Area Forecast Discussion
Issued by NWS Birmingham, AL
FXUS64 KBMX 232118
Area Forecast Discussion
National Weather Service Birmingham AL
418 PM CDT Sun Apr 23 2017
The strong cold front has just exited into Georgia. A few
lingering showers were located from near Phenix City to near
Eufaula and these will soon exit into Georgia too. The latest
Water Vapor Imagery has the upper low spinning over western
Tennessee and far northern Mississippi and this low will continue
into Alabama overnight. As this low moves overhead, kept a small
mention of showers in overnight and into Monday. If you receive
any rainfall, it will barely be measurable. With the cloud cover
and cold air advection, overnight lows will be near 50 degrees.
Slightly warmer tomorrow with highs bouncing back to near 70.
18Z TAF Discussion.
Variable conditions expected across Central Alabama the next 24
hours. Dominant conditions should be MVFR to IFR ceilings. A
strong cold front was still near the Georgia state line early this
afternoon. It appears that the thunder will remain east of all
terminals. Widespread MVFR ceilings cover Alabama, but with a few
breaks, some areas have risen to VFR. With the low level moisture
in place, clouds should fill back in but ceilings will vary by
location. After sunset, the upper low inches even closer and
expect the clouds to completely fill back in and low eventually to
IFR by 10-12z.
Very small rain chances tonight into Monday as an upper low moves
overhead. Northerly flow persists Monday before shifting back
from the south on Tuesday. Critical fire weather conditions are
not expected at this time.
/Issued 341 AM CDT Sun Apr 23 2017/
Today and Tonight.
The surface front has pushed to near the I-65 corridor. Mid-level
water vapor imagery shows high levels of moisture across central
Alabama, with a closed upper low centered over the Missouri Bootheel
and southwest flow over the Gulf Coast Sates. This moist pattern
will continue through tonight as the upper low is forecast to track
southeast into north Alabama tonight. The best chance for rain today
will be along and east of I-65, just ahead of low level boundary.
The majority of the precipitation today will be in the form of
showers. Instability does increase later this morning over the
southeast counties as the surface front approaches this area, and a
few thunderstorms possible. The thunderstorm threat should end by
noontime today as the cooler low level air mass behind the front
overspreads east Alabama. Forcing associated with the proximity of
the upper low will result in a few light showers overnight, mainly
near and just east of the upper low track.
Temperatures will be noticeably cooler today with readings not
changing much during the day due to cold air advection and cloud
cover. Would expect little or no sunshine today due to cool cyclonic
flow around the upper low. Highs will range from the upper 50s in
the northwest counties to near 70 in the southeast. The low clouds
will remain across the area through tonight.
Monday through Sunday.
The low pressure system moves eastward into the Carolinas on Monday.
Continued northerly flow will advect a cooler airmass over Central
AL with daytime highs on Monday could reach a few degrees below
normal for this time of year. The system shifts further east on
Tuesday as upper level ridging builds in ahead of a deepening trough
in the Plains. This will shift the winds back from the south leading
to a warming trend for the rest of the week.
A surface low develops in the Southern Plains on Wednesday and moves
northeastward into the Great Lakes through the day, stretching a
cold front down through the Mississippi River Valley. Previous model
runs have flattened this front out and kept it north of our area;
however, latest runs bring the cold front down through Central AL as
the trough becomes negatively-tilted on Thursday. Both the GFS and
ECMWF are in decent agreement on the 00z runs with the cold front
moving through on Thursday with >2000 J/kg environmental
instability. Models disagree on where the better shear lines up,
with the EC bringing the better shear further south into Central
AL while the GFS keeps it across our northern counties and not
overlapping with the better instability as much. Both models show
the best upper-level support remaining north and west. For now,
will hold off mentioning any severe threat in the HWO. I would
like to see how models trend over the next day or to see if
there`s any run to run consistency.
Upper level ridging builds back in Friday into Saturday as models
hint at a deepening trough over the Western US. A surface low
develops in the Southern Plains Saturday morning and tracks north-
northeastward through the Upper Midwest through the day on Saturday
and stretches another cold front down through the Mississippi River
Valley. Timing and details are still uncertain with this system as
it is just beyond the extended forecast period.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 51 69 51 82 54 / 30 20 0 0 0
Anniston 52 72 53 82 56 / 30 20 0 0 0
Birmingham 53 73 56 84 59 / 20 20 0 0 0
Tuscaloosa 52 74 53 84 58 / 20 0 0 0 0
Calera 52 73 56 83 58 / 20 10 0 0 0
Auburn 52 71 56 80 58 / 20 10 0 0 0
Montgomery 52 76 56 85 58 / 10 10 0 0 0
Troy 50 73 53 84 57 / 10 10 0 0 0