Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 162024
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
324 PM CDT Wed Apr 16 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 233 PM CDT Wed Apr 16 2014

A rather tranquil night is on tap for the area. The surface low
currently in extreme northwest Iowa will move northeastward tonight
and into Wisconsin by daybreak, with the attendant cold front
stretching from northeast MO into west central MO at 12Z. As a
result the surface pressure gradient will weaken this evening. This
along with an end to deep mixing around sunset will result in
quickly diminishing southerly surface winds. Surface winds do remain
southerly all night but due to extensive lower tropospheric ridging
well into the GOM, low level moisture return will be nil and limited
to an increase in mid-hi level moisture. The associated cloudiness
and southerly winds will keep temperatures warmer than last night.

Glass

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 322 PM CDT Wed Apr 16 2014

A weak cold front will move southeastward through our forecast area
Thursday and Thursday night.  The models depict upper level
divergence over our area Thursday and Thursday evening ahead of an
approaching upper level trough.  Moisture and instability will be
limited with this front, but there should still be scattered showers
along and just behind this front Thursday afternoon and night.  The
threat for showers should end Friday morning with a clearing sky as
the upper level trough moves east of the region.  Only slight
cooling is expected behind the front, mainly across northeast MO and
west central IL Thursday afternoon and night.  Temperatures will
warm back up Friday and Friday night as the upper level heights rise
as the upper level trough moves east of our area and as upper level
ridging centered over the southern Plains moves into our area.  Much
warmer, above normal high temperatures are expected on Saturday as
southerly surface/low level flow returns.  The chance of showers
will return to our area Sunday and continue through Monday as a
shortwave approaches and a weak cold front moves southeastward
through our area Sunday night and Monday.  It appears that there
will be more favorable level low moisture and instability present
with this weak front than the front which will move through our area
Thursday and Thursday night and hence a greater threat for showers
and possibly also thunderstorms.  Ony short lived, slight cooling
expected behind this front, then pronounced warming for Wednesday
with an upper level ridge over the region and strengthening sly/swly
surface/low level flow.  The models are forecasting 850 mb
temperatures rising to around 12-16 degrees C by 00z Thursday.

GKS

&&

.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1219 PM CDT Wed Apr 16 2014

The main element to contend with will be surface winds. Southerly
winds will gust to 25+ kts this afternoon, diminishing around
sunset. The wind will slowly and gradually veer to more south
southwesterly during the late night and early morning hours on
Thursday with a wind shift to the west as a weak cold front slowly
pushes across the region. VFR flight conditions will prevail
through the forecast period. Any chance of showers will be beyond
the valid TAF period - Thursday afternoon and evening.

Specifics for KSTL:

The main element to contend with will be surface winds. Southerly
winds will gust to 25+ kts this afternoon, diminishing around sunset.
The wind will slowly and gradually veer to more south southwesterly
on Thursday morning with a wind shift to the west in the mid-late
afternoon associated with passage of a weak cold front. VFR flight
conditions will prevail through the forecast period. Any chance of
showers will be beyond the valid TAF period - Thursday evening.

Glass

&&

.FIRE WEATHER:
Issued at 233 PM CDT Wed Apr 16 2014

20 foot winds are strong and gusty. 10 hour fuel moisture and
relative humidity thus far this afternoon has remained above
criteria for red flag conditions. There are still 2-3 hours left
of potential and I expect that fuel moisture will fall below 9%
and RH will likewise dip at or below 25% in at least parts of the
warning area. Thus we will keep the Red Flag Warning going through
700 pm as scheduled. Conditions will be improved on Thursday with
lighter winds and slightly more moisture along with a cold frontal
passage.

Glass


&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...RED FLAG WARNING until 7 PM CDT this evening FOR Audrain MO-
     Boone MO-Callaway MO-Cole MO-Franklin MO-Gasconade MO-
     Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Marion MO-Moniteau
     MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Shelby
     MO-St. Charles MO-St. Louis City MO-St. Louis MO-Warren MO.

IL...NONE.
&&

$$

WFO LSX






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