.SHORT TERM... 320 AM CST
...Today through Monday night...
Meteorological winter will enter quite gently as dry and very mild weather, with highs 10-20 degrees above seasonal normals, persists through the weekend under the influence of zonal flow aloft. Friday night and Saturday morning could see a period of cloudiness as a weak shortwave passes aloft, but the more significant weather holds off until later in the weekend or early next week.
By Sunday night a strong low level jet develops over, or perhaps just west of, the area ahead of a longwave trough digging deeply into the western CONUS. The GFS/ECM solutions show a 50+ kt jet at 850mb bringing a warm front through Sunday night and PWATs in excess of an inch from Sunday night through Monday night, which would be at the upper end of the climatological range for this time of year. Forcing from this warm and moist advection could even support thunderstorm chances Monday night, but the more widespread chances of rain and possible TSRA would come Monday evening as a strong cold front swings through the area and brings an end to the mild pattern.
The warmest of these four days appears to be Monday behind the warm front that pushes through Sunday night and ahead of the cold front expected to arrive Monday night.
Lenning
&&
.LONG TERM... 320 AM CST
Long Term...Tuesday through Friday...
A significant pattern change has been widely advertised for next week. Behind a cold frontal passage Monday night, Tuesday highs may only drop to near normal values around 40 degrees but the brisk cold advection will be a shock after this mild spell. A secondary cold front Tuesday night will help temperatures fall further toward midweek with highs only reaching the lower 30s...or less...Wednesday and Thursday. Things of course become less certain at this time range, but Friday could be just a bit milder as models suggest flow could turn back to the southwest for a period. Then again, it could be just as cold as the previous two days if the cold advection persists.
At this point it does not appear that any of these reinforcing frontal passages will be associated with much moisture, so snowfall does not look like a major concern with this first round of cold winter temperatures next week.
Lenning
&&
.AVIATION... For the 12Z TAFs...
Quiet VFR conditions with light winds mainly from the south and southwest.
Lenning
&&
.MARINE... 320 AM CST
Mild and moderate southerly to westerly flow will be in place today into Saturday before relaxing on Sunday, then the primary near-term period of concern for the lake comes Sunday night with strong southerly gales. These winds do not relax much before turning westerly behind a cold front Monday night and persisting as gales into Tuesday.
Lenning
&&
.LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None.
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