Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 050015
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
715 PM CDT Mon May 4 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 345 PM CDT Mon May 4 2015

Focus this prd will be on convection assoc with a frontal bndry that
has stalled just NW of the CWA. There have been plenty of convective
debris clouds today from last nights convection that continues to
thin. A few pesky light showers and/or sprinkles have dotted the
area today...esp across cntrl MO. This activity has dvlpd into a
band of very light rain/sprinkles that arcs from near Columbia north
into NE MO and then NW back into a larger area of SHRAs/TSTMs across
ern NE and wrn IA. This band of sprinkles is fcst to drift east this
aftn and should exit the CWA early this evng. The larger batch of
precip is assoc with a weak wave of low pressure riding NE along the
stalled bndry and a subtle short wave. The upper lvl forcing should
be over nthrn IL/shtrn WI by Tuesday mrng causing the precip shield
over NE/IA to slide east overnight. Guidance indicates that the
areal coverage and intensity should increase thru the evng. SFC
based storms are just beginning to fire along the front across KS.
This is the convection that should eventually impact the CWA. Far
nthrn MO has the best chances of seeing precip this evng into the
overnight since that area is closer to sfc bndry and upper lvl
support though there is some question as to how far south convection
will drift. The threat for this scenario would be if storms can
organize and dvlp a cold pool...then the complex would stand a
better chance of pushing further SE. The SVR threat appears to be
limited due to marginal 0-6/0-8 bulk shear of 20-30 kts...though the
nthrn CWA is in a slight risk. SPC has just issued a SVR TSTM watch
across NE KS and NW MO so convective trends will have to be
monitored this evng. It will be another warm night with continued
sthrly flow and Dps in the mid 50s to near 60...so went aoa the
warmest guidance.

2%

.LONG TERM:  (Tuesday through Next Monday)
Issued at 345 PM CDT Mon May 4 2015

An upper level RIDGE will dominate our region thru Tuesday night
before transitioning into a high-height southwest flow aloft pattern
from Wednesday thru Sunday.  A shortwave TROF will then slide thru
our region late Sunday into early Monday.

Above average temps and moisture will persist thru the upcoming
weekend with at least a small chance for rain most days, culminating
in what should be a widespread rain event associated with the strong
shortwave late in the upcoming weekend.

A bit more detail for the next couple of days...beginning with
Tuesday morning it should be mostly quiet, with a small token chance
for the Quincy area and north approaching what should be the cold
front.  During the course of the day, this small chance probably
won`t change much, but we will also add into it the potential for
isolated SHRA/TSRA for the eastern Ozarks of southeast MO northward
towards I-70 with generally weak surface moisture convergence and no
cap with the added benefit of some lift from the Ozarks as well.
This is expected to dissipate by sunset.

The next couple of rounds heading into Wednesday and Thursday look
to be mostly to the north and west due to the tracks of their
associated disturbances, but should progressively affect more and
more of our region moving towards the weekend as the tracks
gradually become more southerly.

Max temps each day look to be in the 80s with min temps in the 60s.

TES

&&

.AVIATION:  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 639 PM CDT Mon May 4 2015

Primary concern for this evening is convection developing and
moving along the stalled front which lies across northern
Missouri. The best chance for storms will be across northern
Missouri into west central Illinois. However, there is some chance
that the ongoing storms in western Missouri will produce a cold
pool which will move more east than northeast and potentially
impact parts of central Missouri. While this is a possibility, the
more likely scenario is to have the storms move in a more
northeasterly direction until they dissipate later tonight.
Elsewhere and otherwise...expect VFR conditions outside of active
convection. Storms should weaken and continue moving northeast out
of the area through tonight. Isolated convection is possible again
on Tuesday afternoon...though probabilities are too small to
include in the terminal forecasts at this time.

Specifics for KSTL:

Expect VFR flight conditions and south-southwest flow to prevail
at Lambert through Tuesday. The thunderstorms currently over
western Missouri should move east-northeast and stay away from the
terminal. There is and off chance that those storms could produce
a strong outflow boundary which may promote additional development
further to the south, and this could affect Lambert; but the
chance of this happening is small, so have not mentioned any
storms in the TAF at this time. There is a slight chance that an
isolated thunderstorm may move over the terminal on Tuesday
afternoon, but the probability is too low to include in the
terminal forecast at this time.

Carney

&&

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

$$

WFO LSX





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