Area Forecast Discussion
Issued by NWS Medford, OR

Home | 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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KMFR 172204
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
304 PM PDT WED SEP 17 2014

.DISCUSSION...CURRENT VISIBLE IMAGE SHOWS THE BULK OF THE CLOUD COVER
ALONG THE COAST AND INTO DOUGLAS AND JOSEPHINE COUNTIES. ELSEWHERE
THE CLOUDS HAVE DECREASED, BUT MOUNTAIN WAVES ARE FORMING WHICH IS
AN INDICATION OF STRONG WINDS ALOFT. WINDS HAVE BEEN CRANKING UP
OVER THE LAST FEW HOURS AND ARE STRONGEST OVER THE RIDGES AND EAST
OF THE CASCADES. ALSO WINDS CONTINUE TO BLOW IN THE SHASTA VALLEY
AND AT LAST REPORT WEED WAS REPORTING A PEAK GUST OF 52 MPH. EAST OF
THE CASCADES KLAMATH FALLS REPORTED A PEAK WIND OF 41 MPH. THE
MODELS OVERALL ARE UNDERESTIMATING THE WIND SPEEDS AND WILL
GENERALLY BE GOING ABOVE GUIDANCE FOR THE ABOVE MENTIONED LOCATIONS.
MODERATE TO STRONG WINDS WILL CONTINUE AT LEAST THROUGH MIDNIGHT FOR
THE AFOREMENTIONED AREAS, THEN SHOULD SLOWLY DECREASE TOWARDS EARLY
THURSDAY MORNING.

PRECIPITATION AHEAD OF THE UPPER LOW CENTERED NEAR 39N/132W IS
MOVING INTO SOUTHWEST OREGON. SO FAR, A COUPLE OF TICKS ON THE RAIN
GAGE HAS SHOWN UP IN CURRY COUNTY, BUT WE`LL SEE MORE AS RADAR
RETURNS SHOW A LINE OF PRECIPITATION MOVING NORTHWARD TOWARDS CURRY
AND WESTERN JOSEPHINE COUNTY. EVEN THEN, WERE ONLY EXPECTING BETWEEN
0.15 AND 0.25 OF AN INCH TONIGHT. ELSEWHERE, PRECIPITATION AMOUNTS
WILL BE LIGHTER AND MOST ALONG AND WEST OF THE CASCADES. ALSO MODELS
ARE HINTING AT SOME ELEVATED INSTABILITY OVER THE WATERS AND
POSSIBLY RIGHT ALONG THE COAST AND WITH A COOL POOL ALOFT MOVING
OVERHEAD THIS EVENING, THEREFORE FELT IT WAS BEST TO PUT IN A SLIGHT
CHANCE OF THUNDER. ALSO WEAK INSTABILITY IS PRESENT FROM AROUND
CRATER LAKE NORTH AND HAVE KEPT A SLIGHT CHANCE THERE.

THE UPPER TROUGH WILL SPLIT AS IT MOVES INLAND THURSDAY AND THIS
WILL BRING SOME GOOD NEWS. FIRST, IT WILL NOT BE AS WINDY COMPARED
TODAY AND SECOND WE`LL HAVE A BETTER CHANCE OF GETTING MEASURABLE
PRECIPITATION, ESPECIALLY WEST OF THE CASCADES. HOWEVER WITH THE
UPPER TROUGH SPLITTING, THIS WILL TEND TO PUT A CAP ON THE AMOUNT OF
PRECIPITATION. AT THIS TIME, WERE EXPECTING BETWEEN 0.10-0.20 OF AN
INCH FOR THE CASCADES, UP TO 0.10 FOR THE COAST RANGE, 0.10 OR LESS
FOR MOST WESTSIDE LOCATIONS AND 0.05 OR LESS EAST OF THE CASCADES.
THE MODELS ARE IN FAIRLY GOOD AGREEMENT SHOWING THE GREATEST
INSTABILITY FROM THE CASCADES EAST, ALTHOUGH SOME INSTABILITY EXIST
IN EASTERN JACKSON COUNTY AND EASTERN DOUGLAS COUNTY.

THE UPPER TROUGH CONTINUES TO SPLIT THURSDAY NIGHT INTO FRIDAY
MORNING AND A CUTOFF LOW WILL DEVELOP FRIDAY AFTERNOON ON CENTRAL
CALIFORNIA. ANY SHOWERS WILL END THURSDAY NIGHT WITH DRY AND WARMER
WEATHER RETURNING FRIDAY AND LASTING THROUGH THE WEEKEND. A THERMAL
TROUGH WILL DEVELOP OFF THE OREGON COAST AND WE COULD SEE INCREASING
OFFSHORE FLOW WITH MODERATE TO POOR RECOVERIES IN WESTERN SISKIYOU
AND SOUTH COAST RANGE IN OREGON.

THE EC AND GFS ARE IN PRETTY GOOD AGREEMENT SHOWING ANOTHER BROAD
UPPER TROUGH DIGGING NEAR 140W AND THIS WILL KICK THE UPPER LOW IN
CALIFORNIA NORTHEAST INTO SOUTHEAST OREGON, BUT IT SHOULD HAVE
LITTLE OR NO IMPACT FOR US.

THE UPPER TROUGH WILL PUSH EAST TOWARDS THE OREGON COAST MONDAY AND
THE GFS AND EC SHOW ENOUGH INSTABILITY ALONG THE NORTHERN CASCADES
IN THE AFTERNOON TO WARRANT A SLIGHT CHANCE OF STORMS.

THINGS COULD GET INTERESTING OUT TOWARDS THE END OF THE FORECAST
PERIOD. THE EC AND GFS ARE IN REMARKABLE GOOD AGREEMENT SHOWING A
MUCH MORE ACTIVE PATTERN STARTING NEXT WEDNESDAY. OF NOTE THE
PREVIOUS 2 GFS RUNS (6Z AND LAST NIGHTS 0Z) WERE SHOWING A STRONG
RIDGE OVER THE AREA WHILE THE EC WAS STILL SHOWING A MORE ACTIVE
PATTERN. INTERESTING ENOUGH, THE RMOP SHOWS A HIGH PROBABILITY (34%
PROBABILITY) OF A STRONG RIDGE SETTING UP OVER THE REGION IN THE
SAME TIME PERIOD, BUT THIS WAS BASED IN PART ON LAST NIGHTS (0Z)
RUN. IT WILL BE INTERESTING TO SEE WHAT THE 0Z RUN WILL SHOW
TONIGHT. FOR NOW WE FELT IT WAS BEST TO INCREASE POPS ENOUGH FOR A
CHANCE MENTION, BUT IF THE EC AND GFS REMAIN IN GOOD AGREEMENT, THE
POPS WILL NEED TO BE ADJUSTED SIGNIFICANTLY HIGHER. IF WE TAKE THE
OPERATIONAL MODELS AT FACE VALUE, WE COULD BE LOOKING AT OUR FIRST
MODERATE TO HEAVY PRECIPITATION EVENT IN QUITE SOME TIME. AGAIN THIS
IS STILL A WAYS OUT AND WE`LL HAVE TO WATCH HOW THE MODELS TREND
OVER TIME. -PETRUCELLI


&&

.AVIATION...BASED ON THE 17/18Z TAF CYCLE...
GUSTY SOUTH AND SOUTHWEST WINDS WILL OCCUR THE REMAINDER OF THIS
AFTERNOON THROUGH MID-EVENING ACROSS THE MOUNTAINS AND EAST SIDE.
THIS WILL RESULT IN TURBULENCE IN THE LOW LEVELS. RAIN PUSHING ONTO
THE COAST AND INTO THE COASTAL MOUNTAINS WILL LEAD TO MVFR
CONDITIONS IN CURRY COUNTY, LOCALLY IFR TO LIFR ALONG THE COAST
WHERE FOG WILL ALSO OCCUR AT TIMES. THIS RAIN WILL SPREAD INLAND
THIS AFTERNOON AND EVENING, AND THEN MORESO, ON THURSDAY. PARTIAL
MOUNTAIN OBSCURATIONS WILL OCCUR FROM THE CASCADES WESTWARD THIS
EVENING THROUGH THURSDAY, EXCEPT NEAR TOTAL ACROSS THE COASTAL
MOUNTAINS. VALLEY CEILINGS WILL BE MOSTLY VFR, EXCEPT IN CURRY AND
JOSEPHINE COUNTIES, WHERE MVFR IS EXPECTED. MVFR VISIBILITIES WILL
OCCUR IN SOME RAIN SHOWERS THIS EVENING THROUGH THURSDAY. THERE IS A
SLIGHT CHANCE OF THUNDERSTORMS ALONG AND NEAR THE COAST THIS
AFTERNOON THROUGH ABOUT MIDNIGHT TONIGHT. BTL


&&

.MARINE...UPDATED 1215 PM PDT WED 17 SEP 2014...
LOW PRESSURE WILL BRING RAIN TODAY THROUGH THURSDAY WITH SOUTH
WINDS AND BUILDING SEAS. THERE IS A SLIGHT CHANCE OF THUNDERSTORMS
LATER THIS AFTERNOON INTO THE EVENING. A DEVELOPING THERMAL TROUGH
WILL LEAD TO INCREASED NORTH WINDS WITH STEEP WIND WAVES FRIDAY
THROUGH FRIDAY NIGHT. SEAS WILL TRANSITION BACK TO BEING DOMINATED
BY A MODERATE SWELL DURING THE WEEKEND. BTL


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 9 PM PDT THIS EVENING FOR ORZ624-625.

CA...RED FLAG WARNING UNTIL 9 PM PDT THIS EVENING FOR CAZ284-285.
     RED FLAG WARNING UNTIL 9 PM PDT THIS EVENING FOR CAZ281.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM
     11 PM THIS EVENING TO 11 AM PDT THURSDAY FOR PZZ370-376.

$$








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