Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 260904
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
404 AM CDT FRI AUG 26 2016

.SHORT TERM...(Through Tonight)
Issued at 402 AM CDT Fri Aug 26 2016

Region is in SW flow aloft with the area between high pressure along
the E Coast and a broad low amplitude trough across the West. Cold
front has stalled aligned roughly along I-70 as of early this mrng.
The short wave and assoc SFC low will continue to drift east thru
the prd across SErn Canada. S/SW flow thru the column will
eventually cause the bndry to begin lifting back N late
today/tonight. This bndry will once again be the focus for SHRA/TSRA
dvlpmnt this aftn. Best chances appear to be along and N of I-70.
PWATs continue to be near 2 inches...so locally heavy rainfall will
be possible...esp if any training occurs. Also...SPC has locations
along and N of I-44 in MO and I-70 in IL in a marginal risk. A
couple thousand Joules of CAPE coupled with 25-40 kts of 0-6 km bulk
shear support SPC. So...a few strong to possibly severe storms are
possibly with gusty winds the primary threat.


There will be plenty of cloud cover today which should help keep
temps in check...esp N of the bndry. Still expect it to be a warm
humid day S and E of the STL metro area. Should be a decent temp
gradient across the FA. Locations N of the bndry that have
substantial cloud cover may not get out of the upper 70s whereas SE
MO and sthrn IL may get close to 90.

2%

.LONG TERM... (Saturday through Thursday)
Issued at 402 AM CDT Fri Aug 26 2016

Saturday through Sunday night

The cntrl CONUS will remain in SW upper flow with a short wave
tracking along the US/Canadian border. The bndry should either be N
of the CWA by the beginning of the prd or be exiting the nthrn FA
Sat mrng leaving the area under sthrly flow for the rest of the
wknd. The advancing warm front will allow the humid unstable air
mass that has been residing across sthrn MO and sthrn IL to
overspread the entire FA. The unstable air mass should lead to PM
SHRAs/TSTMs. Even though there will be a lack of focus...700mb
temps near 10C will allow at least isld/scttrd aftn/evng
SHRAs/TSTMs to dvlp. PWATs are expected to remain above 1.5 inches
keeping the threat for isolated heavy rain. Temps should be near
avg with highs in the mid/upper 80s with lows near 70.

Monday through Thursday

The week begins with zonal flow aloft with the main belt of
westerlies along the US/Canadian border and transitions to a cntrl
CONUS ridge by Wed/Thu. Needless to say SFC flow remain S/SW thru
the prd with no cold front in sight. Given the same unstable air
mass in place...the fcst really doesn`t change...so still expecting
isld/scttrd diurnal convection. High PWATs mean heavy rain remains a
threat. 850 temps in the upper teens to near 20C correspond to high
temps in the 80s...which is very near seasonal norms. Dps though are
fcst to continue to be in the low/mid 70s keeping a summery feel
going.

2%

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1052 PM CDT Thu Aug 25 2016

Convection continues late this evening between UIN and STL.
A weakening cold front extended from near COU to just north of
STL. This front will likely sag just south of the taf sites by
Friday morning. Much of the current shower and thunderstorm
activity should dissipate late tonight, but more convection may
move into the UIN area late tonight/early Friday morning on the
nose of a modest southwesterly low level jet. Scattered diurnal
convection is expected again Friday afternoon into the evening as
the weak front begins to lift back northward with moist and
unstable conditions. Surface winds will be light late tonight and
Friday morning, then east-southeasterly Friday afternoon.

SPECIFICS FOR KSTL: Convection continues late this evening between
UIN and STL. A weakening cold front extended from near COU to
just north of STL. This front will likely sag just south of STL by
Friday morning. Much of the current shower and thunderstorm
activity should dissipate late tonight. Scattered diurnal
convection is expected again Friday afternoon into the evening as
the weak front begins to lift back northward with moist and
unstable conditions. Surface winds will be light late tonight and
Friday morning, then east-southeasterly Friday afternoon.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     88  73  89  73 /  30  40  50  50
Quincy          81  69  86  69 /  50  50  50  50
Columbia        82  69  86  69 /  40  50  50  50
Jefferson City  84  69  86  69 /  40  40  50  50
Salem           87  72  87  71 /  30  40  50  50
Farmington      86  71  86  70 /  30  30  40  40

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX


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