MD 0258 CONCERNING HEAVY SNOW FOR PORTIONS OF ERN CO AND SERN WY
MESOSCALE DISCUSSION 0258
NWS STORM PREDICTION CENTER NORMAN OK
0733 AM CST SAT MAR 09 2013
AREAS AFFECTED...PORTIONS OF ERN CO AND SERN WY
CONCERNING...HEAVY SNOW
VALID 091333Z - 091730Z
SUMMARY...AREAS OF SNOW WITH RATES OF 1.0-1.5 IN/HR WILL DEVELOP
THROUGH THE MORNING OVER PARTS OF THE CO/WY FRONT RANGE...AS WELL AS
THE ADJACENT FOOTHILLS AND HIGH PLAINS. OCCASIONAL NEAR-BLIZZARD
CONDITIONS WILL BECOME MORE LIKELY AFTER 15Z...ESPECIALLY OVER THE
HIGH PLAINS.
DISCUSSION...CYS VWP DATA INDICATE THAT A BARRIER JET HAS BEEN
STEADILY STRENGTHENING DURING THE PAST COUPLE OF HOURS TO THE E OF
THE FRONT RANGE OF THE ROCKIES...WITH NLY FLOW REACHING OVER 30 KT
BELOW 1 KM AGL. SUBTLE STRENGTHENING OF THE BARRIER JET HAS ALSO
BEEN NOTED FARTHER S INTO CO DURING THE PAST HOUR PER FTG VWP DATA.
DURING THE NEXT FEW HOURS...THE BARRIER JET WILL CONTINUE TO
STRENGTHEN E OF THE CO/WY FRONT RANGE...WHILE SFC CYCLOGENESIS
OCCURS OVER ERN CO AND WRN KS.
THE STRENGTHENING CIRCULATION AROUND AN INTENSIFYING SFC LOW OVER
THE CNTRL HIGH PLAINS...SUPERIMPOSED ON A BACKGROUND NE/SW-ORIENTED
LOW-LEVEL BAROCLINIC ZONE...WILL SUPPORT STRENGTHENING 850-700-MB
FRONTOGENESIS THIS MORNING. THE ASCENDING BRANCH OF THE
FRONTOGENETIC CIRCULATION WILL BE AUGMENTED BY ISENTROPIC LIFT ATOP
THE COLD DOME ACCOMPANYING THE BARRIER JET. AND...WITH A
SUFFICIENTLY DEEP LAYER OF SUBFREEZING TEMPERATURES AND A DENDRITIC
GROWTH ZONE EXTENDING FROM AROUND 590 MB TO 530 MB PER THE DNR 12Z
RAOB...SNOW WILL INCREASE IN COVERAGE AND INTENSITY THIS MORNING.
SNOWFALL RATES OF 1.0-1.5 IN/HR WILL BECOME INCREASINGLY COMMON
AFTER 15Z...SPREADING FROM N TO S...AS AFFIRMED BY THE CONSENSUS
AMONGST HIGH-RESOLUTION WRF GUIDANCE AND EXPERIMENTAL SPC SSEO
GUIDANCE. THE HIGHEST SNOWFALL RATES WILL OCCUR WITH CONVECTIVELY
ENHANCED PRECIPITATION OWING TO MEAGER ELEVATED BUOYANCY PER
FORECAST SOUNDINGS. AN ISOLATED LIGHTNING STRIKE OR TWO CANNOT BE
RULED OUT...ESPECIALLY OVER THE HIGH PLAINS.
FURTHERMORE...THE STRENGTHENING SFC PRESSURE GRADIENT/BARRIER JET
WILL BE ACCOMPANIED BY INCREASING WINDS. NLY WINDS OF 15-25 MPH WITH
OCCASIONAL GUSTS REACHING 30-35 MPH -- PERHAPS LOCALLY
STRONGER -- WILL YIELD VISIBILITIES AOB ONE-HALF MILE ALONG WITH
OCCASIONAL NEAR-BLIZZARD CONDITIONS. THE MOST LIKELY AREA FOR THESE
CONDITIONS WILL BE OVER THE HIGH PLAINS -- E OF INTERSTATE 25 --
AFTER 15Z.
..COHEN.. 03/09/2013
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GLD...PUB...BOU...CYS...
LAT...LON 41430572 41790523 41880438 41700406 40960392 40910225
40520221 39660332 38340414 38230507 38890546 40580571
41430572
via SPC Forecast Products http://www.spc.noaa.gov/products/md/md0258.html
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