Flash Flood Warning 3, NWS Huntsville, AL

Area Forecast Discussion
National Weather Service Huntsville AL
532 PM CST Thu Feb 16 2023

...New AVIATION...

.NEAR TERM...
(Remainder of today and tonight)
Issued at 242 PM CST Thu Feb 16 2023

There have been no significant changes to forecast reasoning for
the remainder of the afternoon since the earlier morning update,
with the risk for severe thunderstorms expected to increase from
W-to-E over the next 1-3 hours. Although open warm sector
supercells currently tracking from southeastern MS into central AL
may ultimately reduce the risk for development of discrete
cellular convection prior to the arrival of a cold front in our
region, we still anticipate a broken QLCS featuring organized
multicell clusters and embedded supercells (capable of all severe
hazards) to accompany the front as it shifts eastward into the
local area later this afternoon.

Latest model guidance continues to indicate that the
aforementioned cold front will begin to decelerate considerably as
it crosses the I-65 corridor around 00Z, with the boundary not
expected to exit the southeastern portion of our CWFA until
perhaps as late as 4-5Z this evening. Although this may warrant a
local extension of Tornado Watch 39 to include our three northeast
AL counties, widespread convective overturning and loss of
diurnal destabilization should reduce the overall risk for severe
convection in these zones. What will become more of a concern in
this region (as well as the remainder of the CWFA) is flooding. At
this point, the risk for flash flooding appears highest across
northeast AL, where echo training of moderate-heavy convective
cores may occur for several hours this evening until the cold
front finally clears the region. However, as deep-layer ascent
begins to strengthen downstream from a positively-tilted mid-level
trough crossing the Mid-MS Valley, widespread light-moderate
postfrontal rain will occur for several hours in the wake of the
wind shift, with areal flooding possible elsewhere. In spite of
strengthening cold advection in the wake of the front, low stratus
clouds will limit cooling, with lows predicted to be in the m-u
30s.

&&

.SHORT TERM...
(Friday through Saturday night)
Issued at 242 PM CST Thu Feb 16 2023

Strong synoptic scale forcing for ascent will continue throughout
much of the day tomorrow, until the axis of the positively-tilted
mid-level trough (discussed above) begins to cross the region
during the late afternoon/early evening hours. Thus, we expect a
regime featuring low stratus clouds and isolated light showers or
sprinkles, which could be mixed with a few snow flurries at times.
Given the combination of strong cold advection and low clouds,
highs will struggle to reach the u30s-l40s.

Mid-level flow will quickly transition to a zonal orientation
late Friday night, to the north of a flat subtropical ridge
centered across the southeastern Gulf of Mexico. Thus, we expect
skies to clear rapidly and support optimal radiational cooling
conditions early Saturday morning as a surface ridge builds
northeastward into the TN Valley. A hard freeze will occur this
period, with lows in the l-m 20s. Highs will rebound into the l-m
50s on Saturday, as the low-level ridge translates eastward,
inducing light south-southeasterly return flow. Mid/high-level
cloudiness will begin to increase late in the day as a weak
disturbance ejects northeastward from the southern Plains into the
OH Valley by 12Z Sunday, and this will lead to milder temps in
the m-u 30s Sunday morning.

&&

.LONG TERM...
(Sunday through Thursday)
Issued at 242 PM CST Thu Feb 16 2023

Extended range models still indicate that a pronounced northern
stream trough will shift eastward from northern Plains on Sunday
into the New England vicinity on Monday. A weak cold front related
to this trough is expected to drift southward into the region at
some point on Monday, but low-level moisture return should be
inadequate to support any meaningful chance for precipitation. By
late Monday night, we expect to see a partially modified maritime
airmass return northward across the TN Valley in response to
surface cyclogenesis in the lee of the southern Rockies. Isolated
to widely scattered showers and perhaps a few thunderstorms will
be possible at times from Monday night-Wednesday, but coverage and
intensity will be dictated by the precise location of a slow-
moving warm front. It appears as if a stronger mid-level trough
and accompanying surface low may bring a more widespread coverage
of showers and a few storms to the region Wednesday evening, but
due to uncertainty in the timing and track of this system, we have
kept POPs in the chance range. One thing that appears more
certain is that temperatures throughout the extended portion of
the forecast will be influenced by strengthening and amplification
of the subtropical ridge to our southeast, with highs in the l-m
70s Tuesday-Thursday and lows in the u50s-l60s.

&&

.AVIATION...
(00Z TAFS)
Issued at 532 PM CST Thu Feb 16 2023

Heavy rain and embedded storms will continue to move across the
area this evening, and the primary concerns for TAFs will be
reduced vsbys/cigs due to storms and lightning. Gusty winds up to
25kts will be possible, and winds will shift from southerly to
northwesterly as a cold front moves through this evening. Showers
and storms should come to an end by sunrise, but MVFR cigs may
linger through Friday afternoon.

&&

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

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
538 PM CST THU FEB 16 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0510 PM     FLOOD            UNDERWOOD-PETERSVILLE   34.87N 87.70W
02/16/2023                   LAUDERDALE         AL   EMERGENCY MNGR

            EM RELAYED REPORT OF FLOODING ON HWY 157 AND
            CR 57.

&&

TPB

Special Weather Statement
National Weather Service Huntsville AL
549 PM CST Thu Feb 16 2023

ALZ016-170030-
Cullman AL-
549 PM CST Thu Feb 16 2023

...A strong thunderstorm will impact portions of western Cullman
County through 630 PM CST...

At 548 PM CST, Doppler radar was tracking a strong thunderstorm near
Smith Dam, or 8 miles south of Arley, moving northeast at 30 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Cullman, Hanceville, Good Hope, Dodge City, Baldwin, Vinemont, West
Point, Garden City, Colony and Phelan.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Tornado Watch remains in effect until 700 PM CST for north central
Alabama.

&&

LAT...LON 3389 8709 3390 8710 3391 8708 3399 8715
      3399 8711 3412 8711 3429 8686 3409 8666
      3408 8670 3405 8668 3406 8671 3403 8670
      3403 8672 3398 8677 3389 8705
TIME...MOT...LOC 2348Z 238DEG 26KT 3397 8715

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

AMP

Special Weather Statement
National Weather Service Huntsville AL
618 PM CST Thu Feb 16 2023

TNZ076-096-097-170100-
Franklin TN-Moore TN-Lincoln TN-
618 PM CST Thu Feb 16 2023

...A strong thunderstorm will impact portions of southeastern Moore,
central Lincoln and western Franklin Counties through 700 PM CST...

At 617 PM CST, Doppler radar was tracking a strong thunderstorm over
Fayetteville, moving east at 30 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Fayetteville, Lynchburg, Huntland, Tims Ford Lake, Lexie Crossroads,
Mulberry, Howell, Harmony, Hurdlow and Lois.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Tornado Watch remains in effect until 700 PM CST for Middle
Tennessee.

&&

LAT...LON 3535 8617 3506 8615 3507 8667 3523 8668
      3534 8621 3533 8620 3534 8619
TIME...MOT...LOC 0017Z 264DEG 26KT 3515 8654

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

AMP

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