Severe Thunderstorm Warning 1, NWS Elko, NV

NORTHERN GREAT BASIN FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ELKO NV
157 PM PDT THU MAY 29 2003

.SYNOPSIS...A SOUTH FLOW OF AIR WILL PUSH MOISTURE ACROSS
NORTHEASTERN NEVADA AND PRODUCE A CHANCE OF THUNDERSTORMS THIS
EVENING AND ON FRIDAY. HIGH PRESSURE WILL RETURN TO THE GREAT BASIN
SATURDAY WITH DRY WEATHER EXPECTED THROUGH LATE NEXT WEEK.

.SHORT TERM...WATER VAPOR IMAGERY SHOWS THE UPPER LOW OFF THE CA
COAST LOCATED NEAR 35N...125W AT 18Z IN GOOD AGREEMENT WITH THE
POSITION PROJECTED BY THE 12Z RUNS OF THE ETA AND AVN. THE UPPER
LOW IS HEADED TO THE NORTHEAST TOWARD THE NORTHERN CA COAST THIS
AFTERNOON...WHILE THE UPPER HIGH NEAR THE FOUR CORNERS CONTINUES TO
DRIFT VERY SLOWLY TO THE EAST. MID- AND HIGH LEVEL MOISTURE BETWEEN
THESE SYSTEMS HAS MOVED NORTHWARD ACROSS THE CWA EARLY THIS
AFTERNOON. ISOLATED THUNDERSTORMS HAVE ALREADY FORMED ACROSS
WESTERN SECTIONS OF THE CWA...WHERE H3 DIFFLUENCE ALOFT AND STRONG
SURFACE HEATING HAS CREATED THE BEST CONDITIONS FOR CONVECTION. 12Z
RUNS OF THE ETA AND GFS SHOW H3 DIVERGENCE SHIFTING ACROSS THE
EASTERN CWA THIS EVENING. WITH ETA SHOWING LIFTED INDICES NEAR ZERO
ACROSS THE ENTIRE CWA THROUGH THIS EVENING...AND EXPECT ISOLATED
THUNDERSTORMS WITH THE HIGHEST PROBABILITY IN THE EASTERN CWA. THE
MAIN THREAT THIS EVENING WILL BE DOWNBURST WINDS FROM THUNDERSTORMS
WILL MODEL SOUNDINGS SHOWING A VERY DRY PROFILE BELOW H5. AS THE
UPPER LOW MOVES FROM NORTHERN CA INTO SOUTHERN ID FRIDAY...RR QUAD OF
H3 JET CROSSES THE NORTHERN HALF OF THE CWA. HIGHEST CAPE...NEAR 500
J/KG...AND HIGHEST INSTABILITY WILL BE ACROSS ELKO COUNTY FRIDAY
AHEAD OF A WEAK COLD FRONT WHICH WILL MOVE ACROSS NORTHEASTERN NV
INTO UT FRIDAY EVENING. WINDS AHEAD OF THE FRONT WILL BECOME BREEZY
ACROSS WHITE PINE COUNTY FRIDAY...AS STRONG MIXING BRINGS 20 KT WINDS
AT H7 TO THE SURFACE. COOLING BEHIND THE FRONT WILL BE MINIMAL
SATURDAY AND SUNDAY...AS H5 HEIGHTS FALL AROUND 2 DM SATURDAY AND
RECOVER SUNDAY.

.EXTENDED...UPPER HIGH PROGGED TO MOVE INTO THE GREAT BASIN MONDAY
AND TUESDAY WITH H5 HEIGHTS RISING INTO THE MID TO UPPER 580S WITH
TEMPERATURES REMAINING 8 TO 12 DEGREES ABOVE NORMAL IN THE 80S.
UPPER LOW MOVING TO THE EAST THROUGH THE NORTHERN GULF OF AK BUILDS
A HIGH AMPLITUDE RIDGE ALONG THE PACIFIC COAST OF NORTH AMERICA
WEDNESDAY AND THURSDAY KEEPING TH4E GREAT BASIN IN A DRY NORTHWEST
FLOW WITH TEMPERATURES SLIGHTLY COOLER BUT STILL ABOVE NORMAL.

HYDRO...LAMOILLE CREEK CRESTED AT FLOOD STAGE BETWEEN 01-02Z YTDY
AND HAS SINCE RECEDED. HOWEVER...WITH NEAR RECORD TEMPS AGAIN TODAY
AND STILL SOME HIGH ELEVATION SNOWPACK (ABOVE 9 KFT) EXPECT IT TO
FLOOD AGAIN THIS EVENING. ALSO...CREST PAST TWO DAYS HAS INCREASED BY
ALMOST A HALF FOOT EACH DAY. IF THIS IS THE CASE AGAIN TODAY...
FLOODING WILL BE WORSE BUT IT DEPENDS ON JUST HOW MUCH SNOW IS LEFT
AT HIGH ELEVATIONS. SNOTELS HAVE BEEN BARE FOR A FEW DAYS. CURRENT
FLW ALREADY ADDRESSES ABOVE CONCERNS SO WILL LET IT RIDE AND UPDATE
AS NECESSARY. SMITH

.EKO...FLOOD WARNING FOR LAMOILLE CREEK NEAR LAMOILLE-NVC007.

NVZ030>037-301400-

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE ELKO NV
602 AM PDT THU MAY 29 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND EAST CENTRAL
NEVADA

.DAY ONE...

RECENT WELL ABOVE NORMAL TEMPERATURES HAVE TRIGGERED TREMENDOUS
SNOWMELT IN THE MOUNTAINS. AS A RESULT...SOME STREAMS ARE RUNNING
HIGH. LAMOILLE CREEK REACHED FLOOD STAGE YESTERDAY AFTERNOON AND IS
EXPECTED TO AGAIN THIS AFTERNOON. THEREFORE...A FLOOD WARNING HAS
BEEN ISSUED. SEE WGUS45 KLKN OR RNOFLWLKN FOR DETAILS.

.DAYS TWO THROUGH SEVEN...

A PACIFIC LOW WILL MOVE OVER NORTHWEST NEVADA FRIDAY AND TRIGGER
SHOWERS AND THUNDERSTORMS ACROSS THE AREA. ALTHOUGH A FEW OF THESE
STORMS MAY PRODUCE HAIL AND GUSTY WINDS...MOISTURE IS TOO LIMITED
FOR A MORE WIDESPREAD EVENT.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS TO
THEIR LOCAL NATIONAL WEATHER SERVICE OFFICE.

JW