000 FXUS66 KMFR 092241 AFDMFR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEDFORD OR 241 PM PST THU FEB 9 2012 .DISCUSSION...LATEST VISIBLE SNAPSHOT SHOWS THE BULK OF THE CLOUD COVER OFFSHORE AND NORTH OF THE CWA...BUT WE'LL SEE HIGH AND MID LEVEL CLOUDS GRADUALLY INCREASE OVER THE REGION THROUGH EARLY THIS EVENING AS A SURFACE LOW MOVES NORTHEAST TOWARDS THE OREGON COAST. THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE TRACK OF THE LOW...BUT THEY HAVE TRENDED WEAKER WITH RESPECT TO THE STRENGTH OF THE SURFACE LOW. DESPITE THIS...WINDS ARE STILL EXPECTED TO INCREASE ALONG THE COAST THIS EVENING AND LATER TONIGHT IN THE SHASTA VALLEY AND SOUTH END OF THE ROGUE VALLEY...BUT NOT ENOUGH TO WARRANT ANY WARNINGS OR ADVISORIES. PRECIPITATION WILL REACH THE COAST TONIGHT...THEN MOVE INLAND FRIDAY MORNING. THIS DOES NOT LOOK LIKE A BIG EVENT IN TERMS OF PRECIP AMOUNTS AND WERE NOT EXPECTING MUCH MORE THAN 0.10-0.25 OF AN INCH ALONG THE COAST AND LESSER AMOUNTS FOR MANY INLAND LOCATIONS. SNOW LEVELS WILL BE ABOVE THE MAIN PASSES WITH THIS EVENT...BUT WILL FALL TO AROUND 4000 FEET BY SATURDAY MORNING. THE NAM HAS COME MORE IN LINE WITH THE GFS AND EC SUGGESTING THIS EVENT WILL BE SLOWER TO MOVE OUT SATURDAY. THEREFORE HAVE ADJUSTED POPS HIGHER TO ALLOW FOR AT LEAST A CHANCE OF PRECIPITATION. IT'S POSSIBLE THAT THINGS COULD CLEAR OUT SATURDAY AFTERNOON WEST OF THE CASCADES...BUT CONFIDENCE IS NOT HIGH...SO WE'LL KEEP A SLIGHT CHANCE IN FOR THE AFTERNOON. WEAK SHORTWAVE RIDGING BUILDS INTO THE FORECAST AREA SATURDAY NIGHT INTO SUNDAY. THE MODELS ARE NOW SUGGESTING THE NEXT FRONT WILL HOLD OFF UNTIL SUNDAY NIGHT. SO WE SHOULD GET AWAY WITH A DRY AND MILD DAY. AS A RESULT HAVE TRIMMED BACK POPS QUITE A BIT AND KEPT ANY MENTION OF PRECIPITATION OUT UNTIL SUNDAY NIGHT. THE GFS AND EC ARE IN GOOD AGREEMENT TRACKING THE LOW INTO SOUTHWEST OREGON SUNDAY NIGHT...THEN IN NORTHWEST CALIFORNIA MONDAY MORNING. THERE IS STILL SOME UNCERTAINTY IN THE DETAILS...BUT WE COULD SEE SNOW LEVELS GET DOWN BETWEEN 3000 AND 3500 FEET SUNDAY NIGHT INTO MONDAY MORNING WITH THE BULLSEYE OF PRECIPITATION CENTERED IN SISKIYOU COUNTY. THEREFORE IT'S POSSIBLE WE COULD GET SEVERAL INCHES OF SNOW IN THE MOUNTAINS AND POSSIBLY IN AND AROUND MOUNT SHASTA CITY WHICH WILL HAVE TRAVEL IMPACTS ALONG I-5. -PETRUCELLI .EXTENDED...MONDAY THROUGH THURSDAY. THE ECMWF AND GFS MODELS HAVE BOTH TRENDED SLOWER AND FARTHER SOUTH WITH THE TRACK OF A COLD FRONT AND CLOSED UPPER LEVEL LOW. THIS UPPER LOW IS IN THE STRONGER SOUTHERN BRANCH OF A SPLIT FLOW. POPS WERE RAISED FOR MONDAY...ESPECIALLY FOR SOUTHERN PORTIONS OF SISKIYOU AND MODOC COUNTIES IN ANTICIPATION OF POST-FRONTAL WRAP-AROUND SHOWERS. THE SNOW LEVEL IN OUR AREA LOOKS TO BE AROUND 3500 TO 4000 FEET. THE FOCUS FOR PRECIPITATION LOOKS TO BE SOUTH OF OUR AREA, FROM THE NORTHERN CALIFORNIA COAST INTO THE NORTHERN SIERRA NEVADA AS THE UPPER LOW TRACKS SOUTHEAST INTO NORTHERN CALIFORNIA. THE GFS AND ECMWF SOLUTIONS BOTH SUPPORT A FORECAST OF A FEW INCHES OF SNOW AROUND MOUNT SHASTA. MEANTIME...ANOTHER WEAKER BUT COLDER UPPER LOW WILL MOVE SOUTHEAST TO THE WASHINGTON COAST THEN TURN SOUTH AND MOVE ACROSS OUR AREA ON MONDAY NIGHT. NEITHER MODEL GENERATES MUCH QPF WITH THIS SYSTEM BUT THE SNOW LEVEL MAY LOWER TO AROUND 2500 FEET WITH A SLIGHT CHANCE TO CHANCE OF LIGHT SHOWERS OR FLURRIES ACROSS OUR AREA. ON TUESDAY THE UPPER TROUGH IS FORECAST TO MOVE SOUTHEAST INTO NEVADA WHILE A BROAD BUT WEAK HIGH PRESSURE RIDGE CENTERED FAR OFFSHORE FROM SOUTHERN CALIFORNIA BUILDS NORTHEAST TOWARD THE OREGON COAST. THUS...POPS HAVE BEEN LOWERED FOR TUESDAY INTO WEDNESDAY. FOR THE SECOND HALF OF THE WEEK...THERE IS UNCERTAINTY IN HOW QUICKLY THE NEXT TROUGH WILL ARRIVE AND TO WHAT EXTENT IT WEAKENS THE INFLUENCE OF THE RIDGE BUT THE PATTERN IS VERY LIKELY TO BE ACTIVE. THE FLATTENING OF THE RIDGE MAY OCCUR AS EARLY AS WEDNESDAY NIGHT OR MORE LIKELY AROUND THURSDAY INTO THURSDAY NIGHT. /DW && .AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH THIS EVENING WITH HIGH AND MID LEVEL CLOUDS INCREASING. CIGS WILL GRADUALLY DECREASE TONIGHT...BUT THEY SHOULD REMAIN ABOVE 3000 FT THROUGH 12Z WED FOR INLAND LOCATIONS. HOWEVER AT THE COAST THERE IS A CHANCE FOR MVFR CONDITIONS TO DEVELOP BETWEEN 6-8Z AND LASTING INTO MOST OF FRIDAY MORNING. WINDS WILL INCREASE ALONG THE COAST BETWEEN 5-6Z TONIGHT AND 6-8Z IN THE ROGUE VALLEY. THIS COULD RESULT IN AN INCREASING CHANCE FOR WIND SPEED SHEAR BETWEEN THE SURFACE AND 1500 FT AGL. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...NONE. CA...NONE. PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 10 PM THIS EVENING TO 1 PM PST FRIDAY FOR PZZ350-356. HAZARDOUS SEAS WARNING FROM 10 PM THIS EVENING TO 4 PM PST FRIDAY FOR PZZ350-356-370-376. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS EVENING FOR PZZ350-356-370-376. SMALL CRAFT ADVISORY FOR WINDS UNTIL 1 PM PST FRIDAY FOR PZZ370-376. $$