Damaging Winds in Minnesota, June 17, 2018

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
657 AM CDT Sun Jun 17 2018

.UPDATE...
Issued at 645 AM CDT Sun Jun 17 2018

Updated to include 12z aviation discussion below.

&&

.SHORT TERM...(Today and tonight)
Issued at 511 AM CDT Sun Jun 17 2018

The main concerns for today will be another day of heat and
humidity along with the potential for severe weather and heavy
rain.

Surface analysis early this morning shows an elongated surface
front, originating from a surface low over Hudson Bay, extending
southwest through northwestern Minnesota and continuing into
central Nebraska. Aloft, a large dome of high pressure sits over
the southeastern CONUS while a potent trough is moving onshore the
west coast. In between, strong southwesterly flow remains
prevalent over the area, including a potent broad LLJ in the
35-45kt range. Early morning convection which produce excessive
rains over northern Minnesota and northwestern Wisconsin are
slowly abating. This relative lull in the action will persist
through early afternoon at which point the front will make enough
of a push along with a dissipating cap to allow re-generation of
convection for this afternoon through this evening. Clusters of
poorly-organized thunderstorms are expected to develop in western
Minnesota this afternoon then increase in coverage and possibly
intensity as they shift eastward. With MUCAPEs increasing to the
3000-4000 j/kg range (in tune with PWATs in the 1.5-2.0" range)
with next to no CINH will allow for storms to develop quite ably
but have little in the way of potent upper level support. Thus,
will look for storms that may produce marginally large hail and
downburst and/or straight-line damaging winds. In addition, there
is still the potential for heavy rain with nearly any storm that
forms. While not looking for widespread flash flooding concerns,
the copious rains that has occurred over portions of the area
combined with QPF maximums in the 3-5" range on several models,
isolated flash flooding or area flooding certainly cannot be ruled
out. The best timing for the activity looks to be mid-afternoon
through the mid-evening hours then storms diminishing shortly
after midnight with little to no storm activity during the early
morning hours Monday.

With respect to temperatures, the strongest warming will occur
over central, eastern and southern portions of the WFO MPX
coverage area. Highs are expected to again hit the lower 90s with
dewpoints climbing into the lower 70s. Thus, have maintained the
heat headlines as-is (with the exception being to add in Rusk
County WI as latest guidance has at least a couple hours of 100+
heat indices). With the progression of the front through the area
this evening into the early morning hours, it looks to be through
the entire coverage area by daybreak Monday morning. Modest cold
air advection will allow for lows to drop to between the upper 50s
and upper 60s tonight into Monday morning.

.LONG TERM...(Monday through Saturday)
Issued at 511 AM CDT Sun Jun 17 2018

The surface frontal boundary is anticipated to exit Southeastern
MN and West Central WI to the south Monday. There still remains
a chance for showers and thunderstorms along the boundary during
peak heating. Gulf moisture will still be transported into the
Western Great Lakes region with the upper ridge still in place
over the Eastern CONUS. Thus, there remains the potential for
locally heavy rain with any showers and thunderstorms that do
develop. At this time, the best precip chances will be over IA and
Southern WI, but there still remains a chance that Southern MN
will have some convective activity. Otherwise, Monday will be much
cooler with highs only expected to reach the mid 70s.

Southern MN remains at risk for showers and thunderstorms on
Tuesday with the surface boundary lingering to the South and a
weak impulse along the 500 mb ridge. Otherwise, conditions across
there remainder of the CWA are looking dry and seasonable as
surface high pressure builds-in. Dry conditions are anticipated
for Wednesday before precip chances begin increasing from the
southwest on Thursday as upper level troughing shifts East over
the Central CONUS and surface frontal boundary begins lifting into
MN/WI. Scattered precip and storm chances are expected to
continue through the remainder of the extended period.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 545 AM CDT Sun Jun 17 2018

Another day of scattered to numerous thunderstorms, particularly
for this afternoon through this evening. Some isolated convection
this morning, mainly to the tune of VCTS, can be expected for
mainly eastern MN into western WI. This activity will wane through
the morning hours then more clusters of thunderstorms will develop
mid-to-late afternoon in western MN then gradually push east. Have
only gone to MVFR levels with the later convection but IFR
visibilities are certainly possible. As the front pushes through
the region tonight into tomorrow, winds will swing around to NW
while subsidence within the deeply moist atmosphere will push
ceilings down to MVFR levels (and possibly IFR levels) overnight
through daybreak Monday morning.

KMSP...Few thunderstorms around MSP this morning will force a VCTS
start. After a late morning lull, will look for TSRA to re-develop
around MSP with chances increase late this afternoon through this
evening. May be a little optimistic on the visibility early on
then ceilings may well drop to IFR overnight into tomorrow.

/OUTLOOK FOR KMSP/
Mon...Mainly VFR. Chc MVFR/TSRA. Wind NE 5-10 kts.
Tue...VFR. Wind NE 5-10 kts.
Wed...VFR. Wind ENE 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory until 7 PM CDT this evening for WIZ023>026-028.

     Heat Advisory from 9 AM this morning to 7 PM CDT this evening
     for WIZ016-027.

MN...Excessive Heat Warning until 7 PM CDT this evening for
     MNZ060>063-068>070.

     Heat Advisory until 7 PM CDT this evening for MNZ067-074>078-
     082>085-091>093.

&&

UPDATE...JPC
SHORT TERM...JPC
LONG TERM...AMK
AVIATION...JPC

Hazardous Weather Outlook...CORRECTED
National Weather Service Twin Cities/Chanhassen MN
355 AM CDT Sun Jun 17 2018

MNZ060>063-068>070-180900-
Hennepin-Anoka-Ramsey-Washington-Carver-Scott-Dakota-
355 AM CDT Sun Jun 17 2018

This Hazardous Weather Outlook is for portions of east central
Minnesota.

.DAY ONE...Today and Tonight

An Excessive Heat Warning is in effect. Heat indices of 98 to 103
are expected this afternoon.

Thunderstorms are expected to develop late this afternoon and
evening across the coverage area. There is a Slight Risk of
severe thunderstorms with the main hazards being large hail and
damaging winds. In addition, some storms may contain heavy rain
which may lead to flash flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Thunderstorms are possible Monday into Tuesday and again late
Thursday through Saturday. Severe weather is not expected at this
time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed this afternoon and
evening.

MNZ051-059-066-067-074>078-082>085-091>093-WIZ016-023>028-180900-
Sherburne-Wright-McLeod-Sibley-Brown-Nicollet-Le Sueur-Rice-
Goodhue-Watonwan-Blue Earth-Waseca-Steele-Martin-Faribault-
Freeborn-Rusk-St. Croix-Pierce-Dunn-Pepin-Chippewa-Eau Claire-
355 AM CDT Sun Jun 17 2018

This Hazardous Weather Outlook is for portions of central
Minnesota...south central Minnesota...southeast Minnesota...
northwest Wisconsin and west central Wisconsin.

.DAY ONE...Today and Tonight

A Heat Advisory is in effect. Heat indices of 95 to 100 are
expected this afternoon.

Thunderstorms are expected to develop late this afternoon and
evening across the coverage area. There is a Slight Risk of
severe thunderstorms with the main hazards being large hail and
damaging winds. In addition, some storms may contain heavy rain
which may lead to flash flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Thunderstorms are possible Monday into Tuesday and again late
Thursday through Saturday. Severe weather is not expected at this
time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed this afternoon and
evening.

MNZ041>045-047>050-052>058-064-065-073-WIZ014-015-180900-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-Kandiyohi-
Meeker-Yellow Medicine-Renville-Redwood-Polk-Barron-
355 AM CDT Sun Jun 17 2018

This Hazardous Weather Outlook is for portions of central
Minnesota...east central Minnesota...southwest Minnesota...west
central Minnesota and northwest Wisconsin.

.DAY ONE...Today and Tonight

Thunderstorms are expected to develop late this afternoon and
evening across the coverage area. There is a Slight Risk of severe
thunderstorms for portions of western Wisconsin through central
Minnesota, with a Marginal Risk of severe thunderstorms for
portions of west central Minnesota. The main hazards are large
hail and damaging winds. In addition, some storms may contain
heavy rain which may lead to flash flooding.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Thunderstorms are possible Monday into Tuesday and again late
Thursday through Saturday. Severe weather is not expected at this
time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed this afternoon and
evening.