FXUS66 KHNX 160501
AFDFAT

INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
950 PM PDT TUE JUL 15 2003

WEATHER PATTERN RELATIVELY SUBDUED TONIGHT...ALTHO THERE ARE
SOME MESOSCALE CHANGES IN THE MAKING WHICH WILL EVENTUALLY
LEAD TO A MORE INTERESTING PATTERN IN THE DAYS TO FOLLOW.

FIRSTLY...ONSHORE GRADIENTS ARE SOMEWHAT STRONGER THAN THEY
WERE 24 HRS AGO...AVERAGING CLOSE TO 7.0 MB BETWEEN SFO AND LAS.
HOWEVER...THE MARINE LAYER REMAINS QUITE SHALLOW THIS EVENING...
LESS THAN 1K FEET DEEP ACCORDING TO THE FORT ORD PROFILER AND
ONLY ABOUT 550 FT DEEP AS OBSERVED BY THE 00Z OAK SOUNDING.
NONETHELESS...A MARINE PUSH HAS OCCURED ACROSS THE SACRAMENTO
VALLEY AND NORTHERN SJ VLY. IN THIS REGION...TEMPS AND DEWPOINTS
ARE SEVERAL DEGREES LOWER THAN MONDAY EVENING. WHILE ONSHORE
GRADIENTS SUPPORT A NW BREEZE IN THE CENTRAL AND SOUTHERN SJ VLY 
TONIGHT...THE MARINE LAYER IS FAR TOO SHALLOW ALONG THE COAST
TO SUPPORT ANY COOLING THIS FAR SOUTH. IN THAT RESPECT...MAX
TEMPS LOOK ON TRACK FOR WED...AND THIS IS SUPPORTED BY MOS
GUIDANCE. IF ANYTHING...THE 00Z RUN OF THE MESO ETA CONTINUES
TO NUDGE MAX TEMPS UPWARD A DEGREE OR TWO EACH OF THE NEXT TWO
DAYS...BUT THIS PARTICULAR MODEL HAS BEEN OVERZEALOUS WITH TEMPS
LATELY. 

MORE IMPORTANTLY...THE BROADER PICTURE IS CHANGING ACROSS THE
WEST. THE FIRST HINTS OF CHANGE BECAME EVIDENT OVER THE HIGH
SIERRA THIS AFTN WITH THE PRESENCE OF HIGH BASED CU. THIS IS 
THE INITIAL INDICATION THAT THE DOOR TO MONSOONAL MOISTURE IS
BEGINNING TO OPEN. THAT DOOR WILL OPEN WIDER DURING THE NEXT 48
HRS AS THE CENTER OF THE UPPER LEVEL RIDGE SHIFTS EAST OF THE
ROCKIES AND WIND CURRENTS ALOFT STEER TROPICAL MOISTURE IN THIS
DIRECTION. SURELY...CU DEVELOPMENT OVER THE HIGH SIERRA WILL BE
MORE PRONOUNCED THE NEXT COUPLE OF AFTNS. THE QUESTION IS WHEN
THE INVERSION CAP WILL BREAK. THE 00Z RUN OF THE GFS HINTS THAT
IT COULD BE AS EARLY AS TOMORROW AFTN NEAR THE CREST OF THE
SIERRA FROM TULARE CO SOUTHWARD. THIS MODEL FORECASTS 700-500 MB
REL HUM TO INCREASE TO ABOUT 60% WITH THETA E TEMPS AROUND 336 K.
HOWEVER...RELATIVE HUMIDITIES ARE COMPARITIVELY LOWER WITH THE
00Z MESO-ETA...EVEN THO 850 MB DEWPOINTS ARE FORECAST TO RISE
TO NEAR 8 C. BY THU PM...BOTH MODELS POSITION THE THETA E RIDGE
ALONG THE SPINE OF THE SOUTHERN SIERNEV WITH FURTHER INCREASE
IN MID TO HIGH LEVEL REL HUM. HENCE...ISOLD...HIGH BASED TSTMS WITH
DRY LIGHTNING SEEM A GOOD POSSIBILITY BY THEN. WITH THE ARRIVAL
OF RICHER TROPICAL MOISTURE FRIDAY THRU SATURDAY...ISOLD TSTMS
BECOME A POSSIBILITY AT LOWER ELEVATIONS OF THE SRN SIERNEV...
AND NOT EXCLUSIVE TO JUST THE DAYLIGHT HOURS.  FINALLY...IF YOU 
THOUGHT OUR SJ VLY HEAT HAS BEEN PATHETIC LATELY...THERE WILL
BE ADDED DISCOMFORT TO OUR PATTERN LATER IN THE WEEK. BY FRIDAY...
THE ARRIVAL OF MONSOONAL MOISTURE COULD SEND DEWPOINTS IN SOME
SJ VLY LOCALES CLOSE TO THE 70 DEGREE MARK...ESPECIALLY IN THE
SOUTH VALLEY.    

.HNX...NONE.

$$
DURFEE