Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KLSX 202028
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
328 PM CDT Fri Oct 20 2017

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 328 PM CDT Fri Oct 20 2017

A weak shortwave will continue to lift northward through forecast
area this evening. However, it remains too dry for any pcpn over
forecast area. Otherwise, mid and high clouds to persist with warm
southerly winds. This will help temps remain a bit warmer with lows
only in the mid 50s to low 60s tonight.

On Saturday, decent low level winds to mix down to the surface. That
in conjunction with tightening gradient, winds to pickup from the
south with gusts to 25 to 30 mph at times, especially over
central/northeast MO. Some explicit models showing
isolated/scattered showers/storms developing ahead of main system,
but confidence is low, so kept forecast dry for now. Further west
over central/northeast MO will see activity associated with main
cold front approach, so kept low pops there by the afternoon hours.
With the gusty south winds, temps to warm up into the upper 70s to
low 80s once again.

Byrd

.LONG TERM...  (Saturday Night through Next Friday)
Issued at 328 PM CDT Fri Oct 20 2017

Period begins with amplified flow as a deep trof approaches the
region and upper ridge struggles to remain in place over the SE U.S.
Models continue to struggle with the approaching trof, but are in
fairly good agreement thru Sun morning. Beyond Sun morning, mdls
develop a cut off low across the srn U.S. at various times and
locations.

The main focus thru this period continues to be Sat night into Sun
morning. A line of storms shud be entering the wrn portions of the
CWA during the evening hours Sat. CAPE is somewhat limited during
the evening hours, but deep layer is sufficient to support strong to
severe storms. With the shear vectors oriented along the front,
expect small bowing segments with wind damage as the primary threat.
Still believe these storms will diminish quickly during the evening
as storms move east.

Cooler temps move in with this cdfnt, with even cooler temps
expected on Tues as a secondary fnt pushes south of the area. Expect
stratocu and isod showers behind the front on Tues as a s/w drops
into the area. The going max temps on Tues may still be too warm.

Models now push the thermal ridge back into the area with swly flow
on Wed and continuing into Thurs. This warmup will be short lived
with another cdfnt pushing thru the area on Thurs night and Fri.


Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1237 PM CDT Fri Oct 20 2017

VFR conditions and south winds to persist through forecast
period. Only issue will be possible LLWS late tonight as winds
just off surface pickup to around 40 kts from the south southwest.
So added mention between 06z and 13z for tafs.

SPECIFICS FOR KSTL:
VFR conditions and south winds to persist through forecast period.
Only issue will be possible LLWS late tonight as winds just off
surface pickup to around 40 kts from the south southwest. So added
mention between 07z and 13z for metro area tafs.

Byrd

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     60  80  63  68 /  10  10  80  80
Quincy          59  79  58  61 /  10  10  90  60
Columbia        61  79  56  62 /  10  10  90  50
Jefferson City  62  81  58  63 /  10  10  90  50
Salem           55  79  63  72 /   5   5  70  80
Farmington      58  78  62  67 /  10  10  80  80

&&

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

$$

WFO LSX


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.