506
FXUS63 KMPX 041800
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
100 PM CDT Thu Jul 4 2024

.KEY MESSAGES...

- Thunderstorms and locally heavy rainfall likely today and
  tonight.

- Numerous chances for showers and a few thunderstorms will
  linger into next week with temperatures remaining below
  normal.

&&

.DISCUSSION...
Issued at 402 AM CDT Thu Jul 4 2024

Showers are beginning to advance into and develop across
southwestern MN early this morning. They should reach the Twin
Cities metro in the next few hours. This will be the first of
potentially many rounds during the next 24 hours.

The trough over the northern High Plains will continue digging
southeast this morning, reaching MN this afternoon as a
seasonally potent wave. Forcing will become more focused and a
broad surface low will develop and track across southern MN.
Scattered to numerous thunderstorms are expected by afternoon,
which will continue tonight north of the surface low track and
roughly along the 700 mb low track. This favored area is
expected to stretch from the Redwood Falls area to the Twin
Cities metro. 00Z HREF neighborhood probabilities of greater
than 2 inches within this corridor range from 60 to 80 percent,
and 30 to 60 percent for greater than 3 inches. That`s a strong
signal for heavy rainfall, but there are some limiting factors
to consider for flooding. Many of the CAMs and even the global
guidance indicate rain will not be continuous for several hours.
There should be breaks between rounds which will allow runoff
from becoming excessive. Pwats aren`t too anomalous for this
time of year and rain rates aren`t expected to be too extreme
either. Perhaps some 1-1.5 inch/hr rates will be possible with
the most robust convection, but 1 hr flash flood guidance values
are generally 1.5-2 inches and those rates shouldn`t last an
hour`s time. Areas that do see totals of 3 inches through Friday
morning may have some issues, but these pockets should be
fairly localized. For these reasons, decided against a Flood
Watch at this time but trends will continue to be monitored.

Mid level lapse rates will remain modest and the prospects of
significant surface heating still appear limited given the
extensive cloud cover, so instability will be lacking in most
locations. However, across southern MN there may be better
heating near and south of the low track. Here, there is some
potential for a few stronger storms where CAPE may exceed 1000
J/kg and deep layer shear is better. Some marginally severe
hail and a couple weak tornadoes are possible.

The showers will linger into Friday across eastern MN/WI, but
some scattered activity could redevelop farther west in the
afternoon with breaks in the clouds and some instability
developing within the cyclonic flow.

Multiple waves within a broad north central U.S. trough will
keep precip chances going for much of the remainder of the
period. Nothing looks particularly widespread or heavy, but it
will continue the gloomy and un-Julylike weather for the
region. Temperatures will remain below normal until if/when the
western Ridge builds east. Some of the extended guidance is
hinting at that possibility toward mid-July.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1234 PM CDT Thu Jul 4 2024

Main aviation concern will be the ongoing showers and storms,
which will last through this evening for most. A cluster of
storms are currently developing over south-central MN, which
would bring MVFR/IFR visibilities during the heaviest rainfall
rates. A bit of a lull in precipitation is still expected late
this evening/night, before rain showers and MVFR/IFR ceilings
become more widespread overnight into tomorrow morning. Winds
will remain generally light and variable today, before shifting
out of the N/NW and increasing slightly tomorrow. The strongest
thunderstorms, which could have wind gusts up to 50 mph and
hail greater than an inch, are expected to stay further south
near and along I-90.

KMSP...The first wave of showers have passed this morning, and
the focus turns to the redevelopment of precip to the southwest.
Most of the cells over south-central MN are still elevated, so
the threat for severe weather is lower, but reduced vis and
thunder will still be likely. Storms could move in as early as
1:30-2pm, and would be off and on through the early evening.
Cigs are still on track to drop to low MVFR by this evening and
will likely become IFR late tonight through tomorrow morning.
Isolated showers/storms are possible tomorrow afternoon/evening,
but confidence is low so have kept mention out of the TAF for
now.

/OUTLOOK FOR KMSP/
SAT...Chance PM MVFR SHRA/TSRA. Wind SW 5-10 kts.
SUN...MVFR/SHRA/TSRA likely. Wind SW 10-20 kts.
MON...VFR, chance MVFR. Wind WNW 5-10 kts.

&&

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

&&

$$

DISCUSSION...Borghoff
AVIATION...BED