Severe Thunderstorm Warning 18, NWS Elko, NV

NORTHERN GREAT BASIN FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ELKO NV
130 PM PDT SUN AUG 10 2003

.SYNOPSIS...HIGH PRESSURE NEAR THE FOUR CORNERS WILL CONTINUE TO BE
THE DOMINANT WEATHER FEATURE ACROSS THE GREAT BASIN...WITH SEASONABLY
WARM WEATHER THROUGH TUESDAY. LOW PRESSURE WILL MOVE THROUGH THE
PACIFIC NORTHWEST WEDNESDAY AND THURSDAY...BRINGING A SLIGHT COOLING
TREND. HIGH PRESSURE WILL BRING A RETURN OF ABOVE NORMAL TEMPERATURES
TO NORTHEAST NEVADA FRIDAY THROUGH SUNDAY.

.SHORT TERM...VIS IMAGERY SHOWS CU BUILD-UPS DEVELOPING ACROSS EAST
CENTRAL NEVADA AND ELKO COUNTY EARLIER THAN OBSERVED YESTERDAY. 12Z
SOUNDINGS AMD WATER VAPOR IMAGERY INDICATED A NORTH-SOUTH MOISTURE
GRADIENT WITH GOES PW IMAGERY DISPLAYING AROUND 1 INCH PW ACROSS
EXTREME SOUTHERN NV TO NEAR 0.50 OF AN INCH ACROSS CENTRAL ELKO
COUNTY. 12Z GFS AND ETA RUNS HAVE SOUTHERLY H5 WINDS BETWEEN 15 AND
25 KTS ADVECTING MID-LEVEL MOISTURE INTO THE NORTHEAST CORNER OF NV
THROUGH 00Z. INSTABILITY PARAMETERS FOR THIS AFTERNOON AND EVENING
ARE NOT THAT IMPRESSIVE WITH LIFTED INDICES BETWEEN 0 AND MINUS 1
IN EAST CENTRAL AND EXTREME EASTERN AREAS OF THE CWA...BUT BOTH ETA
AND GFS SHOW FAIRLY STRONG H7/H5 THETA-E RIDGE ACROSS EAST CENTRAL
AND ALONG THE UT BORDER. GIVEN THAT THESE AREAS HAVE SEEN
CONVECTION THE PAST 2 AFTERNOONS...IT LOOKS FAVORABLE FOR SHOWER AND
THUNDERSTORM DEVELOPMENT THROUGH THIS EVENING WITH SOME SIGNIFICANT
RAINFALL AMOUNTS POSSIBLE...CONSIDERING THAT GFS PWS ACROSS THESE
AREAS ARE NEAR 0.75 OF AN INCH. WITH ETA MODEL SOUNDINGS INDICATING
PWS BETWEEN 0.50 AND 0.60 OF AN INCH ACROSS SOUTHWEST AND SOUTH-
CENTRAL ELKO COUNTY...SO WILL USE SHOWERS AND THUNDERSTORM WORDING
THERE. NORTHERN ELKO COUNTY LOOKS TOO STABLE LATER TODAY...AND WILL
GO WITH P/C EAST AND M/CLR WEST FOR THIS ZONE. SHOWER AND
THUNDERSTORM ACTIVITY SHOULD CEASE BY MIDNIGHT WITH NO DYNAMIC
FORCING TO KEEP IT GOING OVERNIGHT. GFS SHOWS THE CORE OF HIGHER PWS
MOVING NORTHEAST INTO SOUTHERN ID MONDAY...AND INSTABILITY LOOKS
WEAKER...SO WILL GO WITH LOW SLIGHT CHANCE POPS FOR EAST CENTRAL AND
ALL OF ELKO COUNTY. H7 WINDS NEAR 20 KTS ACROSS EAST CENTRAL
MONDAY...AND WILL INCLUDE BREEZY WITH TRANSPORT OF WINDS HIGHER ALOFT
TO THE SFC LIKELY. A LITTLE MORE INSTABILITY TUESDAY FOR THE SAME
COVERAGE OF THE CWA AS MONDAY...BUT STILL COMFORTABLE WITH SLIGHT
CHANCES GIVEN LACK OF DYNAMICS AND/OR GREATER MOISTURE.

.LONG TERM...12Z RUN OF THE GFS SHOWED MAJOR DISCREPANCIES WITH THE
00Z AND 06Z RUNS FOR WEDNESDAY AND THURSDAY. THE 12Z GFS SHOWED THE
UPPER LOW JUST OFF THE PAC NW COAST SPLITTING AND RETROGRADING
WEDNESDAY AND THURSDAY...WHILE THE LARGE UPPER HIGH ACROSS THE
MIDSECTION OF THE U.S. BUILT NORTHWESTWARD ACROSS THE NORTHERN
PLAINS INTO WESTERN MT AND EASTERN ID. THIS IS IN MARKED CONTRAST
TO THE PREVIOUS RUNS OF THE GFS WHICH TAKE THE UPPER LOW ACROSS THE
PAC NW LATE WEDNESDAY AND THURSDAY AS AN OPEN WAVE. ON THURSDAY
AFTERNOON THE GFS SHOWS THE TROUGH AXIS ACROSS WESTERN MT...AND THE
GFS SHOWS THE CENTER OF A STRONG...600 DM...H5 UPPER HIGH EXTENDING
FROM EASTERN INTO CENTRAL MT. THIS RESULTS IN A GREATER THAN 20 DM
H5 HEIGHT DIFFERENCE OVER WESTERN MT AT 00Z FRIDAY. THE 00Z UKMET
SOLUTION FOLLOWED THE 00Z GFS RUN...BUT THE 12Z UKMET INDICATES
FAIRLY STRONG SPLITTING OF THE UPPER LOW OFF THE PAC NW COAST
WEDNESDAY AND THURSDAY AND THE SHEARING OF THE TROUGH FRIDAY AND
EARLY SATURDAY...AS IT WEAKENS AND MOVES NORTHEASTWARD INTO SW
CANADA...SIMILAR TO THE 12Z GFS. MAJOR IMPACT ON THE FORECAST AREA
WEDNESDAY AND THURSDAY WOULD BE LESS COOLING AND A WEAKER H5
GRADIENT. WILL BE CAUTIOUS FOR NOW AND ONLY INCLUDE BREEZY CONDITIONS
FOR WEDNESDAY...RATHER THAN THE WINDY CONDITIONS INDICATED BY THE
PREVIOUS RUNS OF THE GFS. THE 12Z GFS SOLUTION ALSO WOULD NOT PRODUCE
A STRONG ENOUGH FLOW TO SCOUR OUT MOISTURE ACROSS THE EASTERN HALF OF
THE CWA. KEPT VERY SLIGHT CHANCES OF SHOWERS AND THUNDERSTORMS IN THE
NORTHEASTERN CORNER OF THE CWA WEDNESDAY AFTERNOON...BUT WILL HAVE TO
WATCH NEXT FEW RUNS AS COVERAGE COULD BE GREATER. STILL FORECASTING A
SLIGHT COOL-DOWN FOR CWA WEDNESDAY AND THURSDAY...ESPECIALLY ACROSS
THE NORTH...BUT THAT MAY CHANGE WITH NEWER MODEL RUNS ALSO. MEDIUM
RANGE MODELS SEEM IN GOOD AGREEMENT FRIDAY THROUGH SUNDAY WITH A
NEARLY ZONAL FLOW ACROSS THE PAC NW AND SOUTHERN CANADA AND GRADUAL
RIDGING ACROSS THE GREAT BASIN FOR A RETURN TO SLIGHTLY ABOVE NORMAL
TEMPERATURES.

.EKO...NONE.

SMITH

NVZ030>037-111300-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ELKO NV
530 AM PDT SUN AUG 10 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND EAST CENTRAL
NEVADA

.DAY ONE...

NO HAZARDOUS WEATHER IS EXPECTED TODAY...HOWEVER BREEZY CONDITIONS
WILL CONTINUE ACROSS EAST CENTRAL NEVADA TODAY AND EARLY THIS
EVENING.

.DAYS TWO THROUGH SEVEN...

NO HAZARDOUS WEATHER IS EXPECTED.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

PELOQUIN