Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 011051
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
551 AM CDT Fri May 1 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 322 AM CDT Fri May 1 2015

Dry and tranquil weather is expected today as weak height rises
commence aloft with the departure of the mid Atlantic upper
low/trof and eastward shift in the upper ridge currently centered
in the southern Rockies. The surface high centered in northern IL
will only meander southeast. This will translate to a nice day with
light winds, lots of morning sun, and some thin high clouds in the
afternoon. Temperatures will be seasonable and forecast highs are
a blend of the warmer MAV MOS and RAP 2m temps.

Glass

.LONG TERM:  (Tonight through Thursday)
Issued at 322 AM CDT Fri May 1 2015

The tail end of a weak short wave passing to the north will bring
an increase in cloudiness overnight. The persistent and ever so
slowly retreating low level anticyclone will limit low level
moisture transport/return to the Plains into Iowa. That said the
increase in mid level moisture and warm advection may be
sufficient for spotty showers across parts of northeast MO. While
southerly flow and WAA becomes better established Saturday and
Saturday night in the wake of the slow retreating anticyclone,
trajectories are poor for low level moisture return. Once again
the main impetus for pops will be mid level moisture, WAA,
glancing influence from passing disturbances, and some marginal
elevated instability leading to slight chance pops across parts of
northeast MO and west central IL. The ridge aloft builds east into
the OH Valley on Sunday and the threat of precipitation takes a
decided northward shift to the vicinity of a cold front moving
through the northern Plains and upper MS Valley. The threat of
showers and thunderstorms will progressively increase late Sunday
night into Monday night as the cold front approaches Sunday night
and then becomes quasi-stationary across northern MO and west
central IL Monday into Monday night. By this time the low level
moisture and hence instability is much improved owing to
persistent s-sw lower trop flow and presence of steep mid level
lapse rates. This front then moves back north by midweek leading
to a diminished precipitation threat, which increases again late
week with the development of southwest flow aloft and accompanying
disturbances and continued low level moisture transport.

Temperatures will be above average beginning this weekend and
continuing all of next week.

Glass

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 550 AM CDT Fri May 1 2015

VFR conditions with light and vrb winds anticipated thru the
period. RA can not be ruled out at UIN late tonight. Otherwise, no
precip anticipated at terminals.

&&

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

$$

WFO LSX







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