Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 231858

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
158 PM CDT Wed May 23 2018

Issued at 100 PM CDT Wed May 23 2018

Updated for 18Z aviation discussion below.


.SHORT TERM...(Today and tonight)
Issued at 358 AM CDT Wed May 23 2018

Thunderstorms developed as promised in far southwest/south
central Minnesota prior to midnight, and slowly spread
east/southeast and continued to form close to the same areas.
Thus, there is an increasing chance of localized flooding in flood
prone areas where locally two to three inches of rainfall is
likely before the thunderstorms begin to dissipate and move east.
There were a few thunderstorm cores that had strong updrafts and
probably produced up to nickel size hail, but most of the hazard
early this morning was related to heavy rainfall, and localized
flooding. In west central Wisconsin, localized dense fog formed
even with a dense overcast cirrus shield after midnight. Although
some areas will likely see the dense fog through sunrise, the fog
isn`t expected to be widespread.

The thunderstorms in far southern Minnesota will likely continue to
form through sunrise along the nose of the modest low level jet
before slowly decreasing in areal coverage. The best chance of
continued thunderstorm activity will be along and south of the
Minnesota River Valley. Typically, as the low level jet decreases in
the morning, thunderstorms should wane. By the mid/late morning
hours, most areas will be dry with the exception in south
central/southeast Minnesota were the remnants of the decaying
thunderstorms will hold. By the afternoon, instability will once
again increase, but there should be an increasing cap limiting re-
firing of the thunderstorms in southern Minnesota. However, I
wouldn`t be surprised to see some activity along any outflow
boundary from the morning thunderstorms. The best potential of re-
firing of the thunderstorms will occur in central Minnesota where
the cap will be weakest. Slowly overnight, precipitation chances
will increase in central, then east central Minnesota, and portions
of west central Wisconsin. However, this is related to the nose of
the low level jet. If this jet decides to move further to the north,
precipitation chances will be much lower.

.LONG TERM...(Thursday through Tuesday)
Issued at 358 AM CDT Wed May 23 2018

An active and hot long term period is on the way, with Memorial
Day looking to be the hottest much of the area has seen in over 10
years (see the climate discussion below for details).

The warmth will build on Thursday as mid level ridging works into
the central CONUS. 925-850MB temps warm well into the +20C`s, and
breezy southerly flow should support deep mixing. There could be
some residual cloud cover from nocturnal convection, but clouds
should scour out sufficiently to achieve highs in the 85 to 95
degree range. An approaching High Plains shortwave and attendant
height falls should help erode any weak CAP that`s in place on
Thursday afternoon and evening. Progged shear is modest, but could
still see sufficient instability to support a few hail/wind-
producing severe thunderstorms. As the low level jet strengthens
on Thursday night, expect convection to spread eastward across the

Friday should be another hot day ahead of the cold front
associated with the low pressure system, with a potential for
85-95 degree readings again. Storms would most likely be primarily
restricted to areas along/east of Interstate 35.

The ridge continues to build this weekend as a closed low rotates
over the southwestern CONUS and a tropical disturbance affects the
Atlantic. While there is often a chance of a dirty ridge (as the
GFS is hinting at), prefer the overall dry and hot scenario the
ECMWF offers through the beginning of next week.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 100 PM CDT Wed May 23 2018

Decaying showers across south central MN will continue to fall
apart this afternoon, but more thunderstorm development across
western MN will impact AXN over the next few hours. Expecting a
pretty quiet night with the precip activity remaining to our north
and west.

KMSP...confidence was high that the showers to our west would fall
apart this afternoon. In addition, those showers have been moving
extremely slow. So, expect VFR conditions throughout.

FRI...Mainly VFR Chc of SHRA/TSRA. Wind SW 5-10 kts.
SAT...VFR. Wind WSW 5-10 kts.
SUN...VFR. Wind W 5 kts.


Issued at 358 AM CDT Wed May 23 2018

Memorial Day looks to have the potential to be the hottest we`ve
seen in over 10 years, and in the top 5 warmest in some locations.
Forecast highs for Monday are 87, 89, and 90 degrees at Eau
Claire, St Cloud, and Minneapolis respectively. Here is how those
would stack up climatologically speaking for Memorial Day:

*Last time we hit 90 degrees or higher on Memorial Day - 94 on
 May 29, 2006
*Record value for Memorial Day - 95 on May 30, 1939
*Top 5 warmest (including ties):
5/30/1939 (95),
5/29/2006 (94),
5/30/1988 (91),
5/30/1994 (91),
5/30/1944 (88),
5/30/2011 (88)

*Last time we hit 90 degrees or higher on Memorial Day - 92 on May
 29, 2006
*Record value for Memorial Day - 92 (occurred on 5/30/1939,
 5/30/1994, and 5/29/2006)
*Top 5 warmest (including ties):
5/30/1939 (92),
5/30/1994 (92),
5/29/2006 (92),
5/30/1988 (91),
5/26/2014 (86)

*Last time we hit 90 degrees or higher on Memorial Day - 95 on
 May 29, 2006
*Record value for Memorial Day - 95 on May 29, 2006
*Top 5 warmest (including ties):
5/29/2006 (95),
5/30/1988 (90),
5/30/1953 (88),
5/30/1994 (88),
5/30/2011 (86)




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