Area Forecast Discussion
Issued by NWS Birmingham, AL

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FXUS64 KBMX 280900

Area Forecast Discussion
National Weather Service Birmingham AL
400 AM CDT Fri Apr 28 2017

Today and Tonight.

Some patchy fog is possible this morning across our southeastern
counties and other low-lying areas across Central AL. The cold
front that pushed south and east of our area last night will
push northward today as a warm front. Strong southerly warm air
advection at 850mb will move in across Central AL. Some
scattered/isolated thunderstorms can`t be ruled out as the warm
front is pushed northward today. 1000-850mb thickness values are
forecast to be over 1400 meters, which could support temperatures
approaching 90 degrees today. However, expected cloud cover with
the warm front could keep the area from reaching that high. NAEFS
is showing anomalous 850mb temperatures above the maximum
climatologically. therefore, have edged away from MOS guidance and
towards the warmer consensus blends. Rain chances will diminish as
we go into the evening hours as the warm front will be well north
of our area.


Saturday through Thursday.

Strong southerly flow will continue on Saturday as a trough
becomes highly amplified over the southern Plains with a ridge
just east of the Carolinas. High heights over the region will be
associated with very warm and somewhat humid conditions on
Saturday. Most of the area should reach the upper 80s, and some
locations may crack the 90 degree mark. A stray shower or storm
cannot be ruled out with dewpoints expected to be in the mid to
upper 60s.

A similar story is expected for the daylight hours on Sunday as
the trough approaches from the west. Conditions will deteriorate
late in the afternoon and into the evening as a QLCS marches
across Mississippi and into Alabama. Instability in advance of the
QLCS should be confined to a relatively narrow corridor with
SBCAPE as high as 1200 J/kg across our West and slowly diminishing
with eastward extent through the event. A strong low-level jet of
45-60kt will support a potential for brief embedded tornadoes and
damaging wind gusts. Directional shear in the early part of the
event appears rather poor with south-southwest winds at 500mb.
These vectors are expected to become more westerly around 06z
Monday, which could actually enhance the threat across our central
and eastern counties through 12z Monday as the QLCS gains
momentum. For now the best chance of severe weather will be
advertised across the West, but could be expanded eastward.

Dry conditions will return for Tuesday behind the front, but this
may be short-lived as disturbances in the northern and southern
streams combine on Wednesday. We could be looking at an extended
period of rain Wednesday afternoon through Thursday due to the
slow progression of a positively-tilted northern stream trough.



06Z TAF Discussion.

MVFR CIGS and VIS move in for most terminals (except KBHM) tonight
and into the early morning hours as winds become light and
variable or calm. After sunrise this morning, expect winds to pick
up from the south to around 5-10kts and mix out the lower VIS and
begin to lift CIGS. By early afternoon, CIGS should lift back for
VFR through the remainder of the afternoon and evening hours with
southerly winds gusting to 20kts at times. Overall, not confident
in how low the VIS will drop this morning with the BR. Have 3-4 SM
in the TAFs right now, but wouldn`t be surprised to see places
like TOI or MGM drop to 1-2SM. Will monitor and amend as




Rain chances will remain low through Sunday afternoon before
increasing rapidly Sunday night into early Monday. There are no
fire weather concerns at this time.


Gadsden     86  66  88  67  86 /  20  10  20  10  20
Anniston    85  67  88  68  86 /  20  10  20  10  20
Birmingham  87  70  89  70  87 /  20  10  20  10  40
Tuscaloosa  87  69  90  69  86 /  20  10  20  10  60
Calera      86  68  88  69  86 /  20  10  20  10  40
Auburn      84  68  87  69  84 /  20  10  20  10  20
Montgomery  89  69  90  69  88 /  20  10  20  10  20
Troy        87  68  89  68  86 /  20  10  20  10  20




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