Debris Flow and Hail in California, July 1 to 3, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1011 AM PDT MON JUL 1 2013

.SHORT TERM DISCUSSION...

.SYNOPSIS...
HEAT WAVE WILL CONTINUE THROUGH MUCH OF THE WEEK WITH MINOR
COOLING TOWARD THE WEEKEND. THE HOTTEST DAYS ARE EXPECTED THROUGH
WEDNESDAY...THOUGH THE FOURTH OF JULY WILL LIKELY BE VERY HOT TOO.
AFTERNOON AND EARLY EVENING THUNDERSTORMS ARE POSSIBLE OVER THE
NORTHERN SIERRA NEVADA MAINLY TO THE SOUTH OF LAKE TAHOE TODAY...
BUT THUNDERSTORM CHANCES WILL SPREAD NORTH AND WEST INTO THE COAST
RANGE AND NORTHERN MOUNTAINS FOR TUESDAY...WEDNESDAY AND
THURSDAY. FOLLOW #HEATWAVE ON SOCIAL MEDIA.

&&

.DISCUSSION...
POWERFUL HIGH PRESSURE CENTERED OVER THE GREAT BASIN CONTINUES TO
DOMINATE THE PATTERN OVER THE REGION BRINGING MORE HOT WEATHER.
MORNING SOUNDINGS SHOW TEMPERATURES ALOFT WARMING FURTHER WITH
INCREASED SUBSIDENCE. SURFACE TEMPERATURES ARE SLIGHTLY COOLER THIS
MORNING THAN YESTERDAY...THOUGH...ABOUT 2 TO 5 DEGREES LOWER.
HUMIDITY LEVELS ARE A LITTLE HIGHER MAKING CONDITIONS FEEL
SLIGHTLY MUGGIER. MAY NEED TO ADJUST AFTERNOON HIGHS DOWN
SLIGHTLY..ESPECIALLY IN THE DELTA AND SOUTHERN SACRAMENTO VALLEY.
HOTTEST DAYS LOOK TO BE TUESDAY AND WEDNESDAY ALTHOUGH INCREASING
CLOUD COVER WILL BECOME MORE OF A FACTOR...BOTH IN POTENTIALLY
COOLING HIGHS A LITTLE AND WARMING LOWS.

A SLIGHT CHANCE OF THUNDERSTORMS CONTINUES THIS AFTERNOON OVER THE
SIERRA AS THE HIGH DRAWS MORE MOISTURE UP IN THE AREA. THIS
SPREADS NORTHWARD ON TUESDAY. WEDNESDAY A SHORTWAVE ROTATES AROUND
THE HIGH WITH PW MOISTURE REACHING A QUITE HIGH LEVEL OF 1.25
INCHES. INSTABILITY AND MOISTURE BRING THE POTENTIAL FOR
MORE COVERAGE OF SHOWERS AND THUNDERSTORMS DOWN INTO THE FOOTHILLS
AND POTENTIALLY INTO THE VALLEY. NAM SUPPORTS THIS BUT LATEST GFS
SUGGESTS BETTER POTENTIAL FOR CONVECTION WEDNESDAY NIGHT INTO
THURSDAY. TEMPERATURES SHOULD BEGIN TO BE SLIGHTLY LESS HOT BY
THURSDAY AS A WEAK TROUGH MOVES IN. HIGHS MAY STILL BE AT CRITICAL
LEVELS WITH SIGNIFICANT COOLING HOLDING OFF TILL THE WEEKEND. EK

&&

.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)

MODEL DIFFERENCES EARLY IN THE EXTENDED FORECAST PERIOD LEAD TO
UNCERTAINITIES IN THE FORECAST WRT HOW QUICKLY TO BEGIN THE
COOLING. 12Z ECMWF-HIRES AND GEM BOTH SHOWING RIDGE BREAKING DOWN
THURSDAY AS UPPER TROUGH MOVES THROUGH. THESE LATEST SOLUTIONS HOWEVER
ARE NOT CONSISTENT WITH PREVIOUS RUNS SO ATTM FORECAST LEANS
TOWARDS THE OPER GFS WHICH MAINTAINS MORE RIDGING OVER THE AREA
THURSDAY. HIGHS IN THE CENTRAL VALLEY AGAIN EXPECTED IN THE 105 TO
110 RANGE. ELEVATED INSTABILITY PROGS SHOWING AVAILABLE MOISTURE
AND CAPE OVER THE MOUNTAINS FOR AFTERNOON THUNDERSTORM POTENTIAL
THURSDAY AND FRIDAY.

GRADUAL HEIGHT AND THICKNESS FALLS EXPECTED FRIDAY THROUGH SUNDAY
LEADING TO SOME SYNOPTIC COOLING. WIDESPREAD TRIPLE DIGIT HIGHS
EXPECTED AGAIN FRIDAY THEN 90S BECOME MORE PREVALENT IN THE
CENTRAL VALLEY OVER THE WEEKEND.

&&

.AVIATION...

STRONG HIGH PRESSURE CONTINUES OVER INTERIOR NORCAL WITH OVERALL VFR
CONDITIONS. ISOLATED THUNDERSTORMS MAY CREATE LOCAL MVFR ALONG THE
SIERRA CREST FROM AROUND TAHOE SOUTH THIS AFTERNOON/EVENING.
DENSITY ALTITUDE INCREASING 3000-4000 FT OVER THE CENTRAL VALLEY
IN THE AFTERNOON DUE TO HEAT. GENERALLY LIGHT WINDS UNDER 10KTS AT
TAF SITES THROUGH THE PERIOD.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING UNTIL 6 PM PDT WEDNESDAY CARQUINEZ STRAIT
AND DELTA...CENTRAL SACRAMENTO VALLEY...CLEAR LAKE/SOUTHERN LAKE
COUNTY...MOTHERLODE...NORTHEAST FOOTHILLS/SACRAMENTO VALLEY...
NORTHERN SACRAMENTO VALLEY...NORTHERN SAN JOAQUIN VALLEY...
SOUTHERN SACRAMENTO VALLEY.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
340 AM PDT MON JUL 1 2013

CAZ013>019-063-064-066>069-021400-
SHASTA LAKE AREA/NORTHERN SHASTA COUNTY-
BURNEY BASIN/EASTERN SHASTA COUNTY-NORTHERN SACRAMENTO VALLEY-
CENTRAL SACRAMENTO VALLEY-SOUTHERN SACRAMENTO VALLEY-
CARQUINEZ STRAIT AND DELTA-NORTHERN SAN JOAQUIN VALLEY-
MOUNTAINS SOUTHWESTERN SHASTA TO NORTHERN LAKE COUNTIES-
CLEAR LAKE/SOUTHERN LAKE COUNTY-MOTHERLODE-
EAST FOOTHILLS/NORTH SACRAMENTO VALLEY-
WESTERN PLUMAS COUNTY/LASSEN PARK-WEST SLOPE NORTHERN SIERRA NEVADA-
340 AM PDT MON JUL 1 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

HOT TEMPERATURES WILL CONTINUE TODAY WITH RECORD HIGHS POSSIBLE MANY
AREAS. WARM OVERNIGHT LOWS WILL BRING LIMITED RELIEF.

* EXCESSIVE HEAT WARNING.....SEE WWUS76 KSTO - NPWSTO FOR DETAILS *

.DAYS TWO THROUGH SEVEN... TUESDAY THROUGH SUNDAY

SIGNIFICANT HEAT WAVE CONTINUES THROUGH MUCH OF THE WEEK. WIDESPREAD
TRIPLE DIGIT HEAT IS EXPECTED ACROSS THE VALLEY AND PARTS OF THE
MOUNTAINS WITH RECORD HIGH TEMPERATURES. APPEARS THAT THE HEAT WAVE
WILL PEAK TUESDAY AND WEDNESDAY WITH ONLY SLIGHT COOLING FOR THE
FOURTH OF JULY HEADING INTO THE WEEKEND.

* EXCESSIVE HEAT WARNING.....SEE WWUS76 KSTO - NPWSTO FOR DETAILS *

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR LOCAL NATIONAL WEATHER SERVICE OFFICE.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SACRAMENTO CA
332 PM PDT MON JUL 1 2013

CAZ069-012315-
WEST SLOPE NORTHERN SIERRA NEVADA CA-
332 PM PDT MON JUL 1 2013

THE NATIONAL WEATHER SERVICE IN SACRAMENTO HAS ISSUED A

SIGNIFICANT WEATHER ADVISORY FOR...
  SOUTH CENTRAL ALPINE COUNTY IN CENTRAL CALIFORNIA
  NORTH CENTRAL TUOLUMNE COUNTY IN CENTRAL CALIFORNIA

UNTIL 415 PM PDT

AT 329 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR KENNEDY MEADOW..MOVING NORTHWEST AT 10 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS
STORM...ALONG WITH HEAVY RAIN AND FREQUENT DANGEROUS LIGHTNING.
BOATERS SHOULD SEEKS THE SAFE HARBOR IF THREATENING WEATHER
APPROACHES.

LOCATIONS IMPACTED INCLUDE...
  RURAL NORTHERN TUOLUMNE COUNTY...
  RURAL SOUTHEASTERN ALPINE COUNTY...
  RURAL SOUTHERN ALPINE COUNTY...

LAT...LON 3829 11966 3841 11986 3850 11973 3844 11966
      3841 11964 3835 11963
TIME...MOT...LOC 2232Z 131DEG 10KT 3839 11973

RB