Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 251101
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
601 AM CDT Wed Mar 25 2015
.SHORT TERM: (Through Tonight)
Issued at 343 AM CDT Wed Mar 25 2015
Primary focus for today is trying to nail down temperatures.
West-northwest wind behind in the wake of the low currently moving
away from the area will continue pushing the cold front south across
the eastern Ozarks this morning. Meanwhile the wave amplifying over
the eastern Rockies will force another round of cyclogenesis over
northern Texas and the resulting low level circulation will
reinforce southerly flow south of the front. The big question is
how far will the front retreat to the north as a result of this warm
advection. Current thinking is that the front will stay south of
the I-70 corridor across the eastern Ozarks today. Used a blend of
guidance to try to minimize bust potential for temperatures today,
but it ended up being near the warmer MAV for most of the are,
except across far southern zones which should be south of the front
and receive more sunshine than the remainder of the area. Down
there am forecasting temperatures above guidance in the low to mid
Attention turns to late this afternoon and evening when warm
advection will produce another round of thunderstorms. Latest short
range guidance is not very impressive with the instability across
our area. As yesterday evening showed, lack of instability usually
leads to less severe weather than expected... So, with that in mind
think the highest severe thunderstorm threat will likely stay across
far southern Missouri and mostly out of our area. However, models
point a 40-50kt low level jet right at the low level baroclinic zone
right along the I-44/I-64 corridor across Missouri and Illinois.
Tremendous 850mb moisture convergence is the result and models all
print out 2+ inches of QPF . Needless to say, it looks like it`s
going to rain...and rain hard. Flash flood watch still looks good.
Decided to extend it to 12Z Thursday morning as a couple of guidance
members keep precip going in the 09-12Z time frame.
.LONG TERM: (Thursday through Tuesday)
Issued at 418 AM CDT Wed Mar 25 2015
Quieter weather still expected for Thursday through Saturday. May
see some lingering showers over southeast Missouri and southern
Illinois Thursday morning, but cooler and drier air will be building
across the area as the longwave trof digs across the central U.S.
and high pressure builds in behind it. A couple of shortwaves will
dive southeast into the trof Friday night and Saturday night. The
first looks to bring precip mainly to western Missouri but we may
get clipped by the second wave Friday night into Saturday morning.
Precipitation (if any) looks very light, but there could be some
rain/snow mix for a while before temperatures warm up Saturday
morning. Speaking of temperatures, it still looks like they`ll be
10 to 15 degrees below normal Thursday through Saturday as the
Canadian high builds down into the Midwest. A hard freeze still
looks pretty likely Friday morning across northern zones, and across
most of, if not the entire CWFA Saturday morning.
Should see temperatures warm up to near or slightly above normal for
Sunday through Tuesday. Medium range guidance is still having some
trouble coming to a consensus with the passage of a couple of waves,
an resulting light rain/showers. Certainly wouldn`t be surprised to
see a few showers Sunday as a weak front moves southeast through the
area; and then again Monday and Tuesday primarily south of I-70 in
the vicinity of the baroclinic zone where the front stalls. Since
it`s so far out there in the forecast and the signal is so weak,
have stuck to very low chance PoPs.
.AVIATION: (For the 12z TAFs through 12z Thursday Morning)
Issued at 553 AM CDT Wed Mar 25 2015
MVFR to IFR stratus covers much of the forecast area this morning
with a west/southwest wind around 10KT. Scattering of stratus
should occur this morning along the southern edge which will
include KCOU and St. Louis Metro terminals. KUIN looks to have
stratus hold tough with ceiling slowly rising.
Wind will become light by midday and eventually east/northeast as
main frontal boundary estabilishes itself to our south this
afternoon and evening. Showers and thunderstorms are expected to
develop during the afternoon across southwest Missouri and
increase in coverage as they move northeast into central and
eastern Missouri this evening. Lowering and thickening cloud trend
expected with periods of rain overnight. Have forecast MVFR but
IFR certainly possible.
Specifics for KSTL:
Stratus holding its own at this time across terminal, but some
clearing/scattering noted on satellite imagery to the southwest.
Expect some scattering to occur this morning with improving
ceiling conditions. Showers and thunderstorms expected to build
back into the area late this afternoon and evening and continue
overnight. Intial southwest wind will become light and then
northeasterly by this evening. The rain should come to an end by
tomorrow morning with north/northwest wind prevailing on Thursday.
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 65 41 49 31 / 40 90 20 10
Quincy 55 34 45 27 / 50 60 5 5
Columbia 62 37 49 30 / 70 80 5 10
Jefferson City 69 39 51 31 / 80 90 5 10
Salem 65 42 47 31 / 10 100 40 5
Farmington 71 42 48 32 / 40 100 40 10
MO...FLASH FLOOD WATCH from this evening through Thursday morning FOR
Crawford MO-Iron MO-Jefferson MO-Madison MO-Reynolds MO-St.
Francois MO-Ste. Genevieve MO-Washington MO.
IL...FLASH FLOOD WATCH from this evening through Thursday morning FOR
Clinton IL-Marion IL-Monroe IL-Randolph IL-St. Clair IL-