National Weather Service Twin Cities Area Forecast Discussion

Data Provided by the National Weather Service

FXUS63 KMPX 110001

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
701 PM CDT Fri Jul 10 2020

.Updated for 00Z Aviation Discussion...
Issued at 654 PM CDT Fri Jul 10 2020


.SHORT TERM...(This evening through Saturday night)
Issued at 316 PM CDT Fri Jul 10 2020

Surface analysis this afternoon shows north-south oriented high
pressure over much of the central CONUS while a weak cold front
forms over south-central Canada and a conglomerate low pressure
area develops over central WY. Aloft, modest ridging is holding
fort, emanating from a deep ridge over the Four Corners region and
extending northeast into the Upper Midwest. A compact disturbance
is shifting eastward within a flattened portion of the ridge over
the northern Rockies.

Plenty of sunshine has spread across the region today with the
deep ridging, pushing highs into the low-mid 80s area-wide. As
high pressure slides off to the east and the combination of the
low out west and the front up north gradually move closer to
MN/WI, clouds will increase across the area overnight into
Saturday morning. With the arrival of the shortwave, scattered
showers/thunderstorms will move into southwestern MN overnight
thru daybreak but generally look to remain south of I-94 and west
of I-35. Could see some activity into the Twin Cities metro but
the bulk of the activity will be west of a Morris-Mankato line.
This activity will dissipate and shift off to the southeast as the
morning progresses, then attention turns to the backdoor cold
front arriving from the north. While the nadir of the front looks
to drop thru Lake Michgan Saturday afternoon and continue pressing
south Saturday night, an additional mid-level disturbance will
accompany the front southward on the western periphery of the
front, aiding in additional showers/thunderstorms to push south-
southeast across the WFO MPX coverage area as the day progresses
on Saturday. Some of these storms may contain brief heavy rain as
PWATs increase to 1.25"-1.50". In addition, with the disturbance
accompanying the front at a favorable time of day, MLCAPE will be
heightened (around 2000 J/kg) and bulk shear will approach 30kt so
there is some potential for wind/hail reaching severe thresholds.
Hence, SPC nudging northward the Marginal Risk on Saturday does
have some merit.

The loss of daytime heating combined with the frontal passage
Saturday evening into Saturday night will bring an end to the
convection not too far into Saturday night, resulting in more
tranquil conditions going into Sunday morning.

.LONG TERM...(Sunday through Friday)
Issued at 316 PM CDT Fri Jul 10 2020

For Saturday night, showers and thunderstorms will be departing
the CWA to the southeast leaving us with mostly clear skies by
early Sunday morning. Sunday`s weather will be nearly perfect with
highs in the low 80s, sunny skies, and light northwest winds.
However, the northwesterly flow will not last long as the low-
level flow will flip to southerly by Monday morning in advance of
an upper-level trough approaching from the Pacific northwest.
Temperatures on Monday morning will start out in the low 60s but
rise into the mid 80s by Monday afternoon. Dewpoints will also
increase into the mid to upper 60s across southern and western MN,
allowing for MLCAPE values in excess of 2500 J/kg across western
MN. This instability combined with the approaching aforementioned
trough will result in a likelihood of thunderstorms initiating in
the eastern Dakotas and extreme western MN. Severe weather is
possible in this region as a broad jetstreak overspreading the
Northern Plains will allow for sufficient bulk shear for rotating
storms. It would not be surprising to see SPC outlook at least a
portion of the MPX CWA for Monday. Nearly of all of the CWA is
expected to see precipitation Monday night as convection grows
upscale traveling eastward along the advancing cold front.

By Tuesday, the upper-level trough will briefly stall over
central Canada due to WAA into the Hudson Bay building the
downstream ridge. From Tuesday into Wednesday, multiple rounds of
showers and thunderstorms are possible for our CWA as separate
embedded impulses rotate through the base of the trough. The good
news it will feel less humid during this time. Larger model
differences begin to arise by Wednesday night as the ECMWF and GEM
become more progressive with the upper-level flow compared to the
GFS. Of more certainty is that temperatures should remain above
normal through the extended period, continuing our seemingly never
ending heat.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 654 PM CDT Fri Jul 10 2020

VFR conditions this evening, with chances for showers and
thunderstorms late tonight and on Saturday. These chances do seem
to be decreasing, but still worth mentioning in the TAFs. There
will be a cluster of storms across southwest Minnesota late
tonight, but then another chance for scattered showers/storms on

The chance for storms late tonight/early morning does appear to
be decreasing. There is another chance late morning and into the
afternoon, so opted to go with a Prob30.

Sun...VFR. Wind N 5 kts.
Mon...VFR. TSRA likely late. Wind SE 10 kts.
Tue...Mainly VFR. Chc SHRA/TSRA. Wind SW 5-10 kts.





NWS MPX Office Area Forecast Discussion