Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 042046
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
346 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 18z TAFs through 18z Tuesday Afternoon)
Issued at 100 PM CDT Mon May 4 2015

The cold front that approached the area last night has stalled
today and is currently aligned from nthrn IL to SE IA to NW MO and
then on into KS. This bndry is not expected to make much more
addtnl progress to the SE today. Pesky -SHRAs have continued to
drift across cntrl MO today with an occnl lightning strike. This
activity should continue to slowly weaken as it works east this
aftn. Another area of remnant SHRAs across cntrl IL will continue
to move away from the area. An expanding area of mainly SHRAs with
isld TSMS across ern NE and SW IA will continue to dvlp and move
east this aftn and into the envg. This activity should be tied to the
bndry which would keep the majority of the activity N of the
terminals...but I do expect KUIN to be impacted tonight and
possibly sooner. KUINs CIGs/VSBYs will be tied to the strength of
the convection...but it is too early to try and pin that detail down
attm. The bndry begins lifting back to the north after midnight
taking the threat of precip with it. The only caveat is if the
convection can get organized and push an outflow bndry SE...and
then the question becomes timing and how far it makes it before
dssptng. Either way Tuesday should be VFR.

Specifics for KSTL:

VFR fcst thru the prd as the nearby bndry should remain too far to
the NW of the terminal to be of any concern. Diurnal cu has dvlpd
once again with plenty of convective debris clouds slowly thinning
thru the aftn. Winds will continue to have a shtrly component.
The only caveat to the fcst is if convection along the bndry
becomes organized and pushes an outflow bndry SE tonight...then
the question becomes timing and how far SE it makes it before
dssptng but not confident enough in this scenario to include attm.

2%

&&

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

$$

WFO LSX




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