Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1212 PM CDT Thu Jun 27 2019

.SHORT TERM...(Today through Friday)
Issued at 345 AM CDT Thu Jun 27 2019

Surface analysis early this morning shows a wavy quasi-stationary
front extending from central Wyoming eastward across the Dakotas
through southern MN on into the northern Ohio Valley region. Aloft,
the pattern continues of a cutoff low over the Pacific NW with a
ridge over the central CONUS.

The overall upper level pattern will change very little over the
next 24-36 hours, as the cutoff low will remain over the Pacific NW
and the ridge over the central states will only continue to build.
However, there are a few distinct shortwave disturbances on the
western fringes of the ridge which will be capable of maintaining or
even enhancing the ongoing MCV over the central Dakotas early this
morning. Along with the stagnant upper level pattern, the surface
front will also move very little as a whole, but segments of the
front will waver which will be key into how convection, and hence
the severe weather threat, will develop over the area today.

Multiple elements promoting severe weather are in place: the nose of
a LLJ, instability (MLCAPE) on the order of 2500-3500 J/kg, bulk
shear approaching 30-35kt and enhanced isentropic lift in the
vicinity of the warm front, especially over western MN. The X-factor
will be how the ongoing convection develops and whether it continues
to drive northward or makes more of a right turn to follow the
front. Multiple versions of the HRRR tend to drive the MCV eastward
over southern MN from 12z onward, pushing it towards the Twin Cities
around 16z-18z. Other models, namely the NAM, keep the MCV well to
the north while the GFS/EC muddy it up and give a less developed
scenario. Given the better initializations of the HRRR, am opting to
stick to that idea and continue the thinking that an organized
cluster of storms will re-develop out of the ongoing system in
southern MN and shift eastward through much of the WFO MPX coverage
area this morning into this afternoon, close to the warm front
location. With organized strong/severe storms of this nature,
damaging straight-line winds will be the main hazard but some hail
cannot be ruled out. SPC maintains a Slight Risk of severe storms
and this is certainly warranted. As noted in its discussion, will
need to see how this scenario evolves in case any upgrades are
needed in later outlooks. Have already seen multiple wind gusts of
45-55kt in the western Dakotas with the ongoing storms.

The other concern with this system is the high PWAT value (over 1.5
inches) and the high efficiency of rainfall developed with the
existing MCS. Again noting the convective features in place, it
would not at all be unreasonable to see fairly widespread 1-2"
rainfall amounts during the day today with isolated higher amounts.
While FFG looks reasonable and may be achieved, not expecting a lot
of flooding issues due to that the ground can take on a lot of rain
and has not received an overabundance of rainfall recently.

By late in the day into the evening, the environment is expected to
be well worked over from the passing MCV. The loss of insolation
will also contribute to a loss of instability so have continued the
idea of diminishing PoPs tonight through Friday. With the possible
exception of isolated showers in interior Wisconsin tomorrow, the
entire coverage area is expected to remain dry as the ridge axis
aloft moves closer to being atop MN/WI. That said, the additional
ground moisture from today's rain will contribute to a highly
moisture atmosphere as evidenced by dewpoints climbing from the mid-
upper 60s today to the upper 60s and lower 70s on Friday. Ongoing
warm air advection will keep highs in the 80s both today and
tomorrow which will allow heat index values to climb into the lower
90s, especially on Friday.

.LONG TERM...(Friday night through Wednesday)
Issued at 345 AM CDT Thu Jun 27 2019

GFS has been very consistent with its heat wave development into
the weekend. This will likely result in heat headlines for at
least a portion of the area.

Upper ridge will build in behind the departing convection Friday
evening and heights build in behind across the central/northern
CONUS. Mid level warming should preclude convective development
through Saturday night. There is a small chance of any convection
that develops into northern MN Saturday night working south into
central MN late. We maintained those small chance PoPs for now.

On Saturday, temperatures should peak out in the 90s across the
area with heat indices around 100 F. Temperatures in the mid/upper
90s and dewpoints in the lower 70s will produce lower 100's heat
indices to the southwest under the deeper southerly flow and
thermal ridge. Temepratures may be tempered somewhat Sunday with
the possibility of more clouds and depending on timing, the front
is progged to work into the area into the afternoon. This may
limit heat indices somewhat, but dewpoint pooling along the front
may produce similar heat conditions, especially over the southern
half of the CWA. Severe potential can be expected with the front
as it works southeast over the area.

The front is progged to stall near/along the MN/IA border early in
the weak as the upper flow becomes flatter/more zonal across
the northern states. We will need to monitor convective trends
with the front in the area. Heavy rain/flood threat could be on
the increase along with periodic bouts of severe weather. Overall
summer is full swing with above normal temperatures expected to
continue this forecast period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1210 PM CDT Thu Jun 27 2019

The main complex of TSRA has moved off to the east/northeast of
MPX CWA, with the exception of KEAU which will have an hour of
TSRA and gusty winds. Winds will begin shifting to the southeast
once again this afternoon, and become gusty in the western half of
Minnesota. TSRA is still likely to redevelop in eastern South
Dakota, or near the surface low in southeast North Dakota. Either
way, TSRA still looks likely in central/southern Minnesota by the
mid/late afternoon. How much activity lingers in southern
Minnesota, and into west central Wisconsin overnight is
questionable. The best scenario is to continue at least a
temporary period of TSRA for KMSP/KRNH/KEAU through the evening,
with IFR/MVFR cigs develop in the wave of the TSRA. Winds will
become east/northeast by Friday morning with VFR likely not until
the afternoon, or at least the late morning.

KMSP...

No TSRA activity is expected until late this afternoon, with the
best chance during the early evening. Otherwise, kept close to the
previous TAF, but did introduce MVFR cigs late tonight.

/OUTLOOK FOR KMSP/

Fri Evening...VFR. Winds E 5 kts.
Sat...VFR. Winds SE 5-10G15 kts.
Sun...VFR. Chc TSRA late. SSW 5-10 kts.

&&

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

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

Hazardous Weather Outlook
National Weather Service Twin Cities/Chanhassen MN
1205 PM CDT Thu Jun 27 2019

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
281715-
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-
1205 PM CDT Thu Jun 27 2019

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

.DAY ONE...This Afternoon and Tonight
Thunderstorms are expected to redevelop later this afternoon into
this evening, mainly from near Interstate 94 southward. A few
severe storms with large hail and damaging wind gusts are
possible, along with locally heavy rainfall.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

The first heat wave of the summer will begin to arrive Friday and
peak this weekend. Highs in the 90s and lows in the 70s are
likely, especially Saturday and Sunday. Heat indices may exceed
100 this weekend. Those who are active outdoors will be at risk
for heat related illness Friday through Sunday.

Thunderstorms will again be possible later in the weekend into
next week with the higher chances coming Sunday night and Monday.
The severe weather risk is low at this time.

.SPOTTER INFORMATION STATEMENT...

SKYWARN spotter activation will not be needed.

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1014 AM CDT Thu Jun 27 2019

MNZ085-271545-
Steele-
1014 AM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT STEELE COUNTY...

At 1014 AM CDT, a strong thunderstorm was located over Owatonna,
moving east at 35 mph.

Winds in excess of 40 mph and nickel size hail are possible with this
storm.

Locations impacted include...
Owatonna, Blooming Prairie, Medford, Ellendale, Lemond, Clinton
Falls, Merton, Moland, Hope, Deerfield, Owatonna Airport and Steele
Center.

This includes the following highways...
 Interstate 35 between mile markers 26 and 49.
 U.S. Highway 14 between mile markers 166 and 182.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

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 4419 9341 4419 9305 4385 9305 4385 9340
TIME...MOT...LOC 1514Z 264DEG 31KT 4411 9317

ETA

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1059 AM CDT Thu Jun 27 2019

WIZ015-025-271700-
Barron-Dunn-
1059 AM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT DUNN AND BARRON COUNTIES...

At 1059 AM CDT, a strong thunderstorm was located near Elmwood, or 16
miles west of Menomonie, moving east at 30 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Menomonie, Rice Lake, Barron, Chetek, Cumberland, Cameron, Colfax,
Boyceville, Turtle Lake, Elk Mound, Eau Galle and Almena.

This includes the following highways...
 Interstate 94 in Wisconsin between mile markers 32 and 56.
 U.S. Highway 53 between mile markers 120 and 152.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

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 4521 9154 4521 9167 4469 9165 4469 9213
      4564 9216 4564 9155
TIME...MOT...LOC 1559Z 266DEG 25KT 4483 9223

ETA

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1126 AM CDT Thu Jun 27 2019

MNZ093-271700-
Freeborn-
1126 AM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN FREEBORN COUNTY...

At 1126 AM CDT, a strong thunderstorm was located near Glenville, or
near Northwood, moving east at 45 mph.

Winds in excess of 30 mph and dime size hail are possible with this
storm.

Locations impacted include...
Glenville, Emmons, London, Twin Lakes and Myrtle.

This includes Interstate 35 between mile markers 1 and 8.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

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 4360 9350 4364 9305 4350 9305 4350 9350
TIME...MOT...LOC 1626Z 268DEG 38KT 4351 9331

ETA

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1149 AM CDT Thu Jun 27 2019

WIZ016-025-027-271745-
Chippewa-Dunn-Rusk-
1149 AM CDT Thu Jun 27 2019

...A STRONG THUNDERSTORM WILL AFFECT RUSK...NORTHEASTERN DUNN AND
CHIPPEWA COUNTIES...

At 1149 AM CDT, a strong thunderstorm was located 8 miles southwest
of Weyerhaeuser, or 16 miles southeast of Rice Lake, moving east at
55 mph.

Winds in excess of 40 mph and pea size hail are possible with this
storm.

Locations impacted include...
Eau Claire, Ladysmith, Chippewa Falls, Lake Hallie, Stanley, Bloomer,
Lake Wissota, Cornell, Cadott, Colfax, Elk Mound and Bruce.

This includes the following highways...
 Interstate 94 in Wisconsin between mile markers 50 and 55.
 U.S. Highway 53 between mile markers 93 and 119.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding. Do not drive your vehicle through flooded
roadways.

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 4537 9092 4486 9092 4486 9177 4521 9179
      4521 9154 4563 9154 4564 9068 4538 9068
TIME...MOT...LOC 1649Z 261DEG 46KT 4532 9149

ETA

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