header1 header2
header3
Untitled Document
header5
Untitled Document


Your Ad Here

You Are Here: Home > forecast > forecast discussion

  Forecast Discussion for Southern Oregon and Northern California  

Forecast: Forecast Discussion | 7 Day Forecast

Forecast Discussion for MFR NWS Office

000
FXUS66 KMFR 310352
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
852 PM PDT THU OCT 30 2014

.DISCUSSION...AM PLANNING TO DO ANOTHER UPDATE THIS EVENING. THE
LAST OF THE THUNDERSTORMS WILL SOON MOVE OUT OF JACKSON COUNTY AND
THEN BE CONFINED TO THE CASCADES OF EASTERN DOUGLAS COUNTY. THESE
CELLS HAVE BEEN INTERESTING BECAUSE WHILE THEY ARE NOT TALL, THEY
HAVE INTENSE CORES AND SUSTAINED ROTATION COUPLETS ALOFT. THERE IS
PROBABLY SOME SMALL HAIL WITH THESE CELLS AND BRIEF INTENSE
RAINFALL, BUT ONLY A FEW LIGHTNING STRIKES AS THEY PASS.
CONVECTION CONTINUES TO POP UP FURTHER SOUTH AS WELL, BUT AT THE
MOMENT, IT IS MUCH WEAKER THAN THE NORTHERN CELLS. RIGHT NOW THE
FORECAST IS OK, BUT WILL WATCH HOW THIS EVOLVES OVER THE NEXT
HOUR, AND THEN LIKELY UPDATE BASED ON RADAR TRENDS. -WRIGHT

&&

.PREV DISCUSSION... /ISSUED 731 PM PDT THU OCT 30 2014/

UPDATE...CONVECTION HAS POPPED UP JUST OUT AHEAD OF THE MAIN
STRATIFORM RAIN FIELD AND LIES IN A LINE FROM ROUGHLY NORTHWEST
SISKIYOU COUNTY NORTH THROUGH WESTERN JACKSON COUNTY INTO EASTERN
DOUGLAS COUNTY. 31/00Z SOUNDING FROM MEDFORD SHOWED LITTLE SURFACE
BASED INSTABILITY, BUT THERE IS INSTABILITY ALOFT (ABOVE ROUGHLY
700 MILLIBARS). LATEST RAP AND NAM GUIDANCE SHOW AN INSTABILITY
AXIS IN THIS AREA, AND SOME OF THE SHOWERS ARE PRETTY HEFTY
WITH 50-60DBZ CORES. THE CORES ARE TOPPING OUT AT AROUND 15,000
FT, WHICH IS ABOVE THE FREEZING LEVEL, SO I CAN`T RULE OUT SMALL
HAIL IN THESE CELLS. HOWEVER, CELL TOPS ARE ONLY REACHING TO
AROUND 20,000 FT, SO AM NOT CONCERNED ABOUT ANYTHING MORE THAN
THAT.

SO FAR, WE`VE SEEN A FEW LIGHTNING STRIKES OVER NORTHERN JACKSON
AND EASTERN DOUGLAS WHICH IS CLOSER TO THE UPPER JET AXIS. THERE
IS REALLY NO REASON TO THINK THIS WON`T CONTINUE FOR A FEW HOURS
AND GRADUALLY SHIFT TOWARD THE CASCADES. GUIDANCE DOES SHOW THINGS
STABILIZING THIS EVENING, BUT WE DID AN UPDATE TO INCLUDE ISOLATED
THUNDERSTORMS UNTIL LATE EVENING. WE WILL RE-EVALUATE AT THAT
POINT. -WRIGHT

AVIATION...FOR THE 31/00Z TAF CYCLE...VFR CONDITIONS WILL
CONTINUE INTO THIS EVENING. A COLD FRONT WILL REACH THE COAST LATER
THIS EVENING THEN MOVE INLAND TONIGHT. THIS FRONT AND ASSOCIATED
RAINFALL WILL RESULT IN VALLEY MVFR AND LOCAL IFR AS IT MOVES INLAND
TONIGHT. A FEW ISOLATED THUNDERSTORMS ARE ALSO POSSIBLE UNTIL AT
LEAST 6Z FOR INLAND LOCATIONS. THIS INCLUDES KMFR. THE FRONT WILL
MOVE EAST OF THE CASCADES FRIDAY AFTERNOON AND VFR CONDITIONS WILL
BE THE PREDOMINATE CONDITION. HOWEVER TEMPORARY MVFR CIGS WITH
PARTIAL MOUNTAIN OBSCURATIONS ARE POSSIBLE IN HEAVIER SHOWERS FRIDAY
AFTERNOON. -PETRUCELLI

PREV DISCUSSION... /ISSUED 302 PM PDT THU OCT 30 2014/

DISCUSSION...VISIBLE SATELLITE SHOWS SOME THICKER CLOUD COVER ASSOCIATED
WITH THE APPROACHING COLD FRONT SPREADING OVER THE COAST. RAIN HAS
ALREADY STARTED FALLING AT THE COAST WITH QUAIL PRAIRIE IN CURRY
COUNTY RECEIVING A TENTH OF AN INCH IN THE PAST HOUR. RAIN AND
CLOUDS WILL STEADILY INCREASE AS THE FRONT SLOWLY PUSHES FURTHER
INLAND THROUGH THE NIGHT.

WINDS WITH THIS FRONT ARE EXPECTED TO BE MUCH LIGHTER COMPARED TO
THE PREVIOUS SYSTEM. SHASTA VALLEY AND THE EAST SIDE WILL STILL
SEE SOME BREEZY CONDITIONS BUT NOTHING LIKE WAS OBSERVED THIS PAST
WEEKEND.

AS FAR AS RAIN IS CONCERNED, THE STEADIER RAIN WILL MOVE THROUGH
THE WEST SIDE LATER THIS EVENING AND THROUGH THE OVERNIGHT HOURS,
MAKING IT TO THE EAST SIDE BY LATE FRIDAY MORNING/EARLY AFTERNOON.
BEHIND THE FRONT, A SHOWERY PATTERN WILL BE THE STORY FOR THE WEST
SIDE DURING THE PRIME TRICK-OR-TREATING HOURS. MOST LOCATIONS WILL
PROBABLY REMAIN DRY DURING THE EVENING, BUT A SHOWER HERE OR THERE
CAN`T BE RULED OUT. THUNDER WAS REMOVED FROM SOME INLAND AREAS
WEST OF THE CASCADES CONSIDERING FAIRLY WEAK INSTABILITY.

AS THE UPPER TROUGH MOVES TO THE EAST OF THE AREA SATURDAY,
SHOWERS WILL DIMINISH. SNOW LEVELS WILL LOWER TO AROUND 5000 FEET
BY SATURDAY MORNING WITH SOME LIGHT SNOW ACCUMULATIONS POSSIBLE.
NO SIGNIFICANT TRAVEL IMPACTS ARE ANTICIPATED. ALSO WITH THE UPPER
TROUGH PASSAGE, MUCH COOLER TEMPERATURES WILL AFFECT THE AREA. FROST
IS A CONCERN FOR SOME WEST SIDE VALLEYS, SO STAY TUNED FOR
MORE INFORMATION AS IT APPROACHES.

LONG TERM...
MONDAY, NOVEMBER 3RD THROUGH THURSDAY, NOVEMBER 6TH, 2014.
MONDAY THROUGH TUESDAY NORTHWEST FLOW AT JET STREAM LEVEL WILL BECOME
PREDOMINATELY WEST. THIS WILL INDUCE LOWER LEVEL WARM AIR ADVECTION
ACROSS THE AREA RESULTING IN SUBSTANTIAL CLOUD COVER ACROSS THE
REGION AND SOME WARM FRONTAL PRECIPITATION. PRECIPITATION
PROBABILITIES HAVE BEEN ADJUSTED TOWARD BOTH CLIMATOLOGY UNDER THIS
PATTERN AND REFORECAST ANALOG PROBABILITIES FROM ESRL`S NCEP GEFS
REFORECAST PAGE. THIS HAS RESULTED IN RAIN LIKELY ALONG AND NEAR THE
COAST AND IN THE UMPQUA BASIN MONDAY THROUGH TUESDAY, WITH LESSER
PROBABILITIES FURTHER SOUTH AND EAST. DIURNAL TEMPERATURES ARE
LIKELY TO REMAIN LOW ON THE WEST SIDE DUE TO CLOUD COVER, WITH
MILDER THAN NORMAL NIGHTS AND SLIGHTLY COOLER THAN NORMAL DAYS.

WEDNESDAY THROUGH THURSDAY THE WARM FRONTAL BOUNDARY WILL LIFT TO
THE NORTH RESULTING IN A PERIOD OF ABOVE NORMAL TEMPERATURES.
THEREAFTER, OPERATIONAL MODELS HAVE BEEN TRENDING TOWARD A WEAKER
SERIES OF LOW PRESSURE SYSTEMS COMING THROUGH ON WEST-SOUTHWEST FLOW
FRIDAY INTO THE WEEKEND OF NOVEMBER 8TH-9TH, WITH MUCH OF THE ENERGY
MOVING SOUTH OF US INTO CALIFORNIA. HOWEVER, A LOOK AT ENSEMBLE
MODEL GUIDANCE FROM THE NAEFS, GFS, ECMWF, AND CFSV2 ALL INDICATE
THE PATTERN REMAINING PROGRESSIVE NEXT WEEK WITH A LOT OF
UNCERTAINTY IN THE LOCATION OF THE STORM TRACK. BTL

MARINE...UPDATED 245 PM PDT THU OCT 31 2014... A COLD FRONT WILL
REACH THE COAST THIS EVENING WITH WINDS AND SEAS DECREASING. WEAK
LOW PRESSURE WILL REMAIN OVER THE WATERS FRIDAY THROUGH FRIDAY
NIGHT. A LONG PERIOD WEST SWELL WILL MOVE INTO THE COASTAL WATERS
FRIDAY NIGHT. HIGH PRESSURE WILL THEN BUILD SOUTHWEST OF THE
WATERS ON SATURDAY THEN WEAK HIGH PRESSURE MOVES OVER THE WATERS
SUNDAY. MODELS ARE FAIRLY CONSISTENT SHOWING ANOTHER LONG PERIOD
NORTHWEST SWELL MOVING INTO THE WATERS MONDAY MORNING. -PETRUCELLI

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$

NWS MFR Office Area Forecast Discussion