Metro all clear: PDS Tornado Watch SE MN & WI
Update 3:30pm:
Particularly Dangerous Situation tornado watch issued until 11pm for much of Wisconsin & southeast Minnesota.
Cities included in the watch are Rochester, Eau Claire, Menomonie, & La Crosse.
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This is a dangerous situation! A major tornado outbreak is possible/likely in Wisconsin through tonight.
-SPC
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 120
NWS STORM PREDICTION CENTER NORMAN OK
320 PM CDT SUN APR 10 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
PARTS OF NORTHEAST IOWA
PARTS OF WESTERN NORTHERN MICHIGAN
SMALL PART OF SOUTHEAST MINNESOTA
MUCH OF WISCONSIN
LAKE SUPERIOR
EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 320 PM UNTIL
1100 PM CDT.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...
DESTRUCTIVE TORNADOES...LARGE HAIL TO 4 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE
MILES EAST AND WEST OF A LINE FROM 5 MILES NORTH NORTHWEST OF
IRONWOOD MICHIGAN TO 45 MILES SOUTH OF CAMP DOUGLAS WISCONSIN.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
DISCUSSION...RAPID DEVELOPMENT OF SEVERE SUPERCELL THUNDERSTORMS
IMMINENT ALONG THE COLD FRONT FROM WI/MN BORDER INTO NERN IA. AIR
MASS HAS DESTABILIZED AHEAD OF FRONT WITH MLCAPES TO 2000
J/KG...COUPLED WITH A VERY INTENSE WIND FIELD WILL LEAD TO POTENTIAL
OF BOTH VERY LARGE HAIL AND TORNADOS WITH ANY SUPERCELL. THERE IS
THE THREAT OF LONG LIVED SUPERCELLS ALONG WITH STRONG/DAMAGING
TORNADOES.
PH
Update 3pm:
The threat for severe weather has shifted east today. The storms just took too long to develop, and now a cold front has pushed through the metro and runs from near Rochester to Hudson, WI.
Temps dropped 15 degrees at the Weather Lab in Deephaven from 74 to 59 between 1:30pm & 3pm Sunday.
The atmosphere has stabilized over the metro, but storms may still develop in southeast Minnesota and Wisconsin...with the most favored area along and east of a line from Rochester to Eau Claire.
SPC has shifted the risk area east accordingly.
A band of showers and a few rumbles of thunder behind the front may still move through tonight into early Monday. Expect windy & colder conditions Monday, with a return to nice weather and highs in the 60s for Tuesday.
PH
Update 2:30pm:
Prime area for development appears to be from near Albert Lea to Stillwater in the next hour. See latest Twin Cities NWS forecast discussion text below...
GOES 1km visible satellite & temps overlay shows best development potential in SE MN & Western WI.
PH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
218 PM CDT SUN APR 10 2011
.DISCUSSION...
.MESOSCALE...
CONDITIONS ARE COMING TOGETHER FOR CONVECTIVE INITIATION BY 330
PM...WITH RAPID DEVELOPMENT LIKELY AFTER...SOME OF WHICH IS
PROBABLE TO BE TORNADIC IN THE REGION. THE MOST FAVORED AREA IN
OUR CWA IS WESTERN WISCONSIN.
THE LATEST HAND SURFACE ANALYSIS DEPICTS THE PRIMARY SURFACE LOW
DEEPENING NEAR LAKE MILLE LACS WITH A STRONG WARM FRONT REACHING
EAST OF THERE AND A COLD FRONT EXTENDING DUE SOUTH...DRAPED ABOUT
30 MILES WEST OF I-35 /AND SEEN ON THE KMPX RADAR/. A SECONDARY
SURFACE CIRCULATION HAS BEEN ANALYZED ALL DAY ON THE COLD FRONT
AND IS APPROACHING MASON CITY. THIS IS OF PARTICULAR INTEREST AS
IT IS WHERE THE INHIBITION HAS RAPIDLY DECREASED...IN FACT THERE
IS NOW NONE ANALYZED OVER CENTRAL INTO NORTHERN IA ON THE LATEST
SPC MESOANALYSIS. JUST AHEAD OF THIS AREA IS POOLED 64-66 SURFACE
DEW POINTS AND ENHANCED MOISTURE CONVERGENCE. THIS AREA OF
SOUTHEAST MN IS ALSO AT THE NOSE OF A VERY STRONG MID-LEVEL JET
/90-100 KT AT 500MB PER PROFILERS AND SEEN ON WATER VAPOR/
ALLOWING FOR DEEPER ASCENT AND SHEAR...ALONG WITH FURTHER MID-
LEVEL COOLING. THE ELEVATED LAPSE RATES ARE ALREADY DRY ADIABATIC
PER THE 18Z MPX SOUNDING. SO THIS INDICATES THAT DEVELOPMENT
SHOULD BE RAPID ONCE THE SURFACE WARMTH AND MOISTURE CAN CONNECT
IN THE VERTICAL WITH SUCH LAPSE RATES. THE CURRENT HRRR AND VSREF
MODELS INDICATE THAT AROUND 330 PM IS THE FAVORED DEVELOPMENT
TIME...WITH THE AREA OF ALBERT LEA TO THE ST. CROIX RIVER VALLEY
MOST LIKELY. STORMS SHOULD EVOLVE TO THE NORTHEAST RAPIDLY. THE
DEEP LAYER SHEAR MAGNITUDE OF 60 TO 70 KTS AND THE FRONTAL
ORIENTATION FAVOR DISCRETE SUPERCELLS...WITH POSSIBLE SPLITS. THE
0-1KM SHEAR VALUES ARE AROUND 20 KTS RIGHT NOW ACROSS THE CWA WARM
SECTOR...AND ARE FORECAST TO INCREASE BY THE RUC TO 25-30 KTS OVER
THE EASTERN TWO TIERS OF COUNTIES. WITH OTHER PARAMETERS IN PLACE
OVER THAT AREA BETWEEN 3:30PM-6PM AND THE SECONDARY SURFACE LOW
MOVING THAT WAY...THAT LOCATION IS THE MOST FAVORED FOR TORNADOES
IN THE FORECAST AREA. EXPLICIT CONVECTIVE RUNS OF THE NMM AND HRRR
HAVE ALSO BEEN INDICATING WHAT APPEAR TO BE SUPERCELL STRUCTURES
NEAR LADYSMITH TO EAU CLAIRE IN THAT TIME. AS FOR OTHER
THREATS...THEY PRETTY MUCH ALL ARE IN PLAY AS DCAPE VALUES ARE
QUITE LARGE...AND THERE IS PLENTY OF INSTABILITY ABOVE -20C FOR
LARGE HAIL. WE HAVE ADAPTED A HIGH TEMPORAL RESOLUTION INTO THE
FORECAST GRIDS THROUGH EARLY EVENING...AND MENTIONED THE CHANCE
FOR TORNADOES IN THE EASTERN TWO TIERS OF COUNTIES...GIVEN IT IS
THE FIRST EVENT OF THE YEAR...ANOMALOUSLY EARLY...AND THAT THERE
ARE SOME PARAMETERS IN LINE FOR STRONG TORNADOES IN THAT AREA. THE
THREAT SHOULD BE EAST OF THE AREA BY 8 PM...POSSIBLY AS EARLY AS 6
PM.
Update 1:35pm:
Tornado watch likely by 2pm according to SPC mesoscale discussion!
MESOSCALE DISCUSSION 0396
NWS STORM PREDICTION CENTER NORMAN OK
0130 PM CDT SUN APR 10 2011
AREAS AFFECTED...EXTREME SERN MN...NERN IA...NWRN IL AND MUCH OF WI
CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY
VALID 101830Z - 102030Z
OUTBREAK OF SEVERE STORMS IS EXPECTED THIS AFTERNOON...INITIALLY
FROM ERN MN THROUGH NERN IA...THEN SPREADING RAPIDLY EWD THROUGH WI
AND EXTREME NWRN IL. SUPERCELLS WITH STRONG TORNADOES...VERY LARGE
HAIL AND DAMAGING WIND WILL BE THE MAIN THREATS. A TORNADO WATCH
WILL LIKELY BE ISSUED BY 20Z.
THIS AFTERNOON A COLD FRONT EXTENDS FROM A DEEP LOW PRESSURE AREA IN E-CNTRL MN SSWWD THROUGH SRN MN...NWRN IA INTO SERN NEB WITH A WARM
FRONT FROM THE SURFACE LOW IN E-CNTRL MN THROUGH NRN WI. THE LOW
WILL DEVELOP EWD TO NEAR THE WI BORDER BY 21Z. NEWD ADVECTION OF
HIGHER THETA-E AIR ALONG A STRONG SSWLY LLJ BENEATH EML PLUME /8.5
C/KM LAPSE RATES/ AND DIABATIC WARMING IS RESULTING IN NEWD
DESTABILIZATION WITH TIME. HOWEVER...THE BOUNDARY LAYER REMAINS
CAPPED BY THE WARM EML AS EVIDENCED BY 18Z MINNEAPOLIS SOUNDING.
UPPER JET IS SHIFTING NEWD INTO THE UPPER MS VALLEY. RAPID ACCAS
DEVELOPMENT RECENTLY OBSERVED FROM NERN IA THROUGH SWRN WI IS LIKELY INDICATIVE OF NEWD EXPANDING ZONE OF AGEOSTROPHIC FORCING WITHIN THE UPPER JET EXIT REGION. THIS FORCING IN CONJUNCTION WITH FRONTAL CONVERGENCE WILL LIKELY MAINTAIN A DEEPER ZONE OF ASCENT THAT SHOULD EVENTUALLY ERODE THE CAP ENOUGH FOR STORMS TO DEVELOP ALONG THE COLD FRONT FROM ERN MN INTO NERN IA. STORMS WILL LIKELY MAINTAIN DISCRETE MODES FOR SEVERAL HOURS AND WILL BE EMBEDDED WITHIN STRONG DEEP LAYER WIND AND VERTICAL SHEAR SUPPORTIVE OF SUPERCELLS. LARGEST HODOGRAPHS ARE EXPECTED ACROSS CNTRL THROUGH NRN WI WHERE NEAR SURFACE WINDS SHOULD REMAIN BACKED TO SLY EAST OF THE SURFACE LOW WITH 0-1 KM STORM RELATIVE HELICITY EXCEEDING 250 M2/S2. STORMS DEVELOPING WITHIN THIS ENVIRONMENT WILL LIKELY BECOME CAPABLE OF PRODUCING STRONG TORNADOES...VERY LARGE HAIL AND DAMAGING WIND.
..DIAL.. 04/10/2011
It looks like storms may develop rapidly this afternoon near the east metro and in southeast Minnesota into western Wisconsin. There is a moderate risk for severe weather and possibly some tornadoes.
Storm development could be rapid. No watches yet...but they could happen soon.
There is a moderate risk for severe storms from the east metro east into Wisconsin through tonight according to SPC.
SPC: Moderate risk from metro east.
Greatest tornado threat includes east metro & much of Wisconsin.
Large hail likely with storms.
Stay tuned today as the severe weather threat unfolds.
PH