Area Forecast Discussion
Issued by NWS Twin Cities, MN

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312
FXUS63 KMPX 272017
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
317 PM CDT Mon Mar 27 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 315 PM CDT Mon Mar 27 2017

Regional visible satellite imagery indicated a fine line of low
clouds, mixed with fog/drizzle in portions of west central
Wisconsin, and south central Minnesota, had slowly eroded along
the northern edge this afternoon. Temperatures under the denser
cloud cover only managed to rise into the 40s, compared to the mid
to upper 50s where sunshine was abundant in the west and central
part of the state.

The main concern overnight is the relatively light winds in the
boundary layer, coupled with abundant moisture near the surface,
to lead for areas of fog to form. HRRR, and other models that
have a visibility parameter, do indicate an expanding area of fog
in south central/southeast Minnesota this evening. The only
parameter that makes things more unlikely for dense fog to form is
the current cloud cover. This area needs to be watched for the
possibility of a dense fog advisory if conditions warrant.
Elsewhere, patchy to areas of fog are likely, but not as
widespread as in the southeast part of the state. Therefore, I
have continued the trend of widespread fog south and east from
Mankato to Red Wing. Any fog that forms overnight should dissipate
by mid morning Tuesday with more sunshine likely by the afternoon
than today. Temperatures should reflect more sunshine with highs
in the 50s, to lower 60s.

.LONG TERM...(Tuesday night through Monday)
Issued at 315 PM CDT Mon Mar 27 2017

The atmosphere is caught in a repeating pattern with a highly
amplified trough that digs over the west coast. Eventually this wave
becomes cut off from the main flow as a northern stream ridge breaks
onshore the Pacific Northwest. The cresting ridge sends the northern
stream jet along the International border, leaving the Midwest in a
split flow regime.

No significant changes from the previous forecast. Model trends
continue to show the precipitation being centered over Iowa and
Wisconsin for Wednesday and Thursday. Still have chances for rain
across the far southeast part of the forecast area, but any rain that
does occur will only amount to a few hundredths of an inch.

That`s about it for precip chances over the next 7 days for the
Upper Midwest. the 7-day rainfall total off from the Weather
Prediction Center has a dry area over much of the NWS Twin Cities
forecast area, and based on the 27.12 GFS/GEM/ECMWF have little
evidence to disagree with that forecast. Temperatures will continue
to be around 5 degrees above the seasonal average for late March
heading into early April.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1225 PM CDT Mon Mar 27 2017

MVFR cigs affecting parts of southern Minnesota, and west central
Wisconsin will be the main aviation concern as
timing/dissipating this afternoon remains questionable. Based on
drier air advecting southward, and remnants of boundary layer
moisture holding near KEAU, the general trend of better conditions
by mid/late afternoon remains likely. Otherwise, later tonight
low clouds/fog will likely reform in south central/southeast
Minnesota and slowly spread east/northeast across eastern
Minnesota. Depth of the moisture remains shallow so only expect
some FG/BR for the most part during the typical morning hours
outside south central/southeast Minnesota and west central
Wisconsin. Winds will remain light from the north/northeast, and
more east Tuesday morning.

KMSP...

Main aviation concern is possible BR later tonight as boundary
layer moisture remains high, whereas mixing in this layer remains
weak. Based on overall trends, 4-5SM BR is likely during the pre
dawn hours. MVFR cigs will likely remain southeast of the
terminal, but close enough for later shifts to watch and possibly
adding to the taf. Winds will remain weak /under 8 kts/ from the
north/northeast this afternoon, and more east Tuesday.

/OUTLOOK FOR KMSP/

Wed...VFR. Chc -RA late. Wind ESE at 7-10kts.
Thu...VFR. Chc -RA. Wind E at 8-10kts.
Fri...VFR. Wind NE 4-8kts.

&&

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

$$

SHORT TERM...JLT
LONG TERM...JRB
AVIATION...JLT



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