Scientific Forecaster Discussion
fxus63 klot 251711
Area forecast discussion
National Weather Service Chicago/Romeoville, Illinois
1111 am CST sun Feb 25 2018
1102 am CST
Gusty winds in place today will continue this afternoon, but
diminish soon after sunset. Although an additional slight increase
in speeds may arrive here by midday with better mixing, don't
anticipate them to be as strong as the winds late last night into
earlier this morning. Warm air advection returns on Monday, and with sunny skies
and southwest winds in place, still expect highs in the 50s on
250 am CST
Monday through Saturday...
Fast on the heels of the current system, another northern stream
shortwave trough and associated sfc low will track quickly east
near the Canadian border. The result will be a quick return to
warm air advection, starting weakly late tonight and with move
vigor Monday into Tuesday with a couple of unseasonably mild days
ahead. Sunshine and southwest winds should allow for high in the
low-mid 50s Monday, warming further into the mid-upper 50s Tuesday
on much stronger southwest winds. Both days should feature a good
deal of sunshine.
Temperature forecast is a bit trickier come Wednesday, with
guidance increasingly suggesting a backdoor front will slip south
into northern Illinois which would result in substantially colder
temperatures, especially near the lake as winds flip easterly
behind the front. Have lowered temps significantly from the
blended model guidance which had highs well into the 50s again,
but with winds off the lake, temps would likely be in the 30s near
the lake and 40s inland north of where ever the front ends up.
European model (ecmwf) and GFS continue to be at odds with the strength of the
storm system scheduled to affect the region later Wednesday into
Thursday. The GFS remains much stronger with the system, which at
this point would largely impact the magnitude of the winds, as
both European model (ecmwf) and GFS solutions would favor high likelihood of rain
Wednesday night into Thursday. Hard to say at this distance
whether cold air will arrive in time for a switch over to snow
before precip ends, but at this point operational models do not
look overly worrisome in regards to appreciable snow accumulation
potential (obviously still time for things to change). In the
wake of this mid-late week system look for fairly moderate
temperatures, probably remaining near or a bit above normal.
for the 18z tafs...
Gusty southwest winds will continue this afternoon, but diminish
soon after sunset. Although an additional slight increase in
speeds may arrive here by midday, don't anticipate them to be as
strong as the winds late last night into earlier this morning.
MVFR ceilings will continue to depart to the east over the next
hour, with all locations observing VFR conditions for the
remainder of the forecast period.
251 am CST
A cold front is sweeping across Lake Michigan early this morning
with strong west to southwest gales in its wake. There may be a
few sporadic storm force gusts to 50 kt at times this morning.
Gales will continue across the lake through the morning and taper
below gale force late this afternoon or early evening. High
pressure will build across the Ohio Valley later today and
continue into Monday which will result in a moderate west to
southwest breeze into early Tuesday. Low pressure moving east
across the Canadian prairies on Tuesday will send another cold
front Down Lake Michigan Tuesday evening/night. Another
potentially significant low will develop over the Central Plains
midweek and lift into the Midwest on Thursday. Gales are a strong
possibility, especially on the backside of this system late in the
lmz779 until 3 PM Sunday.
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