645
FXUS63 KMPX 141120
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
620 AM CDT Sat Sep 14 2024

.KEY MESSAGES...

- Scattered showers expected in eastern Minnesota & western
Wisconsin today. A few thunderstorms are possible, especially if
showers arrive later than sunrise.

- Warmer and generally unsettled weather to continue on and off next
week. The best overall chance for showers looks to be Friday into
Saturday.

&&

.DISCUSSION...
Issued at 310 AM CDT Sat Sep 14 2024

A rather interesting view from GOES satellite imagery this morning
with a narrow line of showers with rumbles of thunder extending from
western Minnesota through the Canadian border. There is then another
narrow gap with a lack of cloud cover from where the showers are
located to the western edge of the Twin Cities metro, at which point
you have widespread cloud cover associated with what will eventually
be our showers stretching all the way through half of Wisconsin. The
low level jet which was expected to be the locus for showers this
morning has yet to fully strengthen, with a 6 degree C dewpoint
gradient stretching into southern Minnesota with our showers more
likely as dew points increase over the next several hours. CAMs have
generally performed poorly in resolving not only the showers off to
the west but also what limited activity thus far in northern Iowa,
with the closest CAM thus far being the HRRR which doesn`t bring
showers into eastern Minnesota until after 18z. For now, the
expectation should still be isolated to scattered showers developing
around sunrise and continuing through much of the day before
dissipating tonight as the forcing and moisture exit to the east.
Those that see showers could see enough intensity for a tenth of an
inch or two, however most will likely remain within a few hundredths
overall which continues our relatively dry stretch for September as
a whole. There is the possibility of a few thunderstorms especially
if the HRRR wins out with mainly afternoon showers, which will
mainly be a nuisance for outdoor activities with little chance for
severe weather with a lack of shear to maintain and instability on
the lower side. Temperatures will remain in the upper 70s to low 80s
with what is our coolest high temperatures forecast over the next
several days with our next likely 70s being next weekend.

After the showers depart later today and overnight, Sunday looks
quiet before we see relatively unsettled weather throughout the week
with on and off chances for showers. This is due to the ridge
overhead weakening with an occluded upper level trough over the
western CONUS dragging a weak area of CVA and brief height rises and
falls with little organization. The position of the occluded system
should keep the greater moisture and lift over the Dakotas with
showers more isolated and weaker as we rely on weaker pockets of
lift within shortwave energy. Unless we see an MCS type feature
moving out of the Dakotas, which is not evident within any of the
guidance right now, we likely miss out on the majority of the
legitimate rain chances that remain off to the west. Our reward will
be continued warmer weather with weak surface high pressure and a
lack of any kind of changes to the airmass until the very end of the
period when temperatures finally drop back to the 70s for highs.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 619 AM CDT Sat Sep 14 2024

VFR becoming potentially MVFR for a few sites later this
morning. -SHRA continues to move into AXN over the next hour or
so before moving northeastward. -SHRA is expected to develop
over our eastern sites later this morning especially after 16z.
Introduced prob30 groupings to reflect current timing for -SHRA
impacts. VFR categories return this evening once this
disturbance clears all sites this evening. Scattered low VFR
clouds may linger through the overnight hours with the potential
of patchy MVFR fog before sunrise near EAU.

KMSP...Only change since the last update is revising the timing for
-SHRA to reach MSP. Timing as of now looks to be between 16 to 18z
before moving east into WI. MVFR cigs still likely by 16z and until
about 23z where categories should improve by this evening. Winds
remain southerly and should range between 5 to 15 knots.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind S 5-10 kts.
MON...VFR. S Chc MVFR/SHRA. Wind S 10-15 kts.
TUE...VFR. Wind SSE 10-15G20 kts.&&

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

&&

$$

DISCUSSION...TDH
AVIATION...Dunleavy