Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 280458
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1058 PM CST Mon Feb 27 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 350 PM CST Mon Feb 27 2017

Surface analysis shows a pair of low pressure centers, both of
which will have some impact on the weather for the WFO MPX
coverage area during the next 30 hours. One low center is over
north-central SD while the second is over northeast CO. Surface
fronts extend nearly E-W from each low, including one that is
draped over southern MN into western WI this afternoon. Aloft, a
generalized zonal flow from WSW to ENE will prevail across the
region, spelling an overall lack of upper level support for
either front as it interacts with a surge of Pacific moisture
moving across the region. The northernmost front looks to nudge
northward, keeping relatively warmer air across the region tonight
into tomorrow. This will mean most of the coverage area will have
low temperatures at or above freezing. The main exception will be
far northwestern portions of the coverage area - mainly far west-
central MN. As precipitation develops overnight, this part of the
coverage area will be susceptible to a wintry mix of light
snow/sleet/freezing rain. Not looking for much at all in the way
of QPF (only a few hundredths) or coverage. That said, the
potential is there for a very light ice glazing along with up to a
couple inches of snow. Each is just shy of hitting criteria for
any supplemental products so have maintain mention in the
Hazardous Weather Outlook. The remainder of the coverage area will
see a mixture of -RA and -DZ, with -DZ being more likely due to
mid-level dry air being entrained between the frontal system to
the north and the one to the south. In addition, some higher
dewpoint air being advected in atop snowpack to the south may
result in patchy to areas of fog over southern and central
portions of the coverage area. The precipitation will linger
through the first half of the day tomorrow then gradually diminish
going into tomorrow evening as the northern low moves into the
Great Lakes and the southern low moves into eastern IA/northwest
IL.

.LONG TERM...(Tuesday night through Monday)
Issued at 350 PM CST Mon Feb 27 2017

After tonights/Tuesday system moves east of our region, the mean
long wave trough will move through the area, which will aid in the
continuation of scattered flurries or light snow from Tuesday
night, and into Wednesday. However, moisture is lacking and upper
level energy is weak. We could get an inch or two, especially in
southwest Minnesota Tuesday night, but nothing to extreme. Another
storm system, moving rapidly to the southeast late Wednesday
night, and into Thursday, is a typical "Alberta Clipper" which
will bring a light dusting on the northeast side of the surface
low. QPF amounts and the relatively weak mid level short wave
associated with this system, should limit snowfall amounts. Maybe
a quick 2-4 inches if the warm air advection regime becomes
stronger than the models appear.

Not too many changes in the extended period, with the coolest air
mass in the next 7 days from Tuesday night, and into Friday. An
upper ridge begins to build across the Upper Midwest by Friday
night/Saturday, leading to temperatures once again rising to above
normal readings for early March. The temperature profile for this
weekend is not extreme, so I don`t anticipate any records.

By late Sunday, and early next week, models diverge on the mean
upper level flow which leads to low confidence on either a warm or
a cooler period/pattern. The EC/GEM are more progressive with a
trough moving across the Upper Midwest, vs. the GFS which is
lagging behind. The GEFS mean 50H flow holds onto the ridge longer
so I did not deviate on temperatures other than the typical
blend.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1058 PM CST Mon Feb 27 2017

Confidence is beginning to wane on the MVFR or lower ceilings
overnight and Tuesday morning as well as on the coverage of the
precipitation. The TAF sites look to be stuck between a new warm
front developing over IA and the old front north of central MN.
Evidence for the ceilings not developing at all are seen in the
NAM and RAP 0.5km CPD`s. The HRRR ceiling forecast shies away as
well. Not totally sold on the idea as the LAMP guidance has hardly
changed this evening on the timing. Therefore, compromised a
little and slowed down the downward trend with the ceilings.
Still feel there will be some light snow Tuesday morning for KAXN.
Better chances for precipitation and MVFR or lower ceilings
develop Tuesday afternoon as the surface winds shift to the north.
In fact, some light snow is now likely for much of the area late
Tuesday night and early Wednesday morning.

KMSP...As alluded to above, confidence is low on the TAF forecast
overnight and early Tuesday morning. Still believe once the wind
begins to shift to the northeast Tuesday morning, MVFR or lower
ceilings will develop along with some drizzle. Also inserted snow
late Tuesday night as an upper trough moves through.

/OUTLOOK FOR KMSP/
WED...MVFR ceilings/-SN likely. Winds NW 5-10 kts.
THU...Chc MVFR/-SN. Winds NW 5-10 kts.
FRI...Mainly VFR. Chc MVFR ceilings. Winds S 5-10 kts.

&&

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

$$

SHORT TERM...JPC
LONG TERM...JLT
AVIATION...RAH



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