Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
000 FOUS11 KWBC 220610 QPFHSD PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 209 AM EDT WED OCT 22 2014 VALID 12Z WED OCT 22 2014 - 12Z SAT OCT 25 2014 ...DAYS 1 -3... ...NORTHERN WA CASCADES... A SUSTAINED PERIOD OF MOIST ONSHORE FLOW AND PERIODS OF UPPER DIVERGENCE AS THE UPPER JET CROSSES SOUTHERN BRITISH COLUMBIA SHOULD CAUSE SNOW AT HIGHER ELEVATIONS OF THE WA CASCADES ON DAY 1. WIDESPREAD HEAVY PRECIPITATION IS EXPECTED. LOW TO MID LEVEL SOUTHERLY FLOW PRODUCES WARM ADVECTION AND KEEPS SNOW ELEVATIONS HIGH. ON DAY 2 THE FLOW BACK WITH THE JET MAXIMA RETREATING BACK NORTH OUT OF OREGON NORTH ACROSS WA WITH THE GFS SHOWING AN IMPRESSIVE 130-150 KT 300 MB JET MAXIMA. COLD ADVECTION WILL BE SLOW TO DEVELOP AS HEIGHTS ONLY GRADUALLY DECREASE...WHICH IS WHY WE STILL EXPECT THE PRIMARY THREAT FOR MODERATE TO HEAVY SNOW TO BE CONFINED TO THE NORTHERN CASCADES IN WA. EXPECT THE SNOW THREAT TO BE LIMITED ON DAY THREE AS THE NEXT ROUND OF WARM ADVECTION ENSUES AHEAD OF A NEW LOW DEVELOPING OFFSHORE. SNOW LEVELS RISE AGAIN AND SNOW TURNS TO RAIN IN MANY CASES. ASCENT IS STRONGER FURTHER WEST IN WA AND OR IN THE GFS AND ECMWF WITH LOW AMOUNTS WHERE ELEVATIONS ARE HIGH ENOUGH FOR SNOW IN THE CASCADES. A BLEND OF THE GFS AND ECMWF WAS USED FOR THE QPF/THERMAL FIELDS. THE NAM WAS AN OUTLIER WITH THE LOW DEVELOPMENT SOUTH OF THE PRIMARY CLUSTER SO ITS SOLUTION WAS GIVEN THE LEAST WEIGHT. THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT. PETERSEN $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.