Special Weather Statement, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
255 PM PDT FRI AUG 8 2014

.DISCUSSION...LITTLE CHANGE IS EXPECTED THROUGH SATURDAY OVER OUR
FORECAST AREA. THINGS CHANGE DRAMATICALLY SUNDAY AS AN UPPER LOW
CURRENTLY NEAR 41N 135W DROP DROPS IN ALONG THE NORTHERN CALIFORNIA
COAST AND THEN GRADUALLY WORKS ITS WAY INLAND BY TUESDAY. WE WILL BE
IN SOUTHEAST TO EAST UPPER FLOW MUCH OF THE TIME, AND WITH PLENTY TO
RIDICULOUS AMOUNTS OF INSTABILITY AND SUFFICIENT MOISTURE, THIS WILL
LIKELY PRODUCE A SIGNIFICANT THUNDERSTORM OUTBREAK. THE MODELS ARE
IN RATHER GOOD AGREEMENT WITH THE HANDLING OF THE UPPER LOW, SO THE
CONFIDENCE IN WHAT FOLLOWS IS HIGH. I WILL BREAK IT DOWN PERIOD BY
PERIOD TO MAKE IT EASIER TO FOLLOW.

TONIGHT THROUGH SATURDAY NIGHT: CUMULUS IS BUBBLING IN THE USUAL
SPOTS FROM CENTRAL SISKIYOU COUNTY ON UP THROUGH THE CASCADES AND
EAST SIDE THIS AFTERNOON. HOWEVER, MARGINAL MOISTURE COUPLED WITH A
LACK OF SYNOPTIC FORCING WILL PREVENT ANYTHING MORE THAN ISOLATED
STORM COVERAGE TODAY. WHATEVER DOES FORM WILL END AS THE SUN SETS
TONIGHT. EVEN THOUGH THE UPPER LOW WILL BE APPROACHING THE CENTRAL
CALIFORNIA COAST TOMORROW, THE FLOW OVER US REMAINS SOUTH TO
SOUTHWEST AND WE STILL WILL HAVE NO OBVIOUS SYNOPTIC FORCING
MECHANISM. THUS, STORM COVERAGE AND TIMING TOMORROW WILL BE SIMILAR
TO TODAY. WE START TO GET A BIT MORE FORCING SATURDAY NIGHT AS THE
FLOW ALOFT TURNS MORE SOUTHEASTERLY. SHORT WAVE ACTIVITY REMAINS
LARGELY CONFINED SOUTHEAST OF US, BUT WE COULD HAVE SOME STORMS
OVERNIGHT ACROSS MODOC AND SOUTHERN LAKE COUNTIES.

SUNDAY: MODELS SHOW TEMPERATURES GETTING RATHER HOT ON SUNDAY WITH
HIGHS NEAR 100 IN MEDFORD. MOISTURE WILL BE GRADUALLY INCREASING
AS WELL, AND THIS WILL ALLOW THE ATMOSPHERE TO GET QUITE UNSTABLE.
BY DAYS END, LIFTED INDICES OF -4C OR LOWER WILL BECOME WIDESPREAD
AND MID LEVEL LAPSE RATES WILL BE OVER 8C/KM. AT THE SAME TIME,
NUMEROUS SHORTWAVES WILL BE ROTATING AROUND THE UPPER LOW AND IN
OVER US. CONVECTION WILL LIKELY START IN THE SOUTHEAST (OR PERHAPS
ALREADY BE ONGOING) SUNDAY MORNING AND WE WILL ALSO HAVE STORMS
INITIATE OFF THE MOUNTAIN RANGES EVENTUALLY. ALL OF THIS WILL BE
MOVING WESTWARD, AND WILL LIKELY BE ABLE TO GET OVER THE CASCADES
ONTO THE WEST SIDE BY LATE SUNDAY. OF MUCH CONCERN IS THAT MANY OF
THESE STORMS MAY BE DRY INITIALLY AND COULD RESULT IN MANY FIRE
STARTS. WE HAVE UPGRADED THE FIRE WEATHER WATCH TO A WARNING START
SUNDAY AFTERNOON AND THEN EXPANDED IT WEST TO COVER MUCH OF THE
WEST SIDE AS WELL BY SUNDAY EVENING.

SUNDAY NIGHT: INSTABILITY, MOISTURE, AND FORCING REMAIN IMPRESSIVE
AND THUS THUNDERSTORMS ARE LIKELY TO CONTINUE THROUGH THE NIGHT.
FLOW REMAINS EAST-SOUTHEAST AND THIS WILL CONTINUE TO DRIVE STORMS
THAT FORM OVER THE MOUNTAINS AND EAST SIDE ACROSS THE MOUNTAINS,
PROBABLY EVEN OUT TO THE COAST AND OFFSHORE. MODELS ARE SHOWING
LITTLE TO NO RAIN WEST OF THE CASCADES SUNDAY NIGHT, WHICH MEANS THE
STORMS WILL LIKELY REMAIN DRY. THE RED FLAG WARNING EXPANDS TO
COVERS EVEN COASTAL AREAS OVERNIGHT SUNDAY NIGHT.

MONDAY AND MONDAY NIGHT: THE LOW HAS HARDLY MOVED MONDAY, AND THUS
IT REMAINS VERY UNSTABLE WITH INCREASING MOISTURE AND CONTINUED GOOD
FORCING OVER OUR AREA. STORMS ARE LIKELY TO REFORM OR SIMPLY
CONTINUE OVER THE AREA MONDAY, INCLUDING WEST SIDE LOCATIONS. STORMS
WILL BECOME WETTER BY THIS TIME, BUT THEY STILL MAY BE PRODIGIOUS
LIGHTNING PRODUCERS. THE RED FLAG WARNING CONTINUES INTO MONDAY
NIGHT FOR ALL AREAS.

TUESDAY: THE LOW FINALLY BEGINS TO LIFT OUT ON TUESDAY. THERE IS
STILL A SIGNIFICANT THUNDERSTORM POTENTIAL OVER LAKE AND KLAMATH
COUNTIES SO THE RED FLAG EXTENDS INTO TUESDAY THERE, BUT ENDS FOR
OTHER LOCATIONS.

THE MODELS HAVE COME INTO SOMEWHERE BETTER AGREEMENT REGARDING THE
REST OF THE FORECAST PERIOD (WEDNESDAY AND BEYOND), BUT CONSIDERABLE
DIFFERENCES REMAIN. A TROUGH IN THE WESTERLIES IS WHAT FINALLY KICKS
THE PERSISTENT LOW OFF CALIFORNIA OUT. THE ECMWF LINGERS THE KICKER
TROUGH OVER OUR AREA THROUGH THURSDAY WHEREAS THE GFS HAS A WEAKER
AND MORE PROGRESSIVE KICKER TROUGH. IT IS OF NOTE THAT THE GFS
HAD A QUITE DIFFERENT PATTERN YESTERDAY, SO ITS RELIABILITY IS IN
QUESTION. NEVERTHELESS, FEW CHANGES WERE MADE TO THE EXTENDED AS
WE DEALT WITH MORE PRESSING ISSUES IN THE SHORT TERM. -WRIGHT

&&

.AVIATION...FOR THE 08/18Z TAFS...STRATUS WITH IFR CIGS IS
POSSIBLE AT THE NORTH COAST INCLUDING KOTH LATE TONIGHT.
OTHERWISE, VFR CONDITIONS WILL PERSIST AT ALL LOCATIONS THROUGH
SATURDAY MORNING. ISOLATED THUNDERSTORMS ARE EXPECTED EAST OF THE
CASCADES AND IN NORTHERN CALIFORNIA THIS EVENING WHICH MAY PRODUCE
GUSTY OUTFLOW WINDS, BUT CONDITIONS WILL REMAIN VFR. -WRIGHT

&&

.MARINE...UPDATED 245 PM PDT 8 AUG 2014...
SEAS WILL REMAIN WIND WAVE DOMINATED THROUGH SUNDAY. THERE WILL BE
AN INCREASE IN NORTH WINDS THIS EVENING AS HIGH PRESSURE
OFFSHORE STRENGTHENS AND A THERMAL TROUGH INLAND DEEPENS. WINDS LATE
TONIGHT INTO SATURDAY MORNING WILL HAVE THE NORMAL DIURNAL
WEAKENING ASSOCIATED WITH THIS PATTERN BEFORE WINDS AND SEAS
BUILD TO A PEAK SATURDAY AFTERNOON. WINDS ARE EXPECTED TO REACH LOW
END GALES BY SATURDAY AFTERNOON...THEREFORE HAVE UPGRADED THE GALE
WATCH TO A WARNING FOR THE SOUTHERN PORTION OF THE OUTER WATERS
SOUTH OF CAPE BLANCO. SUNDAY AND ESPECIALLY MONDAY INTO TUESDAY, THE
THERMAL TROUGH WILL WEAKEN AND PUSH INLAND, RESULTING IN DIMINISHING
WINDS AND SEAS. THE DECREASE IN WIND WAVES EARLY NEXT WEEK WILL BE
PARTIALLY OFFSET BY A SLIGHT INCREASE IN THE HEIGHT OF WEST TO
NORTHWEST SWELL. EXPECT STRONG NORTH WINDS...AND MOST LIKELY SMALL
CRAFT CONDITIONS TO RETURN MID WEEK. DUNCAN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM SUNDAY TO 11 PM PDT TUESDAY FOR
     ORZ617-623>625.
     RED FLAG WARNING FROM 5 PM SUNDAY TO 5 AM PDT TUESDAY FOR
     ORZ618-619.
     RED FLAG WARNING FROM 11 AM SUNDAY TO 5 AM PDT TUESDAY FOR
     ORZ616-620>622.
     RED FLAG WARNING FROM 11 PM SUNDAY TO 5 AM PDT TUESDAY FOR
     ORZ615.

CA...RED FLAG WARNING FROM 11 AM SUNDAY TO 11 PM PDT TUESDAY FOR
     CAZ284-285.
     RED FLAG WARNING FROM 11 AM SUNDAY TO 5 AM PDT TUESDAY FOR
     CAZ280>282.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 AM
     PDT SUNDAY FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT SUNDAY
     FOR PZZ350-356-370-376.
     GALE WARNING FROM NOON SATURDAY TO 5 AM PDT SUNDAY FOR PZZ376.
     HAZARDOUS SEAS WARNING UNTIL 5 AM PDT SUNDAY FOR PZZ376.