Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 251740
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1240 PM CDT Mon Mar 25 2024

...New AVIATION...

.NEAR TERM...
(Rest of Today)
Issued at 851 AM CDT Mon Mar 25 2024

As a mid/upper level low moves in from the west, cloud cover is
forecast to thicken throughout the day and keep high temperatures
in the low to mid 60s. Current gusts throughout the TN Valley are
ranging between 20-30 mph and will increase as the day continues
in response to a pressure gradient over our area in addition to a
50-60 kt low level jet moving in from the west. Low chances (20%
or less) of showers/storms are possible this evening as a cold
front moves in, but will increase in chance overnight-- more on
that in the short term section below. The previous forecast
remains on track with minor adjustments made to account for
current cloud cover and dew point trends. A Wind Advisory is in
effect through 7 AM CDT Tuesday to account for sustained winds
between 20-30 mph with gusts up to 50 mph.

&&

.SHORT TERM...
(Tonight through Thursday)
Issued at 308 AM CDT Mon Mar 25 2024

The mid/upper low will pivot into the mid-Mississippi Valley this
evening and become negatively tilted overnight as another stronger
LLJ (60-70 kt) shifts eastward across the Tennessee and lower
Ohio Valleys. Thus, the threat for even stronger gradient winds
will exist this evening and overnight where sustained winds of
20-30 MPH with gusts to 50-55 MPH will be possible. Again, some
sporatic tree/power line damage cannot be ruled out with gusty
winds this strong which will likely persist through most of the
overnight period. This is addressed in the updated Wind Advisory
which will go through 12z Tuesday.

Meanwhile, a strong surface cold front will progress eastward
through the Mid South tonight, with a prefrontal trough pushing
eastward through the Tennessee Valley overnight. Strong
dynamics/forcing will generate some deep convection along/ahead of
this prefrontal trough -- with very strong shear values (0-6 km
shear of 70+ kts and 0-1 km shear of a staggering 40-50 kts!!).
The main caveat will be the utter lack of any real surface-based
instability of which CAMs and the Grand Ensemble keep displaced
well to our south and west across the ArkLaMiss (where the warm
sector will reside). Model soundings do indicate some meager
elevated instability values of 50-200 J/kg. With wind shear
values this strong, organized, elevated convection will be
present, likely in the form of a line of strong showers and storms
that will likely pass through the area roughly during a 03-09z
window. Though elevated, some of the stronger updrafts may tap
into the stronger winds aloft and create a few strong to
marginally severe storms capable of localized gusty/damaging
winds. For this reason, SPC has maintained a MRGL risk in the
western portion of our CWA -- though again we do think the
overall threat for severe weather is low -- and that gradient
(non-thunderstorm) winds pose the far greater hazard.

PWATs will also continue to increase ahead of the cold front and
into the 1.2" to 1.4" range during this timeframe (90th to 95th
percentile per BMX sounding climatology). This will create an
environment favorable for efficient rain-producing storms. The one
saving grace from any larger hydro/flooding concerns will be the
progressive nature of this convection as it pushes through the
area overnight. The latest ensemble and forecast guidance
continues to trend downward slightly with QPF amounts and for this
reason, WPC has lowered the ERO to MRGL for our area. Storm total
rainfall amounts will still fall within the 1" to 2" range, with
locally higher amounts of around 2.5". These rainfall values may
result in some rises on rivers, creeks, and streams and
potentially a localized flooding issue in a location where
rainfall amounts outperform.

The threat of strong, gradient winds will come to an end by 12z
Tuesday morning as the LLJ lifts NE into Tennessee and Kentucky.
Very high chances of rain overnight (80-100%) will drop to 40-80%
during the morning hours and 20-50% during the afternoon as the
true cold front finally pushes east and any additional convection
begins to taper off from west to east by the afternoon hours.
Southerly flow will help warm temperatures close to 70 degrees on
Tuesday, before winds shift to the NW late in the day and
temperatures drop off quickly Tuesday night -- eventually
settling into the low to mid 40s by early Wednesday morning. A
secondary trough will swing across the Deep South Wednesday and
Thursday, keeping this cooler air mass in place and highs in the
60s and lows in the upper 30s to lower 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...
(18Z TAFS)
Issued at 1240 PM CDT Mon Mar 25 2024

Impactful weather for aviation expected today. Up front, winds
from the southeast will be incredibly gusty - 30-40 kts at times -
through early tomorrow morning. A line of showers with a few
thunderstorms will also push into the area from the west-southwest
overnight. Thunder confidence is higher at MSL than HSV. Ahead of
and along this line of convection, there will be strong wind
shear with 50-60 kts from the south at 2000 ft AGL. Ceilings lower
to MVFR, potentially IFR, with the rain before lifting to MVFR
just at the end of the TAF period as rain exits to the east. AWWs
will be likely overnight.

&&

.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....AMP
LONG TERM....AMP
AVIATION...30


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