Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
657 PM CDT Mon Jul 2 2018

.UPDATE...
Issued at 633 PM CDT Mon Jul 2 2018

Updated to include 00z aviation discussion below.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 245 PM CDT Mon Jul 2 2018

Tonight forecast is highly based on where the convection
originates in west central/central Minnesota this evening. Plus,
where will the outflow boundaries lie as this complex moves
eastward across Minnesota.

Confidence is high that convection will develop near the
Minnesota, North Dakota, and South Dakota border later this
afternoon. This is where instability and moisture convergence is
maximized. Further to the north/northeast, residual moisture from
a complex of storms that developed across South Dakota earlier
this morning, may generate a few storms near Mora, east/southeast
toward Rice Lake before sunset. However, this area is not favored
for anything significant, and confidence is low on development.

Again, tonight's forecast is based on the convection that develops
near the Minnesota/South Dakota/North Dakota border. Most CAMS and
Hires models support some type of development near this area.
Satellite imagery this afternoon also noted an increasing area of
convergence in northeast South Dakota which is likely the place of
initiation. Although I can't rule out a few storms in east
central Minnesota, west central Wisconsin through sunset, this
area will likely be very isolated in nature. Once the storms
develop, forecasters need to pay attention of where the outflow
boundary moves in relation to the low level jet increasing
overnight. There is some indications that this outflow boundary
will move as far southeast as Mankato, to the Twin Cities toward
sunrise. Therefore, there are low percentages as close as the Twin
Cities, but the bulk of the precipitation should remain across
west central to central Minnesota. Severe weather is not out of
the question due to the increasing wind shear aloft and efficient
instability in this layer of higher wind shear. Once storms
develop, I wouldn't be surprised to see a few large hail reports
from west central to central Minnesota. See the latest SPC Day 1
outlook for more information. Otherwise, by Tuesday morning, any
leftover showers or storms will quickly dissipate as the cap
strengthens.

.LONG TERM...(Tuesday night through Monday)
Issued at 255 PM CDT Mon Jul 2 2018

The bulk of precipitation will occur Tuesday night, into Wednesday
night as the main short wave and cold front moves overhead. Ahead
of this front, temperatures and humidity levels will rise again,
and heat indices will approach or exceed 100 degrees in portions
of southern Minnesota, and into west central Wisconsin Wednesday
afternoon. There is a minor chance that high cloudiness may
inhibit full isolation. But still, 850 mb temperatures rise into
the lower 20s which is ample for 90s in this area.

Severe weather is once again possible along this front Wednesday
afternoon and evening. However, wind shear values are lower than
today, so the threat of severe weather will be more isolated.

Thursday through the first part of the weekend will be dry and
less humid as a Pacific/Canadian air mass moves overhead.
Temperatures will fall back to near normal with lower humidity
levels. Past Saturday, this air mass will slide off to the
southeast, with return flow from the south/southwest. This area
will likely be very hot next weekend as the dome of high pressure
remains overhead. This area of high pressure is expected to slide
to the east and be centered across the center of the CONUS next
week.

Confidence is high that the bulk of the heavier and widespread
precipitation event will occur Tuesday night, into Wednesday
night. Confidence is also high that temperatures and humidity
levels will lower for later this week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM CDT Mon Jul 2 2018

All sites start out VFR with the main concern being approaching
convection from the west late this evening through the overnight
hours. Western MN (mainly KAXN) looks to be the most likely site
to be impacted with chances diminishing going east, such that KMSP
and points east may well not see any thunderstorm activity at all.
Still some uncertainty in the placement with hourly models
changing depictions fairly significantly so confidence isn't all
that great. For those sites likely to have precip, have dropped
conditions into MVFR. Otherwise, the only other concern may be
LLWS for western-central MN as the low level jet strengthens
overnight.

KMSP...Am expecting VFR conditions throughout this set but there
is a small chance of convection during the pre-dawn hours through
daybreak with some thunderstorms approaching from the west. At
this point, the activity looks to lift off to the north before
reaching eastern MN so have kept a dry TAF going. In addition,
chances are low for LLWS since the jet looks to remain off to the
west. But, should convection reach MSP, then that means the jet
has also shifted east so that could also impact MSP.

/OUTLOOK FOR KMSP/
Wed...Mainly VFR. Chance MVFR/TSRA late. Winds S 10-15 kts.
Thu...VFR. Winds NW 10-15 kts.
Fri...VFR. Winds NE 5-10 kts.

&&

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

UPDATE...JPC
SHORT TERM...JLT
LONG TERM...JLT
AVIATION...JPC

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
857 PM CDT Mon Jul 2 2018

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
031900-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-
Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington-
Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota-
Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth-
Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk-
St. Croix-Pierce-Dunn-Pepin-Eau Claire-
857 PM CDT Mon Jul 2 2018

This Hazardous Weather Outlook is for portions of central and
southern Minnesota...and west central Wisconsin.

.DAY ONE...Tonight

Scattered thunderstorms are possible across portions of central
Minnesota tonight. Some may be strong to severe with hail being
the main concern.

Flooding continues along the Minnesota River and its tributaries.
Please refer to the Minnesota Department of Transportation for
any road closures due to flooding.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

Periodic thunderstorms are expected Tuesday through Thursday. A
few of the storms could be severe with damaging winds and large
hail being the primary threats.

Heat and humidity will build through mid-week and peak on
Wednesday, when heat indices in the mid 90s to around 100 degrees
are likely.

River flooding will continue along the Minnesota River and its
tributaries into next week. Please refer to the Minnesota
Department of Transportation for any road closures due to
flooding.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation may be needed late tonight in portions
of central Minnesota.

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
835 PM CDT MON JUL 2 2018

MNZ064-030200-
Yellow Medicine-
835 PM CDT MON JUL 2 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN YELLOW MEDICINE
COUNTY THROUGH 900 PM CDT...

At 834 PM CDT, a strong thunderstorm was located over Spring Creek,
or 18 miles southwest of Montevideo, moving northeast at 35 mph.

Dime size hail is possible with this storm.

Locations impacted include...
Clarkfield, Hanley Falls, Spring Creek, Hazel Run, Granite Falls
Airport and Spellman Lake.

This includes U.S. Highway 59 between mile markers 90 and 100.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4481 9584 4489 9574 4477 9551 4472 9540
      4465 9593 4472 9599
TIME...MOT...LOC 0134Z 245DEG 29KT 4471 9591

JPC

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
905 PM CDT MON JUL 2 2018

MNZ064-030300-
Yellow Medicine-
905 PM CDT MON JUL 2 2018

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL YELLOW MEDICINE
COUNTY THROUGH 1000 PM CDT...

At 904 PM CDT, a strong thunderstorm was located 7 miles southwest of
Porter, or 20 miles southeast of Clear Lake, moving northeast at 30
mph.

Dime size hail is possible with this storm.

Locations impacted include...
Clarkfield, Porter, Spring Creek, Hazel Run, Spellman Lake and St.
Leo.

This includes U.S. Highway 59 between mile markers 87 and 97.

LAT...LON 4481 9598 4478 9572 4463 9569 4463 9632
      4464 9637
TIME...MOT...LOC 0204Z 246DEG 28KT 4460 9631

JPC

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
937 PM CDT MON JUL 2 2018

MNZ054-056-064-030300-
Chippewa-Yellow Medicine-Lac Qui Parle-
937 PM CDT MON JUL 2 2018

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN LAC QUI
PARLE...CHIPPEWA AND CENTRAL YELLOW MEDICINE COUNTIES THROUGH 1000
PM CDT...

At 936 PM CDT, radar indicated strong thunderstorms were located
along a line extending from near Montevideo Airport to near Dawson.
Movement was northeast at 40 mph.

Dime size hail is possible with these storms.

Locations impacted include...
Montevideo, Granite Falls, Dawson, Clara City, Clarkfield, Maynard,
Watson, Boyd, Providence, Hazel Run, Asbury and Montevideo Airport.

This includes the following highways...
 U.S. Highway 212 between mile markers 18 and 49.
 U.S. Highway 59 between mile markers 94 and 107.

LAT...LON 4497 9609 4516 9567 4515 9528 4494 9538
      4488 9545 4489 9548 4486 9548 4474 9563
      4469 9616
TIME...MOT...LOC 0236Z 237DEG 34KT 4501 9563 4488 9603

JPC