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Mesoscale Discussion 1579 |
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MESOSCALE DISCUSSION 1579
NWS STORM PREDICTION CENTER NORMAN OK
0108 AM CDT SUN AUG 02 2015
AREAS AFFECTED...PORTIONS N-CENTRAL/NERN MN INCLUDING ARROWHEAD.
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 020608Z - 020815Z
PROBABILITY OF WATCH ISSUANCE...5 PERCENT
SUMMARY...BAND OF STG-SVR TSTMS MAY OFFER ADDITIONAL BUT MORE MRGL
WIND-DAMAGE POTENTIAL ALONG WITH ISOLATED LARGE HAIL...AS IT MOVES
SEWD OVER DISCUSSION AREA. WW IS NOT ANTICIPATED.
DISCUSSION...BAND OF TSTMS AT 06Z EXTENDED FROM NRN BELTRAMI COUNTY
ENEWD ACROSS PARTS OF NWRN ONT JUST NW OF ST. LOUIS COUNTY. THIS
ACTIVITY SHOULD PROCEED SEWD AT SPEEDS VARYING FROM 35-45 KT.
PREVIOUSLY MOST INTENSE/ANCHORING CELL IN THIS CONVECTION PRODUCED
MEASURED 58-KT GUST AT ROSEAU/ROX AT 454Z...WITH APPARENT
ACCELERATION AID FROM DRIER LAYER JUST ABOVE SFC PER MODIFIED INL
RAOB. THAT AND MODEL FCST SOUNDINGS MODIFIED FOR CONDITIONS FARTHER
DOWNSHEAR SUGGEST NEAR-SFC STABLE LAYER WILL DEEPEN AND INTENSIFY
WITH TIME AND FURTHER NOCTURNAL BOUNDARY-LAYER COOLING...REDUCING
BUT NOT ENTIRELY ELIMINATING WIND THREAT IF HOLDING STORM INTENSITY
CONSTANT. ORIGINAL WIND-PRODUCING TSTM HAS WEAKENED
SUBSTANTIALLY...HOWEVER...AND OTHER DEVELOPMENT TO ITS ENE IN
SOMEWHAT MORE STABLE REGIME SHOULD MOVE INTO BORDER COUNTIES OVER
AND S OF BOUNDARY WATERS REGION DURING NEXT 1-2 HOURS.
THIS AREA IS CHARACTERIZED BY SHARP SW-NE-ALIGNED GRADIENT IN
BUOYANCY RELATED TO SLOW-MOVING LOW-LEVEL WARM FRONT ORIENTED NW-SE
OVER THIS REGION. MUCAPE RANGES FROM NEAR 3000 J/KG IN CENTRAL MN
TO LESS THAN 500 J/KG OVER ERN ARROWHEAD...AS BOTH LOW-LEVEL THETAE
AND MIDLEVEL LAPSE RATES DECREASE WITH NEWD EXTENT. BACKBUILDING
INTO MORE MOIST/UNSTABLE AIR CANNOT BE RULED OUT OVER N-CENTRAL/NWRN
MN...BUT IS CONTRAINDICATED ATTM BY PRECONVECTIVE OUTFLOW SURGE
READILY APPARENT IN REFLECTIVITY ANIMATIONS. TSTMS GENERALLY SHOULD
MOVE ESEWD WITHIN AND JUST NE OF TIGHTEST PART OF THAT BUOYANCY
GRADIENT WHERE LOW-LEVEL LIFT WILL BE GREATEST...OCCASIONALLY
OFFERING HAIL AND STG GUSTS.
..EDWARDS/COHEN.. 08/02/2015
ATTN...WFO...DLH...FGF...
LAT...LON 48279532 48659425 48599385 48539379 48529355 48629338
48629285 48519259 48439269 48449250 48239236 48359227
48349201 48229196 48169167 48039155 48039138 48299085
48079074 48109010 47978990 48048977 47988945 47848999
47469104 46859204 48279532
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