(EXTRACTED FROM FXUS63 KLOT 111820)
For the 18Z TAFs...
Sort of complicated forecast this afternoon and evening as low
pressure tracks through the area. The first issue is wind
directions, followed by precipitation type, timing, and duration,
and then focus shifts back to gusty nw winds.
The core of low pressure will pass just to the south of the
terminals, and then spread east of the area tonight. This will
cause SE winds to hold in the 8-11 kt period for a few hours in
the better pressure falls ahead of the low, then as winds shift
further to the E, expect some decrease in speeds. Warm advective
precipitation is attempting to occur farther upstream of the upper
level low across NE IA/SE MN. Expect during the afternoon some
attempt to precipitate over the coming hours, but with drier low
levels expect this would be some light snow or sleet, non
accumulating. As the better forcing approaches RFD around 21-22z,
there could be a brief burst of snow which could put down a quick
coating of snow, possibly even a few tenths of an inch in a short
period. Cigs will fall to MVFR and vsby too, possibly briefly
IFR. As this snow axis shifts closer to the Chicago terminals,
there appears to be some weakening to the stronger forcing, but
there is still a small window for ORD/MDW in the 0z-02z time
frame for a quick coating of snow, medium confidence on timing.
Later this evening there could be a few lingering snow showers,
more so wind driven flurries. CIGS will eventually head back to
VFR. Expect NW winds to exceeds 20-25 kt from a 330-340 direction
after 3z or so at least for a few hours if not longer.
18:58 UTC |
10:58 AM Pacific |
11:58 AM Mountain |
12:58 PM Central |
01:58 PM Eastern