Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 301930
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
230 PM CDT Thu Mar 30 2017

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 230 PM CDT Thu Mar 30 2017

Severe storm threat is expected to end around 20z for our CWA.

At 19z, occluded/stacked LOW is located over west-central MO with a
triple point LOW located just NW of Litchfield, IL.  A cold front
extends south from this triple point, while a warm front extends to
the east of the triple point.  As the stacked LOW continues to track
eastward thru central MO late this afternoon and combined with the
leftover instability from the heating of the day, could see re-
development of showers with the potential for cold air funnels.

Otherwise, the main focus for pcpn from late afternoon thru Friday
morning will be the pivot axis across northeastern MO and central IL
that will remain quasi-stationary thru early evening and then track
southeastward thru most of the CWA overnight as the LOW moves thru
and pulls away.  Showers will be the result of this with thunder
chances minimal.

Persistent cloud cover will keep temps up a bit tonight but should
still drop into the low-mid 40s, and then with clouds continuing
into Friday, will limit temp rises, with expected maxes in the 50s.

TES

.LONG TERM...  (Friday Night through Next Thursday)
Issued at 230 PM CDT Thu Mar 30 2017

The parade of closed lows will continue to bring a chance of
rain to the area every few days over the next week.   GFS/ECMWF/
Canadian are in good agreement that the upper low over the Ohio
Valley early on Friday morning will move well east of the area by
Friday night and Saturday.  This will bring dry weather to the area
Friday night into Saturday while a ridge moves across the area ahead
of the next upper level low.

The next upper low will drop down into the Four Corners region by
late Friday and then into the central CONUS by Sunday.  While the
global models are showing slightly different solutions with respect
to how to resolve the phasing to the two streams, all agree that
showers and scattered thunderstorms will move into Missouri and
Illinois Sunday into Monday.  Then there will be another dry day on
Tuesday as another upper ridge moves across the area before the next
upper low moves into the area by next Wednesday bringing another
chance of showers and thunderstorms.

GEFS MOS mean temperatures generally favor temperatures close to
normal over the next week.  Temperatures may fall below normal by
late in the period as all of the models are showing 850mb
temperatures falling below 0C behind the system the middle of next
week.

Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1242 PM CDT Thu Mar 30 2017

Triple point low pressure system located just north of STL metro
currently, which separates persistent fog and stratus to the north
from somewhat less to the south. A dry line trough extends to the
south of this low pressure system and is the primary trigger for
TSRA development. This should work thru the STL metro TAFs by
18/19z and should be too far east of COU for inclusion into TAF.
Further north in UIN, rain will persist until about midnight.
This will rain will eventually pivot and edge COU later this
evening and STL metro sites overnight, while also expanding the
IFR CIGs southward as well. Some improvement is expected by Friday
afternoon. Otherwise, surface winds will eventually become W-NW at
all sites once the low pressure system exists tonight.

TES

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     46  54  41  61 /  60  10   0   0
Quincy          40  49  37  57 /  70  10   0   0
Columbia        42  55  39  61 /  50   5   0   5
Jefferson City  43  56  40  63 /  50   5   0   0
Salem           47  53  39  59 /  60  30   0   0
Farmington      45  58  39  62 /  50  10   0   0

&&

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

$$

WFO LSX



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