301
FXUS65 KGJT 182328
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
528 PM MDT FRI SEP 18 2020
SHORT TERM
(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 253 PM MDT FRI SEP 18 2020
SATELLITE IMAGERY SHOWS HIGH CLOUDS DRIFTING INTO THE CWA AS A
DEEPENING PACIFIC NW LOW DRAWS MOISTURE INTO THE GREAT BASIN.
FLOW TRANSITIONING TO THE SOUTHWEST AHEAD OF THE TROUGH'S AXIS
WILL ALLOW FOR SOME UPPER LEVEL MOISTURE TO FILTER IN, AND THUS,
RESULT IN AN INCREASE IN HIGH CIRRUS CLOUDS SPREADING ACROSS
EASTERN UTAH AND WESTERN COLORADO THIS EVENING. TEMPERATURES WILL
RUN SLIGHTLY WARMER TONIGHT IN RESPONSE TO CLOUD COVER AND
LIMITED RADIATIONAL COOLING.
THE TROUGH AXIS WILL SWOOP ACROSS THE NORTHERN ROCKIES OVERNIGHT
AND INTO TOMORROW, PRODUCING STRONG SOUTHWESTERLY WINDS ALOFT AS
THE PRESSURE GRADIENT TIGHTENS OVERHEAD. WINDS WILL INTENSIFY ON
SATURDAY AS A SURFACE BOUNDARY APPROACHES FROM THE NORTHWEST. DRY
SOUTHWESTERLY FLOW AHEAD OF THIS SYSTEM WILL PRODUCE CRITICAL FIRE
WEATHER CONDITIONS FOR PORTIONS OF EAST- CENTRAL UTAH. A RED FLAG
WARNING IS NOW IN EFFECT FOR FIRE WEATHER ZONE 490. ELEVATED
MOISTURE NEAR THE BOUNDARY WILL MAINTAIN DECENT CLOUD COVER AS THE
SYSTEM APPROACHES, WHICH WILL ALSO LIMIT THE SPREAD OF FIRE
WEATHER CONCERNS ACROSS NORTHEAST UTAH AND NORTHWEST COLORADO.
HOWEVER, LOCALIZED CRITICAL CONDITIONS ARE POSSIBLE, AS WINDS WILL
BE WHIPPING. ISOLATED SHOWERS WILL FIRE OVER HIGHER TERRAIN ACROSS
NORTHEAST UTAH AND WESTERN COLORADO SATURDAY AFTERNOON, AS THE
SURFACE BOUNDARY DIPS INTO THE CWA. LACK OF LOW LEVEL MOISTURE
TIED TO THIS SYSTEM WILL LIMIT PRECIPITATION FROM REACHING THE
SURFACE ACROSS VALLEY FLOORS, WHILE MOUNTAINOUS TERRAIN WILL
LIKELY ONLY SEE A FEW HUNDREDTHS TO A TENTH OF AN INCH.
THE SYSTEM'S HARD TRACK NORTHWARD ON SATURDAY WILL LIMIT THE
EFFECTS OF THE FRONTAL BOUNDARY TO THE NORTHERN HALF OF THE CWA.
HIGH TEMPERATURES WILL DIP 3 TO 8 DEGREES COOLER ACROSS THE
NORTHERN TIER OF THE CWA, WHILE OUR SOUTHERN REGION WILL REMAIN
FAIRLY CONSISTENT WITH TEMPERATURES OBSERVED TODAY. UNFORTUNATELY,
THESE STRONG WINDS MAY ALSO CARRY A THICKER PLUME OF SMOKE FROM
CALIFORNIA FIRES INTO THE AREA, SO ANTICIPATE ANOTHER HAZY
AFTERNOON. ONCE THE SYSTEM EXITS TO OUR NORTHEAST, WE'LL BE
LEFT UNDER ZONAL FLOW BY SATURDAY NIGHT. DRY WESTERLY WINDS WILL
ALLOW FOR CLEARING SKIES OVERNIGHT...OTHER THAN SMOKE...
LONG TERM
(SUNDAY THROUGH FRIDAY)
ISSUED AT 253 PM MDT FRI SEP 18 2020
HEIGHTS WILL INCREASE SUNDAY IN THE WAKE OF SATURDAY'S TROUGH
PASSAGE AND REMAIN IN A ZONAL OR RIDGING PATTERN THROUGH THE WEEK
IN OUR NECK OF THE WOODS. EXPECT ENOUGH LINGERING MOISTURE FOR
BUILDUPS OVER THE TERRAIN IN THE AFTERNOON INSTABILITY AND
OROGRAPHIC CIRCULATIONS. THE SOUTHERN MOUNTAINS STILL THE MOST
PROBABLE LOCATION TO GET SOME MOISTURE TO THE GROUND AND LIMITED
POPS REMAIN THERE. SPLIT FLOW PATTERN DEVELOPS OVER THE PACIFIC
COASTLINE WITH THE SUBTROPICAL JET LIFTING TOWARD THE 4 CORNERS
LATE MONDAY. VERY DIFFUSE QG PATTERN OVER OUR CWA MONDAY NIGHT
INTO TUESDAY AS THIS JET CORE LINGERS NEAR OUR SOUTHERN BORDER.
THE GFS REMAINS QUITE AGGRESSIVE WITH THE PRECIPITATION DURING
THIS TIMEFRAME AND HAVING DIFFICULT TIME FIGURING OUT WHY. THETA
SURFACES DO SHOW SOME MOISTURE WEAK MOISTURE RETURN IN A SHALLOW
UPGLIDE REGIME. NOT HARD TO MAKE CONVECTION IN THIS SCENARIO AS
MODERATE INSTABILITY WILL BE IN PLACE. CONFIDENCE NOT HIGH MUCH
WILL REACH THE GROUND WITH MODELS NOT TOO AWARE OF THE DROUGHT
CONDITIONS AND THE EVAPORATIVE DEMAND IN THE LOWER LAYERS. THERE
ARE SOME BROAD POPS GOING INTO MONDAY NIGHT THEN AGAIN TUESDAY
WHEN THE NOSE OF THE NORTHERN STREAM JET TRANSLATES ACROSS THE
ROCKIES. CAN SEE SOME PRECIPITATION IMPACTING THE TERRAIN BUT NOT
MUCH OF CHANCE IN THE LOWER ELEVATIONS SO WILL BE INTERESTING TO
SEE HOW THIS PLAYS OUT. CONFIDENCE IS HIGH THE DROUGHT WILL
CONTINUE UNABATED. HIGH PRESSURE BUILDS BACK IN WEDNESDAY AND
THURSDAY AHEAD OF A MUCH STRONGER TROUGH HEADING TOWARD THE PACNW.
FAMILIAR FIRE WEATHER PATTERN SETTING UP TO END OUT THE WEEK AS
THIS TROUGH BEGINS TO LEAN THE RIDGE EASTWARD. HIGH TEMPERATURES
WILL OSCILLATE THROUGH THE FORECAST BUT ULTIMATELY STAY AT OR
ABOVE NORMAL. AS FOR THE PERSISTENT HAZY SKIES...UNTIL A LOT OF
THE BIG FIRES OUT WEST GET PUT OUT IT SEEMS WE HAVE SOME TAP TO
THE SMOKE STREAM.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 528 PM MDT FRI SEP 18 2020
HAZY CONDITIONS WITH HIGH CLOUDINESS WILL PERSIST THIS EVENING AND
INTO SATURDAY MORNING. WINDS WILL BE GRADUALLY INCREASING FROM
THE SOUTHWEST OVERNIGHT WHICH COULD LEAD TO SOME LIGHT MOUNTAIN
WAVE TURBULENCE...WHILE ALSO HELPING TO PUSH SOME OF THE SMOKE OUT
OF THE AREA. MIDLEVEL CLOUDS WILL FILTER INTO THE REGION ON
SATURDAY AFTERNOON WITH GUSTY WINDS OF 20 TO 25 KNOTS DEVELOPING
ACROSS THE AREA AFTER 18Z. WIDESPREAD VFR CONDITIONS WILL PREVAIL
THROUGH THE END OF THE TAF PERIOD.
FIRE WEATHER
ISSUED AT 253 PM MDT FRI SEP 18 2020
WINDS WILL INCREASE OVERNIGHT AND INTO SATURDAY AS A LOW PRESSURE
SYSTEM AND ITS ASSOCIATED FRONTAL BOUNDARY APPROACH THE REGION.
DRY SOUTHWEST FLOW AHEAD OF THE BOUNDARY WILL RESULT IN CRITICAL
FIRE WEATHER CONDITIONS TOMORROW AFTERNOON ACROSS EAST-CENTRAL
UTAH. STRONG WINDS WILL DRAPE ACROSS NORTHEAST UTAH AND NORTHWEST
COLORADO, HOWEVER, INCREASED CLOUD COVER MAY LIMIT RH FROM
DROPPING TO CRITICAL LEVELS FOR THESE REGIONS. EXPECT LOCALIZED
CRITICAL CONDITIONS FOR NORTHERN FIRE WEATHER ZONES, AS WELL AS
ISOLATED SHOWERS AND STORMS DEVELOPING OVER HIGHER TERRAIN DURING
THE AFTERNOON.
GJT WATCHES/WARNINGS/ADVISORIES
CO...NONE.
UT...RED FLAG WARNING FROM NOON TO 8 PM MDT SATURDAY FOR UTZ490.
SHORT TERM...ERW
LONG TERM...15
AVIATION...TGJT
FIRE WEATHER...TGJT
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page