Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 012011

311 PM CDT Mon Sep 1 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 310 PM CDT Mon Sep 1 2014

Heavy rain threat is the primary forecast challenge for tonight.
Another shortwave is moving east-southeast through the longwave
pattern over the Great Plains.  This shortwave will trigger a
south-southwesterly low level jet to increase again this evening,
aimed right at the low level baroclinic zone left over from last
night`s storms.  With plenty of moisture in place over the area and
a baroclinic zone that`s parallel or nearly parallel to the mid
level flow, expect that thunderstorms will form and train over parts
of Missouri and Illinois this evening and tonight.  All short range
guidance shows a tremendous amount of moisture convergence on the
nose of the low level jet tonight...generally along and south of the
I-70 corridor.  Think the axis of heaviest rain will actually be
along and south of the I-44 corridor in Missouri and along and south
of I-70 in Illinois, but I cannot rule out heavy rain a little
further north either.  QPF forecast paints a swath of heavy rain
along this axis between 1.5 and 2 inches.  With the potential for
locally higher amounts, and flash flood guidance running around
2-2.5 inches per hour, will go ahead and issue a flash flood watch
for those areas.  Further north across northeast Missouri and west
central Illinois, there could be some widely scattered/isolated
showers and thunderstorms, but I don`t think these will train and
cause any flooding issues.


.LONG TERM:  (Tuesday through Sunday)
Issued at 344 AM CDT Mon Sep 1 2014

The front and/or effective boundary should linger across the
region on Tue/Tue night before lifting northeastward as a warm
front on Wed/Wed night. The precipitation threat will also lift
northeastward with the warm front during the middle of the week.
Model solutions then depict a cold front moving into the area
towards the end of the week and into next weekend, bringing a
chance of rain and a cooler air mass into the region.



.AVIATION:  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1238 PM CDT Mon Sep 1 2014

Expect VFR flight conditions to prevail through much of the
afternoon. Scattered light showers will continue through the early
afternoon across parts of southeast Missouri. West to southwest
wind will gust to around 24kts. Expecting thunderstorms to
redevelop somewhere over west central or southwest Missouri later
this afternoon and spread northeast into parts of central and
eastern Missouri and southwest Illinois this evening. Storms will
likely train along and south of the I-70/I-44 corridor tonight
producing IFR conditions in heavy rain. Storms should move south
and begin to dissipate between 08-12Z.

Specifics for KSTL:

VFR flight conditions are expected to prevail this afternoon at
Lambert. Latest thoughts are that thunderstorms will develop over
southwest/west central Missouri and spread east-northeast into
eastern Missouri by early this evening. A prolonged period of
thunderstorms with occasional heavy rain will likely impact the
terminal during the mid-late evening. Storms should move south of
the terminal between 06-11Z; timing is uncertain at this time.
After storms exit the STL Metro area, expect MVFR CIGs to rise to
VFR during the morning.



Saint Louis     72  87  71  90 /  90  20  20  40
Quincy          65  83  66  88 /  20   5  10  40
Columbia        68  87  68  91 /  80  10  30  40
Jefferson City  69  87  69  91 /  90  20  30  40
Salem           71  85  68  88 /  90  50  20  30
Farmington      72  85  68  87 /  90  50  30  40


MO...FLASH FLOOD WATCH from 7 PM CDT this evening through Tuesday
     morning FOR Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Iron MO-Jefferson MO-Madison MO-Moniteau MO-Osage MO-
     Reynolds MO-St. Charles MO-St. Francois MO-St. Louis City
     MO-St. Louis MO-Ste. Genevieve MO-Warren MO-Washington MO.

IL...FLASH FLOOD WATCH from 7 PM CDT this evening through Tuesday
     morning FOR Bond IL-Clinton IL-Fayette IL-Madison IL-Marion
     IL-Monroe IL-Montgomery IL-Randolph IL-St. Clair IL-
     Washington IL.



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