will continue to be warm through the near term. Highs
today are expected to top out in the mid 90s inland with lower 90s
at the beaches; although, a few spots may rise into the upper 90s
across south-central Alabama. Low temperatures tonight will be like
we`ve seen recently, in the lower to mid 70s inland and in the upper
70s at the coast. Highs on Wednesday will then be a degree or two
cooler than today. Expect widespread heat indices in the 103-107
degree range both days with a few communities potentially hitting
108 degrees for a brief period of time. Make sure to take extra
precautions if outdoors. Drink plenty of fluids, stay out of the
sun, and check up on relative and neighbors.

Lastly, a LOW risk of rip currents continues through the week for
our southwest Alabama and western Florida Panhandle beaches. /07/26


.SHORT TERM /Wednesday night Through Thursday night/...An upper
trof located mainly over the northeast states and far western
Atlantic extends weakly back westward across the northern Gulf
coast area, although this latter portion is pushed a bit further
south as a massive upper ridge over the remainder of the CONUS
strengthens over the southeast states. A surface trof also remains
in place through the period from Virginia to across the
Carolinas, and extends weakly into central Alabama. Abundant deep
layer moisture will be in place over the area Wednesday evening
with precipitable water values mainly ranging from 2.0-2.25
inches, but subsidence effects associated with the strengthening
upper ridge result in precipitable water values dropping somewhat
to 1.6-1.9 over interior areas by Thursday afternoon while closer
to the coast values will be near 2.1 inches. The subsidence
effects are much more apparent in model soundings over interior
areas, with drying noted above 750 mb along with a mid level cap
developing. While MLCAPE values increase to 2500-3500 J/kg on
Thursday, am expecting that the subsidence effects will limit
convective coverage at least somewhat so have gone with chance
pops over interior areas with good chance pops over the southern
portion of the area. Shear values remain very low, but with the
high MLCAPE values along with mid level dry air will favor storms
producing strong gusty winds, and an isolated severe storm will be
possible. A low risk of rip currents is expected through the
period. Highs on Thursday will be mostly in the lower to mid 90s,
and lows Wednesday night and Thursday night range from the mid
70s inland to the upper 70s at the coast. Heat index values on
Thursday look to mostly range from 105-110, and a Heat Advisory
may end up being required for much of the area. /29


.EXTENDED TERM /Friday Through Monday/...A strong upper level
ridge of high pressure will remain centered over the vicinity of
KS/OK on Friday with the associated ridge axis expected to nose
southeastward across the Lower Mississippi Valley and north
central Gulf Coast region. Hot and humid conditions will persist
across our forecast area underneath this feature on Friday, with
high temperatures forecast to reach into the mid to upper 90s over
most interior locations and from around 90 to the lower 90s along
the immediate coast. Surface dewpoints remaining in the 70s will
result in maximum heat index values in the 106-110 degree range
across much of our area on Friday, with a few spots potentially
reaching up to around 112. A Heat Advisory may be needed Friday if
these trends continue. Precipitable water values will remain
elevated between 1.8 and 2 inches and perhaps locally higher
across much of our region on Friday even with the ridge overhead.
This deep layer moisture along with afternoon heating/instability
and convergence along a weak surface trough axis that may be
oriented over interior portions of the region will likely result
in the development of scattered showers and thunderstorms over the
area again Friday. We will keep POPs between 30-40% for now.

The upper level ridge axis may begin to retrograde westward Saturday
afternoon into Saturday night as an upper level trough deepens
across the Great Lakes/Ohio Valley/Mid-Atlantic region. The heat
will likely persist into Saturday with highs continuing to trend in
the mid to upper 90s inland and lower 90s along the coast. Maximum
heat indices also potentially reach Heat Advisory criteria again
during the day Saturday. Scattered showers and thunderstorms are
also expected to develop again Saturday. A more northwesterly flow
pattern aloft may return Sunday into Monday between the retrograding
ridge over the Plains/Rocky Mountains region and the upper level
trough that should continue to extend from the Mid-Atlantic states
through the Ohio/Tennessee Valley region. Both the GFS and ECMWF
model guidance indicate a very moist airmass remaining in place
across our forecast area within this northwest pattern late this
weekend into early next week which may lead to a favorable set up
for increased convective coverage during the Sunday-Tuesday time
frame. We will have high end scattered to locally numerous coverage
of showers and thunderstorms in the forecast late in the extended
period, particularly going into early next week. High temperatures
may trend slightly cooler in the upper 80s to low 90s by Monday and
Tuesday given the increased cloud cover/precipitation coverage. /21


.MARINE...No impacts are expected aside from higher winds and seas
near isolated to scattered showers and storms. A typical summertime
pattern will continue through much of the week with northerly winds
overnight becoming southerly by the afternoon each day. Southwest to
westerly flow is then expected to develop late this week. Seas will
remain around 1-2 feet through the period. /26




This product is also available on the web at: is the U.S. government's official web portal to all federal, state and local government web resources and services.