Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 021749 AAB

Area Forecast Discussion...UPDATED
National Weather Service Birmingham AL
1149 AM CST Fri Dec 2 2016

For Morning Update and 18Z Aviation.



We have ample sunshine once again today with only a few thin
cirrus to note on satellite. We are warming nicely once again as
our surface ridge center begins to slowly shift from over Alabama
to further to the north with ridging over us beginning to weaken.
Only a few temperature tweaks upward for highs today, but no major
changes to the forecast otherwise.



18Z TAF Discussion.

Surface high pressure will slide to our northeast late in the TAF
period but will maintain VFR conditions through 18z. Cirrus deck
ahead of the next rain system will overspread the area overnight
and lower to 10-12K feet after 12z. A light northerly surface flow
this afternoon will become near calm after 00z and then light
northeasterly after 14z.




Dry conditions are expected today and tonight with relative
humidity values falling into the lower 30s this afternoon.
Widespread showers will return to the area this weekend and remain
in the forecast for the first half of next week.


/Issued 308 AM CST Fri Dec 2 2016/
Today through Saturday.

One more day of dry weather today and tonight as high pressure will
remain over us before sliding to the east on Saturday. As it slides
to the east, an area of rain showers, associated with a disturbance
sliding in from the Gulf Coast, will begin to move closer to the
area. May take a little bit of time Saturday to moisten down to the
surface, so will go will minimal pops in the west through 18Z. Rain
chances go up quickly west of I-65 in the afternoon, while areas in
the east will see a chance closer to sunset.


Sunday through Thursday.

An active southern stream will continue into next week with several
upper level impulses bringing copious amounts of rainfall to
central Alabama. The time periods which look to contain the
heaviest rainfall are during the day Sunday and Monday afternoon
into Monday night. There will likely be a relative lull in the
shower activity Sunday night as a northern stream short wave trof
passes east of the area. Low level easterly flow Sunday and Sunday
night should keep the air mass too stable for thunderstorms. A
surface low will likely form near the upper Texas coast on Monday
and shift rapidly northeast as the main short wave trof ejects out
of northern Mexico. A low level jet will develop across the
central Gulf coast states with 60+ surface dewpoints pushing into
south Alabama Monday afternoon. The GFS model is more aggressive
with the inland surge of higher dewpoints than the ECMWF, and its
convective parameters are higher with regards to CAPE and lifted
indices. The GFS model would produce a minimal threat of severe
storms to the far southern counties Monday afternoon and evening,
but will hold off mentioning severe wording in any of our hazard
products due to more stable ECMWF model. The final push of
showers and storms will be Monday night with the rain exiting east
Alabama Tuesday morning. Because this system originated so far
south, there is no big change in air mass and highs Tuesday and
Wednesday will be in the 60s.

A strong cold front will arrive on Thursday accompanied by a pre-
frontal band of showers. The ECMWF model is much slower with the
passage of the cold front, so confidence is low regarding best
chance of rain and temperatures on Thursday, but the coldest air
of the season will arrive Thursday night and Friday.



Gadsden     61  34  55  44  51 /   0   0  30  90  90
Anniston    61  37  56  46  52 /   0   0  30  90  90
Birmingham  61  39  56  47  53 /   0   0  40  90  90
Tuscaloosa  63  39  56  47  54 /   0   0  60  90  90
Calera      62  39  57  47  55 /   0   0  40  90  90
Auburn      62  40  60  47  56 /   0   0  30  70  90
Montgomery  65  40  61  51  60 /   0   0  40  70  90
Troy        64  39  60  51  62 /   0   0  30  40  80





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