Area Forecast Discussion
Issued by NWS Twin Cities, MN

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844
FXUS63 KMPX 201819
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
119 PM CDT Thu Apr 20 2017

.SHORT TERM...(Today and tonight)
Issued at 446 AM CDT Thu Apr 20 2017

Today will be a typical cool/damp cloudy day which is more common in
March than in April. The current storm system that was overhead
early this morning, still has a broad circulation across the
Northern Plains and Upper Midwest. With this broad circulation, and
not much of an upstream "kicker", the persistent clouds, light rain,
or drizzle will continue through the afternoon, with the most
predominate area of measurable precipitation across central
Minnesota.

Although some light snow will mix in with the precipitation across
central Minnesota today, no accumulation is expected. However, a
persistent northerly wind will keep temperatures from rising too
much from morning lows. If some sun develops in the far southwest
part of Minnesota, a few 50s are possible. However, the
clouds/drizzle or light rain will keep the rest of Minnesota, and
into west central Wisconsin, holding in the 40s.

Not too optimistic on when the cloud cover will depart later
tonight. If skies clear, especially in western Minnesota, patchy
frost is likely. Further to the east, the cloud cover will hold
temperatures a few degrees above freezing. However, if clouds decide
to leave earlier, frost is possible across the rest of Minnesota,
and into west central Wisconsin. The reason for talking about frost
or even a freeze is because of the vegetation that has develop over
the past week. Some of these plants can take a light frost, but if
we drop below freezing it could affect some of the tender plants. It
would be wise to take your plants in tonight just in case.

.LONG TERM...(Friday through Wednesday)
Issued at 446 AM CDT Thu Apr 20 2017

Friday through Sunday...High pressure will drop in from central
Canada, along an upper level ridge axis oriented NW-SW from the
Dakotas through Ontario province Friday and Friday night. This
will allow for plenty of sunshine along with increased
temperatures as H5 heights increase with the arrival of the ridge.
The dry weather will continue through Saturday due to the deep
ridge still having its influence over the area although the ridge
will become more E-W oriented and drop to the south while the
surface high shifts off to the E. A weak cold front will attempt
to slide SE into the region Saturday night into Sunday morning
from the north but will have trouble making much advancement to
the south due to the existing ridge axis plus developing ridging
to the west. As such, only a sliver of slight chance pops will be
maintained along the northern and northeastern tiers of counties
Saturday night through Sunday night. The mild temperatures will
remain into Saturday into Sunday with highs reaching the middle to
upper 60s.

Monday through Wednesday...A much more active pattern awaits the
start of next week as models depict one compact low pressure
system moving onshore the Pacific NW Sunday will move across the
Upper Mississippi River valley region Monday and Monday evening.
This will be followed by a more traditional Panhandle low from the
OK/TX panhandle region Tuesday night through Wednesday. Though
the chances for thunderstorms look best Monday evening, periods of
showers will be in the forecast for much of the first half of
next week. The passage of the low pressure systems will also
result in a gradual decrease in temperatures through the middle of
next week. Highs will drop back into the upper 40s to middle 50s
by Tuesday and Wednesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1246 PM CDT Thu Apr 20 2017

Low pressure at the surface is over the Great Lakes at this time,
but the upper level trough axis is moving through, with a very
broad cloud shield encompassing most of Minnesota and across the
Dakotas. The ceiling heights across the area are gradually lifting
with increased boundary layer mixing. The HRRR is quite optimistic
that the cloud cover in most of MN and through the Dakotas will
begin eroding later this afternoon. Other guidance is much slower
with this, and I tended toward the pessimistic side as well due
to the thickness and western extent of the cloud cover. There will
also be some gust northwest winds today that become calm tonight
as high pressure develops at the surface as the upper ridge pushes
into the eastern Dakotas. This could lead to the development of
some patchy fog, primarily across central MN where the precip
lingered the longest. Introduced some fog at KAXN but not
condiment enough at any other site to add it at this time. That
can be done during future issuances if confidence increases.

KMSP...Looks like we have already risen above the 017 critical
level, and we should stay above that level for the remainder of
the day. We leaned toward the pessimistic side of the guidance,
but some models indicate a rapid erosion of the cloud cover late
this afternoon could lead to a SCT ceiling prior to 00Z. Doubtful,
but a possibility.

/OUTLOOK FOR KMSP/
Fri...VFR. Wind NNE 5 kts.
Sat...VFR. Wind light and variable.
Sun...VFR. Wind light and variable, bcmg SE 5 kts late.

&&

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

$$

SHORT TERM...JLT
LONG TERM...JPC
AVIATION...SPD



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