Flash Flood Watch 2, NWS Huntsville, AL

754 
WGUS64 KHUN 180520
FFAHUN

Flood Watch
National Weather Service Huntsville AL
1220 AM CDT Thu Mar 18 2021

ALZ001>010-016-TNZ076-096-097-180630-
/O.CAN.KHUN.FF.A.0002.000000T0000Z-210318T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
Including the cities of Russellville, Winchester, Fort Payne, Red 
Bay, Cullman, Town Creek, Cowan, Estill Springs, Huntsville, 
Sheffield, Arab, Sewanee, Decatur, Lynchburg, Athens, Muscle Shoals, 
Decherd, Fayetteville, Albertville, Guntersville, Boaz, Rainsville, 
Tuscumbia, Moulton, Florence, and Scottsboro
1220 AM CDT Thu Mar 18 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for portions of Alabama and southern middle 
Tennessee, including the following areas, in Alabama, Colbert, 
Cullman, DeKalb, Franklin AL, Jackson, Lauderdale, Lawrence, 
Limestone, Madison, Marshall and Morgan. In southern middle 
Tennessee, Franklin TN, Lincoln and Moore has been cancelled.

The Flash Flood Watch is cancelled. Flash Flooding is no longer 
expected to pose a threat. However, warnings for areal flooding 
caused by runoff from 3 to 6 inches of rainfall will continue in 
some areas.

$$

KTW

Area Forecast Discussion
National Weather Service Huntsville AL
348 PM CDT Wed Mar 17 2021

.NEAR TERM...(Tonight)
Issued at 348 PM CDT Wed Mar 17 2021

A very active/volatile wx pattern continues to unfold across much of
NE/east cntrl MS into west cntrl AL this Wed afternoon. Much of the
tstm activity is being driven by an active SW flow regime in place
over much of the region, ahead of a potent upper low/trough axis
rotating ewd thru the mid/srn Plains. A lot of this convection is
also occurring along/ahead of a cold front making its way ewd into
the Lower MS Valley. The attendant sfc low is also moving east into
north AR or the Mid South region, with the associated warm front
located from extreme NW MS into NW/cntrl AL. The location of the warm
front and how much farther to the north it tracks will be a key
factor in the development of strong/severe tstms late this afternoon
into this evening.

The latest model suites remain fairly consistent with moving the sfc
low into KY later tonight, thereby pushing the cold front into the
cntrl TN Valley area. This scenario would also lift the warm front
into mid/ern TN and allow low-level instability to spread into the
area. With Bufr soundings/shear profiles continuing to indicate 0-3km
SRH values in excess of 400 m2/s2 and Bulk Shear values near 60kt, a
slight increase in SBCAPE values around 500-1000 J/kg would easily
favor the development of severe tstms into the evening hrs, with the
main threats being damaging winds, large hail and tornadoes. In
fact, supercellular structures late this afternoon into this evening
could produce a few long track/violent tornadoes, before tstms begin
to merge into more of a QLCS line right along the passage of the
front. Again, much of the extent/strength of any strong/severe tstms
will be heavily influenced by the magnitude of the warm sector into
the mid TN Valley area.

Considering some of the intense rainfall rates, some localized/minor
flooding may also be a threat later this evening in locations which
receive multiple rounds of showers/tstms. Lingering showers/tstms
should then begin to taper off to the east by early Thu morning
following the passage of the front, with lows falling mainly into the
lower/mid 50s.

.SHORT TERM...(Thursday through Friday)
Issued at 348 PM CDT Wed Mar 17 2021

The overall wx pattern is then expected to turn more quiet/seasonal
heading towards the end of the work week, as a large area of high
pressure out of the nrn Plains builds into the Midwest/OH Valley
states. Afternoon highs Thu/Fri look to range from the mid 50/near
60F, while lows Thu night trend in the lower/mid 40s.

.LONG TERM...(Friday night through Tuesday)
Issued at 348 PM CDT Wed Mar 17 2021

The quiet pattern continues into the weekend period, as the sfc high
moves into the mid/NE Atlantic states. This should allow for a
gradual warming trend into next week, as highs climb more into the
60s. Optimal radiational cooling may also allow overnight lows to
trend in the mid 30/near 40F thru Mon night. The next chance of rain
still looks to develop on Tue, as another cold front approaches from
the west.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1242 PM CDT Wed Mar 17 2021

Restricted flying conds will be in place for much of the TAF period,
as multiple waves of shra/tsra continue to develop/spread across the
area well into the afternoon/evening hrs. IFR conds will be possible
in some of the heavier shra/tsra, with sfc winds gusting near 30-35kt
at times. All of this will be occurring along/just ahead of a cold
front approaching from the west. The front looks to move thru the
area by Thu morning, with lingering shra/tsra tapering off to the
east. Cigs though may hover near 3-4K ft in the wake of the frontal
passage Thu morning, as sfc flow turns to the SW near 10-12kt with
higher gusts.

&&

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

NEAR TERM...09
SHORT TERM...09
LONG TERM...09
AVIATION...09

For more information please visit our website
at weather.gov/huntsville.

Hazardous Weather Outlook
National Weather Service Huntsville AL
546 AM CDT Wed Mar 17 2021

ALZ001>010-016-TNZ076-096-097-180200-
Lauderdale-Colbert-Franklin AL-Lawrence-Limestone-Madison-Morgan-
Marshall-Jackson-DeKalb-Cullman-Moore-Lincoln-Franklin TN-
546 AM CDT Wed Mar 17 2021

This Hazardous Weather Outlook is for north Alabama and portions of
southern middle Tennessee.

.DAY ONE...Today and Tonight...

Thunderstorms are increasing across the area as a warm front lifts
northward. A few strong to severe storms will be possible early this
morning through around 10 AM. The main threats with these morning
storms will damaging winds, marginally severe sized hail, and a
tornado or two. The main threat area will be along and south of a
Waterloo to Moulton line.

Scattered supercell thunderstorms are expected again this afternoon,
as the atmosphere will become progressively unstable in the wake of
the northward- moving warm front. Although storm coverage will be
scattered, damaging winds, large hail and tornadoes will be possible.
The main threat area will be for strong to severe storms will be for
locations to the south and west of Huntsville.

A third and more widespread threat for severe thunderstorms will
develop ahead of an eastward-moving cold front by late this
afternoon, and persist throughout the evening and into early morning
hours on Thursday. Strong, long-track tornadoes, significant
damaging winds and large hail will all be possible, until the front
clears the region shortly before sunrise on Thursday morning.

In addition to the threat for severe thunderstorms, multiple rounds
of locally heavy rainfall will lead to an enhanced risk for flash
flooding today and tonight, as well as river flooding that may
persist through the end of the week.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday...

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Activation of storm spotters and emergency management personnel is
possible beginning early Wednesday morning. However, activation is
likely today through early Thursday morning.

Please relay any information about observed severe weather to the
NWS while following all local, state, and CDC guidelines.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HUNTSVILLE AL
253 PM CDT WED MAR 17 2021

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

0238 PM     FLOOD            2 N SCOTTSBORO          34.68N 86.04W
03/17/2021                   JACKSON            AL   FIRE DEPT/RESCUE

            ONE FOOT OF WATER FLOWING OVER CEDAR HILL
            ROAD AT E. WILLOW STREET IN SCOTTSBORO.

&&

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