613
FXUS64 KHUN 131700 AAA
AFDHUN

Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
1200 PM CDT Thu Jun 13 2024

...New AVIATION...

.NEAR TERM...
(Rest of Today)
Issued at 956AM CDT Thu Jun 13 2024

An upper-level trough off the east coast of the US will move away
from the TN River Valley today. This should promote northerly flow
at the upper-levels, with some confluence aloft, allowing for
subsidence. A weak surface trough, located along the AL/GA border,
may help spark a shower or two in the afternoon, especially along
the convergence zone. Though, with the synoptic-scale subsidence,
PoPs remain pretty low. Highs are forecast to reach the upper-80s
to lower-90s this afternoon under mostly sunny skies.

&&

.SHORT TERM...
(Tonight through Saturday night)
Issued at 421 AM CDT Thu Jun 13 2024

NWP model consensus indicates that the strong 500-mb subtropical
ridge (discussed above) will build progressively eastward,
becoming centered directly across the TN Valley by Saturday night,
and providing an increasingly favorable environment for hot/dry
conditions. At the surface, a cold front (attached to an area of
low pressure ejecting northeastward across Quebec) will shift
southeastward into the OH Valley by 12Z Friday accompanied by a
weakening band of convection that may result in an increase in
cirrus debris clouds prior to sunrise. Although diurnal
redevelopment of showers and thunderstorms will be possible along
the length of the front on Friday afternoon/evening, present
indications are that this activity will remain north of the I-40
corridor in Middle TN. A frontal wind shift to NE will arrive in
our CWFA Friday evening as the center of a modified Canadian
airmass spreads eastward through the Great Lakes, and should lie
to our immediate southwest on Saturday/Saturday night. However,
cooler/drier air will remain displaced well to our north/east, and
with a narrow axis of dewpoints in the u60s-l70s expected to pool
in the vicinity of the boundary, heat index readings will climb
above 100F across the southwestern half of the region Saturday
afternoon as temps warm into the m-u 90s. As a result of the
increase in low-level moisture, lows will also warm into the lower
70s for most locations Friday and Saturday nights.

&&

.LONG TERM...
(Sunday through Wednesday)
Issued at 421 AM CDT Thu Jun 13 2024

The center of the subtropical ridge is predicted to begin
shifting slowly northeastward and away from the TN Valley on
Sunday, becoming centered across western portions of VA/NC by
Monday. This (along with a surface ridge migrating eastward off
the coast of New England) will result in a gradual increase in
deep-layer SSE flow and atmospheric moisture content, which should
support a minor increase in the coverage of diurnal showers and
thunderstorms early next week. Although some deterministic and
ensemble guidance indicates that this could occur as early as
Sunday afternoon/evening, it currently appears as if our best
opportunity for rainfall will be Monday afternoon/evening.
Afternoon temperatures will peak in the upper 90s for many
locations on Sunday (with a 100F reading or two possible), but it
still appears as if heat index readings will be slightly below
advisory criteria. Highs are currently expected to be several
degrees cooler on Monday due to clouds and precip, but if this
does not materialize, temps will need to be increased.

During the period from Tuesday-Wednesday, global models suggest
that our deep-layer SSE flow regime will be disrupted by a
developing area of low pressure over the southwestern Gulf/Bay of
Campeche, and with more of an influence from the Bermuda ridge to
our east, we expect hot/dry conditions to return. Fortunately, it
appears as if the westward advection of a drier airmass into the
region will limit heat index readings in this regime. Strong
warming of lower-levels from Wednesday onward will likely support
development of afternoon thunderstorms in regions of enhanced
orographic ascent across the central/southern Appalachians on a
daily basis, and with deep easterly flow predicted to the south of
the subtropical high, some of this activity may eventually spill
into northeast AL. However, we have maintained a dry forecast at
this point.

&&

.AVIATION...
(18Z TAFS)
Issued at 1200 PM CDT Thu Jun 13 2024

VFR conditions and light winds will comprise the TAF period
through early Friday afternoon. Other than some mid-level cumulus
in the afternoon today and tomorrow, mostly clear skies are also
anticipated.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.
&&

$$

NEAR TERM...17
SHORT TERM....70
LONG TERM....70
AVIATION...26