797
FXUS64 KHUN 071728
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1228 PM CDT Mon Apr 7 2025

...New AVIATION...

.NEAR TERM...
(Rest of Today and Tonight)
Issued at 1052 AM CDT Mon Apr 7 2025

A deepening surface low will lift northeastward off the Mid-
Atlantic Coast today (from an initial position across western NC),
with light-moderate NNW flow in the boundary layer continuing
across the TN Valley in the wake of the trailing cold front. In
the mid- upper levels, a shortwave trough (initially across AR/LA)
will begin to accelerate east-northeastward in the flow around a
stronger/colder northern stream vort max digging southeastward
into the Upper Great Lakes, and should reach the TN Valley by 0Z.
Broad scale lift downstream from this feature will maintain a
saturated low-level profile across our forecast area this morning,
featuring widespread low stratus clouds and patches of very light
rain/drizzle. However, by this afternoon, we expect cloud bases
to begin rising, with clearing expected to occur from NW-to-SE
late this afternoon/early this evening. Due to the clouds and weak
cold advection, temps will struggle to reach the 55-60F range and
may stay in the lower 50s in elevated terrain.

Surface winds will diminish this evening as the pressure gradient
temporarily relaxes, and this along with clearing skies should
promote a brief period of radiational cooling. However, between
6-12Z, a stronger cold front will shift southward across the
region as the center of a Canadian surface high builds into the
Upper MS Valley. Although strengthening northerly winds and mixing
will likely prevent the formation of frost, temps will
advectively fall into the mid 30s in our TN zones and u30s-l40s
elsewhere.

&&

.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 1052 AM CDT Mon Apr 7 2025

Moderately strong north winds will persist across the local
forecast area tomorrow, with dry NW flow aloft (in the wake of
this evening`s shortwave trough) providing sunny skies. Even so,
the magnitude of low-level cold advection suggests that afternoon
highs will be similar to those observed today. As the center of
the Canadian surface high migrates southeastward from the Lower
Great Lakes/OH Valley into the Mid-Atlantic states Tuesday night,
calm winds and dewpoints perhaps as low as the mid 20s will
support strong radiational cooling. Although we may see a minor
increase in high clouds early Wednesday morning (originating from
convection that will develop across southern IA/northern
MO/western IL; to the east of an approaching surface low over NE),
due to favorable conditions for cooling we have issued a Freeze
Watch for all AL forecast zones that runs from 6-14Z Wednesday,
with widespread development of frost expected as well.

During the period from Wednesday-Wednesday night, the center of
the high will move eastward of the Mid-Atlantic coast with a ridge
axis extending southwestward into the northern Gulf. This
configuration will translate to light southerly return flow with
limited recovery of low-level moisture on Wednesday, allowing
highs to warm back into the m-u 60s. To our northwest, the first
in a series of low amplitude mid-level disturbances will shift
east-southeastward across the central US, undercutting an
amplified 500-mb ridge across central Canada and eventually
resulting in development of a broad longwave trough across eastern
North America later this week. As this occurs, the previously
mentioned surface cyclone (across NE) will develop east-
southeastward across northern MO (Wednesday) and into southern
IL/IN (Wednesday night). A narrow axis of weak convective showers
(and perhaps a thunderstorm) will develop Wednesday night both
along the trailing cold front and in the warm advection regime
immediately ahead of the front as a strengthening WSW low-level
jet promotes modest low-level moisture return. However, present
indications are that this activity may only reach as far SE as
western/middle TN by 12Z Thursday and we will maintain a dry
forecast with warmer lows in the m40s-l50s.

&&

.LONG TERM...
(Thursday through Sunday)
Issued at 1041 PM CDT Sun Apr 6 2025

The aforementioned shortwave will dig through the Great Lakes
region Wednesday night and a cold front will push east followed by
longwave troughing that will dig into the Southeast by the
weekend. A weak cold front will accompany the shortwave passage as
a sfc low lifts into the Great Lakes. Low to medium chances
(20-50%) of showers and maybe even embedded thunderstorms will
increase Thursday morning first over NE AL and southern middle TN
and then spread south and west into the remainder of the Tennessee
Valley Thursday afternoon. The good news is that severe weather
is not expected with this frontal passage. The upper level trough
pushes to the east at the end of the week, bringing back dry
weather to start the weekend.

&&

.AVIATION...
(18Z TAFS)
Issued at 1228 PM CDT Mon Apr 7 2025

Although very low stratus clouds and patches of lgt RA/DZ have
impacted northern AL terminals for much of the morning, latest
trends in radar data suggest that the risk for precip has shifted
to the east of the terminals. Recent sfc obs indicate that cloud
bases are beginning to rise, and the clearing line should reach
MSL/21Z and HSV/0Z. After a brief period of generally clear skies
and lighter WNW winds this evening, a strong cold front will
arrive arnd 8Z, and may be accompanied by a fast-moving band of
mid-level stratus (not indicated in the TAFs at the present time).
Sfc flow will veer to NNE in the wake of the front and remain in
the 7G15 knot range thru the end of the period.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Freeze Watch from late Tuesday night through Wednesday morning
     for ALZ001>010-016.

TN...None.

&&

$$

NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...25
AVIATION...70/DD