Special Weather Statement, NWS Twin Cities, MN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1157 AM CDT THU AUG 23 2012

.PREV DISCUSSION...
/ISSUED 409 AM CDT THU AUG 23 2012/

OVERVIEW...SEVERAL CHANCES FOR RAIN IN THE COMING DAYS WITH NEAR
TO ABOVE NORMAL TEMPS THROUGH THE WEEKEND.

SURFACE LOW IN THE PLAINS NOT SHOWING MUCH CHANGE IN INTENSITY BUT
IT IS SLIDING EAST WITH TIME. 3MB 6-HR MSLP CHANGE IN WEST
CENTRAL MN THIS MORNING. PRESSURE FALLS NEARLY CO-LOCATED WITH NOSE
OF THE LLJ AND MOISTURE TRANSPORT. ALSO IN THIS VICINITY IS A NICE
POCKET OF MUCAPE INCREASE OVER THE LAST 3 HOURS...ROUGHLY 400-600
J/KG TO GO ALONG WITH THE THICKNESS RIDGE. NO SURPRISE WE ARE
GENERATING SHOWERS AND STORMS THIS MORNING. THE 850MB JET TAKES
ITS TIME BEFORE SLIDING EAST...BUT THINK THE PRECIP FOCUS WILL BE
ACROSS THE NORTHERN FORECAST AREA AND INTO NORTHERN MN AND
NORTHWEST WI. THESE SHOWER WILL TAKE QUITE SOME TIME TO CLEAR
ESPECIALLY WITH THE WARM FRONT IN THE AREA.

EVEN WITH THE PRECIP LARGELY MOVING OUT DURING THE
AFTERNOON...THIS RAIN WILL PLAY A HUGE ROLE IN THE TEMPERATURE
FORECAST TODAY. THERE IS LARGE BUST POTENTIAL HERE. THE TEMP
PROFILE AND EXPECTED CLEARING IN FAR SOUTHERN MN WARRANTS LOWER
90S...BUT THERE SHOULD BE A SHARP CUTOFF BETWEEN LOWER 80S AND
LOWER 90S DEPENDING ON WHERE THE CLOUDS END UP...PERHAPS EVEN
BISECTING THE METRO.

AFTER A RELATIVE LULL IN ACTIVITY ON FRIDAY...STRONG UPPER LOW
CURRENTLY OFF THE COAST OF BRITISH COLUMBIA DIVES INTO NORTH
DAKOTA AND THEN LIFTS OFF TOWARD LAKE WINNIPEG BY MID DAY
SATURDAY. STRONG DYNAMICAL FORCING IS NORTH...BUT GOOD THETA-E
ADVECTION EXTENDS WELL SOUTH INTO THE MID/UPPER MISSISSIPPI RIVER
VALLEY. THERE IS A SECONDARY AND MUCH WEAKER SURFACE LOW IN THE
SOUTHERN PLAINS THIS WEEKEND...BUT THAT WASHES OUT WITH TIME.

IN THE EXTENDED...LONGWAVE FLOW FAVORS AN UPPER RIDGE OR WEAK
UPPER HIGH PREVAILING OVER THE SOUTHWEST CONUS AND PORTIONS OF THE
CENTRAL CONUS...AND A MEAN LONGWAVE TROUGH ALONG THE EAST COAST.
THIS FAVORS ABOVE NORMAL TEMPS OVER A LARGE PORTION OF THE COUNTRY
OUT SIDE OF THE EAST COAST...WHICH ALSO SHOULD BE FAIRLY WET.

&&

.AVIATION.../18Z TAF ISSUANCE/

CONVECTION HAS ALREADY BEGUN ACROSS WC MN EARLY THIS AFTN WHICH IS
LIKELY THE BEGINNING OF AN ACTIVE AFTN...ESPECIALLY EARLY AT
RWF/STC...THEN TRANSITIONING TO THE E/SE LATE THIS AFTN/EVENING.

KEPT TIMING CLOSE TO AN EXPERIMENTAL PRODUCT THAT ILLUSTRATES THE
HIGHER PROBABILITY OF CONVECTION BASED ON SPECIFIC PARAMETERS
ACROSS RWF/STC BETWEEN 18-22Z.

ANYWAY...THE INITIAL CONVECTION ACROSS WC MN WILL LIKELY MOVE N/NE
DURING THE EARLY AFTN...THEN AFT 20Z...A LINE OF CONVECTION WILL
MOST LIKELY DEVELOP ACROSS SW MN...AND BEGIN TO MERGE WITH THE
CONVECTION TO THE N. THIS WILL LEAD TO HIGHER PROBABILITIES OF
TSRA AT RWF/STC THRU 22Z...THEN MSP/RNH AFT 23Z. AXN WILL LIKELY
BE TOO FAR NW FOR ANY WIDESPREAD CONVECTION. ALTHOUGH THERE COULD
BE VCSH OR +SHRA IN THE SW PART OF THE TAF AREA. WINDS WILL BE
GENERALLY FROM THE S/SW THIS AFTN...AND GUSTY FOR RWF. EXPECT A
DECREASE DURING THE EVENING...THEN INCREASING ONCE AGAIN AFT
15Z/24. ALTHOUGH FG/IFR CIG POTENTIAL IS POSSIBLE AT STC/RWF
DURING THE EARLY MORNING HRS...KEPT CIGS VFR...WITH ONLY IFR
VSBYS. TIMING AND HOW WIDESPREAD THE VSBYS/CIGS BECOME IS LOW.

MSP...A LINE OF CONVECTION WILL LIKELY DEVELOP W/SW OF THE
TERMINAL SITE UNTIL AFT 23Z...THEN BECOMING NUMEROUS TO WIDESPREAD
BETWEEN 23-02Z. CONFIDENCE IS FAIRLY HIGH FOR TSRA...BUT TIMING
REMAINS THE PROBLEM ALONG WITH HOW LOW TO TAKE VSBYS. WILL
CONTINUE WITH VFR CIGS...AND A TEMPORARY PERIOD OF MVFR VSBYS.
THIS WILL LIKELY CHG BASED ON HIGH WIDESPREAD THE CONVECTION GETS
WEST OF MSP. WINDS WILL BE GENERALLY FROM THE SW/S DURING THE NEXT
24-30 HRS...WITH A FEW GUSTS ARND 20 KTS THIS AFTN.

KMSP...

/OUTLOOK FOR KMSP/
FRI...VFR TSRA/SHRA EAST OF THE TERMINAL SITE.
SAT...VFR EARLY...BECOMING VFR WITH TSRA/SHRA BY LATE IN THE DAY
OVERNIGHT.
SUN...SHRA/TSRA NEAR THE AREA...BUT BETTER PROBABILITIES OF TSRA
EAST OF TERMINAL SITE AFT 18Z. ..JLT..

&&

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

CLF/JLT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
455 AM CDT THU AUG 23 2012

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
241000-
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-
455 AM CDT THU AUG 23 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHERN MINNESOTA... AND WEST CENTRAL WISCONSIN.

.DAY ONE...TODAY AND TONIGHT

A FEW THUNDERSTORMS ARE POSSIBLE ACROSS CENTRAL MINNESOTA AND
WESTERN WISCONSIN THIS MORNING AND EARLY AFTERNOON. THERE SHOULD
BE A BREAK IN THE ACTION FOR A FEW HOURS BEFORE MORE THUNDERSTORMS
ARE POSSIBLE THIS EVENING. THE THREAT FOR SEVERE WEATHER LOOKS
LOW.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THE WEATHER WILL BE ACTIVE OVER THE NEXT FEW DAYS WITH MULTIPLE
CHANCES FOR THUNDERSTORMS. THE THREAT FOR SEVERE WEATHER THIS
WEEKEND IS ALSO LOW.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTER ACTIVATION WILL NOT BE NEEDED.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1116 AM CDT THU AUG 23 2012

MNZ055-056-231645-
CHIPPEWA-SWIFT-
1116 AM CDT THU AUG 23 2012

AT 1111 AM CDT...WEATHER SERVICE RADAR WAS TRACKING A STRONG
THUNDERSTORM NEAR MILAN. THIS STORM WAS MOVING NORTHEAST AT 20 MPH.

HAIL UP TO NICKEL SIZE AND WINDS UP TO 30 MPH ARE EXPECTED WITH THIS
STORM.

* LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
  MILAN.
  BIG BEND CITY.

LAT...LON 4527 9579 4515 9565 4506 9590 4512 9599
TIME...MOT...LOC 1616Z 235DEG 16KT 4513 9588

SPD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1124 AM CDT THU AUG 23 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1111 AM     HAIL             ESE MILAN               45.11N 95.91W
08/23/2012  M0.88 INCH       CHIPPEWA           MN   TRAINED SPOTTER

&&

SPD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1130 AM CDT THU AUG 23 2012

MNZ055>057-231715-
CHIPPEWA-KANDIYOHI-SWIFT-
1130 AM CDT THU AUG 23 2012

AT 1127 AM CDT...WEATHER SERVICE RADAR WAS TRACKING STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM 3 MILES SOUTHEAST OF
APPLETON TO 7 MILES SOUTHEAST OF DANVERS TO 4 MILES EAST OF DE GRAFF.
THESE STORMS WERE MOVING NORTHEAST AT 30 MPH.

HAIL UP TO NICKEL SIZE AND WINDS UP TO 30 MPH ARE EXPECTED WITH THESE
STORMS.

* LOCATIONS IN OR NEAR THE PATH OF THESE STORMS INCLUDE...
  BENSON
  MURDOCK.
  DE GRAFF.
  DANVERS.
  BENSON.
  SUNBURG.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS THUNDERSTORM COULD INTENSIFY QUICKLY...SO BE READY TO ACT IF A
WARNING IS ISSUED.

&&

LAT...LON 4541 9578 4540 9529 4540 9494 4512 9520
      4512 9552 4515 9598
TIME...MOT...LOC 1630Z 246DEG 28KT 4519 9595 4522 9561
          4525 9536

SPD

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1230 PM CDT THU AUG 23 2012

MNZ047-048-055-231830-
POPE-STEVENS-SWIFT-
1230 PM CDT THU AUG 23 2012

AT 1228 PM CDT...WEATHER SERVICE RADAR WAS TRACKING THUNDERSTORMS
ALONG A LINE EXTENDING FROM 10 MILES NORTHEAST OF BENSON TO 25 MILES
SOUTHWEST OF MORRIS. THESE STORMS WERE MOVING NORTHEAST AT 25 MPH.
MORE STORMS WERE DEVELOPING SOUTH OF GLENWOOD.

HAIL UP TO PENNY SIZE AND WINDS UP TO 30 MPH ARE EXPECTED WITH THESE
STORMS.

* LOCATIONS IN OR NEAR THE PATH OF THESE STORMS INCLUDE...
  CLONTARF.
  GILCHRIST.
  SEDAN.
  DANVERS.
  BENSON.
  MORRIS.
  GLENWOOD.
  STARBUCK.
  LAKE MINNEWASKA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO THE
STORM TO BE STRUCK BY LIGHTNING. SEEK SAFE SHELTER IMMEDIATELY.

IF ON OR NEAR LAKE MINNEWASKA...GET OUT OF THE WATER AND MOVE
INDOORS OR INSIDE A VEHICLE. REMEMBER...LIGHTNING CAN STRIKE OUT TO
15 MILES FROM THE PARENT THUNDERSTORM. IF YOU CAN HEAR THUNDER...YOU
ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. DON'T BE CAUGHT ON THE
WATER IN A THUNDERSTORM!

&&

LAT...LON 4568 9515 4526 9539 4527 9611 4564 9618
TIME...MOT...LOC 1728Z 225DEG 20KT 4540 9538 4533 9604

TDK