Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 062214
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
314 PM PDT FRI MAY 6 2016

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT...
HIGH CLOUDS FROM CONVECTION ACROSS NEVADA THIS MORNING HAVE
OVERSPREAD MUCH OF THE AREA THIS AFTERNOON. WHILE THIS HAS LIMITED
SURFACE HEATING SOME TODAY, SOME SHOWERS AND THUNDERSTORMS HAVE
DEVELOPED ACROSS PORTIONS OF LAKE, MODOC, AND SISKIYOU COUNTIES.
THUS FAR, SOME ONE HOUR RAINFALL AMOUNTS OF 0.20 TO 0.30" HAVE
BEEN OBSERVED WITH THESE CELLS IN MODOC AND SISKIYOU COUNTIES.
WITH STORMS MOVING SOUTHWEST AROUND 30 MPH SOME GUSTY WINDS ARE
POSSIBLE. HOWEVER, AT THIS TIME NONE OF THE ACTIVITY IS
THREATENING TO REACH SEVERE THRESHOLDS OVER THE NEXT HOUR.

WHAT APPEARS TO A BIT OF A CONCERN AS WE HEAD THROUGH THE
AFTERNOON INTO THE EVENING IS THE POSSIBILITY OF TRAINING SHOWER
AND THUNDERSTORM ACTIVITY ACROSS SOME OF THESE SAME AREAS. ALSO,
EXTENSIVE HEAVIER SHOWERS AND THUNDERSTORMS ACROSS NORTHERN
NEVADA ARE LIKELY TO BRING AN EXTENSIVE AREA OF RAINFALL ACROSS
THE SOUTHEAST SIDE THIS EVENING, PROBABLY IN EXCESS OF A HALF OF AN
INCH ACROSS MUCH OF MODOC COUNTY. THUS, THE PRIMARY CONCERN
THROUGH THIS EVENING WILL BE URBAN AND SMALL STREAM FLOODING,
POSSIBLE FLOODING ON AND NEAR BURN SCAR AREAS FROM RECENT YEARS,
AND, SHOULD THIS HEAVY RAIN STALL OVER SNOWPACK AREAS, MORE
EXTENSIVE FLOODING WILL BE POSSIBLE. WHILE SEVERE WIND AND HAIL IS
STILL A THREAT THROUGH THE EVENING SUSPECT IT WILL BE ISOLATED AT
MOST DUE TO THE FACT THAT SHORTWAVE ENERGY AND SURFACE DYNAMICS
TO SUPPORT IT ARE FAIRLY WEAK. 500MB TEMPERATURES ARE GENERALLY
WARMING THIS AFTERNOON AND EVENING. HAVE USED THE HRRR FOR MANY
OF THE FORECAST REFINEMENTS TODAY, BUT HAVE ALSO ADJUSTED THAT AS
OBSERVED CONDITIONS ARE A BIT DIFFERENT.

FOR THE WEST SIDE THERE IS STILL SOME THREAT OF SHOWERS AND
ISOLATED THUNDERSTORMS, ALBEIT LESS THAN THE EAST SIDE AND
NORTHERN CALIFORNIA, AS THE DYNAMICS ARE NOT AS FAVORABLE.

TONIGHT THROUGH SATURDAY SHOWER AND THUNDERSTORM ACTIVITY WILL
WEAKEN AND THEN RE-FIRE AGAIN. HOWEVER, INSTABILITY IS LESSER
TOMORROW AS THE UPPER LEVEL LOW WILL BE FURTHER SOUTH AND EAST.
THIS WILL BE PARTIALLY COUNTERACTED BY INCREASED SURFACE HEATING
DUE TO LESS CLOUD COVER. WHILE MOST GUIDANCE KEEPS SHOWERS AND
STORMS EAST OF THE CASCADES, THE SREF AND NAM12 DO SUPPORT SOME
POTENTIAL ALONG AND NEAR THE CASCADES. LOCALIZED HEAVY RAINFALL
WILL STILL BE OF SOME CONCERN AS PWATS WILL BE 0.75" TO JUST OVER
1 INCH- SIMILAR TO TODAY. BTL

.LONG TERM...SUNDAY THROUGH FRIDAY...
THE UPPER LOW WILL CONTINUE TO SLOWLY MOVE INTO THE FOUR CORNERS
SUNDAY MORNING AND AN UPPER RIDGE WILL NOSE IN FROM THE WEST, BUT
THEN WILL RETREAT WESTWARD SUNDAY AFTERNOON AS A SHORTWAVE MOVES
SOUTHEAST INTO EASTERN WASHINGTON. AT THE SURFACE A WEAK FRONT
WILL MOVE THROUGH THE NORTHWEST PART OF THE REGION EARLY SUNDAY
MORNING INCREASING THE ONSHORE FLOW. THE MARINE LATER COULD
THICKEN ENOUGH TO WARRANT A SLIGHT CHANCE OF LIGHT RAIN OR DRIZZLE
MAINLY NORTH OF THE UMPQUA DIVIDE. COULD NOT RULE OUT A SLIGHT
CHANCE IN PARTS OF THE ILLINOIS VALLEY, GRANTS PASS AND THE NORTH
END OF THE ROGUE VALLEY. ELSEWHERE IT WILL REMAIN DRY. ANOTHER
SHORTWAVE WILL MOVE INTO EASTERN WASHINGTON AND NORTHEAST OREGON
ON MONDAY, BUT THE TRACK IS NOT FAVORABLE FOR PRECIPITATION, SO IT
WILL REMAIN DRY. AN UPPER RIDGE WILL BUILD OFF THE COAST TUESDAY
WITH A THERMAL TROUGH DEVELOPING AT THE COAST. THE MODELS DIFFER
WITH THE DETAILS AFTER TUESDAY, BUT CONDITIONS ARE EXPECTED TO
REMAIN DRY WITH ABOVE NORMAL TEMPERATURES IN THE AFTERNOON.
THEREFORE, FORECAST HIGH TEMPERATURES WERE INCREASED FOR THE
TUESDAY THROUGH THURSDAY TIME PERIOD. THE MODELS SHOW AN UPPER LOW
MOVING TOWARDS THE CALIFORNIA COAST LATE NEXT WEEK WHICH COULD
BRING INCREASING MOISTURE AND INSTABILITY, BUT IT`S STILL A WAYS
OUT AND THE DETAILS ARE LIKELY TO CHANGE. FOR NOW WE`LL KEEP IT
DRY WITH ABOVE NORMAL TEMPERATURES. -PETRUCELLI

&&

.AVIATION...FOR THE 06/18Z TAF CYCLE...THE MAIN CONCERN INTO THIS
EVENING WILL BE ISOLATED TO SCATTERED THUNDERSTORMS. ANY STORMS WILL
BE CAPABLE OF PRODUCING MVFR AND OCCASIONAL IFR CIGS, VERY HEAVY
RAIN, SMALL HAIL AND GUSTY OUTFLOW WINDS. SHOWERS AND
THUNDERSTORMS WILL START OUT ISOLATED EARLY THIS AFTERNOON, THEN
WILL BECOME MORE NUMEROUS FROM LATE THIS AFTERNOON INTO THIS
EVENING WITH A GENERAL MOVEMENT FROM EAST TO WEST, THEN NORTHEAST
TO SOUTHWEST TOWARDS THIS EVENING. THE GREATEST THREAT FOR
THUNDERSTORMS IS FROM THE CASCADES/SISKIYOUS EAST, BUT STORMS MAY
ADVANCE AS FAR WEST AS JACKSON COUNTY (INCLUDING KMFR) LATE THIS
AFTERNOON. SHOWERS AND STORMS DIMINISH LATE THIS EVENING WITH VFR
CONDITIONS EXPECTED, EXCEPT FOR THE COAST WHERE MVFR AND LOCAL IFR
CIGS WILL DEVELOP EARLY THIS EVENING AND CONTINUE INTO SATURDAY
MORNING. -PETRUCELLI

&&

.MARINE...UPDATED 500 AM PDT FRI 6 MAY 2016...FEW CHANGES WERE MADE
TO THE MARINE FORECAST THIS MORNING. NORTH WINDS WILL INCREASE AGAIN
THIS AFTERNOON AND CONTINUE INTO THE EVENING. THIS TREND OF STRONG
NORTH WINDS/STEEP SEAS IN THE AFTERNOON/EVENINGS AND LULLS AT NIGHT
WILL LIKELY CONTINUE THROUGH THE WEEKEND. A GALE WARNING REMAINS IN
EFFECT THROUGH THIS EVENING OVER THE SOUTHERN WATERS WITH SMALL
CRAFT ADVISORIES ELSEWHERE. MODELS HAVE MAINTAINED THE POTENTIAL FOR
GALES OVER THE WEEKEND AND GALE WATCHES REMAIN IN EFFECT. THESE WILL
LIKELY BE UPGRADED LATER TODAY. -WRIGHT

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FLASH FLOOD WATCH UNTIL 11 PM PDT THIS EVENING FOR ORZ030-031.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT THIS
     EVENING FOR ORZ022.

CA...FLASH FLOOD WATCH UNTIL 11 PM PDT THIS EVENING FOR CAZ080>085.

PACIFIC COASTAL WATERS...
- SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR
  PZZ350-356-370-376.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT THIS
  EVENING FOR PZZ350-356-370.
- GALE WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ356-376.
- GALE WATCH FROM SATURDAY MORNING THROUGH SUNDAY EVENING FOR
  PZZ376.

$$

BTL/MAP/DW



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