Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 040850
AFDBMX

Area Forecast Discussion
National Weather Service Birmingham AL
350 AM CDT Sat Apr 4 2020

.SHORT TERM...
/Updated at 0339 AM CDT Sat Apr 04 2020/

Through Sunday.

Overall ridging has taken hold of the Southeast and will keep the
region fairly dry through tonight. Temperatures will warm into the
upper 70s/low 80s today with scattered to broken mid to high level
clouds. Clouds linger into the evening hours aloft with lows
dropping into the 50s.

There will be an increase in moisture and clouds on Sunday as a weak
front boundary remains to our west. A disturbance tries to slide
along the front and could result a few diurnally driven showers in
the north and northwest, so included a slight chance of showers here
in the afternoon. With that said it looks like the ridge will hold
firm and keep most of the area dry once again with highs in the
upper 70s to low 80s once again.

16

.LONG TERM...
/Updated at 0339 AM CDT Sat Apr 04 2020/

Sunday night through Saturday.

Ridging builds in across the region Sunday night as the very weak
frontal boundary slides southward into Central AL. The boundary
is really only noticeable in the wind fields as a subtle shift
from light southerly flow to light northerly flow. There`s really
no meaningful gradient in the isotherms or isodrosotherms. Because
of this, I don`t expect much shower activity Sunday night due to
the lack of surface forcing and the presence of upper level
subsidence. Nevertheless, the boundary will become stationary
across the area, and on Monday afternoon, there could be some
afternoon showers/thunderstorms in the northern half of Central
AL, but coverage should be limited.

A weak upper level shortwave lifts out of South Texas and across the
Gulf States on Tuesday as the low level ridging begins to flatten
somewhat. An increase in the low level jet will bring in quite a bit
of moisture out of the Western Gulf of Mexico, leading to PWATs
approaching or exceeding 2.00", which is well above our
climatological max for this time of year. NAEFs picks up on this
anomaly as well, showing PWATs in the 99th percentile and 2-3
standard deviations above the mean. I say this because despite our
forcing being pretty weak as the subtle upper level shortwave rides
over the weak surface boundary, we should see widespread showers and
thunderstorms due to the abundant moisture building in. Some of
these storms will likely produce higher rain rates; however, due
to the quick progression of this system, I don`t expect any
widespread flooding issues.

Also on Tuesday, an upper level cut-off low develops over the
Pacific Coast, which prevents ridging from building in across the
Gulf States behind the departing shortwave Tuesday night. Instead,
we get more zonal flow aloft and another, weaker, shortwave impulse
on Wednesday that will once again increase shower/thunderstorm
activity.

The forecast for the second half of the week becomes even more
muddled as model guidance struggles with resolving when/how the
upper level cut-off low phases back in with the main synoptic waves.
This could occur fairly quickly on Thursday as the GFS suggests, or
it could hold off until Friday/Saturday as the Euro suggests. For
now, I`ve kept a more general forecast for Thursday through Saturday
with 40-50% PoPs with thunderstorms. This system will need to be
monitored for a potential of severe weather as some individual
model runs hint at stronger storms when the main trough finally
does propagate across the CONUS. However, due to substantial
differences in model timing, evolution, and placement of this next
system, I will not add any mention of severe weather in the
hazardous weather outlook at this time.

25/Owen


&&

.AVIATION...
06Z TAF Discussion.

VFR conditions expected for the next 24 hours and beyond with
light and variable winds. Mid and high level clouds will continue
to move overhead but the lower levels of the atmosphere will
remain dry.

Note: ASN will have an AMD NOT SKED for its TAF UFN due to comms
issues.

16


&&

.FIRE WEATHER...

A general warming trend is expected to continue the next few
days. Min RHs will be in the 30-40% range over the weekend with a
gradual increase in moisture for next week. The next meaningful
chance of rain will come next Tuesday, with chances for
thunderstorms continuing through the rest of next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Gadsden     77  54  79  55  81 /   0  10  10   0  30
Anniston    78  55  80  56  81 /   0  10  10   0  20
Birmingham  79  58  81  59  82 /   0  10  10   0  20
Tuscaloosa  81  59  82  59  83 /   0  10  10   0  20
Calera      79  57  80  58  81 /   0  10  10   0  20
Auburn      79  57  80  58  81 /   0  10  10   0  10
Montgomery  81  59  83  59  85 /   0  10  10   0  10
Troy        82  60  83  60  84 /   0  10  10   0  10

&&

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

&&

$$


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