Area forecast discussion
National Weather Service St Louis MO
248 am CDT Wednesday may 22 2013
Short term...(through tonight)
issued at 138 am CDT Wednesday may 22 2013
Focus continues to be precipitation chances today.
Given model performance over the past 24 hours...have lower than
normal confidence in forecast for today. To add to this low
confidence...the latest model data suggests thunderstorms and rain should be much more
widespread across southern MO into Arkansas associated with the rather strong
short wave currently rounding the base of the upper low. This short wave still
has the potential to produce some precipitation later this morning if the
low level jet can respond behind the line of convection across the southern US.
Another short wave currently over southern Nebraska is forecasted to round the base of
the upper low later today. This short wave should help initiate isod to scattered
convection this afternoon along the cold front. Believe best chances
will be across southeast MO and SW/S cntl Illinois where low level lapse rates
will be steeper. Any precipitation that develop this afternoon should
dissipate quickly with sunset.
As for temperatures...trended at or below coolest MOS across the northwestern third of
the County Warning Area and near the warmest MOS elsewhere for today. Trended a
little cooler tonight as the County Warning Area will be behind the cold front.
However...did not go too much cooler as cloud cover should help kept
temperatures a little warmer.
Long term...(wednesday through next tuesday)
issued at 314 PM CDT Tuesday may 21 2013
The majority of the precipitation should be east of the MS river
in Illinois or further east at daybreak and continue to move
eastward as the shortwave trough and attendant cold front move east.
Cooler and drier air will overspread the region in the wake of the
front and any additional precipitation threat after middle-morning
should be from isolated diurnal showers. Another secondary cold
front will push through the area Wednesday night ushering high pressure
and even cooler air into the area. This large high will dominate
the area Thursday into Friday.
Not much has changed in the extended ranges of the forecast. An
upper ridge will dominate the central U.S. With the ridge axis
remaining just west of Missouri Sat-Mon. This will place US just
downstream of the ridge crest and subject to weak short waves
topping the ridge. These disturbances combined with return flow
and low level warm air advection on the backside of the retreating low level high
pressure system will bring a prolonged threat of showers and
thunderstorms to primarily the northern half of the County Warning Area from Sat
through Monday night. Thereafter the upper ridge axis moves to our
east...precipitation chances diminish and temperatures warm.
Glass
&&
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1148 PM CDT Tuesday may 21 2013
Recent radar imagery is showing rain developing in far southwest
Missouri that will move northeast and impact the St. Louis metropolitan
taf sites before 12z. A weak storm system will move across northern
Missouri on Wednesday which may bring light showers to KUIN during
the afternoon. Expect many VFR conditions through the period
except for MVFR conditions with showers.
Specifics for kstl...rain developing over southwest Missouri will
move northeast the next few hours and move into the terminal
before 12z. Otherwise...dry and VFR conditions are expected.
Britt
&&
Preliminary point temps/pops...
Saint Louis 56 71 49 72 / 10 10 0 0
Quincy 53 66 46 69 / 10 20 0 0
Columbia 53 70 49 71 / 10 10 0 0
Jefferson City 54 71 50 72 / 10 5 0 0
Salem 57 70 46 70 / 10 20 0 0
Farmington 55 73 47 71 / 10 10 0 0
&&
Lsx watches/warnings/advisories...
MO...none.
Illinois...none.
&&
$$
Weather forecast office lsx
