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Area Forecast Discussion (AFD)

Issued by NWS Birmingham, Alabama (BMX)

                            
000
FXUS64 KBMX 270537
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
1237 AM CDT Thu Jun 27 2019

.UPDATE...
For 06Z Aviation.

&&

.SHORT TERM...

Radar mosaic suggests that the MCV has moved into western 
Georgia, but an extensive arcing outflow boundary extends from 
Cullman County to Lee County, serving as a source of lift for 
continued thunderstorm development. PoPs have been adjusted to 
account for this activity. It's uncertain how much southward 
progress this activity will have this evening as the MCV continues
to push eastward and the outflow boundary encounters a slightly 
drier low-level air mass with decreased MLCAPE, and also 
considering cell motions largely parallel to the outflow boundary 
and a recent weakening trend. Large dew point depressions are 
allowing for gusty winds as the outflow boundary moves through, 
but DCAPE is limited by some mid-level moisture, limiting the 
overall microburst potential.

A larger scale MCV is currently located over southeast MO.
Convection associated with this feature has a westerly component
of motion, and is not expected to impact the area overnight. By
tomorrow, however, the MCV continues to drift southward. Increased
PoPs a bit across the west tomorrow for this reason, and also due
to increased low-level convergence as easterly low-level flow
moves in as low-level ridging strengthens over VA/NC. Increased
DCAPE and mid-level lapse rates suggest some strong storms
tomorrow afternoon as well.

32/Davis

Previous short-term discussion:
This morning, the last push from an overnight MCV in Mississippi 
brought light showers from Tuscaloosa to Birmingham. This activity
has come to an end with a layer of high stratus remaining over 
the area. Highest rain chances this afternoon will be focused in 
northeastern Alabama where outflow and remnant boundaries can be 
viewed on visible satellite imagery supplemented by orographic 
effects. With the high center positioned over southern Mississippi
per surface analysis, thunderstorms will generally progress north
to south this afternoon as winds become more north-northeasterly.
Kept slight pops in through midnight since activity has been 
persistent into the early evening, but expect intensity to follow 
seasonal trends and decrease shortly after sunset. Otherwise, 
heating was slowed this morning by the cloud cover, but a few 
breaks in the clouds have allowed temperatures to catch up and 
warming is back on track. Therefore, no changes to the afternoon 
highs were necessary in this update.

86

.LONG TERM...
Thursday through Tuesday.

A cliche summer pattern will be in place across Central Alabama 
into the long-term with jet stream activity retreating northward 
toward the US/Canada border. Primary upper-level synoptic features
will include the persistent trough/upper-low near the Pacific 
Northwest and a broad, longwave ridge across the eastern CONUS. A 
weak upper- level trough near our area Thursday is expected to 
cutoff from easterly flow and generally rotate westward along the 
base of the ridge, with many mesoscale eddies/MCVs evident in 
vorticity prognostics. It's placement to our southwest and effects
from the ridge will promote little change in our tropical airmass
the next several days. As such, most days will feature afternoon 
diurnally forced showers & thunderstorms as low-level 
destabilization occurs, including sea breeze thunderstorms along 
the Gulf Coast. Afternoon highs in the 80s/90s will continue, with
overnight lows generally falling to the 60s/70s as dewpoints 
remain in that range. Though we're bound to get a strong storm at 
some point during this time, no obvious severe weather threat is 
currently forecast.

40/Sizemore

&&

.AVIATION...
06Z TAF Discussion.

Leftover MCS has moved back into the eastern portions of the 
area. Really only impact this will have will be to keep rain 
chances to the north and south of TAF sites. ANB and ASN could see
a light rain, but restrictions area not anticipated through 12Z. 
Look for generally VFR conditions through the day. There could be 
some convection during the afternoon for the northern sites so 
added in prob30 for tsra at all northern sites through 2Z.

16

&&

.FIRE WEATHER... 

Afternoon high temperatures will be at or slightly above normal 
through the week. Minimum relative humidity values should remain 
in the 40s-50s most areas but some areas in the southeast may drop
into the upper 30s this afternoon afternoon. Rain chances appear 
on most days and in most areas as afternoon showers and 
thunderstorms are expected, but coverage should stay scattered or 
less.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     91  66  90  67  90 /  30  10  20  20  30 
Anniston    92  68  91  68  91 /  30  10  20  20  30 
Birmingham  93  70  92  71  92 /  30  10  20  20  30 
Tuscaloosa  94  70  92  71  92 /  40  10  20  20  30 
Calera      92  68  90  68  90 /  30  10  20  20  30 
Auburn      91  70  90  71  89 /  10  20  20  20  30 
Montgomery  93  70  93  71  92 /  20  10  20  20  30 
Troy        92  69  91  70  90 /  20  20  30  20  40 

&&

.BMX WATCHES/WARNINGS/ADVISORIES/...
None. 

&&

$$