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fxus63 klsx 212022 

Area forecast discussion
National Weather Service Saint Louis MO
322 PM CDT Mon Oct 21 2019

Short term... (through late Tuesday night)
issued at 321 PM CDT Mon Oct 21 2019

A strong surface low across eastern Minnesota will slowly lift
northeastward toward Lake Superior by Tuesday afternoon. This will
act to keep a tight pressure gradient across the bi-state region.
Winds will slacken slightly tonight before re-intensifying behind
a secondary cold front which is expected to move through by
Tuesday morning. Sustained westerly wind speeds of around 20 mph
with gusts of 25-35 mph are forecast, with the highest values
across northern sections of the forecast area.

Temperatures are forecast to be seasonally cool through Tuesday
night. Lows tonight should be mostly in the low to mid 40s, with
highs on Tuesday in the upper 50s to low 60s. Continued to lean a
bit toward the warmer mav guidance for highs tomorrow due to deep
mixing and plentiful sunshine across much of the region, though
strengthening low-level cold air advection behind the secondary cold
front will help to offset these factors. Portions of northeast
Missouri and west-central Illinois may also get clipped by the
south/southwestern edge of the wraparound stratus. If this were to
occur and linger long enough during the day, readings in these
locations may end up being a couple of degrees cooler than forecast.
A Crystal clear sky is expected Tuesday night along with lighter
winds as a surface high approaches from the south-Central Plains.
These conditions should be favorable for radiational cooling
resulting in lows several degrees cooler than tonight. Temperatures
Tuesday night are forecast to bottom out in the upper 30s to low 40s
across the area.


Long term... (wednesday through next monday)
issued at 321 PM CDT Mon Oct 21 2019

Models agree better with the evolution of the next cold front on
Wednesday/Wednesday night and its associated surface low tracking
north of the Great Lakes. This front should pass through the region
by Thursday morning. Ahead of this front, temperatures on Wednesday
should rebound back into the mid 60s to low 70s which is near to
slightly above normal. This front is expected to slow its
equatorward progress Thursday and Thursday night and at least some
energy ejecting out of the Southern Plains is forecast to bring a
chance of light rain to the region Thursday/Thursday night. The
deterministic GFS/European model (ecmwf) continue to diverge on how to handle this
aforementioned energy. The European model (ecmwf) for several runs now has closed
this system off before ejecting it out early this weekend. This has
some support from the operational CMC as well. However, the GFS is
more progressive, moving this shortwave trough through the area
Thursday night. Looking at the GFS ensemble members, all of them
behave like the operational run, progressing this shortwave trough
into the Ohio Valley by Friday morning. All this being said,
certainly a low confidence forecast, particularly Thursday night
through Sunday. If the system is progressive like the GFS suggests,
dry and cooler than normal weather would be in store Friday through
Saturday. The ECMWF, with its cutoff low forecast ejecting out on
Saturday, would likely result in milder temperatures along with
another round of rain for this upcoming weekend. For now, leaned
toward the GFS solution based on climatology and high agreement with
its ensemble members but kept a mention of light rain for this
weekend in case the slower, cutoff solution which the European model (ecmwf)/CMC
suggest does indeed verify.



Aviation... (for the 18z tafs through 18z Tuesday afternoon)
issued at 1145 am CDT Mon Oct 21 2019

Cold front has moved through all of the terminals. Any threat of
showers has also moved off to the east along with winds now out of
the west/southwest. Gusty winds will be the main story through
Tuesday morning. Strongest gusts will be this afternoon at kcou
and KUIN with highest gusts near 40 mph. The gusts will subside
tonight but remain up near 20-30 mph across the region. Winds will
veer slightly to the west by Tuesday morning with wind gusts
picking back up by 900-1000 am.

Specifics for kstl:

Any threat for showers or MVFR ceilings has recently moved off to
the east with the passage of a cold front. Winds have veered to
the west/southwest and gusts will likely stay near 30-35 mph
through the afternoon. Gusts will continue overnight, but should
subside more toward 20-25 mph. The primary wind direction will
become more westerly by Tuesday morning along with another uptick
in speed.



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