Area Forecast Discussion
Issued by NWS Huntsville, AL

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634
FXUS64 KHUN 270300
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
1000 PM CDT SUN JUN 26 2016

.UPDATE...
Evening update to public forecast.

&&

.DISCUSSION...
Current short term forecast grids are in good condition this evening,
with no significant changes required in this update. Latest radar
data indicates that remnants of early evening convection continue to
dissipate across Cullman county, and this trend should persist for
the next hour or so. Of more concern, however, is the gradual
development of deeper convective cells across middle TN -- with
indications in satellite data that this regime will expand southward
into northern portions of AL/MS very shortly. Most short term
guidance is in agreement that a subtle mid-level vort max will drop
southward across the region overnight around the retrograding
subtropical high over the southern Plains, and this should provide
sufficient ascent to offset the development of weak boundary layer
CINH. Based on this, we will be increasing POPs a bit and including
the potential for thunderstorms throughout the night, as elevated
CAPE is more than adequate for the development of lightning with the
stronger updrafts. Based on amount of rainfall that was received
today, light flow regime will favor the development of patchy early
morning fog, and this will be included in the forecast as well.
Temps/dewpoints and winds look good, with no adjustments required.

70/DD

&&

.AVIATION...
(Issued 703 PM CDT SUN JUN 26 2016)
For 00Z TAFs: VFR conds currently observed at both HSV/MSL, with
radar indicating no immediate concern for convection at MSL.
Cluster of tsra which recently impacted HSV continues to drift ssewd,
but additional development along outflow may warrant amds early this
evening. Otherwise, expect VFR conds to prevail thru early Mon
morning, with sct to ocnly bkn layers of high-based cu and as. With
both terminals experiencing at least some pcpn today, threat for
early morning br/fg will continue in lgt flow regime, and have
included tempo for 4SM btwn 10-12Z. A more pronounced sw flow will
develop after sunrise, as a prefrontal sfc trough drops swd from the
Ohio Valley. Convection will begin to develop ahead of this bndry by
17Z, with fairly widespread coverage anticipated btwn 19-23Z as
bndry pushes swd thru the region. Sfc winds will shift to nnw by end
of TAF period.

70/DD

&&

.PREV DISCUSSION...
(Issued 703 PM CDT SUN JUN 26 2016)
(Issued 241 PM CDT SUN JUN 26 2016)
Deep layer ridging over much of the region continues to dominate the
overall synoptic pattern. A couple minor perturbations rotating
around the eastern periphery of the ridge in the mid/upper level flow
will help maintain some weak upper level support for scattered
showers and thunderstorms through the beginning of the week. We`ll
finally see a break in the pattern as a trough digs through the Great
Lakes Region and shifts a surface front across the eastern US. Behind
the front, high pressure will reestablish by mid week with drier air
advecting into the area.

For the rest of today and tonight: At the surface at the moment, a
weak and nearly stationary boundary is wedged across much of the TN
Valley. Plenty of moisture and instability is again available this
afternoon to support scattered showers and thunderstorms, with a
couple storms potentially on the strong side. Theta E axis just
south of the area matches up well with a couple area of convergence
along the wedge front across the area helping to maintain and develop
convection this afternoon. Given the current situation, will let the
chance PoP wording (40-50 percent) ride through this evening. While
most convection will be diminishing after sunset, anticipate a couple
showers or a storm to linger along old outflow boundaries through
midnight. With the help of some cloud cover, temps are on track to
peak in the low/mid 90s with apparent temps in the upper 90s to low
100s.

For tomorrow: models continue to depict a weak mid/upper level wave
shifting again through the region. Once again, plenty of moisture and
instability will be available to be tapped into with some upper level
support as evident on model soundings. Expecting better thunderstorm
coverage tomorrow compared to past couple of days and cannot rule out
a severe thunderstorm or two developing during the late
afternoon/early evening hours.

For the rest of the period... frontal passage expected by late
Tuesday with surface ridging building in behind. Drier and slightly
cooler air will establish by mid week. The front itself is expected to
stall south of area and lift back further north later towards the
weekend, helping to increase rain chances.

Barron

&&

.HUN Watches/Warnings/Advisories...
AL...NONE.
TN...NONE.
&&

$$

For more information please visit our website
at weather.gov/huntsville.



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