672
FXUS65 KGJT 060008
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
608 PM MDT SUN JUL 5 2020
UPDATE
ISSUED AT 608 PM MDT SUN JUL 5 2020
HAVE EXPANDED THE RED FLAG WARNING FOR TUESDAY AND THE FIRE
WEATHER WATCH FOR WEDNESDAY TO INCLUDE THE LOWER ELEVATIONS OF
COLORADO FIRE WEATHER ZONE 295 (PAGOSA SPRINGS AREA). FUELS REMAIN
CRITICALLY DRY AND ENOUGH AREAL COVERAGE ON LATEST MODEL RUNS TO
JUSTIFY THE EXPANSION. OTHERWISE, NO CHANGES TO THE CURRENT
FORECAST PACKAGE.
SHORT TERM
(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 225 PM MDT SUN JUL 5 2020
DIURNAL CONVECTION DEVELOPED AGAIN OVER THE RIDGES AROUND MIDDAY
THANKS TO 500-1000 J/KG CAPE AND PRECIPITABLE WATER VALUES
0.60-0.80 INCH FROM EASTERN UT ACROSS WESTERN CO. COVERAGE WAS
GREATER THAN EXPECTED EARLIER, AND HAVE UPDATED NEAR THE TERM
FORECAST TO ACCOUNT FOR THAT. THE UPPER LEVEL RIDGE AXIS LIES FROM
NORTHERN AZ OVER THE FOUR CORNERS THEN ACROSS TO NORTHEAST CO. ON
THE BACKSIDE, DRIER AIR IS WORKING ITS WAY EASTWARD AS EVIDENCED
BY A LACK OF CONVECTION OVER THE MOUNTAINS OF CENTRAL UT AND
LATEST MESOANALYSIS OF PRECIPITABLE WATER NOW SHOWING VALUES ONLY
PEAKING OUT AROUND 0.60 OVER WESTERN CO AND FALLING OFF TO 0.30
OVER CENTRAL UT. CONVECTION WILL THEREFORE HAVE AN EARLIER DEATH
NEAR THE UT/CO BORDER THOUGH KEEP GOING INTO THE EARLY EVENING
ALONG HE CO DIVIDE. BRIEF HEAVY RAINFALL UP TO A THIRD OF AN INCH
PER HOUR IS POSSIBLE, ALONG WITH GUSTY OUTFLOW WINDS AND
LIGHTNING.
THE SKY WILL CLEAR TONIGHT AND MONDAY WILL BE A TAD WARMER THAN
TODAY THANKS TO THE AMPLIFICATION OF THE UPPER LEVEL RIDGE OVER
OUR AREA. ISOLATED SHOWERS AND THUNDERSTORMS WILL BE LIMITED TO
THE DIVIDE WITH THE DRIER AIR IN PLACE.
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 225 PM MDT SUN JUL 5 2020
AS WE'VE BEEN DISCUSSING THE PAST FEW DAYS, THIS PERIOD WILL BE
HIGHLIGHTED BY CRITICAL FIRE WEATHER CONDITIONS AND HOT WEATHER.
AN UPPER LEVEL TROUGH IS ON TRACK TO MOVE FROM THE PAC NW THROUGH
MT TUESDAY. THIS PUSHES THE UPPER LEVEL RIDGE TO OUR SOUTHEAST AND
TIGHTENS THE HEIGHT GRADIENT OVER OUR REGION. WITH DEEP MIXING
THIS TIME OF YEAR, EXPECT THE UPPER LEVEL WINDS TO MIX DOWN TO THE
SURFACE BY LATE MORNING TUESDAY AND CONTINUE THROUGH THE EARLY
EVENING. GUSTS OF 25 TO 35 MPH ARE LIKELY FOR MUCH OF THE REGION,
AND THIS WILL COMBINE WITH VERY WARM AND DRY AIR TO CREATE
CRITICAL FIRE WEATHER CONDITIONS.
IN THE WAKE OF THE UPPER LEVEL TROUGH LIFTING OUT TO THE NORTH,
MODERATE SOUTHWESTERLY FLOW REMAINS OVER THE AREA WEDNESDAY.
TEMPERATURES MAY DROP A DEGREE OR TWO THANKS TO A MINOR SURGE OF
COOLER AIR BEHIND THE TROUGH, BUT THIS SHOULD REALLY BE NEGLIGIBLE.
CONSIDERING THE UPPER LEVEL HEIGHT GRADIENT IS FORECAST TO BE
ABOUT THE SAME AS ON TUESDAY, THERE IS LIKELY TO BE ANOTHER
AFTERNOON OF BREEZY AND WARM/DRY CONDITIONS LEADING TO CRITICAL
FIRE WEATHER CONDITIONS.
EXTENDED MODELS AND ASSOCIATED ENSEMBLES ARE LOCKING INTO THE IDEA
OF A LARGE 600 DECAMETER RIDGE OF HIGH PRESSURE DEVELOPING OVER NM
AND THE FOUR CORNERS...PUSHING HEIGHTS UP OVER OUR REGION. THIS
WILL HELP DECREASE THE WINDS, BUT INCREASE THE TEMPERATURES
THURSDAY THROUGH SUNDAY. IF THIS PATTERN HOLDS, MAX TEMPS BY
FRIDAY AND THE WEEKEND WILL BE THE WARMEST OF THE SUMMER SO FAR,
AND 8 TO 12 DEGREES ABOVE NORMAL. 100 TO 105 WILL BE LIKELY FOR
THE LOWER VALLEYS, AROUND 90 FOR POPULAR MOUNTAIN COMMUNITIES, AND
65 TO 75 FOR HIGH ALPINE REGIONS.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 608 PM MDT SUN JUL 5 2020
ISOLATED SHOWERS AND THUNDERSTORMS WILL PERSIST EAST OF A LINE
FROM KHDN TO KDRO THROUGH 03Z THIS EVENING. GUSTY OUTFLOW WINDS TO
30 MPH AND LIGHT RAINFALL WILL ACCOMPANY THE STORMS. KASE, KEGE,
KHDN AND KGUC WILL SEE A 20-30 PERCENT CHANCE OF BEING IMPACTED
AS SHOWERS DECAY. CLEARING CONDITIONS AFTER 03Z WITH ANOTHER ROUND
OF ISOLATED MOUNTAIN CONVECTION EXPECTED AFTER 18Z MONDAY. WINDS
WILL BE LIGHT AND TERRAIN DRIVEN WITH MOSTLY CLEAR CONDITIONS AWAY
FROM SHOWERS.
FIRE WEATHER
ISSUED AT 225 PM MDT SUN JUL 5 2020
MODERATE SOUTHWESTERLY FLOW CAUSING GUSTY WINDS 25 TO 35 MPH WILL
BE FAIRLY WIDESPREAD TUESDAY LATE MORNING THROUGH EARLY EVENING
FOR MUCH OF THE REGION BELOW 9000 FEET. RELATIVE HUMIDITY WILL BE
QUITE LOW... IN THE SINGLE DIGITS AND LOW TEENS. CONFIDENCE IS
HIGH FOR CRITICAL FIRE WEATHER CONDITIONS, SO REPLACED THE WATCH
WITH RED FLAG WARNING FOR TUESDAY. WINDS AND TEMPERATURES MAY BE A
TOUCH LOWER WEDNESDAY, BUT STILL SUFFICIENT TO RESULT IN LOW
MINIMUM RELATIVE HUMIDITY AND THE POSSIBILITY FOR ANOTHER DAY OF
RED FLAG CONDITIONS. SINCE CONFIDENCE IS NOT AS HIGH AS FOR
TUESDAY AT THIS TIME, HAVE OPTED TO GO WITH A FIRE WEATHER WATCH
FOR WEDNESDAY AFTERNOON AND EVENING, EXCLUDING UTAH ZONE 486 DUE
TO WINDS POTENTIALLY LIGHTER IN THAT ZONE.
GJT WATCHES/WARNINGS/ADVISORIES
CO...RED FLAG WARNING FROM 10 AM TO 9 PM MDT TUESDAY FOR COZ200>203-
205-207-290-292>295.
FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR COZ200>203-205-207-290-292>295.
UT...RED FLAG WARNING FROM 10 AM TO 9 PM MDT TUESDAY FOR UTZ486-487-
490-491.
FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR UTZ487-490-491.
UPDATE...JDC
SHORT TERM...BM
LONG TERM...BM
AVIATION...JDC
FIRE WEATHER...BM
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