Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 282046
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
346 PM CDT Sat Mar 28 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 345 PM CDT Sat Mar 28 2015

Quiet weather tonight under shortwave ridging ahead of the next
shortwave trof.  Should see temperatures fall off fairly quickly
this evening under a clear/mostly clear sky and light wind.
However, think the temperature drop will be arrested overnight by
increasing mid and high clouds ahead of the shortwave and also
increasing southerly wind as the surface pressure gradient tightens
ahead of the surface wave. Stuck pretty close to blended guidance
for lows tonight, but those lows may occur a few hours before
sunrise, with perhaps nearly steady or slowly rising temperatures
through 12Z.

Carney

.LONG TERM:  (Sunday through Next Saturday)
Issued at 345 PM CDT Sat Mar 28 2015

Northwest upper level flow will prevail thru Tuesday across our
region, with mostly quiet wx and a pair of weak cold fronts dropping
thru.

The only sensible wx forecast for this stretch is for Sunday, as an
upper level disturbance edges our area to the north and west with
strong WAA on the front-end.  A band or two of showers is expected
to form from this as a result, with the highest probs to the north
and east of STL where likelys PoPs were retained, but more scattered
coverage heading into central MO and the Ozarks.

Otherwise, temps should warm up pretty well Sunday despite clouds
and rain, with at or above MOS for most sites forecasted, which
would result in 50s most areas with low 60s in central MO.

Despite a cold front moving thru late Sunday, temps on Monday are
expected to be warmer with flow already backed from the SW again.
The higher MOS values for max temps favored with decent sunshine
anticipated.

This warming trend should continue into Tuesday with another front
coming down, but not until afternoon.  Did not go as high as the MEX
MOS values, which would have had more confidence in them with a
slightly later FROPA, but nevertheless, went with max temps in the
low 70s for most areas.  There is the potential for a low confidence
shower event late Monday night into Tuesday associated with WAA, but
this is not nearly as strong as the Sunday event.  For now
maintained the dry forecast.

The Tuesday front will then linger thru much of the second half of
the work week as upper flow shifts to more from the W-SW.
Persistent shower and thunderstorm chances will reflect this period
with mild temps.  Some room to go even higher on temps south of the
front Wednesday and Thursday if confidence can be increased in rain
holding off, but very little skill in those specifics this far out.

Temps expected to return to below normal following this wet period
on Saturday with another cold front moving thru and a bit better
cool airmass moving in.

TES

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1236 PM CDT Sat Mar 28 2015

Upper level disturbance which caused some light snow this morning
over central Missouri has moved south of the area and residual VFR
clouds are slowly clearing/dissipating from north to south. Expect
clouds to continue to clear, and VFR flight conditions to prevail
at least through the night. A cold front will drop into the area
on Sunday afternoon. Some guidance is hinting at MVFR ceilings
ahead of the front, but this seems unlikely at this time since the
lower atmosphere is quite dry, and it doesn`t look like there will
be much chance for moisture to return ahead of the front. Wind
will increase from the south-southwest ahead of the front and there`s
some concern for low level wind shear in the early morning around
sunrise. Left out mention for now as wind shear conditions look
marginal, but will pass along to the next shift to re-evaluate
for the 00Z TAFs. Wind will become gusty up to around 25kts by mid
morning.

Specifics for KSTL:

VFR flight conditions will prevail at Lambert at least through
tonight into Sunday morning. Some guidance is hinting at MVFR ceilings
ahead of a cold front Sunday afternoon, but this seems unlikely at this
time since the lower atmosphere is quite dry, and it doesn`t look
like there will be much chance for moisture to return ahead of the
front. Wind will increase from the south-southwest ahead of the
front Sunday morning and there`s some concern for low level wind
shear in the early morning around sunrise. Left out mention for
now as wind shear conditions look marginal, but will pass along to
the next shift to re-evaluate for the 00Z TAFs. Wind will become
gusty up to around 25kts by mid morning. Expect some
isolated/widely scattered showers Sunday afternoon, but little or
no impact to the terminal.

Carney

&&

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

$$

WFO LSX




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