National Weather Service Raw Text Product

547 
FXUS64 KMOB 232247 CCA
AFDMOB

Area Forecast Discussion
National Weather Service Mobile AL
411 PM CST Sat Dec 23 2023

...New NEAR TERM, LONG TERM, MARINE...

.NEAR TERM...
(Now through Monday)
Issued at 406 PM CST Sat Dec 23 2023

A large upper cutoff low will evolve over the central US Sunday night 
into Monday, with a potent negatively tilted shortwave ejects over 
the lower Mississippi Valley Sunday night. This will allow for deep 
southwesterly flow to develop Sunday through Monday as PWATS climb 
to around 1.5 inches. Given rather impressive divergence aloft, 
fairly good synoptic ascent will overspread the area leading to 
roughly a 24 hour period of moderate to potentially heavy rainfall. 
A warm front will surge northward across the gulf Sunday night and 
approach the coast as a surface low forms west of the Mississippi 
River. This front will likely provide the focus for heavier rainfall 
but will stay just offshore keeping the better surface based 
instability away from the coast and limiting thunderstorm potential. 
The rain will then begin to taper off from west to east throughout 
the day Monday. Temperatures will be mild with lows Sunday night 
climbing into the mid 50s inland to low 60s along the coast. Highs 
on Monday will approach 70 degrees.

Heavy Rainfall Impacts...While this setup is a good one for rain 
given the plentiful synoptic support and deep moisture, this setup 
does not scream flooding potential. PWATS are certainly there as 
they will approach 1.5 to 1.75 inches along the coast, but with the 
combination of continued dry conditions (still in a drought) and 
lack of appreciable rain the last two weeks it will be tough to 
overcome flash flood guidance. Based off of our flash flood guidance 
we would need to see 2 to 4 inches in an hour and 3 to 6 inches in 3 
hours to begin flooding given our soil conditions. The current 
forecast is for roughly 1 to 3 inches spread out across roughly a 24 
hour period. That is probably not going to do much but create a few 
mud puddles and help chip away at our rainfall deficit. WPC has 
retained a Marginal Risk in excessive rainfall outlook for most 
of the forecast area. 

Wind Impacts...Winds will be gusty overnight Sunday night as a 
rather strong low level jet increases during the evening and the 
surface low deepens leading to a rather tight gradient across the 
area. This will allow for winds to get gusty for a time with 
frequent gusts in the 30 to 35 mph range Sunday night. This will be 
just below wind advisory criteria but things could get a little 
blustery and folks may want to consider securing loose outdoor items 
or we might have a few inflatable Santa's thinking they are actually 
flying.

Beach/Coastal Impacts...As with most coastal systems we will likely 
experience the usual gambit of coastal hazards throughout the 
period. Increasing southerly flow over the Gulf waters will allow 
for wave heights to quickly increase. As wave heights increase with 
the southerly fetch, surf heights will climb leading to increased 
threats of life threatening Rip Currents and large waves. Surf 
heights look to climb to 6 to 8 feet with the potentially to 
increase to up to 9 feet depending on how strong the winds get 
offshore Sunday night. Confidence is not quite all there to warrant 
a High surf warning; however, a high end high Surf Advisory 
conditions are likely. 

The final coastal hazard in question is the potential for coastal 
flooding. As winds increase significantly Sunday afternoon and 
Sunday night, this should lead to some minor coastal flooding. 
Current PETSS guidance has a 50th percentile of around 1.6 to 1.7 
feet mean high high water (MHHW) and reasonable worst case or 10 
percentile of around 2.1 feet MHHW in Mobile bay. We usually start 
to see flooding of the Mobile Bay Causeway around 1.7. Therefore, we 
have issued a Coastal Flood Advisory during this time frame to 
include the entire coastline, especially considering the large 
breaking waves on top of a high tide likely leading to wave runup 
and overwash along flood prone barrier islands of the Florida 
Panhandle and coastal Alabama. BB/03 /22

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 406 PM CST Sat Dec 23 2023

A small chance of rain is possible over eastern-most portions of the 
forecast area Monday evening as a post system cold front moves east 
of the forecast area. Northwesterly post frontal flow moves a drier 
and cooler airmass over the region in the wake of the front. A 
series of reinforcing cold fronts move over the region through the
rest of the week in the wake of a series of passing shortwaves 
maintaining the cool, dry northerly flow. The forecast remains dry
through the week. Temperatures quickly drop to well below 
seasonal norms under the northerly flow. High temperatures in the 
upper 50s northwest of I-65 to mid 60s well southeast Tuesday drop 
into the low 50s north of Highway 84 to upper 50s near the coast on 
Saturday. Low temperatures in the mid to upper 40s well northwest of 
I-65 to mid 50s southeast Monday night drop into the upper 20s to 
low 30s north of Highway 84 to near 40 along the coast Friday night. 
Freezing temperatures begin to creep back into the forecast over 
northwestern-most portions of the forecast area Wednesday night, and 
spread increasing south through the end of the rest of the week. 
/16

&&

.MARINE...
Issued at 406 PM CST Sat Dec 23 2023

Winds...Southeasterly to southerly winds will quickly increase late 
tonight into Sunday to Small Craft Advisory criteria, and persist 
through Monday before decreasing and turning northwesterly behind a 
cold front. The strongest winds will likely occur late Sunday 
afternoon through Sunday night as frequent gusts to gale force will 
be possible. Therefore, a Gale Watch is now in effect for that time 
period for our Gulf marine zones. 

Seas...Waves will build late tonight through Sunday evening with 
wave heights climbing to 8 to 11 feet across the Gulf waters. Waves 
in the bays will likely increase to 2 to 3 feet. Waves slowly 
diminish through the week. /22

&&

.PRELIMINARY POINT TEMPS/POPS...
Mobile      56  66  58  72  50  60  40  58 /  10  90 100  40  10   0   0   0 
Pensacola   58  67  62  71  56  63  45  59 /   0  70 100  70  10   0   0   0 
Destin      58  69  63  71  60  68  48  62 /   0  60 100  90  20  10   0   0 
Evergreen   49  67  56  70  50  63  37  59 /   0  50 100  80  20  10   0   0 
Waynesboro  51  65  55  72  44  58  37  58 /   0  90 100  40  10   0   0   0 
Camden      49  66  55  69  47  58  37  56 /   0  50 100  80  20   0   0   0 
Crestview   49  68  58  70  53  66  40  60 /   0  50 100  90  20  10   0   0 

&&

.MOB WATCHES/WARNINGS/ADVISORIES...
AL...High Rip Current Risk from Sunday morning through Tuesday 
     afternoon for ALZ265-266.

     High Surf Advisory from noon Sunday to 9 PM CST Monday for 
     ALZ265-266.

     Coastal Flood Advisory from 3 PM Sunday to 3 AM CST Monday for 
     ALZ265-266.

FL...High Rip Current Risk from Sunday morning through Tuesday 
     afternoon for FLZ202-204-206.

     High Surf Advisory from noon Sunday to 9 PM CST Monday for 
     FLZ202-204-206.

     Coastal Flood Advisory from 3 PM Sunday to 3 AM CST Monday for 
     FLZ202-204-206.

MS...None.
GM...Small Craft Advisory from 3 PM Sunday to 6 AM CST Monday for 
     GMZ630>633.

     Small Craft Advisory from 3 PM Sunday to noon CST Monday for 
     GMZ634>636.

     Small Craft Advisory from midnight tonight to 3 PM CST Sunday 
     for GMZ650-655-670-675.

     Small Craft Advisory from 6 AM to 3 PM CST Monday for GMZ650-655-
     670-675.

     Gale Watch from Sunday afternoon through late Sunday night for 
     GMZ650-655-670-675.

&&

$$

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