000
FOUS11 KWBC 121819
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
218 PM EDT MON MAY 12 2008

VALID 00Z TUE MAY 13 2008 - 00Z FRI MAY 16 2008

DAYS 1 TO 3...

...CNTRL ROCKIES...

NO MAJOR CHANGES TO THE PREV FORECAST...WITH THE 12Z MDLS SHOWING
FAIRLY GOOD AGREEMENT WITH REGARD TO THE SHRTWV ENERGY SEEN
CURRENTLY DIGGING SEWD ACRS THE GREAT BASIN AND TWD THE FOUR
CORNERS REGION. THE CONSENSUS OF THE GUIDANCE SUPPORTS THE
DEVELOPMENT OF A RATHER ROBUST MID/UPR LVL LOW BY EARLY TUE OVER
SRN UT AND AZ...AND THEN GRADUALLY PUSHING EWD OUT TWD THE SRN
HIGH PLAINS BY WED NIGHT AND THU. DESPITE RELATIVELY MODEST LVLS
OF MOISTURE FOR THE CLSD LOW TO WORK WITH...THE DYNAMICS WILL BE
QUITE IMPRESSIVE WITH THE 00Z ECMWF AND 12Z NAM SHOWING ENHANCED
UPR LVL DIFFLUENCE AND STG UVVS ASSOC WITH THE MID LVL DEFORMATION
ZONE. THIS COUPLED WITH STEEP LAPSE RATES AND OROGRAPHICS WILL
SUPPORT MDT TO LOCALLY HVY SNOWFALL MON NIGHT AND TUE ACRS ESP THE
HIGH TERRAIN OF CNTRL AND WRN CO...WITH THE SNOWFALL THREAT THEN
TAPERING OFF TUE EVE. SNOWFALL TOTALS IN THIS AREA OF LOCALLY UP
TO 1 FOOT WILL BE POSSIBLE. BY EARLY WED THOUGH...MOST OF THE
GUIDANCE SHOWS A SUBSTANTIAL DEEP LYR RIDGE DEVELOPING ALONG THE
WEST COAST...WHICH GIVEN ITS PROXIMITY TO THE ROCKIES WILL BE
ALLOWING FOR SNOW LVLS TO GRADUALLY RISE. SOME ADDITIONAL SHRTWV
ENERGY IS PROGGED TO SLIDE SSEWD DOWN THE EAST SIDE OF THE
AMPLIFYING RIDGE WED AND THU...BUT ANY ADDITIONAL SNOWFALL SHOULD
BE CONFINED TO THE HIGHER PEAKS OF CNTRL CO AND SHOULD ALSO BE
LIMITED TO A FEW INCHES AT THE MOST. HPC FOLLOWED A SOLN CLOSE TO
THAT OF THE 00Z ECMWF AND 12Z NAM REGARDING THE EVOLUTION OF THE
AFOREMENTIONED ENERGY.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

ORRISON
$$