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Office: BMX

FXUS64 KBMX 210507
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1207 AM CDT Tue Aug 21 2018

.UPDATE...
For 06Z Aviation.

&&

.SHORT TERM...
Through Tonight.

Once again convective activity has been confined to areas south
of I-20. An outflow boundary from overnight convection pushed into
northwest Alabama this morning. Satellite imagery shows an area
void of cumulus west of I-65 on the stable side of the boundary.
For this evening, isolated convection will occur north of I-20
with decreasing rain across the south. Meso-scale models show a
line of storms developing near the MS river by sunset and
spreading eastward across MS this evening. Models have been
consistent with decaying this system as it approaches West
Alabama. SPC has portions of our nw counties under a marginal
risk, but given weakening trend expected, will not mention any
severe storms at this time. However, the line could produce strong
winds of 35 to 45 mph as it passes through Marion and Lamar
counties. Do not expect much shower or thunderstorm activity
across our southern counties once current activity dissipates, as
forcing shifts upstream towards the upper trof.

58/rose

.LONG TERM...
Tuesday through Sunday.

A surface cold front will sweep across Alabama on Tuesday into
Tuesday night as a relatively strong upper-level trough moves
from the Ohio Valley toward the East Coast. The forward speed of
this system continues to trend slightly faster in the newest model
runs, and the highest rain chances have been shifted farther
southeastward beginning at 12Z Tuesday. Due to the lack of daytime
heating, activity along the front may be at a relative minimum as
it passes through the I-59 corridor in the mid to late morning
hours. Convection should increase along the front during the early
to mid afternoon along and south of I-85.

A much drier airmass will overspread the region Tuesday night and
remain in place through Thursday. Morning temperatures should fall
into the low to mid 60s for many locations in our northern
counties with upper 60s elsewhere.

The development of deep-layer easterly flow is likely to cause a
moistening trend on Friday and into the weekend. This may mark the
end of the rain-free period with a return to daily afternoon and
evening convection focused along and south of I-20.

87/Grantham

&&

.AVIATION...
06Z TAF Discussion.

Area of convection that moved across Mississippi this evening is
falling apart as it moves into Alabama. Do not anticipate any
TSRA at the terminals tonight, maybe a passing showers. MVFR/IFR
cigs are already developing behind today's activity and ahead of
the approaching front. We remain in an area of increased low level
moisture ahead of front. Stratus should last into the morning
hours. Front looks to push through most of Central Alabama during
the day Tuesday with winds shifting to the west and becoming gusty
for some during the day, clearing out for Tuesday night.

08

&&

.FIRE WEATHER...

Rain chances remain high through Tuesday with the approach and
passage of a cold front. Dry conditions are expected behind the
front for Wednesday and Thursday. Low stratus and patchy fog will
be possible this morning and again on Tuesday morning, with
conditions improving with sunrise each morning. There are no fire
weather concerns at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     86  67  86  63  86 /  40   0   0   0   0
Anniston    87  68  86  65  86 /  50  10   0   0   0
Birmingham  88  69  87  66  87 /  40   0   0   0   0
Tuscaloosa  90  69  89  67  88 /  30   0   0   0   0
Calera      87  68  87  66  87 /  40   0   0   0   0
Auburn      86  70  85  67  86 /  60  10   0   0   0
Montgomery  90  71  89  69  89 /  60  10   0   0   0
Troy        89  71  88  68  89 /  60  10   0   0   0

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
None.

&&

$$



Office: MOB FXUS64 KMOB 210424 AAB AFDMOB Area Forecast Discussion...UPDATED National Weather Service Mobile AL 1124 PM CDT Mon Aug 20 2018 .DISCUSSION...See updated information for land areas and aviation discussion below. && .UPDATE...Have updated to place chance pops over the northwesternmost portion of the area for weakening convection approaching from the northwest. Made other minor adjustments. /29 && .AVIATION... 06Z issuance...Convection approaching from the northwest will diminish upon entering the area tonight, then additional convective development begins first near the coast in the early morning and develops inland during the day on Tuesday. VFR conditions prevail during the period except for localized low ceilings tonight and IFR/MVFR conditions with the convection. Light southerly winds tonight become southwest to west near 10 knots on Tuesday. /29 && .PREV DISCUSSION... /issued 623 PM CDT Mon Aug 20 2018/ DISCUSSION...Updated for latest aviation discussion below. AVIATION... 00Z issuance...Isolated convection diminishes this evening then redevelops near the coast late tonight. The convection increases in coverage on Tuesday mainly along and south of the I-65 corridor. While VFR conditions prevail through the period, some localized low ceilings and patchy fog will be possible late tonight and IFR/MVFR conditions will accompany the showers and storms. Light and variable winds tonight become southwest to west near 10 knots on Tuesday. /29 PREV DISCUSSION... /issued 410 PM CDT Mon Aug 20 2018/ NEAR TERM /Now Through Tuesday/...One more wet day expected across the region on Tuesday before a pattern change brings in a drier airmass. Scattered to numerous showers and a few thunderstorms moving northeast across much of the forecast area this afternoon are already beginning to diminish in coverage, but will still be possible in some locations through the early evening hours. Late evening and overnight we only expect isolated convection near the coast and offshore over the Gulf. A surface trough/front just to the northwest of the forecast area by late tonight will begin to work into extreme northwestern portions (Choctaw, Wayne counties) of the forecast area by late in the day on Tuesday. This will result in slightly drier air beginning to filter into those counties by the end of the day, but most of the forecast area will remain in the very moist airmass just in advance of the trough/front with scattered to numerous showers and thunderstorms again expected from mid morning and into the afternoon on Tuesday. Highest rain chances on Tuesday generally expected to be over the southern and eastern portions of the forecast area. Low temperatures tonight generally in the low to mid 70s. High temperatures on Monday expected to mostly be in the lower 90s, except for some upper 80s near the immediate coast. 12/DS SHORT TERM /Tuesday night Through Thursday night/...An upper level trough axis extending across the Ohio and Tennessee Valley and southward to near the AL/GA border early Tuesday evening will progress eastward toward the Eastern Seaboard late Tuesday night into early Wednesday morning. An associated weak cold front or trough axis will push southward across our forecast area Tuesday evening into late Tuesday night, bringing a light northwest to north wind flow and a much drier airmass (precipitable water values lowering to 1.0" to 1.5") to the region into Wednesday. Aside from lingering isolated showers and storms ahead of the approaching boundary over southern and southeastern portions of the area Tuesday evening/night, we expect no precipitation Wednesday into Thursday night underneath the much drier and more subsident airmass that will be in place across our region. Lower surface dewpoints will allow for slightly cooler temperatures, especially Wednesday night and Thursday night, when lows are expected to range in the mid to upper 60s over interior portions of the region. Daytime highs should average close to seasonable levels Wednesday and Thursday. /21 LONG TERM /Friday Through Monday/...An upper level ridge of high pressure stretching from Texas to the Lower Mississippi Valley Friday is forecast to build eastward across the Tennessee Valley and over much of MS/AL/GA this weekend into early next week. Deep layer moisture will still trend upward across our forecast area on the southern fringe of this building feature this weekend into early next week, so the increase in precipitable water values along with sufficient daytime heating and instability, convergence along the seabreeze, and perhaps weak perturbations in the mid level flow will result in the return of scattered daily showers and thunderstorms Saturday through Monday. Temperatures should average close to seasonable norms each day through the extended forecast period. /21 MARINE...A surface ridge of high pressure over the eastern Gulf will shift southward through midweek in response to a weak trough or frontal boundary that will be approaching from the north. This weak trough/front will move offshore late Tuesday night or early Wednesday morning, then stall over the marine area later in the week. A light to moderate south to southwesterly flow will continue over the marine area in advance of the front, followed by a light offshore flow Wednesday through Thursday. High pressure to the north of the marine area will shift off the Atlantic east coast by Friday, with windflow over the coastal waters returning to light onshore. Little change in seas is expected. 12/DS && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob