Area Forecast Discussion
Issued by NWS Twin Cities, MN

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235
FXUS63 KMPX 192344
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
544 PM CST Thu Jan 19 2017

.UPDATE...
Issued at 528 PM CST Thu Jan 19 2017

Updated to include 00z aviation discussion below.

&&

.SHORT TERM...(This evening through Friday)
Issued at 330 PM CST Thu Jan 19 2017

Earlier fog that moved slowly northward across eastern Minnesota,
and western Wisconsin, dissipated by the early afternoon.
However, deeper moisture that was evident on regional satellite
imagery, and local observations that had ceilings of 5-6k, was
spreading northward. Where skies were sunny for most of today,
temperatures climbed into the upper 30s to lower 40s. Elsewhere,
where clouds and fog were more prevalent, temperatures struggled to
reach the mid 30s. A few areas in south central/southeast Minnesota
where the dense fog held throughout the day, temperatures only rose
slightly above freezing.

Regional satellite and radar does show an expanding area of light
rain/showers moving into far southeast Minnesota as of 3 pm. This is
the main forecast concern as how far westward the deeper moisture
expands and whether freezing rain occurs in the colder areas of west
central Minnesota, and west central Wisconsin overnight.

Weather models have been very inconsistent with the shallower
moisture which led to temperatures and overall sky conditions
forecast problems today. However, the synoptic scale details have
been consistent on the evolution of the deeper moisture, and
associated upper level energy moving across the eastern forecast
area tonight. This is where both the moisture and lift will
generate an expanding area of light rain/drizzle across southeast
Minnesota before sunset, and northward into east central Minnesota,
and west central Wisconsin this evening. The best lift and moisture
depth remains in western Wisconsin where the best potential of
steadier rainfall is expected.

Although temperatures should remain above freezing, some of the
local terrain could drop to near freezing in west central Wisconsin.
But, the potential of widespread freezing rain is not expected,
therefore, an advisory has not been issued. Cooler temperatures are
expected further to the east into central Wisconsin which has led to
a freezing rain advisory tonight. Otherwise, the area of light rain
will slow lift across east central Minnesota, and west central
Wisconsin northward into central Minnesota and northwest Wisconsin
Friday morning. This is also where the higher chances of
precipitation will occur.

.LONG TERM...(Friday night through Thursday)
Issued at 330 PM CST Thu Jan 19 2017

The longer term continues to show a couple of precipitation
events possible if current model trends hold.

The first event develops as an upper trough lifts northeast into
the cwa. Thermal structure of the boundary layer suggests rain.
Surface temperatures will be critical and there could be a small
threat of freezing rain or possibly some sleet over the far west
into Saturday morning. The GEFS plumes and overall probabilities
show mainly rain Friday night into Saturday with perhaps the
change over to wet snow over the west later Saturday night into
Sunday. The main brunt of qpf appears to roll over the eastern cwa
into Saturday night as the trough/forcing moves through...with
amounts mainly on the light side...generally less than two tenths
of an inch.

The next weather system to affect the region appears to move in
next Tuesday and lingers into Wednesday. It appears to be moving
in a little faster than previous runs. The latest long term CIPS
extended analogue guidance shows a good probability of a snow band
affecting much of the cwa during this period. Models show a
deepening surface low traveling across Iowa into southern
Wisconsin which is a decent path for snow across our area. The 12z
GEFS probabilities are showing a greater than 40% chance of snow
accumulation of greater than 4 inches. There does remain some
small probabilities (generally less than 30%) of a rain/snow mix
in the far southeast cwa early in the period. We will continue to
monitor model trends but models so far have been fairly
consistent with this system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 528 PM CST Thu Jan 19 2017

Plenty of low-level moisture with light southeast winds will
contribute to prolonged IFR-or-worse conditions for all sites
overnight, both for ceiling and visibility. In addition, MSP and
the WI TAF sites may deal with occasional rounds of -DZ or -RA
overnight through the first half of tomorrow. Once conditions drop
to IFR (or worse), conditions are expected to stay as such through
the day tomorrow. Conditions may well drop to worse than currently
advertised but will advertise IFR conditions then amend as needed
to LIFR/VLIFR.

KMSP...VFR conditions to start then conditions go downhill this
evening. Timing will be a little tricky but confidence is high
that IFR conditions will be realized by later this evening and
remain in place through the day tomorrow. Conditions may even drop
to LIFR at times, mainly due to ceilings. Some -RA is possible
overnight through the morning push but is not expected to be
freezing. Nevertheless, conditions in the morning are not expected
to be favorable for high rates.

/OUTLOOK FOR KMSP/
SAT...MVFR/IFR with chc -RA. Winds E 5-10 kts.
SUN...MVFR likely. Winds NW 5 kts.
MON...MVFR likely. Winds NW 5 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...JPC
SHORT TERM...JLT
LONG TERM...DWE
AVIATION...JPC



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