Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 292056
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
356 PM CDT Wed Apr 29 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 330 PM CDT Wed Apr 29 2015

Shortwave over southeast Missouri will continue moving south tonight
while the second wave up over the northern Great Lakes region
likewise dives south into the Ohio Valley.  GFS and NAM are pretty
insistent there will be precipitation on the western side of the
wave as the vortmax chain dives south through Illinois.  This looks
reasonable and there this some light rain already showing up on
radar over southern Michigan.  Kept low chance/slight chance PoPs
going east of the Mississippi river for this evening...tapering off
after 06Z.  Temperatures may be a little tricky between the variable
cloudiness which would tend to keep things a little warmer, and
light northerly flow which should provide a little cool advection
tonight.  Bumped temperatures up a bit over guidance to account for
the increased cloud cover, but generally stuck with lows in the mid
to upper 40s.

Carney

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 355 PM CDT Wed Apr 29 2015

(Thursday and Friday)

Another weak ridge of high pressure will build down across the
Mississippi River while upper level ridging develops aloft.  This
should keep the area cooler than today with little or no chance of
precipitation.  Temperatures near normal highs in the upper 60s to
low 70s with lows mainly in the mid 40s look good.

(Saturday through Wednesday)

Upper level pattern will start to transition to a more zonal flow
over the Midwest over the weekend.  The low level ridge will shift
east over the Atlantic Seaboard which should swing our winds around
to the south-southwest.  Guidance has trended a little drier and a
little further north with the best low level baroclinicity, so I`ve
shifted the chances for precip a bit northward from the previous
forecast, but the flavor is still the same.  Increasing chances for
showers and thunderstorms primarily across northern Missouri into
central Illinois into early next week with temperatures rising above
normal into the upper 70s and low 80s.  Models are advertising
another amplified wave over the western CONUS by midweek.  GFS and
ECMWF do print out some precip over the area on Wednesday, but the
timing of the precip will likely change several times over the next
7 days.  Stuck with mid-high chance PoPs with continuing warm
temperatures rather than some of the higher PoPs recommended by
guidance for Wednesday.

Carney

&&

.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1152 AM CDT Wed Apr 29 2015

Scattered high based diurnal cumulus clouds will continue to develop
across the area this afternoon. These clouds should dissipate
early this evening with loss of daytime heating, but VFR low-mid
level cloudiness will drop southward through IL tonight ahead of
an upper level disturbance. These clouds should impact UIN and the
St Louis metro area tonight. It appears that any showers should remain
east of the taf sites tonight. N-nwly surface winds will continue
through the period as the surface ridge centered over the northern
Plains builds southward into the region tonight.

Specifics for KSTL: Scattered cumulus clouds around 7000 feet in
height can be expected this afternoon. These clouds should
dissipate early this evening, but VFR low-mid level cloudiness
across northern IL will advect southward through STL tonight.
These clouds should shift south-southeast of STL by Thursday
afternoon. N-nwly surface winds will continue through the period.
The strongest wind speeds of 12-14 kts should occur Thursday
afternoon.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     50  68  46  70 /  10   5   0   5
Quincy          45  67  42  69 /   5   5   0  10
Columbia        48  70  45  71 /   0   0   0   5
Jefferson City  48  71  43  72 /   0   0   0   5
Salem           47  64  43  68 /  30  10   0   0
Farmington      44  68  40  68 /  10   5   0   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





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