Special Weather Statement, NWS Mobile, AL

Area Forecast Discussion
National Weather Service Mobile AL
616 PM CDT Sat Aug 21 2021

.NEAR TERM UPDATE /Now Through Sunday night/...An upper level low pressure
system will remain centered over northern Virginia through
tonight with troughing extending southwest into the southeastern
states. The upper level low will then dance the Fujiwara with
Henri over the Mid-Atlantic, helping to pull Henri into the
northeastern U.S. on Sunday and pivoting the trough axis eastward.
An upper level high pressure system on its heels centered over
the ArkLaTex region will persist through the near term. This
continues to promote northerly to northwesterly flow aloft over
the area through Sunday. At the surface, high pressure remains
centered over the northern Gulf of Mexico through Sunday as it
weakens. Weak disturbances within the upper level flow round the
periphery of the trough/ridge pair, with our next one expected
this afternoon and evening with scattered to at times numerous
showers and thunderstorms are expected to develop over the area
this afternoon into early evening. PWATs remain in the 2.1 to 2.3
inch range, and afternoon SBCAPE/MLCAPE values will peak around
2,500/1,500j/kg respectively. This will support robust
thunderstorms development, and likewise, with relatively slow
moving convection, very heavy rainfall with storms. The main area
of concern this afternoon will be north of a line from Waynesboro
MS to Florala AL, where SPC has a marginal risk for severe
thunderstorms. DCAPE values remain rather low, only around 500 to
750j/kg, owing to a rather moist atmospheric column. This should
help preclude stronger wind gusts with storms, although extensive
water loading of updrafts with storm collisions could support a
stronger gust or two. The local area also remains in a marginal
risk for excessive rainfall today. By this evening, overall
convective coverage should decrease to mainly isolated over the
region. Highs this afternoon remain on track to reach the lower to
middle 90's, with lows tonight in the middle 70's. Heat indices
will range between 100 and 105 degrees. A High Risk of rip
currents remains in place through tonight due to remaining swell
from Hurricane Grace, high tidal ranges, and an outgoing tide
during the afternoon and evening.

Sunday will be rather similar to today, with the next upper level
disturbance moving slowly southward throughout the day, mainly
over the eastern portion of the forecast area. We therefore
anticipate scattered to perhaps numerous showers and thunderstorms
at times, with similar coverage to today. This will particularly
be the case further east as you head into the central FL panhandle
and south-central AL closer to the stronger section of the upper
level disturbance. SBCAPE/MLCAPE values will likely approach the
3,000/2,500j/kg range respectively, along with DCAPE values
around 1,000j/kg. The potential remains for gusty winds with
storms. PWATs remain high in the 2 to 2.4 inch range, continuing
to favor very heavy rainfall with thunderstorms and continue the
potential for nuisance flooding. Afternoon temperatures will
generally be in the lower to middle 90's, with heat indices in the
101 to 107 degree range. /22

&&

.AVIATION...
00Z issuance...VFR conditions prevail outside of showers and
thunderstorms. Underneath any showers and storms this evening,
expect temporary MVFR to IFR ceilings/visibility. Convection wanes
into the evening, allowing for VFR conditions to continue to
dominate. Tomorrow is a repeat of today, with afternoon showers
and thunderstorms. VFR conditions outside of convection, and MVFR
to IFR tempo ceilings/visibility underneath convection. MM/25

&&

.PREV DISCUSSION... /issued 352 PM CDT Sat Aug 21 2021/

NEAR TERM UPDATE /Now Through Sunday/...An upper level low pressure
system will remain centered over northern Virginia through
tonight with troughing extending southwest into the southeastern
states. The upper level low will then dance the Fujiwara with
Henri over the Mid-Atlantic, helping to pull Henri into the
northeastern U.S. on Sunday and pivoting the trough axis eastward.
An upper level high pressure system on its heels centered over
the ArkLaTex region will persist through the near term. This
continues to promote northerly to northwesterly flow aloft over
the area through Sunday. At the surface, high pressure remains
centered over the northern Gulf of Mexico through Sunday as it
weakens. Weak disturbances within the upper level flow round the
periphery of the trough/ridge pair, with our next one expected
this afternoon and evening with scattered to at times numerous
showers and thunderstorms are expected to develop over the area
this afternoon into early evening. PWATs remain in the 2.1 to 2.3
inch range, and afternoon SBCAPE/MLCAPE values will peak around
2,500/1,500j/kg respectively. This will support robust
thunderstorms development, and likewise, with relatively slow
moving convection, very heavy rainfall with storms. The main area
of concern this afternoon will be north of a line from Waynesboro
MS to Florala AL, where SPC has a marginal risk for severe
thunderstorms. DCAPE values remain rather low, only around 500 to
750j/kg, owing to a rather moist atmospheric column. This should
help preclude stronger wind gusts with storms, although extensive
water loading of updrafts with storm collisions could support a
stronger gust or two. The local area also remains in a marginal
risk for excessive rainfall today. By this evening, overall
convective coverage should decrease to mainly isolated over the
region. Highs this afternoon remain on track to reach the lower to
middle 90's, with lows tonight in the middle 70's. Heat indices
will range between 100 and 105 degrees. A High Risk of rip
currents remains in place through tonight due to remaining swell
from Hurricane Grace, high tidal ranges, and an outgoing tide
during the afternoon and evening.

Sunday will be rather similar to today, with the next upper level
disturbance moving slowly southward throughout the day, mainly
over the eastern portion of the forecast area. We therefore
anticipate scattered to perhaps numerous showers and thunderstorms
at times, with similar coverage to today. This will particularly
be the case further east as you head into the central FL panhandle
and south-central AL closer to the stronger section of the upper
level disturbance. SBCAPE/MLCAPE values will likely approach the
3,000/2,500j/kg range respectively, along with DCAPE values
around 1,000j/kg. The potential remains for gusty winds with
storms. PWATs remain high in the 2 to 2.4 inch range, continuing
to favor very heavy rainfall with thunderstorms and continue the
potential for nuisance flooding. Afternoon temperatures will
generally be in the lower to middle 90's, with heat indices in the
101 to 107 degree range. /22

SHORT TERM /Sunday night Through Tuesday night/...An amplified
pattern is noted in the height field aloft with the axis of an upper
level trof of low pressure aligned from the New England states to
the Carolinas Sunday night into Monday. It is this feature that
influences the poleward motion of tropical cyclone Henri, making
landfall and lifting up across the New England States, an area of
the CONUS that does not normally see such an occurrence. Southwest
of the upper trof, an upper level ridge of high pressure will be centered
over the ArkLaTex. Between these two upper level features, a mean
northerly flow aloft will be positioned atop a slow southward
moving surface pressure trof. Embedded mid-level impulses and the
surface trof would favor enough ascent within a deeply moist
environment for a north to south push of scattered storms Sunday
night from across the I-65 corridor to and off the coast. Stronger
storms pushing southward across the region could still produce
locally heavy rainfall, frequent lightning and brief strong and
gusty winds. The upper ridge builds and expands eastward across
the Lower MS River Valley early next week.

As discussed from the previous shift, forecasters continue to see
indications in the 21.12Z data that deep layer moisture decreases
somewhat for the start of next week as the upper ridge builds in
from the west. Even so, there is enough moisture in place and with
a weak surface pressure trough across our region along with
daytime heating and instability, a modest chance of storms remains
in the forecast Monday and Tuesday. Potentially likely along the
I-10 corridor both afternoons. Away from storms, heat indices
Monday could approach a range from 105 to 110. A heat advisory may
become required if these trends continue. A MODERATE rip current
risk remains in place through Monday night. /10

EXTENDED TERM /Wednesday Through Saturday/...Deep layer ridge is
forecast to be aligned from the Appalachians to TX Wednesday.
The ridge weakens slightly late in the week. On the southern
periphery of the ridge, an inverted pressure trough moves
west northwest across the FL Peninsula Thursday and up into the
southeast on Friday. Forecasters see no end in the hot and muggy
pattern with scattered to locally numerous showers and
thunderstorms developing each afternoon. /10

MARINE...A broad ridge of high pressure will remain in place over
the northern Gulf through early next week then weaken slightly by the
middle part of next week. A light to occasionally moderate
southwesterly to westerly flow will continue through Monday,
becoming southerly to southeasterly on Tuesday. Seas will remain
around 2 feet through Tuesday, increase to 3 to 4 feet Wednesday and
Thursday due to a southeasterly fetch. /22

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk until 4 AM CDT Sunday for ALZ265-266.

FL...High Rip Current Risk until 4 AM CDT Sunday for FLZ202-204-206.

MS...None.
GM...None.
&&

This product is also available on the web at:
http://weather.gov/mob

Special Weather Statement
National Weather Service Mobile AL
445 PM CDT Sat Aug 21 2021

ALZ054-057-212230-
Wilcox AL-Butler AL-
445 PM CDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of northern Butler and
east central Wilcox Counties through 530 PM CDT...

At 444 PM CDT, Doppler radar was tracking a strong thunderstorm 10
miles northeast of Pine Apple, or 18 miles southwest of Mosses,
moving southeast at 15 mph.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Greenville.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3196 8686 3196 8645 3189 8645 3165 8660
      3197 8703 3205 8697 3205 8686
TIME...MOT...LOC 2144Z 304DEG 13KT 3201 8692

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

Special Weather Statement
National Weather Service Mobile AL
515 PM CDT Sat Aug 21 2021

ALZ056-059-212300-
Conecuh AL-Escambia AL-
515 PM CDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of northeastern
Escambia and southeastern Conecuh Counties through 600 PM CDT...

At 515 PM CDT, Doppler radar was tracking a strong thunderstorm over
Castleberry, or 10 miles southwest of Evergreen, moving east at 15
mph.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Castleberry.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3125 8717 3140 8713 3138 8672 3108 8679
TIME...MOT...LOC 2215Z 287DEG 14KT 3130 8705

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

Special Weather Statement
National Weather Service Mobile AL
527 PM CDT Sat Aug 21 2021

FLZ205-212315-
Okaloosa Inland FL-
527 PM CDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of central Okaloosa
County through 615 PM CDT...

At 527 PM CDT, Doppler radar was tracking a strong thunderstorm 5
miles southwest of Baker, or 10 miles west of Crestview, moving east
at 15 mph.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Crestview and Baker.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3054 8646 3054 8650 3056 8653 3055 8654
      3066 8679 3085 8679 3079 8639
TIME...MOT...LOC 2227Z 283DEG 13KT 3074 8674

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

Special Weather Statement
National Weather Service Mobile AL
528 PM CDT Sat Aug 21 2021

ALZ060-212315-
Covington AL-
528 PM CDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of southeastern
Covington County through 615 PM CDT...

At 528 PM CDT, Doppler radar was tracking a strong thunderstorm 6
miles north of Lockhart, or 6 miles north of Florala, moving east at
15 mph.

HAZARD...Winds in excess of 30 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Florala and Lockhart.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3099 8638 3103 8647 3120 8641 3117 8619
      3099 8619
TIME...MOT...LOC 2228Z 287DEG 13KT 3110 8636

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...30 MPH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MOBILE AL
640 PM CDT SAT AUG 21 2021

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

0330 PM     FLASH FLOOD      1 E FORT WALTON BEACH   30.42N 86.61W
08/21/2021                   OKALOOSA           FL   LAW ENFORCEMENT

            FLASH FLOODING FROM HEAVY RAINFALL CLOSED
            HUGHES ST. NE BETWEEN EGLIN PKWY NE AND BEAL
            PKWY NE. HIGH WATER RESCUES OF THREE ADULTS
            AND ONE CHILD FROM FLOODED VEHICLES.

&&

MM

Special Weather Statement
National Weather Service Mobile AL
653 PM CDT Sat Aug 21 2021

ALZ059-FLZ203-205-220100-
Escambia AL-Okaloosa Inland FL-Santa Rosa Inland FL-
653 PM CDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of south central
Escambia, northwestern Okaloosa and northeastern Santa Rosa Counties
through 800 PM CDT...

At 653 PM CDT, Doppler radar was tracking a strong thunderstorm 10
miles southeast of Riverview, or 13 miles southeast of Brewton,
moving southeast at 15 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...
Baker.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3086 8714 3106 8702 3093 8659 3064 8679
TIME...MOT...LOC 2353Z 300DEG 15KT 3093 8698

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

MM