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Mesoscale Discussion 669 |
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MESOSCALE DISCUSSION 0669
NWS STORM PREDICTION CENTER NORMAN OK
1051 PM CDT FRI APR 29 2011
AREAS AFFECTED...PARTS OF WRN ND
CONCERNING...HEAVY SNOW
VALID 300351Z - 300915Z
AREAS OF RAIN SHOULD CHANGE TO SNOW AFTER MIDNIGHT ACROSS NWRN
ND...WITH SNOWFALL RATES INCREASING TO AROUND 1 INCH PER HOUR BY 09Z
AND CONTINUING THROUGH AT LEAST 12Z. ALTHOUGH WARMER GROUND
TEMPERATURES MAY TEMPER ACCUMULATIONS...THE COMBINATION OF THE
EXPECTED SNOWFALL RATES AND STRENGTHENING NW SURFACE WINDS TO 35-40
KT INTO EARLY SATURDAY MORNING WILL INCREASE THE LIKELIHOOD FOR
BLIZZARD CONDITIONS.
AT 03Z...SURFACE OBSERVATIONS INDICATED TEMPERATURES WERE REMAINING
AROUND 40 F ACROSS NWRN ND...WHILE VALUES OVER SWRN ND HAD ALREADY
FALLEN INTO THE LOWER-MID 30S. THE WARMER TEMPERATURES ARE LIKELY
DUE TO ONGOING LOW LEVEL WAA WITHIN THE NRN PERIPHERY OF A DEEPENING
LOW PRESSURE AREA LOCATED IN NORTH CENTRAL ND. HOWEVER...MODELS
SUGGEST SURFACE TEMPERATURES SHOULD COOL AFTER MIDNIGHT OVER NWRN ND
PER DYNAMIC COOLING ATTENDANT TO STRONG HEIGHT FALLS WITH A
DEEPENING MID-UPPER LEVEL LOW OVER THE DAKOTAS THROUGH 12Z. AS THIS
PROCESS OCCURS...A COLD FRONT IS EXPECTED TO ADVANCE INTO WRN ND
AFTER 06Z. INCREASING LOW LEVEL CONVERGENCE ALONG THIS BOUNDARY
CONCURRENT WITH THE HEIGHT FALLS WILL SUPPORT SUFFICIENT UVVS OVER
NWRN ND FOR INCREASED PRECIPITATION RATES...WHILE COOLING THERMAL
PROFILES FAVOR SNOW.
..PETERS.. 04/30/2011
ATTN...WFO...BIS...
LAT...LON 49000155 48370223 47310262 47250366 47570397 48450397
49000400 49000155
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