Heat in Alabama, June 14, 2022

Area Forecast Discussion
National Weather Service Huntsville AL
306 PM CDT Tue Jun 14 2022

...New NEAR TERM, SHORT TERM, LONG TERM...
...Very Hot Temperatures and Heat Advisory to Continue Overnight
into Wednesday...

.NEAR TERM...
(Tonight)
Issued at 245 PM CDT Tue Jun 14 2022

A broad dome of high pressure is centered over the region and just
to the NE of the forecast area attm. A short wave trough embedded
along the SE-S side of the upper ridge is helping to drive
convective development to our E-SE this afternoon. Steering flow
and low-lvl instability is aiding further convective development
along a broad outflow boundary SWRD through GA...which will
eventually move into SE AL and northern FL later today. Thus, the
main axis of convection will remain well to our south.
Nevertheless, easterly outflow in the northern periphery of the
outflow will meet up with WSW flow in SE portions of the area,
leading to weak low-lvl convergence and the prospect for isolated
SHRA/TSRA in those areas this afternoon. However, with generally
weak forcing comes low POPs, and only ~20 POPs are in our SE areas
from this afternoon into the early evening. Otherwise, conditions
will remain hot/warm into the overnight. A decision was made to
maintain the Heat Advisory overnight since we are in the midst of
a heat event and with Heat Advisory criteria expected to be
exceeded again tomorrow. We appreciate the collaboration with
surrounding offices regarding this matter today.

&&

.SHORT TERM...
(Wednesday through Friday)
Issued at 245 PM CDT Tue Jun 14 2022

The broad upper ridge will maintain dominance over the region
through the short term, likely leading to a string of days in
which Heat Advisories will continue to be necessary. The primary
caveat to daytime temperatures will involve the prospect for
showers/thunderstorms that develop as a result of weak short wave
maxima rotating around the periphery of the broad upr ridge
across our domain. This appears most likely to occur along the
Appalachians, with convection developing/evolving along theta-e
rich air to our SE-S. Nevertheless, low chance POPs will be
maintained Wed afternoon/evening and again Thursday afternoon
primarily in SE areas, closer to the forcing/instability axis.
Afternoon temperatures each day are expected to be in the mid/upr
90s as the hot air mass in assoc/w the upr ridge essentially
remains in place. Dew points may be largely status-quo, however,
some mixing with a plume of drier air along the western periphery
of the moister air mass may intrude into our area at times.
Anyway, dew points in the 70s look likely to remain in place in
large part, yielding heat indices around 105 F each day. Thus, the
Heat Advisories are likely to continue each day.

Although conditions are expected to be similar on Friday, a brief
shift in the pattern is likely to take shape as the broad upr
ridge retrogrades to the west. The ridge will begin to become more
meridionally oriented leading to downstream trough development in
the East CONUS. A cold front is expected to move across the area
late Friday or Friday night, ushering in a drier continental air
mass across the region. Some showers and thunderstorms may form
along/ahead of the front Friday afternoon/evening. Robust CAPEs,
high PWs and steep low-lvl lapse rates suggest strong winds
possible with any activity.

&&

.LONG TERM...
(Friday night through Tuesday)
Issued at 245 PM CDT Tue Jun 14 2022

At this point, conditions during the long term appear to be dry
with lower dew points/humidity in the area during the weekend.
Thus, a cessation of the Heat Advisories will probably occur
during the weekend. However, the upr ridge is expected to build
eastward again over the region by early next week. This time, the
plume of hot air emanating out of the source region in the Srn
High Plains/Southwest may be even hotter as depicted in forecast
values of 850 mb temps. Values around 22-25C have been indicated
by the guidance suite. The big difference is that dew point
temperatures are expected to be lower during this next round of
heating next week. With an expectation for rapidly drying upper
layer soils through the period, along with lower RHs, more
sensible heating will occur, leading to hotter daytime air
temperatures. Forecast temps were hedged higher than NBM 50th
percentiles, but even higher values may be expected, especially if
the upper bound of 850 mb temps pan out. Currently, the forecast
includes temps around 100F on Tuesday, but higher values towards
105F are not out of the question.

&&
.CLIMATE...
Issued at 245 PM CDT Tue Jun 14 2022

For longer term interests, the CPC has included the region in a
High Risk of Excessive Heat for the June 22-24 period. See the
8-14 Day U.S. Hazards Outlook from the Climate Prediction Center
for more information.

&&

.AVIATION...
(18Z TAFS)
Issued at 1230 PM CDT Tue Jun 14 2022

VFR conditions expected at KHSV and KMSL TAF sites over the next
24 hours. The only caveat is a low probability (~20%) of SHRA/TSRA
mainly at KHSV. An upper-lvl low rotating SWWRD is instigating
SHRA/TSRA development in areas of N-C GA attm. Although the upr
low feature and better instability will tend to continue to steer
convection SWWRD through 00Z (and potentially after), outflow
boundaries may reach our area and instigate further SHRA/TSRA,
with slightly better chances at KHSV due to closer proximity.
Simple advection of the current outflow suggests this would not
occur until after 00Z.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT this evening for ALZ001>010-016.

     Heat Advisory from 11 AM to 7 PM CDT Wednesday for ALZ001>010-
     016.

TN...Heat Advisory until 7 PM CDT this evening for TNZ076-096-097.

     Heat Advisory from 11 AM to 7 PM CDT Wednesday for TNZ076-096-
     097.

&&

NEAR TERM...KDW
SHORT TERM....KDW
LONG TERM....KDW
AVIATION...KDW

Hazardous Weather Outlook...UPDATED
National Weather Service Huntsville AL
1102 AM CDT Tue Jun 14 2022

ALZ001>010-016-TNZ076-096-097-151130-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
1102 AM CDT Tue Jun 14 2022

...HEAT ADVISORY IN EFFECT UNTIL 7 PM CDT THIS EVENING...
...HEAT ADVISORY IN EFFECT FROM 11 AM TO 7 PM CDT WEDNESDAY...

This Hazardous Weather Outlook is for north central Alabama,
northeast Alabama, northwest Alabama and southern middle Tennessee.

.DAY ONE...Today and tonight.

Afternoon heat indices will once again approach or exceed 105
degrees across much of the outlook area. A Heat Advisory remains in
effect until 7 PM today.

Isolated to widely scattered thunderstorms are possible across the
southeastern portion of the outlook area this afternoon and evening.
A few strong to severe storms producing gusty winds up to 60 MPH,
large hail and frequent lightning will be possible.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Afternoon heat indices will again approach or exceed 105 degrees
from Wednesday through Friday. A Heat Advisory is now in effect from
11 AM until 7 PM Wednesday. A Heat Advisory may also be needed
Thursday and Friday.

Isolated to scattered mainly afternoon thunderstorms are also
possible Wednesday through Friday. A few of these storms may produce
strong gusty winds, small hail and brief heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

70/DD