Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 251829
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
129 PM 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 18z TAFs through 18z Thursday Afternoon)
Issued at 100 PM CDT Wed Mar 25 2015
Busy fcst prd with significant system passing thru the center of
the country. A warm front extends from a sfc low across
panhandles of OK/TX to SE ME and sthrn IL on into OH vly.
Meanwhile...a cold front is currently pushing SE thru IA/KS and
has made it into ntrhn MO. The low will track along the sthrn
front and is fcst to move from the sthrn Plains today to the OH
vly tomorrow. These systems will combine with upper lvl energy to
produce widespread rain and TSTMs across the area from this aftn
thru the night and should be pushing east of the STL metro terminals
by 12Z Thursday. IFR stratus continues to erode to the north early
this aftn....extending from MHL to MYJ to PPQ to 3LF to SLO. KUIN
is expected to be on the edge of the clearing this aftn and CIGs
may not dsspt as CIGs are expected to fill in behind the advancing
cold front. May be too optimistic with CIG fcst for KUIN this
aftn/evng. An area of SHRA/TSMS has dvlp across SE KS/SW MO. This
activity is expected to increase in coverage as it moves NE arriving
in KCOU around 21Z-22Z. Precip is expected to continue to expand
to the NE this evng lasting most of the night along and south of
I44 in MO and I70 in IL. CIGs tonight may be lower than fcst as
models indicate IFR CIGs dvlpng...but held off til a start time
can be better established. Model consensus clears any low CIGs out
around 12Z with skies clearing drng the mrng and NNW winds the
rest of the day.
Specifics for KSTL:
VFR fcst til 00Z...then a several hr prd of possible TSTMs with
persistent rain the rest of the night. Models indicate the CIG
fcst for tonight may not be low enough with IFR CIGs a possibility.
Any low CIGs that dvlp are expected to clear around 12Z with VFR
conditions expected tomorrow with skies clearing drng the mrng and
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 65 40 52 34 / 40 90 20 10
Quincy 55 34 48 28 / 40 60 5 5
Columbia 62 37 52 32 / 70 80 5 20
Jefferson City 69 38 52 33 / 70 90 5 20
Salem 65 42 51 32 / 10 100 40 5
Farmington 71 39 51 32 / 40 100 40 10
MO...FLASH FLOOD WATCH from 7 PM CDT 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 7 PM CDT this evening through Thursday
morning FOR Clinton IL-Marion IL-Monroe IL-Randolph IL-St.
Clair IL-Washington IL.