Area Forecast Discussion
Issued by NWS Sacramento, CA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

000
FXUS66 KSTO 302226
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
326 PM PDT TUE JUN 30 2015

.SYNOPSIS...
VERY HOT WEATHER CONTINUES ACROSS THE REGION THIS WEEK. SIERRA
THUNDERSTORMS THROUGHOUT THE WEEK WITH SHOWERS OR SPRINKLES
POSSIBLE IN PORTIONS OF THE VALLEY THURSDAY AND FRIDAY.

&&

.DISCUSSION...
TEMPERATURES STILL LOOK TO BE VERY HOT FOR MUCH OF THE VALLEY
NORTH OF INTERSTATE 80 WITH HIGHS BETWEEN 105-115 DEGREES AND
OVERNIGHT LOWS IN THE UPPER 70S TO AROUND 80. THE EASTERN COASTAL
RANGE FOOTHILLS WILL ALSO BE HOT INCLUDING MUCH OF SOUTHERN LAKE
COUNTY SO WE HAVE NOT ONLY UPGRADED THE WATCH TO AN EXCESSIVE HEAT
WARNING, BUT HAVE EXPANDED THE AREA OF CONCERN. ANY RESIDENTS OR
VISITORS WHO MAY SEEK RELIEF NEAR SHASTA LAKE OR CLEARLAKE SHOULD
BE AWARE THAT THESE AREAS ARE INCLUDED IN THE WARNING.

CURRENT TEMPERATURES ARE RUNNING ANYWHERE FROM 6-12 DEGREES
WARMER THAN YESTERDAY. REDDING AT 3PM WAS 110 WHICH IS NEARING
THE RECORD OF 111 (2014). OUR OTHER CLIMATE SITES SHOULD REMAIN A
FEW TO SEVERAL DEGREES BELOW RECORD LEVELS.

RADAR THIS AFTERNOON IS SHOWING PLENTY OF LIGHTNING AND
THUNDERSTORM ACTIVITY, BUT IT IS OCCURRING JUST SOUTH AND EAST OF
OUR CWA...AS PREDICTED BY THE HRRR MODEL THIS MORNING. A FEW
THUNDERSTORMS MAY BRUSH OUR SOUTHEASTERN CWA BORDERS AS THE
AFTERNOON PROGRESSES.

FOR TOMORROW ONWARD, MODELS ACROSS THE BOARD REMAIN CONSISTENT
IN THE HOT WEATHER WITH MONSOONAL MOISTURE OVER THE MOUNTAINS. FOR
AREAS SOUTH OF INTERSTATE 80, THE DELTA BREEZE WILL BEGIN ITS
RETURN ON THURSDAY ALLOWING THIS AREA TO BE COOLER THAN WEDNESDAY.
AREAS NORTH OF I-80 WILL NUDGE DOWNWARD, BUT STILL REMAIN VERY
HOT.

THE CHALLENGE THIS WEEK IS HOW THURSDAY AND FRIDAY WILL PLAY OUT
IN THE VALLEY. THE GFS CONTINUES TO BE THE BIGGEST PROPONENT FOR
BRINGING PRECIPITATION INTO THE VALLEY ON THURS & FRI WITH PW
VALUES RANGING 1.25 TO 1.6 INCHES IN OUR REGION. HOWEVER, MOST OF
THAT MOISTURE WILL BE AROUND 500 MB AND HIGHER SO THERE IS
QUESTION AS TO WHETHER WE WILL GET ACTUAL THUNDERSTORMS/SHOWERS OR
JUST SPRINKLES IN THE VALLEY INSTEAD. FOR NOW, HAVE KEPT MENTION
OF THUNDERSTORMS IN COORDINATION WITH OUR NEIGHBORING FORECAST
OFFICES. ANOTHER QUESTION RELATED TO THE MONSOONAL MOISTURE IS HOW
MUCH THE CLOUD COVER WILL TRAP HEAT THURSDAY NIGHT INTO FRIDAY
MORNING. IF MUCH OF THE SKY REMAINS CLOUDY OVERNIGHT, THEN
OVERNIGHT LOWS WILL BE VERY WARM. IF SKIES AREN`T AS CLOUDY AS
EXPECTED, THEN MORE COOLING MAY OCCUR WHICH COULD TRIGGER AN
EARLIER CANCELATION OF THE EXCESSIVE HEAT WARNING.
JBB

&&
.EXTENDED DISCUSSION (SATURDAY THROUGH TUESDAY)

OVER THE WEEKEND, INTERIOR NORCAL IS SANDWICHED BETWEEN A FOUR
CORNERS UPPER HIGH AND AN OFFSHORE UPPER LOW. SOUTH TO SOUTHEAST
FLOW ALOFT WILL CONTINUE TO DRAW MONSOONAL MOISTURE INTO THE
AREA. MAIN INSTABILITY, AND THUS THREAT OF SHOWERS AND
THUNDERSTORMS, IS DEPICTED OVER THE MOUNTAINS IN THE AFTERNOONS
INTO EARLY EVENINGS. DRIER AND MORE STABLE SOUTHWEST FLOW ALOFT
DEVELOPS LATE SUNDAY INTO TUESDAY AS THE UPSTREAM UPPER LOW DRIFTS
NORTHWARD, SLIGHTLY CLOSER TO THE NORCAL COAST. AS A RESULT, THE
THREAT OF AFTERNOON DEEP MOIST CONVECTION SHIFTS EAST OF THE
SIERRA NEVADA CREST.

HIGH TEMPERATURES THROUGH THE EXTENDED FORECAST PERIOD WILL BE
COOLER. MAX READINGS WILL RANGE FROM THE MID 80S IN THE DELTA TO
AROUND 100 IN THE NORTHERN SACRAMENTO VALLEY, WITH UPPER 70S TO
AROUND 90 FOR THE MOUNTAINS AND FOOTHILLS.     JCLAPP

&&

.AVIATION...

UPPER HIGH OVER ROCKIES EXTENDS OVER NORCAL AND CONTINUES
SOUTHERLY FLOW ALOFT AND HOT TEMPS. ISOLD TSTM OVER SIERRA NEVADA
BETWEEN 22Z- 02Z. AFTERNOON DENSITY ALTITUDES MAY BE HIGH WED/THU.
JCLAPP
&&

.STO WATCHES/WARNINGS/ADVISORIES...
EXCESSIVE HEAT WARNING FROM 2 PM WEDNESDAY TO 8 AM PDT FRIDAY
FOR CENTRAL SACRAMENTO VALLEY-CLEAR LAKE/SOUTHERN LAKE COUNTY-
MOUNTAINS SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY-
NORTHEAST FOOTHILLS/SACRAMENTO VALLEY-NORTHERN SACRAMENTO VALLEY-
SHASTA LAKE AREA / NORTHERN SHASTA COUNTY.

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.