Cottage Grove, Minnesota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

228
FXUS63 KMPX 182026
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
326 PM CDT Wed Jun 18 2025

.KEY MESSAGES...

- Scattered showers and thunderstorms through early evening
  across southern/eastern MN and WI.

- Thunderstorm complexes capable of heavy rain, damaging winds,
  and large possible during the overnight hours Thursday and
  Friday. The best chance Friday night will be north of I-94.

- Hot and very humid this weekend with heat indices above 100
  degrees. An Extreme Heat Watch will be issued shortly.

- The active weather pattern continues next week with the
  potential for heavy rain.

&&

.DISCUSSION...
Issued at 326 PM CDT Wed Jun 18 2025

Scattered thunderstorms have developed along a line extending
from Mora to Redwood Falls. A few other isolated cells are also
developing in advance of the line. None of them are particularly
strong, but do contain heavy rainfall. Activity will settle
southeast early this evening and should dissipate after dusk.
The rest of the night appears quiet and dry, with lows in the
upper 50s and lower 60s.

The active pattern continues for Thursday and Friday ahead of
intense heat and humidity for the weekend. West northwest mid
level flow with embedded disturbances will track from the
northern Plains to Great Lakes through Friday night. A warm
front will be set along the I-94 corridor Thursday. The front
will be the main foci for thunderstorm development during the
day, but a strengthening 40-50 kt LLJ should bring development
into the warm sector Thursday night. Moderately steep mid level
lapse rates (6-7 C/km) and 40-50 kts of deep layer shear could
give enough support for a few severe storms capable of large
hail and damaging winds. Otherwise, scattered to numerous
showers and thunderstorms are expected. By Friday morning,
convection should be dissipating with the veering of the
nocturnal LLJ to the east. By afternoon, a redevelopment of the
LLJ should occur and will strengthen markedly to 50-60 kts
Friday night. The nose of the jet will focus across central or
northern MN. In addition, as the hot and humid airmass begins to
work in, 700 mb temperatures could exceed +15C as early as late
Friday afternoon south of I-94 and greater than +17C area wide
by early Saturday morning. This points to significant capping
(+12C at 700 mb is a typical subjective isotherm to determine if
convection is supported or suppressed). With the nose of the LLJ
to the north and unfavorable 700 mb temperatures across the
southern half or two thirds of MN, the better bet is for any
thunderstorm development to remain across northern MN Friday
night. If an intense MCS can develop and track eastward on the
periphery of the ridge, there`s an outside chance it can
penetrate deeper into the more unfavorable area, but chances
remain quite high the southern end of it will remain north of
I-94.

The airmass set for this weekend is quite impressive. The
strength of the ridge across the Ohio Valley will lead to
climatologically extreme heights and temperatures aloft across
parts of the Great Lakes and Upper Midwest. 850 mb temperatures
are expected to reach +25 to +27C with 925 mb temps of +28C to
+31C. This type of airmass could support highs in the mid 90s to
low 100s. In addition, dew points in the mid to upper 70s will
significantly raise the risk of heat illness. Heat indices of
100 to 110 are becoming increasingly likely. Further, gusty
winds Saturday night with dew points remaining in the upper 60s
to lower 70s will keep low temperatures well into the 70s or
even low 80s. An Extreme Heat Watch will be issued shortly for
the whole region Saturday afternoon into Sunday evening. Because
this will be the first hot and humid airmass of the season and
the conditions will be climatologically impressive, this will be
a particularly hazardous event. It should be noted the airmass
will start moving in late Friday and lows Friday night will also
be well into the 70s barring any significant convection. A Heat
Advisory may also be necessary for parts of the area Friday
afternoon through Saturday morning until the watch takes effect.

A cold front will push through Sunday night as a shortwave
breaks down the northwestern portion of the large ridge. The
ridge will keep southwest flow over the Plains and Upper Midwest
and won`t allow the front to stray too far southeast. Continued
moisture advection along the boundary and favorable jet dynamics
will mean repeated rounds of showers and thunderstorms early
next week. There is some uncertainty where the boundary will
stall, but generally southern/eastern MN and WI stand the best
chance at heavy rainfall totals through midweek. If the ridge is
a bit stronger than forecast, then this could shift northwest
some. One thing that seems more certain will be a significant
cool down, especially with post frontal showers and storms next
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1258 PM CDT Wed Jun 18 2025

Mainly VFR conditions today, but there will be scattered
MVFR/IFR showers and thunderstorms across the region. For now,
have a Prob30 during the afternoon/evening when the storms will
be most widespread. Heavy downpours are the main threats, but
could have localized gusty winds and small hail with any storms.
These will diminish toward sunset and fall apart overnight.

KMSP...
Mainly VFR conditions, but could have some showers/thunderstorms
near KMSP this afternoon. Most likely time frame is 21-24Z this
evening, but they could last beyond that before diminishing
around sunset. Winds will be light and primarily out of the
northwest to southwest.

/OUTLOOK FOR KMSP/
THU...VFR, slgt chc MVFR/-TSRA. Wind SW 5kts.
FRI...VFR/MVFR, chc IFR/TSRA. Wind S 5-10kts.
SAT...VFR and hot. Wind S 10-15G20 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Extreme Heat Watch from Saturday afternoon through Sunday
     evening for Anoka-Benton-Blue Earth-Brown-Carver-Chippewa-
     Chisago-Dakota-Douglas-Faribault-Freeborn-Goodhue-
     Hennepin-Isanti-Kanabec-Kandiyohi-Lac Qui Parle-Le Sueur-
     Martin-McLeod-Meeker-Mille Lacs-Morrison-Nicollet-Pope-
     Ramsey-Redwood-Renville-Rice-Scott-Sherburne-Sibley-
     Stearns-Steele-Stevens-Swift-Todd-Waseca-Washington-
     Watonwan-Wright-Yellow Medicine.
WI...Extreme Heat Watch from Saturday afternoon through Sunday
     evening for Barron-Chippewa-Dunn-Eau Claire-Pepin-Pierce-
     Polk-Rusk-St. Croix.

&&

$$

DISCUSSION...Borghoff
AVIATION...JRB