Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 241755
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1255 PM CDT Fri Apr 24 2015

.UPDATE:
Issued at 1238 PM CDT Fri Apr 24 2015

Raised high temperatures a tad for mainly southern and northern
sections of the CWA. Otherwise the previous forecast is on track.
Lots of clouds this afternoon and breezy with seasonable
temperatures. Best chance of precipitation will across parts of
central and southeast Missouri...namely spotty to scattered showers.


Glass

&&

.SHORT TERM: (Through Sunday)
Issued at 235 AM CDT Fri Apr 24 2015

Heights continue to rise across the central CONUS as the deep
cyclone that brought a period of cool weather to the eastern half
of the country spins across New England. Meanwhile, a shortwave
located across southern California and Arizona is expected to move
toward and across the region over the next 48 hours.

Warm advection ahead of the system is well underway with a marked
increase in cloud cover over the last 6 hours.  Guidance in good
agreement that at least a few showers will develop this morning, but
confidence in coverage and how far east they will traverse in
question with dry low level air mass still entrenched across the
CWA. Have kept PoPs less than 30 percent today with the highest
values across central Missouri and the eastern Ozarks.  Otherwise,
believe temperatures will be a touch cooler than yesterday due to
the cloud cover with highs in the lower to middle 60s.

Chances of showers and thunderstorms really ramp up tonight as the
storm system approaches. Believe the best time for rapid development
and increase in coverage of preciptiation across the eastern half of
the CWA will occur between 05Z and 09Z. Then a dry slot punches
northeast through the CWA and quickly shifts the focus for rainfall
north and east of the CWA after 10Z. Highest threat of severe
weather has been pushed west across Kansas where best moisture
return will occur along with dry-line interaction.

The shortwave is forecast to become sheared as it moves in an
easterly direction across northern Missouri with the surface low
tracking east-southeast along Interstate 70 on Saturday. Along and
north of the low track, showers and clouds will help keep
temperatures cooler, while in the warm sector the threat of severe
thunderstorms may be realized across parts of southeast Missouri as
temperatures rise into the 70s. Not your typical setup for severe
weather in April, but can`t rule out a few severe storms mainly
south of St. Louis Saturday afternoon.

Cold front sweeps across the remaining CWA Saturday night with rain
ending from north to south. Should see some sunshine on Sunday, but
temperatures will once again struggle to climb back into the 60s
with cold advection taking place.

CVKING

.LONG TERM: (Monday through Thursday)
Issued at 235 AM CDT Fri Apr 24 2015

Temperatures to moderate next week with a dry forecast. Cutoff low
appears to remain south of the CWA Monday through Wednesday with a
large ridge developing across the Rockies by midweek.

CVKING

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1238 PM CDT Fri Apr 24 2015

Multi-layered clouds are occuring across the region at midday with
all sites VFR at this time. A large area of MVFR cigs will advance
into central MO/KCOU later this afternoon, gradually overspreading
the other terminals later this evening. Main precipitation through
mid-evening will be spotty showers with little if any impact. A
better threat of showers and thunderstorms will exist during the
later part of the evening into the overnight hours and this will
be possible in 2 modes. The first being showers and thunderstorms
which orginate in southeast MO and push northeast and then a large
region of showers and thunderstorms which develops in KS late this
afternoon/this evening and moves east-northeast. Flight conditions
will deteoriate overnight with IFR developing and lasting into the
morning hours.

Specifics for KSTL:

VFR flight conditions are expected until later this evening. Any
precipitation during this time period should be sprinkles or
spotty short-lived showers with little if any impact.

Later this evening a better threat of showers and thunderstorms
will exist and it will coincide with the arrival of MVFR cigs.
Showers and possibly thunderstorms which orginate in southeast MO
will move northeast potentially impacting the terminal after
03-04z. Following this first batch, a large region of showers and
thunderstorms which develops in KS late this afternoon/this
evening may move into KSTL after 09z. Flight conditions will
deteoriate overnight with IFR developing and lasting into Saturday
morning. An additional threat of thunderstorms may unfold after
19-20z Saturday however due to the uncertainty will refrain from
mentioning in the current TAF.

Glass

&&

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

$$

WFO LSX





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