Special Marine Warning 271, NWS Mobile, AL

989 
FZUS74 KMOB 232232
MWSMOB

Marine Weather Statement
National Weather Service Mobile AL
532 PM CDT Mon Aug 23 2021

GMZ631-632-232241-
/O.CAN.KMOB.MA.W.0271.000000T0000Z-210823T2315Z/
532 PM CDT Mon Aug 23 2021

...THE SPECIAL MARINE WARNING IS CANCELLED...

The affected areas were...
Mississippi Sound...
South Mobile Bay...

The thunderstorms have moved out of the warned area and no longer 
pose a significant threat to boaters.

LAT...LON 3021 8837 3017 8812 3012 8811 2987 8812
      2994 8832
TIME...MOT...LOC 2231Z 340DEG 30KT 2988 8796 2997 8817 3006 8845 

$$

GMZ650-232315-
/O.CON.KMOB.MA.W.0271.000000T0000Z-210823T2315Z/
532 PM CDT Mon Aug 23 2021

...A SPECIAL MARINE WARNING REMAINS IN EFFECT UNTIL 615 PM CDT...

For the following areas...
Coastal waters from Pensacola FL to Pascagoula MS out 20 NM...

At 531 PM CDT, strong thunderstorms were located along a line
extending from 19 nm south of Sand Island Lighthouse to 10 nm
southwest of Farewell Buoy to 10 nm southwest of Petit Bois Pass,
moving south at 30 knots.

HAZARD...Wind gusts 34 knots or greater.

SOURCE...Radar indicated.

IMPACT...Small craft could be damaged in briefly higher winds and 
         suddenly higher waves.

Strong thunderstorms will remain over mainly open waters.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to safe harbor immediately as gusty winds and high waves are
expected.

Frequent lightning is occurring with these storms. If caught on the
open water stay below deck if possible, keep away from ungrounded
metal objects.

&&

LAT...LON 3021 8837 3017 8812 3012 8811 2987 8812
      2994 8832
TIME...MOT...LOC 2231Z 340DEG 30KT 2988 8796 2997 8817 3006 8845 

HAIL...0.00IN
WIND...>34KTS

$$

MM

Area Forecast Discussion
National Weather Service Mobile AL
354 PM CDT Mon Aug 23 2021

.NEAR TERM UPDATE /Now Through Tuesday/...Ongoing isolated to low-end
scattered showers and thunderstorms across the southern portion of
the forecast area will dissipate this evening, while remaining
rainfree across the north. SBCAPE/MLCAPE values will likely peak
around 2,500/2,000j/kg respectively, with DCAPE values increasing to
over 1,000j/kg, which could result in gusty winds with the stronger
storms. With limited convective and cloud coverage, high
temperatures will reach the mid 90's, with an isolated spot or two
reaching the upper 90's. Given this, and the higher relative
humidity values across far southeastern MS and coastal counties of
AL/FL, a heat advisory remains in effect until 7 PM.

Tuesday will feature a similar setup to today with convection
generally offshore overnight/early morning then transitioning
further inland during the afternoon and evening. The main forcing
mechanisms will be the seabreeze boundary as it surges inland and by
areas reaching convective temperatures. Mid-level dry air will be
more pronounced, and may put a lid on anything more than an isolated
to at times scattered coverage. DCAPE values will be much higher, in
the 1,200 to 1,500j/kg range and will foster strong downdrafts with
any storm. This will have to be monitored for our wet microburst
risk Tuesday. This is particularly the case given most substantial
drying exists just above the 0C wetbulb near 675 to 700mb. On the
flip side, with the drier and slightly warmer mid- levels we should
see lower SBCAPE/MLCAPE values upwards of 2,000/1,500j/kg
respectively. This may help to limit thunderstorm intensity/depth.
Highs Tuesday will be in the lower to middle 90's, with heat index
values ranging between 102 and 107 degrees.
/22

&&

.SHORT TERM /Tuesday night Through Thursday night/...An upper level
shortwave system over the northern Caribbean moves north into an
upper level trough over the Eastern Conus, reaching the north-
central Gulf coast by Friday morning. An upper level ridge over most
of the central Conus Tuesday night shifts/build east to join with
upper level high pressure off the East Coast. More shortwave energy
moving though/digging an mean upper trough over the northwestern
quarter of the Conus shifts the ridge east, eventually moving it to
over the Carolina coast. A surface ridge stretching west over the
northern Gulf coast shifts north, stretching west from the Carolinas
to over the Tennessee River Valley by Friday morning. A band of
higher moisture levels (precipitable h20 levels 2.0"-2.3") over the
eastern Southeast shifts west over the forecast area and nearby
Wednesday through Wednesday night, then east of the forecast area
Thursday into Thursday night (with precipitable h20 values dropping
into the 1.7"-2.0" range Thursday) as the upper low approaches the
forecast area from the southeast. Guidance is advertising an uptick
in moisture levels as the upper low moves over/near (depending upon
the model) the forecast area.

With the shifting moisture levels/ approaching upper system comes an
upward trend in PoPs from Tuesday into Wednesday. The higher PoPs
then shift west with best chance of rain Thursday being over the
Lower Mississippi River Valley to western Southeast. A surface
trough on the south side of the surface ridge moves north over the
Southeast helps with the rain chances. Looking at the possibility
strong to severe storms Wednesday, guidance is advertising 1500-
2000J/kg range with DCapes topping out in the 600-800J/kg range,
pretty marginal values. Also, with a lack of dry layer in the
mid/upper levels will help to decrease the risk of any strong to
severe storms. Thursday, with drier air moving in, eastern portions
of the forecast area are expected to see an bit of an increase in
instability to around 2000J/kg, with DCapes remain on the marginal
side, topping out in the 600-800J/kg range. There is some drier
layers in the mid and upper levels. Even so, the risk of damaging
downbursts remains low to moderate.

Temperatures will see a downward trend with the higher PoPs and
associated rain coverage. High temperatures around to below seasonal
norms are expected Wednesday and Thursday, topping out in the upper
80s to around 90 each day. Low temperatures are expected to see a
downward trend, from low to mid 70s inland to mid to upper 70s along
the coast, to around 70 inland and low to mid 70s along the coast
Thursday night as lower moisture levels allow better overnight
cooling at the beginning of the period. Heat Indices in the 98-102
degree range Wednesday drop into the upper 90s to around 100
Thursday.
/16

&&

.EXTENDED TERM /Friday Through Monday/...The upper level shortwave system
over the forecast area moves off and upper level high pressure over
the Carolinas builds southwest over the Southeast. High pressure
remains rather modest, though does bring temperatures rising to
around seasonal norms. Rain chances remain above as moisture levels
increase, along with several shortwave impulses moving through the
ridge through the Extended.
/16

&&

.MARINE...A light to occasionally moderate mainly westerly flow
will continue into Tuesday, becoming southerly Tuesday afternoon.
Southeasterly to easterly flow will then take hold midweek through
the remainder of the period. Scattered to numerous showers and
storms can be expected over the marine area each day. Seas will
remain around 1 to 2 feet into midweek, building to 3 to 4 feet
Thursday and Friday due to the southeasterly to easterly fetch. /22

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      74  93  75  89  73  89  71  89 /  20  40  30  80  40  70  20  50
Pensacola   78  92  76  87  75  88  73  89 /  30  40  40  80  50  60  30  60
Destin      79  90  77  89  76  88  74  87 /  30  50  40  80  40  50  30  60
Evergreen   74  97  74  90  72  90  70  90 /  10  40  10  80  20  50  10  50
Waynesboro  73  93  73  91  72  87  68  88 /  10  20  10  60  20  70  10  40
Camden      74  94  74  91  73  87  69  89 /  10  20  10  60  20  50  10  40
Crestview   74  92  73  89  72  91  70  89 /  20  50  30  80  40  50  20  60

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT this evening for ALZ261>266.

FL...Heat Advisory until 7 PM CDT this evening for FLZ201>206.

MS...Heat Advisory until 7 PM CDT this evening for MSZ078-079.

GM...None.
&&

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

Special Weather Statement
National Weather Service Mobile AL
411 PM CDT Mon Aug 23 2021

ALZ263-265-232200-
Mobile Coastal AL-Mobile Central AL-
411 PM CDT Mon Aug 23 2021

...Strong thunderstorms will impact portions of southwestern Mobile
County through 500 PM CDT...

At 410 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 5 miles west of Theodore to near Grand Bay to
near Helena. Movement was east 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...
Tillmans Corner, Theodore, Grand Bay, Bayou La Batre and Coden.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3034 8820 3036 8819 3037 8822 3036 8825
      3033 8826 3037 8826 3037 8824 3039 8829
      3037 8831 3040 8834 3039 8840 3049 8840
      3063 8829 3061 8811 3058 8809 3060 8810
      3060 8806 3057 8809 3043 8810 3033 8818
TIME...MOT...LOC 2110Z 279DEG 14KT 3056 8827 3044 8836 3045 8849

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

MM

Special Weather Statement
National Weather Service Mobile AL
424 PM CDT Mon Aug 23 2021

FLZ205-206-232215-
Okaloosa Inland FL-Okaloosa Coastal FL-
424 PM CDT Mon Aug 23 2021

...A strong thunderstorm will impact portions of southwestern
Okaloosa County through 515 PM CDT...

At 423 PM CDT, Doppler radar was tracking a strong thunderstorm over
Mary Esther. This storm was nearly stationary.

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...
Wright, Fort Walton Beach, Eglin AFB, Mary Esther, Ocean City, Lake
Lorraine, Shalimar and Cinco Bayou.

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.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3041 8666 3041 8680 3045 8680 3058 8676
      3049 8654 3043 8656 3043 8659 3046 8659
      3045 8660 3044 8660 3043 8661 3042 8659
      3041 8659 3040 8661 3040 8660 3039 8657
      3040 8667 3039 8680
TIME...MOT...LOC 2123Z 103DEG 3KT 3042 8665

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

MM