Damaging Wind in Colorado, June 20, 2003

WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
755 AM MDT FRI JUN 20 2003

SHORT TERM...
QUICK UPDATE TO ADD WEATHER AND CLOUDS TO COLORADO ZONES 17...18>20.
SHORT WAVE KICK A LINE OF SHOWERS AND THUNDERSTORMS MOVING TO THE
NORTHEAST AT 25 MPH. MAY HAVE TO ADJUST GRIDS IN A FEW MORE HOURS.

TODAY AND TONIGHT...SHORT WAVE ROTATING THROUGH SWRN CO STILL
PRODUCING SHOWERS AND THUNDERSTORMS OVER THE FOUR CORNERS AND SAN
JUAN MTNS...WITH ISOLATE SHOWERS OVER NERN UT. ETA/MESO ETA AGREE
WELL WITH INITIAL POSITION OF LARGER AZ SHORTWAVE TROUGH...AS SHOWN
IN SATELLITE AND ON RUC. GFS SEEMED TOO WEAK AND UNORGANIZED WITH
THIS FEATURE. THIS WAVE SHOULD ROTATE ENE AND THRU THE SRN THIRD OF
THE CWA AND NMEX THIS AFTERNOON.

MEASURABLE RAIN FELL IS JUST ABOUT EVERY ZONE FRIDAY WITH PLENTIFUL
RAIN OVER SEVERAL MTN RANGES. DEW PTS WILL START OF IN THE 40S THIS
MORNING WITH MAX RHS RELATIVELY HIGH FOR THIS TIME OF YEAR.
CLOUDINESS DEVELOPING AHEAD OF AZ SHORTWAVE WILL SPREAD NE AND OVER
MUSH OF THE CWA THIS MORNING AND EARLY AFTERNOON. THESE FACTORS
SHOULD SLOW DOWN THE PROJECTED WARM UP AND HELP PREVENT RH FROM
BOTTOMING OUT TOO FAST. HAVE DECREASED FORECAST MAX TEMPS AND
INCREASED FORECAST MIN RH A BIT. PERIOD OF LOW RH SHOULD BE
RELATIVELY BRIEF AS WELL. WINDS WILL DEFINITELY INCREASE THIS
AFTERNOON AND THESE COMBINED WITH RECENT LIGHTNING WILL RAISE FIRE
WEATHER CONCERNS. BLV WINDS WILL LOCALLY REACH OR EXCEED RED FLAG
CRITERIA...BUT WITH TEMPS NOT ALL THAT HOT AND RH NOT ALL THAT LOW...
AND THE FACT THAT FINE FUELS GOT WET IN MANY PLACES THURSDAY...WILL
ONLY HEADLINE THE PARAMETERS OF CONCERN AND NOT ISSUE RED FLAG
WARNING.

PATTERN REMAINS TROUGHY TONIGHT...WITH ANOTHER WEAK TROUGH MOVING
THROUGH ABOUT MIDNIGHT. DRIER CONDITIONS WILL FINALLY GET HERE AS
DEW POINTS SHOULD DROP 10 DEGREES OR MORE OVERNIGHT. IT SHOULD BE
COOLER UNDER CLEARER SKIES.    CUOCO

LONG-TERM DISCUSSION...
SATURDAY-SUNDAY...BROAD TROUGH OVER THE WEST WITH WEST-SOUTHWEST FLOW
ACROSS THE FORECAST AREA. WAVE MOVES ACROSS THE NRN ROCKIES WITH
FRONTAL BOUNDARY SAGGING INTO NE UT/NW CO SAT. SURFACE REFLECTION MAY
NOT BE THAT NOTICEABLE...A FEW DEGS COOLER PERHAPS...WITH 700 MB
BAROCLINIC ZONE STAYING JUST TO THE NORTH. HOWEVER...SHOULD TEND TO
PROMOTE SOME BREEZY CONDITIONS DURING THE AFTERNOONS FOR SOME CONCERN
FOR FIRE WX. TIME-HEIGHT SECTIONS SHOW ATMOSPHERE DRYING...ALTHOUGH
HOLDS ONTO SOME MID-LEVEL RH ACROSS THE NORTHERN THIRD. WILL KEEP
SMALL CHANCES OF TSTMS ACROSS THE NORTH BUT REMOVE FROM THE SOUTH.

MONDAY-TUESDAY...MODELS SEEM TO BE CONVERGING IN SIMILAR SOLUTION OF
DIGGING NE PAC TROUGH INTO THE NWRN GREAT BASIN/NRN CA BY 12Z TUE.
WHILE NOT TOO MUCH OF CHANGE FOR THE GFS...IS MORE SIGNIFICANT CHANGE
FOR THE EC. THIS WOULD KEEP GENERALLY DRY SW FLOW ACROSS THE AREA...
AND WITH STRENGTHENING FLOW ALOFT AS GRADIENT TIGHTENS...EXPECT A
HEIGHTENING OF FIRE WX CONCERN FOR WIND/LOW RH. ENOUGH MID-LEVEL
RH STILL INDICATED ACROSS THE NORTH WITH SMALL DISTURBANCE TO KEEP
ISOLATED TSTMS IN ACROSS THE NORTH ON MON.  JAD

THURSDAY AND FRIDAY...GFS CONTINUES TO BE FASTER THAN THE ECMWF WITH
EASTWARD PROGRESSION OF TROUGHS FOR THIS PERIOD.  GFS BRINGS IN A
RELATIVELY STRONG TROUGH FOR LATE JUNE INTO THE GREAT BASIN...BUT
EJECTS NORTHEAST BEFORE REACHING COLORADO...WITH THE TRAILING
PORTION OF THE SHORT WAVE SKIRTING OUR NORTHWEST CORNER.  THESE
SYSTEMS WOULD MAKE IT BREEZY AND DRY WITH TEMPERATURES A LITTLE BELOW
NORMAL. PF

.GJT...NONE.