000
FXUS65 KVEF 172235
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
330 PM PDT SAT MAY 17 2008
.SYNOPSIS...A STRONG AREA OF HIGH PRESSURE WILL BE OVER THE SOUTHERN
GREAT BASIN AND MOJAVE DESERT THE NEXT SEVERAL DAYS...RESULTING IN
RECORDING BREAKING HEAT. A TROUGH OF LOW PRESSURE WILL BEGIN TO
PROVIDE RELIEF BY WEDNESDAY ALONG WITH A SLIGHT CHANCE OF
THUNDERSTORMS ACROSS THE HIGHER ELEVATIONS. TEMPERATURES WILL THEN
RETURN TO BELOW NORMAL LEVELS BY THURSDAY.
&&
.SHORT TERM...AN AREA OF STRONG HIGH PRESSURE CURRENTLY LOCATED OFF
OF THE CENTRAL CALIFORNIA COAST WILL REMAIN NEARLY STATIONARY OVER
THE NEXT 36 HOURS AND THEN MOVE SLOWLY EAST...BECOMING CENTERED OVER
SOUTHERN CALIFORNIA BY MONDAY AFTERNOON. THIS WILL PROVIDE RECORD
BREAKING TEMPERATURES FOR MANY LOCATIONS...INCLUDING THE LAS VEGAS
VALLEY SUNDAY THROUGH TUESDAY. TEMPERATURES ARE EXPECTED TO REACH
ABOVE THE EXCESSIVE HEAT CRITERIA OF 105 FOR LAS VEGAS ON MONDAY AND
WE HAVE ISSUED AN EXCESSIVE HEAT WATCH FOR MONDAY. THICKNESSES...700
AND 850 MB TEMPERATURES INCREASES ON SUNDAY AND MONDAY THAT WILL BE
REFLECTED IN A FEW DEGREES OF WARMING AT THE SURFACE EACH DAY.
MODELS IN FAIRLY GOOD AGREEMENT WITH TROUGH ALONG THE WEST COAST AND
ASSOCIATED LOW CENTERED OVER WASHINGTON STATE. ALTHOUGH HEIGHTS
BEGIN TO DECREASE WITH THE APPROACHING TROUGH ON TUESDAY...EFFICIENT
MIXING SHOULD ENABLE TEMPERATURES TO AGAIN REACH NEAR BUT AT THIS
POINT REMAIN BELOW EXCESSIVE HEAT CRITERIA.
.LONG TERM...A DRAMATIC CHANGE IN OUR WEATHER WILL TAKE PLACE ON
WEDNESDAY AS A DEEP UPPER LEVEL TROUGH DROPS OUT OF THE PAC NW AND
PLUNGES THROUGH THE WESTERN CONUS. WE WILL GO FROM A PERIOD OF
BRIGHT BLAZING SUNSHINE TO ONE OF MUCH MORE IN THE WAY OF
CLOUDS...BELOW NORMAL TEMPERATURES AND EVEN THE SLIGHT CHANCE FOR
PRECIPITATION. AHEAD OF THE TROUGH WEDNESDAY WILL BE OUR LAST WARM
DAY...HOWEVER AS THE TROUGH APPROACHES H7 TEMPS WILL LOWER BY AROUND
12C ACROSS THE AREA...QUITE A DROP FROM TUESDAY. STILL WE SHOULD
START OFF WARM AND UNLESS TIMING OF THE UPPER TROUGH AND ASSOCIATED
COLD FRONT CHANGE...WE SHOULD SQUEEZE OUT ONE MORE DAY OF ABOVE
NORMAL TEMPERATURES...ESPECIALLY IN EASTERN PARTS OF THE CWFA. THE
APPROACHING UPPER TROUGH WILL KICK UP THE WINDS AS THE SFC P-GRADS
TIGHTEN. LOOKING AT TWO AREAS FOR GUSTY WINDS WEDNESDAY AFTERNOON
INTO EARLY THURSDAY NIGHT...FIRST AHEAD OF THE UPPER
TROUGH...ESPECIALLY ACROSS THE MOJAVE DESERT WHERE THE LAX-DAG GRAD
IS PROGGED TO BE AROUND 8 MB PER THE GFS. PER COORDINATION WITH
WFO/S PSR AND SGX HAVE BUMPED UP WINDS FOR HERE...AND YET AGAIN THIS
SPRING WE MAY NEED TO HOIST ANOTHER WIND ADVISORY FOR THE SAN
BERNARDINO COUNTY DESERTS...AT THE LEAST THE AREA AROUND DAGGETT.
THE SECOND AREA FOR GUSTY WINDS LOOKS TO BE ACROSS THE SOUTHERN
GREAT BASIN WHERE THE RNO-LAS IS PROGGED BY THE GFS TO BE 13 MB. GFS
PROGS A 130KT+ H25 JET AIMING RIGHT DOWN THE SIERRA. ANOTHER WIND
ADVISORY MAY BE NEEDED FOR THE SOUTHERN GREAT BASIN ZONES FOR GUSTY
NORTHWEST WINDS...AND LOCAL GUSTY NORTHWEST WINDS AT THE LEAST NOT
UNREASONABLE IN THE LV VALLEY. EXPECT THE APPROACH OF THE UPPER
TROUGH TO BRING US THE SLIGHT CHANCE FOR SHOWERS AND
THUNDERSTORMS...MAINLY ACROSS LINCOLN AND MOHAVE COUNTIES.
BY THURSDAY A DEEP UPPER TROUGH WILL BE CARVED OUT OVER THE WESTERN
CONUS THAT LOOKS TO HOLD THROUGH AT LEAST SATURDAY...IF NOT INTO
MEMORIAL DAY. MODELS INCLUDING THE 12Z OPERATIONAL GFS SHOW A CLOSED
LOW FORMING NEVADA BY THURSDAY. TEMPS LOOK TO AVERAGE A GOOD 8-14
DEGREES BELOW NORMAL. GIVEN THE BIG TEMPERATURE DROP...WE LOOKED UP
TO SEE IF THERE HAVE BEEN ANY OTHER PERIODS IN MAY WITH SUCH A
DROP...AND FOUND BACK IN MAY OF 2006 THE HIGH TEMP IN LAS VEGAS WENT
FROM 98 DEGREES ON THE 20TH...TO JUST 78 DEGREES ON THE 22ND. SO
WHILE THIS WILL BE A REAL SHOCKER...IT IS NOT UNPRECEDENTED. HAVE
LOWERED HIGHS AGAIN AND STILL MAY NEED TO PULL THEM DOWN MORE.
BIGGEST WILDCARD WITH LONG RANGE TEMPS IS CLOUD COVER...WHICH IS
VARIABLE IN A PERIOD WHERE IT WILL BE DETERMINED BY THE TIMING OF
ENERGY THAT ROTATES THROUGH THE BASE OF THE TROUGH OR THE CLOSED
LOW. ALTHOUGH THERE IS NOT AN IMPRESSIVE AMOUNT OF MOISTURE...GIVEN
THE COLD POOL ALOFT...HAVE KEPT IN SLIGHT CHANCES OF SHOWERS THROUGH
THE EXTENDED. ENOUGH DAYTIME INSTABILITY LOOKS TO BE THERE...SO WENT
WITH TSTMS FOR THE DAY BUT AT NIGHT THINK IT STABILIZES ENOUGH TO
JUST CALL IT SHOWERS. LOOKED AT MODEL SOUNDINGS...AND THEY SHOW
INVERTED V LOOK...SO CAN/T RULE OUT SOME GUSTY WINDS GENERATED BY
ANY CONVECTION THAT DEVELOPS. WHILE THE FORECAST MAY HAVE A WET LOOK
TO IT...TIMING OF PRECIP WILL BE DRIVEN LARGELY BY WHEN ANY ENERGY
MOVES ON THROUGH...SO WHILE WE HAVE IN POPS FOR A LARGE LENGTH OF
TIME...MANY TIMES IT MAY JUST BE DRY WITH A SCT-BKN CLOUD DECK.
&&
.AVIATION...FOR MCCARRAN...LIGHT WINDS AT 10 KTS OR LESS LOOK TO
CONTINUE TONIGHT INTO TOMORROW. DIURNAL SOUTHWEST WINDS THIS EVENING
THROUGH BETWEEN 12Z-15Z SUN. AFTERWARDS...VARIABLE WINDS ARE
EXPECTED...THEN WINDS LOOK TO GO NORTHEAST AROUND 18Z SAT. OTHER
THAN A FEW CIRRUS IT SHOULD BE CLEAR THROUGH TOMORROW.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...VARIABLE WINDS GENERALLY LESS THAN 10 KTS WITH A MOSTLY
CLEAR SKY LOOKED FOR THROUGH TOMORROW.
&&
.CLIMATE...NEAR RECORD TO RECORD BREAKING HIGH TEMPERATURES ARE
EXPECTED IN THE OWENS VALLEY AND NORTHWEST SAN BERNARDINO COUNTY
SATURDAY...AND ACROSS THE REST OF THE MOJAVE DESERT SUNDAY THROUGH
TUESDAY. RECORD HIGH MINIMUM TEMPERATURES ALSO LOOK POSSIBLE AT LAS
VEGAS. RECORDS FOR SEVERAL STATIONS IN OUR AREA...AS WELL AS SOME
STATISTICS ON TRIPLE DIGIT TEMPERATURES FOR LAS VEGAS ARE BELOW.
RECORD HIGHS...
LOCATION SATURDAY SUNDAY MONDAY TUESDAY
5/17 5/18 5/19 5/20
---------------------------------------------------------------------
LAS VEGAS 102/1970* 103/1973 102/2006* 102/2005
BISHOP 97/1954 100/1954 98/1954 96/1984
DAGGETT 103/2006 102/1954 103/2006 103/1984
NEEDLES 110/2006 110/2006 110/2006 109/2005
* INDICATES THE LAST TIME A RECORD HIGH WAS REACHED.
RECORD HIGH MINIMUMS FOR LAS VEGAS...
5/18...77/2006
5/19...80/2006
5/20...77/2006 AND PREVIOUS YEARS
5/21...76/2005
FOR LAS VEGAS...THE AVERAGE DATE OF THE FIRST TRIPLE DIGIT
TEMPERATURE IS MAY 25TH. THE EARLIEST TRIPLE DIGIT TEMPERATURE WAS
ON MAY 1 1947. THE LATEST OCCURRENCE OF THE FIRST 100 DEGREE OR
BETTER TEMPERATURE WAS JUNE 30 1965.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...EXCESSIVE HEAT WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
EVENING FOR NVZ016-017-020>022.
AZ...EXCESSIVE HEAT WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
EVENING FOR AZZ002-003-036.
CA...EXCESSIVE HEAT WATCH FROM MONDAY AFTERNOON THROUGH MONDAY
EVENING FOR CAZ522>527.
&&
$$
CZYZYK/STACHELSKI
HTTP://WEATHER.GOV/LASVEGAS
