Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 260004
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
704 PM CDT Mon Mar 25 2024

...New AVIATION...

.NEAR TERM...
(Tonight)
Issued at 200 PM CDT Mon Mar 25 2024

A mid to upper level cutoff low moving through the central
Plains, bringing increased cloud cover to the TN Valley this
afternoon/evening. As this continues into the OH River Valley,
this is expected to weaken overnight into an open wave and lift
northeastward. A sfc low pressure system in the upper Mississippi
Valley has developed, contributing to an increased pressure
gradient over the Tennessee Valley due a sfc high pressure system
off the coast of the Carolinas.

In addition to these features, a 50-60 kt low level jet has begun
to influence the Tennessee Valley this afternoon and is forecast
to strengthen during the overnight hours. As this mixes down to
the surface, it will contribute to increased gradient (non-
thunderstorm) winds reaching gusts around 50-55 mph. We currently
have a Wind Advisory out through 7 AM CDT Tuesday to account for
this. If winds over perform, a High Wind Warning may be
considered. We will be monitoring these winds very closely as we
move into the evening/overnight hours. Tree damage, downed
powerlines, and property damage will be possible during this time
of increased winds.

Later this evening into the overnight hours, an unorganized line
of storms is forecast to move into the TN Valley from the SW. Low
thunderstorm chances (20-30%) are forecast to begin around 5-7 PM
CDT before progressing eastward, increasing in chance and coverage
overnight into the early morning hours. As far as severe
potential goes, there is a low chance of severe weather with these
storms. Sfc instability continues to look extremely limited
throughout the area. In addition to this, cold air damming is
occurring due to the placement of the sfc high to our east and is
contributing to subsidence in northeast AL/southern middle TN.
Damaging winds, in response to ample shear and the aforementioned
LLJ, will continue to be the primary threat (both thunderstorm and
non thunderstorm). Despite hodographs indicating streamwise
vorticity in the lower levels coupled with an influx of SRH
(600-850 m2/s2), the lack of sfc CAPE will minimize the tornado
threat.

PWATs during the overnight period are forecast to be around
1.2-1.4"-- nearing or exceeding 90th percentile values per BMX
sounding climatology. This means these storms will be capable of
producing heavy rainfall, however, this may also be limited by
lack of instability and the fast motion of the storms. We will be
monitoring the storm motion in respect to the convergence axis
ahead of the cold front. If the heavy rainfall axis shifts from
N-S to be more E-W oriented, the flooding threat may increase as
the storms continue eastward. Our current storm total rainfall
forecast between this evening through Wednesday morning is 1-2".
Locally, higher amounts (up to 3-4") are possible. However, these
amounts are most likely going to remain south of our area (over
west central AL) at this time.

&&

.SHORT TERM...
(Tuesday through Thursday)
Issued at 200 PM CDT Mon Mar 25 2024

Tuesday morning, high chances (80-90%) of showers/storms are
forecast to continue impacting areas east of I-65 while medium
chances (40-70%) follow west of I-65. These showers/storms are
forecast to gradually end from west to east as we move into the
afternoon hours and the cold front moves through the Tennessee
Valley. Behind the cold front, dry air is forecast to filter in
under the influence of sfc high pressure from the southern
Plains. This sfc high pressure is forecast to continue moving
southeastward-- reaching the TN Valley by late in the week (more
on this in the long-term section below). During this time, dry
weather is forecast with highs in the 60s and lows in the 40s.

&&

.LONG TERM...
(Thursday night through Sunday)
Issued at 308 AM CDT Mon Mar 25 2024

A strong area of high pressure to the west will shift eastward
across the Tennessee Valley and Deep South Friday into the
upcoming Easter holiday weekend. The end result will be ample
sunshine and a pronounced warming trend as winds veer back to the
south. Dry conditions will also continue as the forecast will
remain devoid of any rain. Highs on Friday will return to the
upper 60s to lower 70s -- with mid/upper 70s forecast both
Saturday and Easter Sunday.

&&

.AVIATION...
(00Z TAFS)
Issued at 704 PM CDT Mon Mar 25 2024

Regional sfc observations indicate that a lower stratus layer is
in the process of developing eastward across the region, within
the moist advection regime ahead of an approaching prefrontal sfc
trough. At this point, we anticipate an overcast layer of MVFR
stratus to be in place at MSL/1Z and HSV/3Z. Clusters of showers
and perhaps a few embedded TSRA will also spread northeastward
this evening ahead of the trough, with TEMPO groups for this
activity included btwn 1-5Z/MSL and 3-7Z/HSV. Prevailing sfc flow
will remain from SE at 20G30 kts, but with a rapid increase in the
southerly low-level jet (up to 70-80 knots) predicted over the
course of the evening, we have included LLWS to begin the forecast
period. Present indications are that the prefrontal sfc trough
and narrow band of more intense convection (currently across the
Lower MS Valley) will arrive at MSL arnd 6-8Z and HSV arnd 8-10Z,
bringing IFR conds and lightning/convective wind gusts up to 50-60
knots. Light rain and low stratus clouds will continue for
several hours in the wake of the convective band, but winds will
subside and shift to SSW reducing concern for wind shear. Rapid
clearing is expected from W-to-E btwn 16-20Z as winds shift to WSW
in the wake of the cold front.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...Wind Advisory until 7 AM CDT Tuesday for ALZ001>010-016.

TN...Wind Advisory until 7 AM CDT Tuesday for TNZ076-096-097.

&&

$$

NEAR TERM...HC
SHORT TERM...HC
LONG TERM...AMP
AVIATION...70/DD


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