Area Forecast Discussion
Issued by NWS Twin Cities, MN

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913
FXUS63 KMPX 210355
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1055 PM CDT Mon Mar 20 2017

.UPDATE...For 06z Aviation discussion below

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 313 PM CDT Mon Mar 20 2017

A band of mid and high clouds continues to work across the area this
afternoon with clear skies just to the north.  The clouds continue
showing signs of breaking up and sagging slowly southward, so
central MN will see clearing this afternoon and evening, which may
reach the Twin Cities before dark.

A frontal boundary dropping through tonight will bring a reinforcing
high into the region.  No precipitation expected this period and
skies will become partly cloudy to mostly sunny tomorrow.  A weak
shortwave will ride the upper ridge to our southwest tonight, but
with the high pushing in from the north, dry northerly flow will win
out and prevent any precipitation from reaching southern MN, instead
keeping it all to our south.  Temperatures will be cooler tomorrow
though, with highs in the mid to upper 40s for the most part.

.LONG TERM...(Tuesday night through Monday)
Issued at 325 PM CDT Mon Mar 20 2017

The main long term concern is the timing of the next storm system
and overall temperatures trends.

Initially we have a quiet weather pattern really through
Wednesday night as the large, cool, high pressure system exits to
the east. The deterministic models have been fairly consistent
with the timing of the influx of increased moisture and the
movement of the western conus trough. Best shot of rain moves in
Thursday and exits the area Thursday night. We continued the high
pops trend for this period. Precipitable water values do increase
to over an inch as the upper trough/forcing arrives, so locally
heavy rainfall over over an inch is certainly possible as the
system moves through. The thunder potential does exist as the
warm front lifts close to southern Minnesota Thursday night. The
GEFS probability plots for >500 J/kg cape range around 40%
Thursday night across southern central MN and then trail off into
Friday morning. We introduced slight chance for thunder for now
and see how well the models continue to show this convective
potential.

The models diverge some on how quickly they move this initial
cutoff circulation to the east. The GFS holds onto the moisture
longer than the ECMWF. We will hold onto some lower end chance
pops into Saturday night for this slower model depiction.

The pattern favors a stormier period...with the next southwest
trough moving in quick on the Friday systems heals. This will
bring an another chance for mainly rain again by Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1056 PM CDT Mon Mar 20 2017

VFR through the period with only few-sct high clouds. North-
northwest winds generally at 5-10kts with gusts in the mid/upper
teens on Tuesday late morning & afternoon. Shift to northeast
occurs Tuesday eve.

KMSP...No concerns with high confidence in the TAF.

/OUTLOOK FOR KMSP/
Wed...VFR. Chance MVFR with -RA/-SN late. Wind SE 5-10 kt.
Thu...MVFR with -RA likely in afternoon & night. Wind SSE 10-15
kt.
FRI...MVFR with -RA likely. Wind NE 10 kt.

&&

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

$$

SHORT TERM...SPD
LONG TERM...DWE
AVIATION...LS



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