Area Forecast Discussion
Issued by NWS St. Louis, MO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLSX 250919
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
419 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
70s.

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.

Carney

.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.

Carney

&&

.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1145 PM CDT Tue Mar 24 2015

Showers and thunderstorms to be east of taf sites by 06z
Wednesday. So main issue will be cigs across region as ifr sc deck
slides southeast overnight. Some breaks in overcast, but feel that
cigs will not scatter out til mid to late morning. Some patchy fog
possible as well, so kept mvfr vsby in tafs. During the day today
will see mid and high clouds before next system moves in during
the late afternoon and evening hours. KUIN to be on northern
fringes of precipitation so just have vcnty shower mention there
for now after 02z Thursday. KCOU should see storms move in by 01z
Thursday and STL metro area after 02Z Thursday with better chances
after 05z Thursday. As for winds through the forecast period, west
winds to veer to the northeast late in the day then back to the
north and pickup as system slides along frontal boundary that is
just south of I-70 corridor.

Specifics for KSTL:
Showers and thunderstorms to be east of metro by 06z Wednesday.
So main issue will be cigs across region as ifr sc deck slides
southeast overnight. Some breaks in overcast, but feel that cigs
will not scatter out til late morning. Some patchy fog possible
as well, so kept mvfr vsby in taf. During the day today will see
mid and high clouds before next system moves in during the late
afternoon and evening hours. STL metro area will see precipitation
move in by 02Z Thursday with better chances after 05z Thursday.
As for winds through the forecast period, west winds to veer to
the northeast late in the day then back to the north and pickup as
system slides along frontal boundary that is just south of I-70
corridor.

Byrd

&&

.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

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
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-
     Washington IL.

&&

$$

WFO LSX





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.