Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 311815

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
115 PM CDT TUE MAY 31 2016

.SHORT TERM...(Today and tonight)
Issued at 330 AM CDT Tue May 31 2016

A band of showers and decaying thunderstorms across western
Minnesota will continue tracking east this morning. Lightning
activity has decreased significantly in the last couple hours with a
stabilizing atmosphere. Still, a large area of moderate rain will
make for a wet morning across the county warning area. The rain will
likely break up across eastern Minnesota and western Wisconsin later
this morning.

Surface low pressure currently over southeastern North Dakota will
lift north then retrograde westward along the Canadian border this
afternoon. This will slow the cold front`s eastward progression into
Wisconsin, and as the atmosphere destabilizes again, a regeneration
of showers and thunderstorms from south central Minnesota to western
and northern Wisconsin is expected. The greatest chance will be east
of a line from Fairmont, to Mankato, St Paul, and Mora. The main
threat with these storms will be heavy rainfall from training cells
and seasonably high pwats around an inch and a half. The activity
will linger well into this evening across western Wisconsin while
the dry slot brings clearing skies to the west.

.LONG TERM...(Wednesday through Monday)
Issued at 330 AM CDT Tue May 31 2016

Longer term issues are timing of frontal exit wednesday morning
and wraparound shower potential over the northern cwa wednesday.
then development of next trough Thursday night/Friday with
cooling trend lingering into the weekend.

Initially...deterministic runs suggest front will have exited the
cwa by by 12z wednesday. Threat of instability showers under the
upper low continues and will hold any pop mainly along and north
of I-94. Cooler air drops into the area wednesday along with lower
clouds. This is expected to limit overall warming during the day
with highs struggling to warm through the 60s in the cloudier
northern cwa. Clearing trend is expected Wednesday night with
surface high spreading into the west. Winds should diminish and
with cool overnight lows.

Return flow and waa patten ahead of the nest trough will develop
mid clouds and the threat of showers/thunder Thursday night. We
confined the threat to mainly along and south of the MN river
valley for now. Both the GFS and ECMWF drop the next trough into
the region Friday and Friday night. Timing of trough brings the
system into the cwa during the day Friday...during peak heating.
Model instability increases modestly along with deep layer appears there will some threat of strong/severe storms
Friday into Friday for the area.

Following the front...the upper low develops over the great lakes
region. The GFS has trended like an earlier ECMWF run...more
amplified and slower moving the closed low east. Both suggest
chance of showers/thunder both days as the system exits slowly to
the east. The below normal temperature trend should linger into
early next week.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 115 PM CDT Tue May 31 2016

At 1730z, the cold front extended from about Waseca to St. Paul,
with thunderstorms rapidly developing along it from central IA
into wrn WI. The field that looks to have the best shot at
getting a TSRA is EAU, and here, with the HopWRF and HRRR showing
a line of storms working through EAU around 22z, felt confident
enough to go with a prevailing TSRA between 2130z and 2230z. For
RNH/MSP any activity looks to be more scattered in nature at these
locations, so maintained nothing more than VCTS. LAMP winds have
not had enough of a west component to them behind the front, so
followed the HRRR forecast with winds. Wednesday, sfc low over
north central ND will continue to fill as it moves across the
Canadian border. CU rule supports a BKN-OVC cu/sc field developing
area wide Wednesday morning. As for chances that cloud field will
be MVFR or VFR, MVFR is likely for AXN, possible for STC, and
unlikely for everyone else.

KMSP...The HRRR had been supporting storm development over the
western Twin Cities, but with front already east of MSP, TSRA
chances will be better east of the field. Still, expect some TSRA
nearby for the first hour or two, so left the VCTS in. The HRRR
has had a better handle on wind direction than the LAMP, so
followed it for the wind forecast. Expect the cu field to rapidly
develop after 13z Wednesday. Likely starting out near 3k ft, but
quickly working toward 5k ft for the afternoon.

THU...VFR. Winds WNW 5-10 kts.
FRI...VFR. TSRA likely with chc MVFR. Winds S 5-10 kts.
SAT...MVFR likely. Chc -shra. Winds NW 10-15 kts.


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