271
FXUS65 KGJT 170221
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
821 PM MDT TUE JUL 16 2019
UPDATE
ISSUED AT 817 PM MDT TUE JUL 16 2019
UPDATED TO REMOVE EXPIRE RED FLAG HEADLINE. CRITICAL FIRE WEATHER
CONDITIONS WILL REDEVELOP WEDNESDAY AFTERNOON AND EVENING ACROSS
MOST OF EASTERN UT AND WESTERN CO.
SHORT TERM
(TONIGHT THROUGH WEDNESDAY NIGHT)
ISSUED AT 339 PM MDT TUE JUL 16 2019
THUNDERSTORM COVERAGE WAS A BIT FURTHER WEST THAN MODELS INDICATED
AS THE MODELS SEEM TO BE HAVING A TOUGH TIME HANDLING THE REMNANT
MOISTURE AND DRYING THINGS OUT TOO QUICKLY. THE FOCUS FOR ACTIVITY
APPEARS TO BE SHIFTING EASTWARD LATE THIS AFTERNOON WITH THE FOCUS
SHIFTING TOWARDS THE SAN JUANS AND WEST ELKS BY THIS EVENING.
EXPECT MOST ACTIVITY TO END AFTER SUNSET. THE HRRR AND TO SOME
EXTENT NAMNEST IS SHOWING SOME ISOLATED THUNDERSTORMS MOVING IN
FROM THE SOUTH ACROSS THE SOUTHERN VALLEYS AND SAN JUANS LATE THIS
EVENING INTO THE EARLY MORNING HOURS ON WEDNESDAY. PRECIPITABLE
WATER (PW) VALUES, ALTHOUGH THEY ARE DECREASING ACROSS MUCH OF THE
AREA, DO SHOW A BUMP UP ABOVE 0.75 TOWARDS AN INCH IN THIS REGION
OVERNIGHT. MODELS HAD A VERY HARD TIME PICKING UP ON THE OVERNIGHT
CONVECTION LAST NIGHT, SO AM LEANING TOWARDS THIS OCCURRING.
INCREASED POPS IN THIS AREA OVERNIGHT WITH ACTIVITY DISSIPATING
BY SUNRISE.
MUCH DRIER AIR MOVES IN FOR WEDNESDAY AS PW VALUES DROP BELOW 0.5.
THE GRADIENT TIGHTENS A BIT WITH BETTER MIXING AS AN UPPER LEVEL
TROUGH SWINGS ACROSS THE REGION. ENOUGH PW REMAINS NEAR THE FOUR
CORNERS FOR ISOLATED STORMS POSSIBLE OVER THE SAN JUANS WEDNESDAY
AFTERNOON, BUT FOR THE MOST PART, EXPECT ANOTHER HOT AND DRY DAY
WITH CRITICAL FIRE WEATHER CONDITIONS EXPANDING TO INCLUDE ALL
LOWER ELEVATIONS OF EASTERN UTAH AND WESTERN COLORADO. UPGRADED
THE FIRE WEATHER WATCH FOR REMAINING VALLEY ZONES TO A RED FLAG
WARNING FOR WEDNESDAY AND EXPANDED IT TO INCLUDE THE UINTA BASIN
ZONE AS IT LOOKS CRITERIA WILL BE MET THERE AS WELL.
LONG TERM
(THURSDAY THROUGH TUESDAY)
ISSUED AT 339 PM MDT TUE JUL 16 2019
A MUCH DRIER WESTERLY FLOW WILL FOLLOW BEHIND THE TROUGH PASSAGE
WEDNESDAY, WITH WARM AND DRY CONDITIONS REMAINING THROUGH THE END
OF THE WEEK. THINKING THIS TROUGH WILL ACT TO FINALLY PUSH THE
LINGERING MOISTURE OUT OF THE REGION. SOME BREEZY CONDITIONS MAY
OCCUR DURING THE AFTERNOONS WITH POTENTIAL FOR CRITICAL FIRE
WEATHER CONDITIONS, ESPECIALLY ACROSS THE NORTHERN ZONES THAT
REMAIN IN CLOSER PROXIMITY TO THE UPPER LEVEL JET. DECIDED NOT TO
ISSUE ANY FIRE WEATHER WATCH FOR THURSDAY YET WITH THE RED FLAG
WARNING ONGOING FOR BOTH TODAY AND WEDNESDAY, AS CONDITIONS APPEAR
MARGINAL AT THIS TIME, BUT SOMETHING FOR LATER SHIFTS TO REASSESS.
AN UPPER LEVEL TROUGH WILL MOVE ACROSS THE NORTHERN ROCKIES, NEAR
CANADA ON FRIDAY, ALLOWING THE RIDGE OF HIGH PRESSURE TO BUILD
BACK OVER THE REGION BY THE WEEKEND. THIS WILL ALSO ALLOW MORE
MOISTURE TO ENTER THE REGION FROM THE SOUTHWEST AS PW VALUES
INCREASE ABOVE 0.75 INCHES ON SATURDAY AND ABOVE AN INCH BY EARLY
NEXT WEEK. THIS WILL INCREASE THUNDERSTORM POTENTIAL AND COVERAGE
WITH BETTER CHANCES FOR WETTING RAIN BY EARLY NEXT WEEK. THE ONE
CONCERN WITH THIS MOISTURE SURGE IS THE POSITION OF THE HIGH AS IT
IS DIRECTLY OVERHEAD AS OPPOSED TO THE MORE FAVORABLE EAST OF THE
DIVIDE POSITIONING. THE EC SEEMS TO HAVE COME AROUND TO AGREEMENT
WITH THE GFS ON THE MORE WESTERLY POSITION. SO, THE MONSOONAL
MOISTURE AXIS WILL BE FORCED THROUGH NEW MEXICO AND ARIZONA, INTO
NEVADA AND WESTERN UTAH. WE WILL STILL SEE SOME MOISTURE INCREASE,
BUT IT MAY NOT BE AS ROBUST OR WIDESPREAD WITH STORM COVERAGE AS
REMNANTS OF THAT MOISTURE PLUME WILL GET ENTRAINED AND RECYCLED
AROUND THE HIGH. REGARDLESS, LOOK FOR AN INCREASE IN SHOWERS AND
THUNDERSTORMS THIS WEEKEND TOWARDS EARLY NEXT WEEK WITH CONTINUED
ABOVE NORMAL TEMPERATURES.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 459 PM MDT TUE JUL 16 2019
EXPECT BREEZY SOUTHWEST WINDS FROM 10 TO 15 MPH AT MOST TAF SITES
THROUGH EARLY THIS EVENING WITH OCCASIONAL GUSTS AS HIGH AS 30 MPH.
ISOLATED SHOWERS AND THUNDERSTORMS WILL OCCUR MAINLY OVER THE
HIGHER TERRAIN WITH LITTLE CHANCE FOR TAF SITES TO BE IMPACTED BY
RAIN, THOUGH STRONG AND UNPREDICTABLE OUTFLOW WINDS TO 40 MPH ARE
POSSIBLE. SHOWERS AND THUNDERSTORMS WILL DIMINISH BEFORE MIDNIGHT.
FEWER THUNDERSTORMS ARE EXPECTED WEDNESDAY AFTERNOON.
FIRE WEATHER
ISSUED AT 817 PM MDT TUE JUL 16 2019
DRY, BREEZY AND HOT CONDITIONS ARE EXPECTED TO REDEVELOP WEDNESDAY
AFTERNOON AND BRING A REPEAT OF CRITICAL FIRE WEATHER CONDITIONS
OVER MUCH OF EASTERN UT AND WESTERN CO. HOT AND DRY CONDITIONS
WILL CONTINUE THROUGH THE END OF THE WEEK WITH SOME BREEZES DURING
THE AFTERNOONS. SUNDAY BRINGS THE FIRST CHANCE OF RAIN WITH
CHANCES INCREASING A BIT EACH DAY NEXT WEEK.
GJT WATCHES/WARNINGS/ADVISORIES
CO...RED FLAG WARNING FROM NOON TO 8 PM MDT WEDNESDAY FOR COZ200-202-
203-207-290-292.
UT...RED FLAG WARNING FROM NOON TO 8 PM MDT WEDNESDAY FOR UTZ486-487-
490-491.
UPDATE...CC
SHORT TERM...MDA
LONG TERM...MDA
AVIATION...CC
FIRE WEATHER...CC
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