Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 081006

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
406 AM CST Fri Dec 8 2017

.SHORT TERM...(Today and tonight)
Issued at 406 AM CST Fri Dec 8 2017

The odd and highly amplified pattern featuring thundersnow in
south Texas and 40 degree temperatures in the Yukon spells
meridional flow here. The wave to watch today is currently located
just west of Hudson Bay. It will dive due south through the day,
bringing a brief round of accumulating snow to the eastern half
of the CWA late this afternoon and early evening. As the snow
begins to arrive, mid and upper levels begin to dry out, leaving a
relatively shallow moist layer. This moist layer, however, is
coincident with the DGZ and the strongest omega which should get
some decent snow showers going. The highest rates should last
maybe an hour or two given the fast motion of the system so 1-1.5
inches can be expected at most.

Further west, the moist layer is even shallower, but again is
coincident with the DGZ while CAA helps steepen lapse rates into
that layer. Such a set up warrants low chance PoPs with little or
no accumulation.

.LONG TERM...(Saturday through Thursday)
Issued at 406 AM CST Fri Dec 8 2017

The trough lifts out Saturday night with temperatures likely
rising overnight into the 20s. Westerly flow will bring a Pacific
airmass in Sunday ahead of another clipper system Sunday night and
Monday. The ECMWF has shifted west again with the stripe of
accumulating snow, favoring the central and eastern CWA
potentially making for a troublesome commute. The rest of the
guidance is further east, more northeastern Minnesota and
Wisconsin. Maintained chance PoPs for most of the forecast area,
highest PoPs in Wisconsin where likelies continue. This one could
bring 2 or 3 inches. Strong CAA on the backside of the system
will likely bring another round of scattered snow showers or
flurries, along with wind gusts of 30 to 40 mph Monday afternoon.

This pattern is expected to persist for at least the next week with
weak disturbances diving southeast across the Upper Midwest. It
remains to be seen whether we will be more on the mild side or
the cold side of these, but with the storm track very nearby most
of the accumulating snow would fall to the north and east.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1231 AM CST Fri Dec 8 2017

No major changes from the previous forecast other than to increase
wind speeds Friday evening. MVFR clouds should slide down from the
north this morning, with snow developing mainly at the eastern
sites later this afternoon. KRNH and KEAU could see IFR/LIFR
visbys as the snow moves through. As mentioned earlier, northerly
wind gusts in excess of 30 kts are possible Friday evening.

Snow should arrive around 22-23Z, but the heaviest snow should be
to the east of KMSP. Overall amounts should be less than an inch.
Look for strong northerly wind gusts Friday evening and overnight.

Sat...Chc MVFR in morning. Wind NW 10G15-20kts.
Sun...VFR. Wind WNW SW 10G15 kts.
Mon...MFVR with chc IFR/-SN. Wind NW 15G25 kts.




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