Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
321 AM CDT WED AUG 10 2016

.SHORT TERM...(Today and tonight)
Issued at 322 AM CDT Wed Aug 10 2016

The short term concerns are timing and severity of convection
along with flooding threat into tonight.

Initial complex moving into west central MN now will move across
central MN through at least mid morning. Severity may diminish some
after 12z...but strong winds and torential rain may linger some.
This will drop an outflow boundary over central MN today...and will
refocus convective threat in the vicinity of this boundary into the
late afternoon.  Conditional nature of cloud trends and overall
heating potential has added uncertainty to heat indices rising to
100 over much of southern MN. We opted to continue mention in the
HWO for the 95 to 100 scenario.

Numerous variety of hires solutions to the overnight convection
leaves high level of uncertainty to QPF forecast.  We will continue
the higher pop solution for now...as believe some convection will
drop south and east over the region during the night as upper trough
approaches. Still should see high rainfall rates with any organized
convection if that does develop...with PW's still forecast to rise
around 2 inches.  Because of the high uncertainty in overall
location/development of convection into tonight...will leave any
flood watch to later forecasts for tonight period. The severe
weather threat will exist into tonight as well...as modest
instability...shear and boundary will come into play.  Mid level
lapse rates are unstable generally 7-8 C/km...so strong convective
winds and hail will be a definite threat and if a well organized
boundary remains... we could see an isolated tornado threat...mainly
over central MN late afternoon/early evening.

.LONG TERM...(Thursday through Tuesday)
Issued at 322 AM CDT Wed Aug 10 2016

The long term period will start off on an activate note, with
showers and thunderstorms likely ongoing Thursday morning as
strong isentropic upglide occurs ahead of the approaching front
stretching from northwestern MN across eastern SD. The primary
concern on Thursday will be heavy rainfall, given the precipitable
water bullseye of 2+ inches will be centered over the area. May
quite possibly need a flood watch over at least a portion of the
area, but will need to see how the Wednesday convection pans out
first and what areas get a decent amount of rainfall. Any severe
storms would be tied to the frontal passage Thursday
afternoon/eve, although at this point the shear looks fairly weak
and destabilization will be tough to come by given anticipated
convection earlier in the day.

Could see some lingering showers and thunderstorms in the far east
(west central WI) on Friday, but for the most part dry weather is
expected in the wake of the front through the weekend.
Temperatures will retreat below climatological normals, with highs
generally in the 75 to 80 degree range on Saturday and Sunday.

Next week features the transition to semi-zonal flow, which will
mean the opportunity for quick/fleeting precip chances as weak
impulses traverse the fast-moving flow. Temperatures will also
return to near to above normal values for mid-August.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1046 PM CDT Tue Aug 9 2016

The overnight convective trends are becoming more clear. Storms
in south central and southwest ND will likely track eastward
overnight, with KAXN having the best chance for TSRA after 09z.
Short term solutions would move this activity to the north of KSTC
during the morning with only some showers reaching as far south
as KRWF and KMSP. With very moist low level air in place across
the region, there is still the threat for fog and stratus,
especially at KRNH and KEAU where high level cloudiness will be
minimal from the thunderstorms approaching from ND. Therefore,
kept the MVFR or lower conditions in. After the morning convection
on Wednesday, further development will likely not occur until
evening. This activity will likely be across the eastern Dakotas
as well as central and northern MN. Some prob groups were inserted
at KAXN and KSTC with confidence pretty high on occurrence. Light
winds overnight becoming SE 10-15 knots on Wednesday with some
gusts to 20 knots across western MN.

KMSP...Thunderstorms along the ND/SD border late this evening
will likely move into west central MN near KAXN around 09z with a
weakening trend as they spread eastward. There is a small threat
at this point for some showers reaching the airfield around 13z
with a VCSH group inserted. After that, dry conditions expected
until until early Thursday morning when a more aggressive SHRA/TSRA
event is expected.

/OUTLOOK FOR KMSP/
Thu...VFR. MVFR/TSRA likely. Wind S 10KTs.
Fri...VFR. Wind NW 10KTs.
Sat...VFR. Wind NW 5-10kts.

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

SHORT TERM...DWE
LONG TERM...LS
AVIATION...RAH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
337 AM CDT WED AUG 10 2016

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
110845-
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-
337 AM CDT WED AUG 10 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MINNESOTA...EAST CENTRAL MINNESOTA...SOUTH CENTRAL MINNESOTA...
SOUTHEAST MINNESOTA...SOUTHWEST MINNESOTA...WEST CENTRAL
MINNESOTA...NORTHWEST WISCONSIN AND WEST CENTRAL WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS THAT DEVELOPED OVER THE DAKOTAS WILL MOVE ACROSS
WESTERN AND CENTRAL MINNESOTA THIS MORNING. A FEW OF THESE STORMS
ARE EXPECTED TO BE SEVERE...WITH DAMAGING WIND GUSTS BEING THE
PRIMARY THREAT. IN ADDITION...HEAVY RAINFALL WILL BE POSSIBLE WITH
THESE STORMS...WITH A CHANCE FOR LOCALIZED FLOODING.

THE CHANCE FOR SHOWERS AND THUNDERSTORMS WILL EXPAND SOUTH AND
EAST THIS AFTERNOON AND TONIGHT TO INCLUDE THE ENTIRE OUTLOOK
AREA. A FEW OF THESE STORMS COULD BE SEVERE...WITH DAMAGING
WINDS AND LARGE HAIL. A TORNADO OR TWO COULD ALSO OCCUR...MAINLY
OVER CENTRAL MINNESOTA. TORRENTIAL RAINFALL AND THE POTENTIAL FOR
FLOODING ALSO APPEAR TO EXIST...ESPECIALLY ALONG AND NORTH OF
INTERSTATE 94.

HEAT INDICES ARE EXPECTED TO RISE TO BETWEEN 95 AND 100 DEGREES
DURING THE AFTERNOON AND EARLY EVENING HOURS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORM CHANCES WILL CONTINUE INTO THURSDAY NIGHT. HEAVY
RAINFALL AND THE POTENTIAL FOR FLOODING WILL REMAIN THE PRIMARY
THREAT...ALTHOUGH A FEW STORMS COULD BE CAPABLE OF PRODUCING LARGE
HAIL AND DAMAGING WINDS.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS MORNING
ACROSS WEST CENTRAL MINNESOTA...AND ACROSS MUCH OF THE OUTLOOK
AREA THIS AFTERNOON AND EVENING.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
503 AM CDT WED AUG 10 2016

MNZ054>056-101100-
CHIPPEWA-LAC QUI PARLE-SWIFT-
503 AM CDT WED AUG 10 2016

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHERN SWIFT...
NORTHERN LAC QUI PARLE AND NORTHWESTERN CHIPPEWA COUNTIES...

AT 502 AM CDT...RADAR INDICATED STRONG THUNDERSTORMS WERE LOCATED
ALONG A LINE EXTENDING FROM BENSON AIRPORT TO NEAR APPLETON TO NEAR
NASSAU. MOVEMENT WAS EAST AT 25 MPH.

WIND GUSTS UP TO 50 MPH AND HALF INCH HAIL ARE POSSIBLE WITH THESE
STORMS.

LOCATIONS IMPACTED INCLUDE...
BENSON...MADISON...APPLETON...MILAN...BELLINGHAM...MARIETTA...
ODESSA...CERRO GORDO...HAGEN...DE GRAFF...DANVERS AND HOLLOWAY.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THESE STORMS...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.

THESE STORMS MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO
STATIONS AND AVAILABLE TELEVISION STATIONS FOR ADDITIONAL INFORMATION
AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

LAT...LON 4524 9645 4526 9634 4525 9629 4522 9627
      4518 9610 4524 9610 4524 9612 4529 9611
      4533 9576 4535 9526 4513 9552 4490 9645
TIME...MOT...LOC 1002Z 276DEG 21KT 4533 9566 4519 9597 4513 9644

DWE