150 
FPUS65 KLAS 230955
AFDLAS

MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
255 AM PDT MON JUN 22 1998

SYNOPSIS...ISOLATED AFTERNOON AND EVENING THUNDERSTORMS WILL OCCUR
ACROSS PARTS OF SOUTH CENTRAL NEVADA TODAY AND WEDNESDAY. ELSEWHERE
...A DRY SOUTHWEST FLOW ALOFT WILL REMAIN IN PLACE THROUGH THE MIDDLE
OF THE WEEK ALLOWING FOR BREEZY AFTERNOON AND EVENINGS.

DISCUSSION...LONGWAVE PATTERN OF UPPER RIDGE ALONG 150W AND TROUGH
OVER WRN STATES CONTINUES WITH ONLY MINOR CHANGES EXPECTED THROUGH
WEDNESDAY. NRN PORTION OF MEAN TROUGH OVER THE WESTERN STATES WILL
WEAKEN AND LIFT NE ACROSS THE NRN ROCKIES LATER TODAY AND TONIGHT.
ANALYSIS OF 24 CHANGES SHOWS MOISTURE HAD INCREASED ACROSS MUCH OF
NORTHERN AND CENTRAL NV WITH 700 MB DEWPOINT AXIS FROM JUST S OF RNO
TO EKO AT 00Z. MOISTURE AND INSTABILITY COUPLED WITH LOW AND MID
LEVEL CONVERGENCE ZONE WILL GIVE RISE TO ISOLATED THUNDERSTORMS
ACROSS SOUTH CENTRAL NV TODAY...NORTH OF A LINE FROM GOLDFIELD TO
CALIENTE.  NOT MUCH CHANGE ELSEWHERE WITH TEMPERATURES UP A DEGREE OR
TWO OVER MONDAY AS LOWER LEVELS WARM SLIGHTLY.

SHORTWAVE TROUGH CURRENTLY MOVING OVER TOP OF ERN PACIFIC RIDGE THEN
DIGS SE INTO WRN CANADA WED AND INTO THE PAC NW THU.  IN ADVANCE OF
THIS SYSTEM...HEIGHTS INCREASE WED WITH WARM ADVECTION ALOFT NOTED ON
ALL THE MODELS.  THAT COUPLED WITH THE WEAKENING OF CONVERGENCE ZONE
WILL LIKELY INHIBIT CONVECTION ACROSS SOUTH CENTRAL NV. FOR NOW JUST
REDUCED MENTION TO SLIGHT CHANCE AND CONFINED IT TO FAR NRN REACHES. 
TEMPERATURES WARMING SOME 2 TO 4 DEGREES WED WITH DIURNAL BREEZES
CONTINUING TO ACROSS THE DESERTS AND ESPECIALLY THE PLATEAUS OF NW AZ
EACH DAY. 

IN THE EXTENDED...SHORTWAVE DROPS INTO NRN GREAT BASIN AND REINFORCES
THE MEAN TROUGH POSITION OVER THE WESTERN STATES INTO SATURDAY (SAME
OLD STORY). LATEST MRF INDICATES SLIGHTLY HIGHER 500 MB HEIGHTS OVER
SRN NV THAN PREVIOUS RUN. THESE DIFFERENCES ARE MINOR AND FEEL
PERSISTENCE THE BEST WAY TO GO. SO DRY...BREEZY AND SLIGHTLY BELOW
NORMAL TEMPERATURES WILL COVER THU-SAT PERIODS. LAS 000. NEMETH