Area Forecast Discussion
Issued by NWS St. Louis, MO
FXUS63 KLSX 261835
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1235 PM CST THU NOV 26 2015
.SHORT TERM: (Through Late This Afternoon)
Issued at 316 AM CST Thu Nov 26 2015
Focus continues to be precip chances thru the afternoon.
Expect strong sly winds to continue thru today. A strong swly LLJ is
expected to continue over the region today as well. Mdls continue to
depict broad areas of moisture convergence across the area today.
This is expected to result in light SHRA off and on thru much of the
day. The better chances appear to continue to be across nrn portions
of the CWA. Believe will continue with higher PoPs across this area,
tho expect little accumulation with these SHRA.
That said, the area of more stratiform and somewhat heavier RA shud
be moving into the nwrn portions of the CWA late this afternoon into
the evening hrs.
Another forecast problem for today is temps. While expect extensive
cloud cover across the area, the strong sly flow shud help push
temps warmer. Have trended slightly above the cooler guidance for
.LONG TERM: (Tonight through Wednesday)
Issued at 418 AM CST Thu Nov 26 2015
(Tonight through Saturday )
Not many changes to the prev forecast thru this period. Mdls are in
fairly good agreement and have slowed onset of stratiform precip
this evening. Other main change was to speed up swd progression of
precip tomorrow night into Sat.
Despite this slower onset timing, have kept the Flood Watch as-is
except to extend the watch to 18z Sat. While precip will likely
continue into Sat afternoon, believe the heaviest precip will have
ended, tho a residual flooding threat may linger.
Focus begins to shift to p-type issues late Fri night into Sat
morning, and again late Sat night into Sun morning. As the large
arctic airmass builds into the area, cold air will advect into the
region as precip comes to an end. Have not trended as cold as some
guidance and future forecasts may need to speed up the CAA and pull
the FZRA further swd sooner than the current forecast. There is also
some indication that the low level cold air may be deep enuf that
sleet will also be possible. With sfc temps being warmer, believe
that chances for ice accumulation are low, especially given the low
chance of occurrence. Will need to continue to monitor this time
period and watch trends with future updates.
(Sunday through Wednesday)
Again, not many changes from the prev forecast for this period. The
GEM continues to be a cold soln and have trended twd the warmer
GFS/ECMWF solns. Have continued low PoPs thru Mon due to differences
among mdl guidance. However, it appears all precip shud be out of
the area on Tues.
.AVIATION: (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1212 PM CST Thu Nov 26 2015
Strong and gusty sly surface winds will continue this afternoon.
A strong cold front extending from WI southwest through
northwestern MO into the TX Panhandle will move southeastward
through the taf sites tonight and early Friday morning. While
there may be a few showers ahead of this front, most of the
widespread and persistent rain will occur along and just behind
this front. The front will move through UIN and COU late this
evening and through the St Louis metro area around 12Z Friday with
the surface wind shifting to a n-nwly direction after fropa. The
cloud ceiling will lower as the rain moves, eventually dropping
to around 1000 feet in UIN and COU late tonight and in the St
Louis metro area early Friday morning. A strong s-swly low level
jet will lead to LLWS conditions tonight in the St Louis metro
area with winds forecast at 2000 feet in height of 45-50 kts.
Specifics for KSTL: Strong and gusty sly surface winds will
continue this afternoon. Although there may be a brief light
shower or sprinkle later this afternoon into the evening, the
persistent and heavier rain should hold off until late tonight
then continue through at least Friday morning. S-swly winds of
45-50 kts at 2000 feet in height tonight will lead to LLWS
conditions. The cloud ceiling will drop into the MVFR catagory
late tonight, then down to around 1000 feet by early morning. The
surface wind will shift to a n-nwly direction after a fropa around
.PRELIMINARY POINT TEMPS/POPS:
Saint Louis 70 50 52 39 / 20 100 100 80
Quincy 67 38 39 33 / 60 100 60 30
Columbia 69 39 39 34 / 60 100 90 70
Jefferson City 69 41 42 35 / 50 100 100 70
Salem 65 57 58 42 / 20 100 100 90
Farmington 64 57 57 39 / 20 100 100 100
MO...Flood Watch from 6 PM CST this evening through Saturday morning
FOR Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-
Gasconade MO-Iron MO-Jefferson MO-Madison MO-Moniteau MO-
Montgomery MO-Osage MO-Reynolds MO-St. Charles MO-St.
Francois MO-St. Louis City MO-St. Louis MO-Ste. Genevieve
MO-Warren MO-Washington MO.
IL...Flood Watch from 6 PM CST this evening through Saturday morning
FOR Clinton IL-Madison IL-Monroe IL-Randolph IL-St. Clair