Area Forecast Discussion
Issued by NWS Medford, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 060400
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
800 PM PST THU MAR 5 2015

.DISCUSSION...06/00Z NAM IN. 06/00Z GFS IN THROUGH 84HR.

MOSTLY CLEAR SKIES PREVAIL ACROSS THE MEDFORD CWA THIS
EVENING...EXCEPT FOR SOME HIGH CLOUDS AND SOME DEVELOPING MARINE
STRATUS OVER THE COASTAL WATERS. EXPECT SOME LOW CLOUDS AND FOG
TO DEVELOP LATER TONIGHT OVER THE COQUILLE AND UMPQUA
VALLEYS...AND POSSIBLY THE ILLINOIS AND LOWER KLAMATH VALLEYS
AS WELL.

THE NORTHERN HEMISPHERIC ANALYSIS CONTINUES TO SHOW A RATHER
AMORPHOUS 3 TO 4 WAVE PATTERN AROUND THE GLOBE...WITH THE COLDEST
AIR OVER NORTHEAST CANADA. NOT MUCH CHANGE IN THIS PATTERN IS
EXPECTED OVER THE NEXT SEVERAL DAYS.

A LONG WAVE RIDGE OVER THE WEST COAST ISN`T GOING TO GO ANYWHERE
ANYTIME SOON. AT THIS POINT IT LOOKS LIKE IT WON`T START TO MOVE
OUT TO THE EAST UNTIL NEXT MONDAY AT THE EARLIEST.

SO...UNTIL THEN...MOSTLY CLEAR SKIES WITH ABOVE NORMAL INLAND
TEMPERATURES WILL PERSIST...WITH THE FOLLOWING EXCEPTIONS:

THERE WILL BE INCREASING COVERAGE OF MARINE STRATUS OVER THE
COASTAL WATERS AND ALONG THE COAST...AND POSSIBLY EVENTUALLY INTO
THE UMPQUA BASIN. THIS WILL BE DUE TO A SOUTHERLY SURGE OF
MOISTURE ROTATING AROUND A WEAK LOW OFFSHORE. INITIALLY THIS LAYER
WILL BE QUITE SHALLOW...AND UPPER LEVEL CONDITIONS DO NOT SUPPORT
RAPID DEEPENING...SO IF THIS MANAGES TO EVENTUALLY GET INLAND
DURING THE OVERNIGHT HOURS IT LIKELY WILL ONLY MAKE IT TO THE
LOWER UMPQUA BASIN.

THERE WILL ALSO BE LATE NIGHT THROUGH EARLY MORNING LOW CLOUDS
AND FOG DUE TO TERRESTRIAL COOLING OVER SOME OF THE WESTERN
VALLEYS. THE COVERAGE WILL DECREASE WITH TIME AS THE AIRMASS AND
THE GROUND BELOW IT CONTINUES TO DRY OUT.

LONG TERM DISCUSSION FROM THE THURSDAY AFTERNOON AFD...TUESDAY
THROUGH FRIDAY. THERE IS ENOUGH AGREEMENT IN THE LONG RANGE
GUIDANCE, INCLUDING THE DETERMINISTIC MODELS AND THEIR RESPECTIVE
ENSEMBLE MEANS, TO SAY THAT WE CAN EXPECT A CHANGE IN THE WEATHER
PATTERN NEXT WEEK. THIS IS TO SAY THAT THE RIDGE PROVIDING THE
DRY, UNUSUALLY WARM WEATHER THROUGH MONDAY WILL FINALLY BREAK DOWN
ALLOWING A LARGE UPPER LOW OFFSHORE (OUT NEAR 150W) TO GRADUALLY
EDGE EAST TOWARD THE WEST COAST. BROAD SOUTHWESTERLY FLOW WILL
DEVELOP AHEAD OF THIS SYSTEM TUESDAY AS THE RIDGE AXIS SHIFTS TO
SOUTHERN CALIFORNIA AND THE GREAT BASIN. WE SHOULD BE ABLE TO
SQUEEZE OUT ANOTHER DRY DAY, BUT HAVE INDICATED A SLIGHT CHANCE OF
RAIN ALONG THE COAST.

PRECIPITATION CHANCES INCREASE ACROSS THE AREA TUESDAY NIGHT THROUGH
WEDNESDAY NIGHT AS THE UPPER LOW MOVES EAST OF 140W ALLOWING SHORT
WAVES ROTATING AROUND IT TO MOVE ONSHORE. SNOW LEVELS LOOK PRETTY
HIGH ONCE AGAIN...AVERAGING BETWEEN 6000 AND 7000 FEET. BY
THURSDAY, MODELS DIVERGE IN HOW THEY BRING THIS SYSTEM ONSHORE INTO
THE WEST COAST. SOME SOLUTIONS OPEN UP THE SYSTEM INTO A TROUGH AND
MOVE IT INTO WASHINGTON AND OREGON, WHILE OTHERS MAINTAIN THE UPPER
LOW AND BRING IT INTO CALIFORNIA. EITHER WAY, EXPECT POPS NEAR OR
ABOVE CLIMATOLOGY FOR MOST OF THE AREA THROUGH THURSDAY WITH
DIMINISHING CHANCES BY FRIDAY AS THE SYSTEM MOVES INLAND. WE`LL SEE
A DOWNWARD TREND IN HIGH TEMPERATURES DURING THE PERIOD DUE TO THE
INCREASED CLOUD COVER AND PRECIPITATION POTENTIAL. LOW TEMPERATURES,
HOWEVER, WILL LIKELY EDGE HIGHER FOR THE SAME REASONS. OVERALL
THOUGH, TEMPERATURES PROBABLY STAY ABOVE NORMAL. SPILDE

&&

.AVIATION...FOR THE 06/00Z TAF CYCLE...VFR AREA WIDE FOR THE NEXT 24
HOURS EXCEPT FOR AREAS OF IFR LOW CLOUDS AND FOG IN THE COQUILLE
VALLEY AND THE UMPQUA BASIN INCLUDING KRBG TOWARD SUNRISE FRIDAY.
THIS SHOULD BURN OFF BY LATE MORNING. PETRUCELLI

&&

.MARINE...UPDATED 230 PM PST THURSDAY 5 MAR 2015...WINDS WILL
REMAIN RELATIVELY LIGHT WITH LOW SEAS LOW THROUGH FRIDAY NIGHT. A
THERMAL TROUGH WILL REDEVELOP SATURDAY WITH NORTH WINDS
INCREASING. IT`S POSSIBLE THEY COULD REACH SMALL CRAFT OVER THE
SOUTHERN WATERS LATE SATURDAY AFTERNOON AND EVENING. THE THERMAL
TROUGH WILL WEAKEN SATURDAY NIGHT INTO SUNDAY WHILE HIGH PRESSURE
REMAINS NORTHWEST OF THE WATERS. LIGHT WINDS AND LOW SEAS WILL
CONTINUE INTO EARLY NEXT WEEK. THE WAVE WATCH BULLETIN AND ENP
WAVE MODELS SHOW AN INCREASING SOUTHWEST SWELL STARTING NEXT
WEDNESDAY AFTERNOON AND LASTING INTO NEXT THURSDAY. THE WAVE WATCH
BULLETIN SHOWS SOUTHWEST SWELLS HEIGHTS REACHING 14 FEET BY
WEDNESDAY EVENING. HOWEVER SUSPECT THE WAVE HEIGHT IS OVERDONE FOR
THE FOLLOWING REASONS. FIRST, THE LOW PRESSURE THAT WOULD BE
GENERATING THE FRESH SWELL IS NOT PROJECTED BY THE EC OR THE GFS
TO BE THAT STRONG AND SECOND IT`S THE FIRST TIME THE WAVE WATCH
AND ENP WAVE MODEL ARE SHOWING THIS. FUTURE SHIFTS WILL NEED TO
MONITOR THIS TREND. -PETRUCELLI

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$

15/15/15


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