Wildfire in Colorado, May 19 to 20, 2002

WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
402 AM MDT SUN MAY 19 2002

...CORRECTED FOR TUE DISCUSSION...

THUNDERSTORMS AND LIGHTNING WILL INCREASE TODAY FROM THE SINGLE
LIGHTNING STRIKE IN THE CWA THAT OCCURRED THIS AFTERNOON OVER THE
SAN JUAN MTNS...BUT NOT GREATLY SO. THE REST OF THE TSTMS WERE EAST
OF THE CWA BORDER ASSOCIATED WITH THE HIGHER DEW PTS ALIGNED ALONG A
AXIS FROM SW TO NE FROM NWRN NM TO SCNTRL CO. TODAY...HIGHER SFC DEW
PTS IN THE LOWER 30S PUSHING NORTH OVER NM AND ERN AZ SHOULD MOVE
INTO THE CO FOUR CORNERS AND THE SAN JUANS. ACCORDING TO THE RUC
AND MESOETA...THE MAIN AXIS OF HIGHER SFC DEW PT WILL REMAIN
ALONG OR JUST EAST OF THE EASTERN CWA BORDER. THERE ALSO MAY BE
REMNANT SURFACE BOUNDARIES FROM NMEX CONVECTION EARLIER. ON THE
NEGATIVE SIDE...THE LAYER FROM JUST ABOVE TO SFC TO 600 MB REMAIN DRY
...WHICH MIGHT LIMIT DEEP CONVECTION...ESPECIALLY OVER THE VALLEYS...
AND DECREASE THE CHANCE FOR MOISTURE TO REACH THE GROUND.

LOOKING UPSTREAM...A MINOR VORT MAX AND SOME MID-LVL MOISTURE CAN
BE SEEN TRAVELING NE FROM THE NRN BAJA INTO SW AZ. THESE FEATURES
APPEAR MORE IMPRESSIVE IN THE WV CHANNEL THAN ON IR. MODEL TIME-HTS
AND FCST SOUNDINGS OVER SW CO/SE UT SHOW A PATCH OF 70 PERCENT RH
ABOVE 600 MB LATE THIS EVENING...WITH A MINOR VORT MAX AND A LITTLE
UVV. LOWER LEVELS REMAIN VERY DRY HIGHER SFC DEW PTS SLIDE EAST.
THESE FEATURES HAVE A KNACK FOR PRODUCING MORE CLOUDINESS ONCE
REACHING CO...BUT USUALLY THE VORTICITY MAXIMA ARE STRONGER THAN WITH
CURRENT FEATURE. BLV THAT AFTER A MOSTLY SUNNY-PARTLY CLOUDY
AFTERNOON...WILL SEE AN INCREASE IN CLOUD...BUT WILL PARE BACK THE
BROAD MOSTLY CLOUDY FORECAST FOR TONIGHT TO COVER ONLY THE SW CO AND
THE SOUTHERN MOUNTAINS AND CALL FOR MAINLY DRY THUNDERSTORMS...WITH
FEWER SHOWERS.

MONDAY CONTINUES TO APPEAR AS A DAY OF INCREASING SOUTH WINDS WITH A
DRY SLOT OVER THE CWA. MODELS CONTINUE TO SHOW THE TENDANCY WITH
THE NEXT BIG WEST COAST TROUGHT TO SHUNT THE MOISTURE AND BEST
DYNAMICS TO THE NORTH BEFORE THEY CAN AFFECT ERN UT AND WRN CO. TUE
STILL APPEARS TO BE THE BIG DAY...FOR SURFACE WINDS CERTAINLY AND
MAYBE SIGNIFICANT DEEP CONVECTION...THE LATTER BEING LESS CERTAIN.
TIME OF TRUE SFC FROPA APPEARS A BIT MUDDY. AVN CARRIES THICKNESS
PACKING INTO THE AREA TUE MORNING...BUT WINDS CONTINUE FROM SOUTH
PARALLEL TO THICKNESS LINES...SO TUESDAY SHOULD BE COOLER. THEN
STRONG WIND SHIFT WITH SECONDARY THICKNESS DECREASES AND BETTER
MOISTURE ARRIVES TUE EVENING. SO TUE SHOULD START OFF WITH A WINDY...
BUT DRY PROFILE...COOLING DAYTIME TEMPERATURES...FOLLOWED BY A MORE
NOTICABLE CHANGE TUE NIGHT. SO...TUE NIGHT MAY BE THE TIME PERIOD TO
FOCUS ON FOR SIGNIFICANT WEATHER.

EXTENDED (WED-SAT)...EC/AVN CONTINUE TO DIVERGE WED-THU IN HANDLING
THE PROGRESSION OF THE NEGATIVE TILTED TROUGH WORKING THROUGH OMEGA
PATTERN. AVNX REFORMS CLOSED LOW ACROSS WY AND MOVES IT INTO NRN
PLAINS WED WHILE EC SLOWER AND MORE NW WITH LOW CTR...PLACING IT OVER
THE NRN ROCKIES BY THU. BOTH SIMILARLY SHOW AN UPSTREAM SYSTEM
APPROACHING B.C./PAC NW BY FRI...AND WILL LEAN TOWARD THE AVNX. BEST
CHANCE OF PCPN FOR THE NRN HALF ON WED. SOME SNOW NORTHERN MTNS ON
WED WITH AVNX 700 MB TEMPS -2 TO -3 CELSIUS. WITH AVNX STILL SHOWING
SOME LINGERING TROUGHINESS INTO THU...WILL KEEP SLIGHT CHANCE OF
SHOWERS FOR THE NORTH ON THU...THEN DRY WEATHER FRI AND SAT WITH
WARMING TEMPS. ANOTHER TROF SHOWN DEVELOPING OVER THE FAR WEST ON SAT
TURNING FLOW TO THE SOUTHWEST ACROSS ERN UT/WRN CO. JAD

WESTERN COLORADO AND EASTERN UTAH EMERGENCY MANAGERS SHOULD MAINTAIN
A NORMAL LEVEL OF WEATHER AWARENESS TODAY.

.GJT...NONE.