SWOMCD
SPC MCD 020113
COZ000-WYZ000-020615-
MESOSCALE DISCUSSION 2283
NWS STORM PREDICTION CENTER NORMAN OK
0813 PM CDT TUE NOV 01 2011
AREAS AFFECTED...ROCKIES OF SRN WY AND NRN/CNTRL CO...AS WELL AS THE
ADJACENT HIGH PLAINS
CONCERNING...BLIZZARD
VALID 020113Z - 020615Z
BANDS OF HEAVY SNOW WITH RATES TO 2 IN/HR WILL DEVELOP FROM N TO S
OVER THE ROCKIES OF SRN WY AND NRN/CNTRL CO...AS WELL THE ADJACENT
HIGH PLAINS DURING THE EVENING AND OVERNIGHT HOURS. BLIZZARD
CONDITIONS WILL LIKELY DEVELOP OVER THE CO HIGH PLAINS...PRIMARILY
AFTER 06Z.
WATER VAPOR LOOP DEPICTS A POTENT MID/UPPER-LEVEL IMPULSE WITHIN THE
BASE OF A LONGWAVE TROUGH OVER THE WRN CONUS...WITH AN ATTENDANT
250-MB JET STREAK FEATURING SWLY CORE WINDS AROUND 120 KT OVER CO.
STRONG ASCENT WITHIN THE LEFT-EXIT REGION OF THIS FEATURE AUGMENTED
BY DOWNSTREAM DCVA...COUPLED WITH A NNWWD-SLOPING BAROCLINIC ZONE
WILL INDUCE A STRENGTHENING FRONTOGENETIC CIRCULATION OVER THE
ROCKIES AND ADJACENT HIGH PLAINS. ATTENDANT LOW-LEVEL ASCENT WILL
ALLOW WSW-ENE-ORIENTED SNOW BANDS TO DEVELOP SWD DURING THE NEXT
SEVERAL HOURS...AIDED BY INCREASING SLANTWISE CONVECTION. SNOWFALL
RATES TO 2 IN/HR WILL BE LIKELY WITHIN THESE SNOW BANDS...HIGHEST
ALONG THE IMMEDIATE FRONT RANGE AND ADJACENT FOOTHILLS. AN ISOLATED
LIGHTNING STRIKE OR TWO WILL BE POSSIBLE WITH THE HEAVIEST SNOW.
MEANWHILE...THE LOW-LEVEL PRESSURE PATTERN WILL SUPPORT
STRENGTHENING ELY/UPSLOPE FLOW AS AN ISALLOBARIC RESPONSE TO SFC
PRESSURE RISES TO THE E/NE. IN TURN...ADIABATIC COOLING AND AN
ASSOCIATED MESO-RIDGE AND BARRIER JET WILL DEVELOP JUST EAST OF THE
FRONT RANGE...WHICH IS ALREADY BEING MANIFESTED IN THE PRONOUNCED
NLY SURGE AND PRESSURE RISES OBSERVED INVOF DENVER. THIS WILL ALLOW
SUBFREEZING AIR IN SERN WY TO QUICKLY SURGE SWD JUST EAST OF THE
FRONT RANGE AND SUPPORT SNOW...WHILE ALSO STRENGTHENING ISENTROPIC
ASCENT FOR PARCELS WITH TRAJECTORIES EMANATING FROM THE EAST. THIS
WILL ENHANCE SNOWFALL RATES FROM FORT COLLINS TO DENVER AFTER 05Z.
FARTHER EAST OVER THE HIGH PLAINS OF NERN/E-CNTRL CO...SNOWFALL
RATES MAY ONLY REACH 1 IN/HR. HOWEVER...THE AFOREMENTIONED
MESO-RIDGE WILL TIGHTEN THE LOW-LEVEL PRESSURE GRADIENT SUFFICIENTLY
TO PRODUCE NLY TO NELY WINDS TO 35 MPH WITH FREQUENTLY HIGHER GUSTS.
THESE WINDS WILL COMBINE WITH BURSTS OF HEAVIER SNOW TO GENERATE
BLIZZARD CONDITIONS...PREDOMINANTLY AFTER 06Z. THE SNOW AND BLIZZARD
CONDITIONS WILL LIKELY PERSIST THROUGH MUCH OF THE NIGHT...WHILE
TAPERING OFF FROM N TO S WEDNESDAY MORNING.
..COHEN.. 11/02/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GLD...PUB...BOU...CYS...GJT...
LAT...LON 38250618 39260663 40410674 41250640 41470592 41430535
40940419 40760327 40500233 39540222 38460342 37860531
38250618
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