943
FXUS66 KHNX 210836
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
136 AM PDT SUN JUL 21 2019
SYNOPSIS
A WARMING TREND BEGINS TOMORROW WITH WIDESPREAD TRIPLE
DIGIT HEAT EXPECTED ACROSS THE LOWER ELEVATIONS ALL OF NEXT WEEK.
MONSOONAL MOISTURE WILL BEGIN TO MOVE INTO THE REGION ON MONDAY FOR
A CHANCE OF AFTERNOON THUNDERSTORMS OVER THE MOUNTAINS BEGINNING
TUESDAY.
DISCUSSION
WATER VAPOR IMAGERY SHOWS AN AREA OF MID AND UPPER
LEVEL MOISTURE AND AN ASSOCIATED VORTICITY CENTER MOVING NORTHWARD
TOWARD THE CENTRAL CALIFORNIA COAST. THIS MOISTURE APPEARS TO BE
RATHER SHALLOW AND WITH THIS INITIAL PUSH, I DON'T EXPECT ANY
CONVECTION TO DEVELOP. MEANWHILE TO THE SOUTHEAST, DECAYING
CONVECTIVE COMPLEX OVER SOUTHERN ARIZONA IS PUSHING WEST TOWARDS
THE LOWER COLORADO RIVER AREA AND THIS IS ADDING SOME ADDITIONAL
MOISTURE FEED INTO EXTREME SOUTHEAST CALIFORNIA. ALL OF THIS
ACTIVITY IS JUST THE BEGINNING OF A FUNDAMENTAL CHANGE TO A
MONSOONAL PATTERN OVER THE REGION OVER THE NEXT SEVERAL DAYS AS
WELL AS A PERIOD OF HOT WEATHER.
MODELS PUSH THE OFFSHORE MID LEVEL MOISTURE UP THE COAST AS THE
WEAK SHORTWAVE HEADS INTO NORTHERN CALIFORNIA. AGAIN, CONVECTION
LOOKS TO BE NOT VERY LIKELY FROM THIS FEATURE. OVERNIGHT TONIGHT
AND MONDAY THE UPPER LEVEL FLOW PATTERN INTO SOUTHERN AND CENTRAL
CALIFORNIA BECOMES SOUTHERLY AND THE SOUTHEAST (HENCE THE MONSOON
TERMINOLOGY) AND ADDITIONAL MID LEVEL MOISTURE GET ADVECTED
NORTHWARD. THE NAM12 MODEL IS FASTEST WITH THE ARRIVAL OF THE
MOISTURE WHILE THE GFS IS ABOUT 12 HOURS SLOWER. IT APPEARS IN
EITHER CASE, FOR THE SIERRA ON MONDAY THAT THUNDERSTORMS WILL NOT
DEVELOP UNTIL TUESDAY AS THE MOISTURE WILL COMBINE WITH DAYTIME
HEATING OVER THE HIGH COUNTRY TO BREAK THROUGH ANY INVERSIONS OR
"CAPS" THAT MAY BE PRESENT AT OR ABOVE 14000 FEET MSL. MODELS
PRETTY MUCH KEEP ADDITIONAL SURGES OF MOISTURE INTO THE AREA FROM
THE SOUTH OR SOUTHEAST THROUGH MUCH OF THE WEEK, THUS DAILY BOUTS
OF AFTERNOON AND EVENING THUNDERSTORMS WILL BE POSSIBLE OVER THE
SIERRA AND KERN COUNTY MOUNTAINS GENERALLY NORTH AND EAST OF
TEHACHAPI.
AS FOR TEMPERATURES, THE HOTTEST STRETCH OF WEATHER WILL OCCUR
THIS WEEK AS THE DESERT SOUTHWEST HIGH PRESSURE SYSTEM BUILDS INTO
CENTRAL CALIFORNIA. TRIPLE DIGIT HIGHS WILL OCCUR AT ALL LOWER
ELEVATION LOCATIONS BEGINNING ON MONDAY WITH THE HEAT BUILDING
THROUGH THE WEEK. AT THIS TIME THE HOTTEST DAYS WILL OCCUR IN THE
WEDNESDAY THROUGH FRIDAY TIME RANGE AS THE RIDGE REACHES ITS
MAXIMUM STRENGTH. OF COURSE IN THIS SCENARIO, IF THUNDERSTORM
COMPLEXES DEVELOP AND SPREAD LOTS OF MID LEVEL CLOUDS INTO THE
FORECAST AREA THEN THE HEATWAVE WILL GET A BREAK. WE WILL HAVE TO
SEE IF THIS HAPPENS LATER THIS WEEK. ALL IN ALL THE FIRST
"MONSOON" EPISODE WILL OCCUR THIS WEEK SO HOT WEATHER WITH SIERRA
THUNDER WILL BE THE THEME OF THE WEEK.
AVIATION
VFR CONDITIONS CAN BE EXPECTED ACROSS THE CENTRAL
CA INTERIOR DURING THE NEXT 24 HOURS.
AIR QUALITY ISSUES
NONE.
CERTAINTY
THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS HIGH.
THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS MEDIUM.
CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT
WWW.WEATHER.GOV/HNX/CERTAINTY.HTML FOR ADDITIONAL INFORMATION
AN/OR TO PROVIDE FEEDBACK.
HNX WATCHES/WARNINGS/ADVISORIES
NONE.
PUBLIC...DUDLEY
AVIATION....DUDLEY
WEATHER.GOV/HANFORD
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