ACUS01 KWNS 172002
SWODY1
SPC AC 172000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT SAT JUL 17 2010
VALID 172000Z - 181200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF MN/NORTHERN
IA/WESTERN WI AND FAR EASTERN DAKOTAS...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE
MIDWEST/UPPER MS RIVER VALLEY...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
NORTHEAST STATES...
...UPPER MIDWEST/UPPER MS VALLEY...
SCATTERED SEVERE STORMS INCLUDING SUPERCELLS WILL CONTINUE TO
DEVELOP ALONG/NORTH OF A RETREATING/BUT NOW CONVECTIVELY REINFORCED
WARM FRONT FROM FAR SOUTHEAST ND SOUTHEASTWARD ACROSS CENTRAL MN TO
CENTRAL WI. ADDITIONAL DEEP CONVECTIVE DEVELOPMENT SEEMS PROBABLE
LATE THIS AFTERNOON/EARLY EVENING FROM NEAR A SURFACE TRIPLE POINT
ALONG THE SOUTHEAST ND/NORTHEAST SD BORDER VICINITY...SOUTHWESTWARD
ALONG THE SOUTHEASTWARD ADVANCING COLD FRONT ACROSS EASTERN SD TO
NEB. FOR ADDITIONAL DETAILS...SEE MESOSCALE DISCUSSION 1335.
IN EITHER CASE...AN INITIAL SUPERCELLULAR MODE /WITH TORNADO AND
LARGE HAIL POTENTIAL/ WILL YIELD TO UPSCALE/MCS-TYPE GROWTH THIS
EVENING/TONIGHT...WITH AN APPRECIABLE/WIDESPREAD DAMAGING WIND
THREAT INCREASING ACCORDINGLY ESPECIALLY ACROSS THE SOUTHERN HALF OF
MN/NORTHERN IA/FAR WESTERN WI.
CONSULT THE LATEST WATCHES/MESOSCALE DISCUSSIONS FOR THE MOST
CONTEMPORARY GUIDANCE.
...LOWER GREAT LAKES TO NORTHERN NEW ENGLAND...
HAVE INTRODUCED A SLIGHT RISK FOR PORTIONS OF THE REGION...AS IT
APPEARS THAT MULTICELLULAR STORMS AHEAD OF A SOUTHEASTWARD SAGGING
COLD FRONT MAY POSE A THREAT FOR MAINLY DAMAGING WINDS ESPECIALLY
ACROSS PORTIONS OF UPSTATE NY INTO FAR NORTHERN NEW ENGLAND.
...CAROLINAS...
DAMAGING WIND THREAT ASSOCIATED WITH AN MCS ACROSS NC SHOULD BECOME
INCREASINGLY ISOLATED THE REMAINDER OF THE AFTERNOON.
..GUYER.. 07/17/2010
.PREV DISCUSSION... /ISSUED 1119 AM CDT SAT JUL 17 2010/
...MIDWEST...
A LARGE UPPER RIDGE REMAINS IN PLACE OVER THE SOUTHWEST STATES
TODAY...WHILE A SERIES OF LOW-AMPLITUDE SHORTWAVE TROUGHS PROGRESS
EASTWARD ACROSS THE NORTHERN TIER OF STATES. ONE WELL-DEFINED
SHORTWAVE TROUGH IS MOVING ACROSS EASTERN MT INTO THE DAKOTAS. THIS
FEATURE WILL HELP TO INITIATE VIGOROUS THUNDERSTORM ACTIVITY LATER
THIS AFTERNOON AND TONIGHT ACROSS THE UPPER MIDWEST. STORMS ARE
EXPECTED TO FORM INITIALLY NEAR A DEVELOPING SURFACE LOW/COLD FRONT
SURGING SOUTHEASTWARD ACROSS EASTERN ND/SD. STRENGTHENING SOUTHERLY
LOW LEVEL WINDS AHEAD OF THE LOW WILL TRANSPORT 60S TO LOWER 70S
DEWPOINTS IN THIS REGION...YIELDING AFTERNOON MLCAPE VALUES OF
2000-3000 J/KG. BACKED LOW LEVEL WINDS AND AMPLE WEST-NORTHWESTERLY
MID LEVEL WINDS WILL PROVIDE FAVORABLE EFFECTIVE SHEAR AND LOW LEVEL
HELICITY FOR SUPERCELLS. VERY LARGE HAIL AND ISOLATED TORNADOES
WILL BE POSSIBLE THROUGH MID EVENING. HOWEVER...THE NUMBER OF
STORMS AND INCREASING LARGE SCALE FORCING WILL PROMOTE UPSCALE
ORGANIZATION WITH THE POTENTIAL FOR FAST-MOVING BOW ECHOES ACROSS
PARTS OF SOUTHERN MN/NORTHERN IA. WIDESPREAD DAMAGING WINDS ARE
POSSIBLE ACROSS THIS REGION. GIVEN THE MOIST/UNSTABLE AIR MASS IN
PLACE...A SEVERE MCS MAY TRACK AS FAR SOUTHEAST AS NORTHERN MO BY
18/12Z WITH A CONTINUED RISK OF LOCALLY DAMAGING WINDS.
...NC/VA...
A LONG-LIVED MCS IS MOVING ACROSS PARTS OF VA/NC...WITH OCCASIONAL
REPORTS OF LOCALLY DAMAGING WINDS. THIS SYSTEM IS LIKELY TO PERSIST
MUCH OF THE DAY AND TRACK EASTWARD TOWARD THE COAST. MLCAPE VALUES
OVER 2000 J/KG AND 25-30 KNOT WESTERLY MID LEVEL WINDS WILL MAINTAIN
A RISK OF GUSTY/DAMAGING WINDS THROUGH THE MAX HEATING CYCLE.
...LOWER GREAT LAKES...
BROAD CYCLONIC MID LEVEL FLOW IS PRESENT TODAY OVER THE GREAT LAKES
REGION...WITH A WEAK COLD FRONT SAGGING ACROSS LOWER MI. VARIOUS
MODEL SOLUTIONS DIFFER ON THE EXTENT OF CONVECTIVE DEVELOPMENT ALONG
THIS FRONT LATER THIS AFTERNOON FROM NORTHERN NEW ENGLAND INTO
OH/MI. DESPITE UNCERTAINTY IN COVERAGE OF STORMS...CONDITIONAL RISK
WILL EXIST FOR MULTICELL CONVECTION CAPABLE OF DAMAGING WINDS
THROUGH THE EVENING.
...SOUTHERN AZ...
EASTERLY DEEP LAYER FLOW AROUND THE SOUTH SIDE OF AN UPPER LEVEL
HIGH WILL HELP TO PROPAGATE CONVECTION THAT MAY FORM OVER EASTERN AZ
THIS EVENING INTO THE LOWER DESERTS. SURFACE DEWPOINTS IN THE LOWER
60S...COMBINED WITH STRONG HEATING AND INCREASING PWAT VALUES
SUGGEST THE RISK OF MORE WIDESPREAD THUNDERSTORM ACTIVITY. LOCALLY
DAMAGING WINDS WILL BE LIKELY WITH MORE ORGANIZED STORM CLUSTERS.
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