Freeze Watch 7, NWS Eureka, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
503 AM PST MON DEC 2 2013

.SYNOPSIS...A STRONG COLD FRONT WILL BRING A RAINY DAY TO
PORTIONS OF NORTHWEST CALIFORNIA TODAY, FOLLOWED BY MUCH COLDER
TEMPERATURES FOR TUESDAY AND THE REST OF THE WEEK. SKIES WILL
CLEAR TUESDAY BUT BRISK NORTHERLY WINDS WILL REMAIN.

&&

.SHORT-TERM(TODAY THROUGH WEDNESDAY MORNING)...
KBHX RADAR IS SLOWLY PICKING UP ON DRIZZLE AND LIGHT RAIN ALONG
THE NORTH COAST AS THE SATURATED LAYER GRADUALLY INCREASES IN
DEPTH. A DEEP UPPER- LEVEL TROUGH WITH ORIGINS IN ALASKA WILL DROP
SOUTHWARD TOWARD NORTHERN CALIFORNIA TODAY AND TONIGHT. THIS WILL
SEND A STRONG SFC COLD FRONT THROUGH THIS AFTERNOON AND THIS
EVENING. DESPITE THE STRENGTH OF THE FRONT, IT WILL BE RUNNING
INTO HIGH PRESSURE AND WILL LOSE ITS PUNCH AS IT APPROACHES, WITH
A WEAKENING LOW-LEVEL JET AND ASSOCIATED CONVERGENT FLOW. EXPECT A
QUICK SHOT OF STEADY RAIN DRIVEN BY THIS WEAKENING LOW-LEVEL
CONVERGENCE, AMOUNTING TO A QUARTER TO A HALF INCH ACROSS THE
NORTH COAST AND ADJACENT INTERIOR. AMOUNTS WILL FALL OFF TO BARELY
MEASURABLE SOUTH OF CAPE MENDOCINO AND OVER EASTERN TRINITY COUNTY
WHERE ANY RAIN WILL HOLD OFF UNTIL THIS AFTERNOON. THE RAIN WILL
TAPER OFF LATER THIS AFTERNOON OVER DEL NORTE COUNTY, ENDING THIS
EVENING ACROSS THE REMAINDER OF NW CA.

THE UPPER TROUGH WILL PASS THROUGH ON TUESDAY, BRINGING SOME OF THE
COLDEST AIR OF THE SEASON. 850 MB DROP QUICKLY TO -2C TO -4C, WITH
H5 TEMPS -25C TO -30C. SNOW LEVELS WILL DROP BELOW 2000 FT LATE
TONIGHT INTO TUESDAY MORNING...BUT FORTUNATELY THE BULK OF THE
ENERGY ASSOCIATED WITH THIS TROUGH WILL TRACK WELL NORTH AND EAST OF
NORTHERN CALIFORNIA, WITH MUCH DRIER AIR IN THE WAKE OF THE COLD
FRONT. MODELS HINT AT A LITTLE ISOLATED SHOWER ACTIVITY WITH THE
UPPER TROUGH, BUT MOST AREAS TONIGHT INTO TUESDAY MORNING WILL
BE DRY. EXPECT LITTLE OR NO SNOW ACCUMULATION BUT SOME FLAKES MAY BE
SEEN ACROSS THE HIGHWAY 299 PASSES EARLY TUESDAY MORNING IF THERE IS
STILL ANY LEFTOVER SHOWER ACTIVITY. SKIES WILL CONTINUE TO CLEAR ON
TUESDAY, BUT BRISK NORTHERLY WINDS AND TEMPERATURES ONLY IN THE 40S
FOR MOST OF NW CA WILL MAKE IT FEEL RATHER UNCOMFORTABLE.

THE MAIN HAZARD TO BE CONCERNED WITH FOR THIS FORECAST PACKAGE WILL
BE NEAR RECORD COLD LOW TEMPERATURES WEDNESDAY THROUGH FRIDAY
MORNING. COMPARING 500 MB HEIGHTS AND 850 TEMPERATURES TO OTHER
HISTORICAL COLD OUTBREAKS IN EARLY DECEMBER 2009 AND 1972...THIS
UPCOMING COLD SNAP CERTAINLY COMPARES WITH 2009, BUT TEMPERATURES
ALOFT DO NOT LOOK QUITE AS COLD. WITH THIS IN MIND, THINK LOW
TEMPERATURES IN THE UPPER 20S AND LOW 30S WILL BE A GOOD BET ALONG
THE COAST, WITH TEENS AND LOW TWENTIES FOR THE INTERIOR. FREEZE
AND HARD FREEZE WATCHES WILL LIKELY BE NEEDED SOON FOR THE COASTAL
ZONES. AAD

.LONG TERM (WED THRU SUN)...LITTLE CHANGE TO THE ONGOING FORECAST.
MODELS CONTINUE TO INDICATE VERY COLD TEMPS FOR THE LAST HALF OF THE
WEEK. THE MAIN ISSUE IN THE EXTENDED IS THE TIMING AND STRENGTH OF
ANY SHORTWAVES THE PULSE DOWN THE MERIDIONAL FLOW FROM THE CANADIAN
ARCTIC. EACH OF THESE SHORTWAVES WILL BE A REINFORCING SURGE OF COLD
UNSTABLE AIR AND COULD PRODUCE SHOWERS AS THEY PASS. THESE SHOWERS
COULD BE HEAVY AT TIMES. WELL BE WATCHING THE NEXT COUPLE OF DAYS
TO SEE IF ANY SNOW ACCUMULATION IS POSSIBLE WITH THESE SHORTWAVES
AND/OR THE POTENTIAL FOR ANY DEEP CONVECTION. WITH THIS IN MIND, I
INCREASED THE POPS FOR THE SECOND HALF OF THE WEEK TO SHOW AT LEAST
A SLIGHT CHANCE OF PRECIPITATION WITH WHEN THE MODELS HAVE THE
SHORTWAVES ROLLING THROUGH. TIMING AND INTENSITY WILL NEED TO BE
ADJUSTED IN SUBSEQUENT FORECAST CYCLES. OVERALL, THE COLD PATTERN
LOOKS TO REMAIN INTO THE WEEKEND. EVEN THEN, MODELS DIVERGE IN THEIR
SOLUTIONS WITH SOME HOLDING ON TO A COLD PATTERN INTO EARLY NEXT
WEEK AND OTHERS BRINGING A RIDGE OVER THE AREA. CONFIDENCE IN THE
FORECAST IS HIGH FOR THE SECOND HALF OF THIS WEEK, BUT IS LOW FOR
LATE IN THE WEEKEND INTO EARLY NEXT WEEK. PREP FOR THE COLD AND STAY
WARM. BFG

&&

.AVIATION...
NOT THE EASIEST FORECAST FOR THE NEXT 24 HOURS. CONDITIONS ALONG THE
NORTH COAST ARE HIGHLY VARIABLE, WITH PERIODIC LIFR CONDITIONS AND
MIXED WITH MVFR CONDITIONS. MEANWHILE VALLEY FOG AND VIFR CIGS HAVE
DEVELOPED INLAND WHERE SKIES OTHERWISE REMAIN CLEAR. EXPECT THIS TO
ERODE LATER THIS MORNING, WHILE CONDITIONS TEND TO BECOME MORE
PERSISTENTLY IFR AT THE COAST AS A COLD FRONT APPROACHES TODAY. RAIN
WITH THIS FRONT WILL INCREASE IN INTENSITY LATER THIS MORNING BEFORE
TAPERING OFF FROM NORTH TO SOUTH LATER AFTERNOON. MENDOCINO COUNTY
WILL SEE MUCH LESS RAINFALL THIS AFTERNOON, WITH CIGS GENERALLY
REMAINING ABOVE 2000 FT AT KUKI AND VSBYS MAINLY ABOVE 5SM. AAD

&&

.MARINE...OPC SURFACE ANALYSIS OVERNIGHT SHOWS HIGH PRESSURE OVER
THE EAST PACIFIC DRIFTING TOWARD THE WEST WHILE WEAKENING. THIS IS
ALLOWING FOR WINDS TO EASE AND OPENING THE DOOR FOR A COLD FRONT TO
SINK INTO THE AREA. AS OF ABOUT 3AM THIS MORNING WINDS ARE RUNNING
IN THE 5 TO 15 KT RANGE WITH HIGHEST WINDS NEAR THE MAJOR POINTS AND
CAPE MENDOCINO. OVERALL WAVE HEIGHT IS RUNNING IN THE 6 TO 7 FT
RANGE AT ABOUT 13 SECONDS. THIS SHOULD HOLD TRUE FOR MUCH OF THE
DAY. HOWEVER, AS THE COLD APPROACHES WINDS ARE EXPECTED TO TAKE A
SHORT TURN TO THE WEST WHICH WILL LIKELY KICK UP A LITTLE CHOP. THIS
WILL BE A SHORT LIVED TURN BECAUSE AS THE FRONT PASSES WINDS WILL
TURN FROM NORTH AND INCREASE. AN UPPER TROUGH OVER THE WESTERN USA
AND UPPER RIDGE OVER THE EASTERN PACIFIC WILL BE THE PERFECT
INGREDIENTS FOR A STRONG GRADIENT SURFACE PRESSURE GRADIENT ALONG
THE PACIFIC NORTHWEST COAST. THIS WILL BRING WINDS UP TO NEAR GALE
ACROSS THE OUTER WATERS ACCOMPANIED BY THE RESULTANT SEAS. SEA
HEIGHTS COULD BE A TOUCH UNDERDONE IN THE FORECAST DUE TO UPSTREAM
WAVE DEVELOPMENT PROPAGATING INTO THE NWCA WATERS. PEAK SEAS IN THE
FORECAST ARE IN THE 13 FT RANGE, BUT COULD BE AS HIGH AS 15 FT AT
ABOUT 11 SECONDS. MOST MODELS INDICATE THE UPPER TROUGH SHIFTING
EAST OVER THE WEEKEND WHICH WOULD ALLOW THE WINDS AND THEN THE WAVES
TO COME DOWN. WITH A ROUGH WEEK AHEAD KEPT THE SMALL CRAFT
ADVISORIES FOR THE OUTER WATERS BUT OPTED TO ISSUE FOR MENDOCINO
COAST NEAR SHORE WATERS AS WELL DURING THE PEAK WINDS/SEAS. THERE IS
THE SLIGHTEST CHANCE OF GALES SOUTH OF MENDOCINO, BUT CONFIDENCE IS
VERY LOW SO NO PRODUCTS ISSUED. THE OTHER CONCERN BITTERLY COLD
TEMPERATURES ENTERING THE AREA ON TUESDAY. IF OUT, PREPARE FOR
UNSEASONABLY COLD TEMPS. BFG

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...

SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PST FRIDAY PZZ470.

SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 9 PM PST TUESDAY PZZ455.

SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 9 PM PST FRIDAY PZZ475.

&&

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HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE EUREKA CA
517 AM PST MON DEC 2 2013

CAZ001>004-076-031330-
REDWOOD COAST-MENDOCINO COAST-NORTH COAST INTERIOR-
UPPER TRINITY RIVER-MENDOCINO INTERIOR-
517 AM PST MON DEC 2 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST CALIFORNIA.

.DAY ONE...TODAY AND TONIGHT.

A COLD FRONT WILL MOVE THROUGH TODAY WITH A PERIOD OF RAIN
ESPECIALLY NORTH OF MENDOCINO COUNTY. SNOW LEVELS WILL DROP TO
AROUND 2000 FEET BY TUESDAY MORNING. LITTLE IN THE WAY OF SHOWER
ACTIVITY WILL LINGER AFTER THE COLD AIR MOVES IN, SO LITTLE TO NO
SNOW ACCUMULATION IS EXPECTED.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

EXPECT SUBSTANTIALLY COLDER TEMPERATURES TUESDAY THROUGH AT LEAST
THURSDAY, ALONG WITH GUSTY WINDS EACH AFTERNOON. LOW TEMPERATURES
WEDNESDAY AND THURSDAY MORNING WILL DROP WELL INTO THE TEENS
ACROSS INTERIOR VALLEYS WITH SUB-FREEZING TEMPERATURES POSSIBLE
ALONG THE COAST.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.