961
FXUS65 KGJT 201206
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
606 AM MDT SUN OCT 20 2024
KEY MESSAGES
- A STRONG CLOSED LOW PRESSURE SYSTEM WILL WOBBLE OVER ARIZONA
BEFORE KICKING NORTHEAST ACROSS CENTRAL COLORADO LATE THIS
AFTERNOON AND EVENING. THIS KEEPS HEAVIEST PRECIPITATION
CONCENTRATED OVER THE FOUR CORNERS REGION TODAY WHERE THE
FOCUS FOR THUNDERSTORM DEVELOPMENT WILL BE.
- MODERATE TO HEAVY SNOWFALL RATES WILL CONTINUE TO IMPACT
TRAVEL CONDITIONS OVER SOUTHERN COLORADO'S MOUNTAIN CORRIDORS.
SNOW IS MOST LIKELY TO ACCUMULATE ON ROADWAYS DURING THE
OVERNIGHT PERIOD WITH IMPROVEMENT DURING THE AFTERNOON.
- COLD AIR SETTLING IN BEHIND THE SYSTEM AS CONDITIONS DRY AND
CLEAR COULD LEAD TO FREEZING TEMPERATURES IN SOME OF THE
SOUTHERN VALLEYS AND SOME POCKETS OF THE WHITE AND YAMPA RIVER
BASINS MONDAY NIGHT.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 411 AM MDT SUN OCT 20 2024
THE CLOSED CUT OFF LOW IS CONTINUING TO SPIN THIS MORNING OVER
CENTRAL ARIZONA. SATELLITE IMAGERY WOULD APPEAR TO INDICATE THE
APPROXIMATE LOCATION IS NEAR FLAGSTAFF. ENHANCEMENT IS STILL
BEING SEEN ACROSS SOUTHWEST COLORADO AMONG THE SOUTHERN VALLEYS
INTO THE SOUTHERN SAN JUAN MOUNTAINS WHERE HEAVIER PRECIPITATION
CONTINUES TO FALL. SOME LIGHTNING STRIKES ARE EVIDENT NEAR
FARMINGTON, NEW MEXICO WHICH WILL BE ENTERING INTO LA PLATA
COUNTY SO IN ADDITION TO MODERATE TO HEAVY RAIN OVER DURANGO AND
CORTEZ, CAN EXPECT SOME RUMBLES OF THUNDER SHORTLY. THIS
CONVECTION SHOULD ACT TO INTENSIFY RATES, ESPECIALLY IN THE
MOUNTAINS SO THE WINTER STORM WARNING THROUGH THIS EVENING IN
THE SOUTHERN SAN JUANS STILL LOOKS ON TRACK AND AM IN AGREEMENT
WITH THE TIMING SINCE THIS STORM SYSTEM HAS DECIDED TO STALL AND
DELAY ITS EVENTUAL NORTHEAST PROGRESSION THROUGH WESTERN
COLORADO. A 90 KT JET IS STILL POSITIONED ON THE EASTERN SIDE OF
THE LOW, WHICH FAVORS STRONG SOUTHERLY OROGRAPHICS INTO THE
SOUTHERN SAN JUANS. SEVERAL VORT LOBES WILL ROTATE AROUND THE
LOW KEEPING THIS AREA FAVORED FOR MORE PRECIPITATION. THIS LOW
WILL EVENTUALLY LIFT OUT OF ARIZONA INTO SOUTHEAST UTAH BY
LATE THIS AFTERNOON BEFORE TRACKING EASTWARD ACROSS SOUTHWEST TO
CENTRAL COLORADO TONIGHT AND ARRIVE OVER EAST-CENTRAL COLORADO
BY MONDAY MORNING. THIS IS MUCH LATER THAN EARLIER MODELS
INDICATED, HENCE THE EXTENSION IN END TIME OF THE WINTER
WEATHER HIGHLIGHTS YESTERDAY. THESE APPEAR ON TRACK FOR NOW, BUT
WILL LET THE DAY SHIFT REASSESS WHETHER THESE NEED TO BE
EXTENDED ANY FURTHER. THINKING WITH THE QUICK PROGRESSION LATE
THIS AFTERNOON AND EVENING OF THE LOW AS IT WILL MOVE ACROSS THE
CENTRAL PORTIONS, THE RATES SHOULD LESSEN OVER THE SAN JUANS BY
LATE THIS EVENING AS THE FOCUS SHIFTS TO THE CENTRAL COLORADO
MOUNTAINS AND ALONG THE DIVIDE. AT THIS TIME, THE SOUTHERN SAN
JUANS LOOK TO PICK UP AN ADDITIONAL 6 TO 10 INCHES OF SNOW WITH
AN ADDITIONAL 2 TO 5 INCHES OF SNOW OVER THE NORTHWEST SAN
JUANS. SNOWFALL ACROSS THE CENTRAL MOUNTAINS LOOKS TO BE IN THE
2 TO 6 INCH RANGE IN TOTAL THROUGH MONDAY MORNING, SO DO NOT
ANTICIPATE A NEED FOR ADDITIONAL WINTER WEATHER HIGHLIGHTS
ALTHOUGH THE COMMUTE MONDAY MORNING OVER THE PASSES COULD BE
IMPACTED. AS STATED PREVIOUSLY, THIS IS A RELATIVELY WARM SYSTEM
WITH NOT MUCH COLD AIR. THEREFORE, SNOW LEVELS HAVE BEEN FAIRLY
HIGH ABOVE 10KFT. EVEN NOW, TELLURIDE WHICH SITS AT JUST ABOVE
9KFT IS STILL INDICATING PRECIPITATION TYPE OF RAIN. SO THIS HAS
BEEN THE TRICKY BIT OF THIS FORECAST IS FORECASTING SNOW LEVELS
AND THAT OF COURSE IMPACTS HOW MUCH SNOW ACCUMULATES AND WHERE.
THINKING THE CURRENT WINTER WEATHER HIGHLIGHTS OVER THE SAN
JUANS CAPTURE IT PRETTY WELL FOR THE DURATION OF THIS SYSTEM.
AS THIS LOW MOVES ACROSS THE STATE LATE THIS AFTERNOON AND
EVENING, PRECIPITATION WILL SPREAD FURTHER NORTH AND IT WILL BE
A PRETTY WET DAY FOR MOST AREAS WITH VALLEY RAIN AND MOUNTAIN
SNOW AND WET ROADS DURING THE DAY TIME DUE TO THE MILDER NATURE
OF THIS SYSTEM. LIGHT SNOW WILL LINGER OVER THE DIVIDE MONDAY
MORNING BUT SHOULD COME TO AN END WITH DRIER CONDITIONS EXPECTED
FOR MONDAY AFTERNOON AND EVENING AND CLEARING SKIES AS HIGH
PRESSURE MOVES IN BEHIND THIS LOW. TEMPERATURES WILL TREND NEAR
SEASONABLE WITH SLIGHTLY ABOVE SEASONABLE TO THE NORTH AND
SLIGHTLY BELOW SEASONABLE TO THE SOUTH.
IN TERMS OF POTENTIAL FREEZING TEMPERATURES TONIGHT IN THE LOWER
VALLEYS, IT LOOKS LIKE THE SOUTHERN COLORADO VALLEYS WILL BE
NEAR FREEZING OR SLIGHTLY ABOVE AND IT DOESN'T LOOK WIDESPREAD
ENOUGH FOR A HARD FREEZE. PLUS, THE SLOWER PROGRESSION OF THIS
LOW HAS RESULTED IN PERSISTENT CLOUD COVER AND THINKING THERE
WILL BE TOO MUCH CLOUD COVER TONIGHT TO ALLOW FOR EFFICIENT
RADIATIONAL COOLING. HOWEVER, MONDAY NIGHT INTO TUESDAY MORNING
AFTER THIS SYSTEM MOVES OUT LOOKS MORE LIKELY TO SEE BELOW
FREEZING TEMPERATURES IN THESE HIGHER VALLEYS OF NORTHWEST
COLORADO, SOUTHWEST COLORADO AND ALONG THE I-70 CORRIDOR EAST OF
GLENWOOD SPRINGS. THIS WILL BE SOMETHING TO KEEP AN EYE ON
LOOKING FORWARD FOR POTENTIAL SEASON ENDING FREEZE BUT IT LOOKS
LIKE IT WILL HAVE TO WAIT TILL MONDAY NIGHT.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
ISSUED AT 411 AM MDT SUN OCT 20 2024
BEHIND THE LOW, RIDGING TRIES TO MOVE IN FROM THE WEST, BUT
LONGWAVE TROUGHING ACROSS SOUTHERN CANADA PRETTY MUCH KEEPS ANY
RIDGE KNOCKED DOWN THROUGH THE COMING WEEK RESULTING IN A DRY
ZONAL FLOW ALOFT. THIS ZONAL FLOW WILL BRING A RETURN OF DRY
WARM WEATHER TO EASTERN UTAH AND WESTERN COLORADO. THERE WILL BE
ENOUGH SUBSIDENCE TO KEEP SKIES MOSTLY CLEAR THROUGH THE WEEK.
THE ONLY EXCEPTION WILL BE SOME BANDS OF HIGH CLOUDS PASSING
ACROSS THE REGION AS A SHORTWAVE PASS WELL TO THE NORTH LATE
TUESDAY INTO WEDNESDAY AND AGAIN TOWARDS THE END OF THE WEEK.
TEMPERATURES WILL WARM TO FIVE TO TEN DEGREES ABOVE NORMAL BY
WEDNESDAY WHERE IT WILL REMAIN GOING INTO NEXT WEEKEND.
AVIATION /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 603 AM MDT SUN OCT 20 2024
SHOWERS WILL CONTINUE ACROSS SOUTHWEST COLORADO INTO SOUTHEAST
UTAH THIS MORNING WITH SOME ISOLATED THUNDERSTORMS POSSIBLE
AFFECTING KDRO AND KTEX WITH MVFR/IFR CONDITIONS AND ILS
BREAKPOINTS BEING REACHED IN SHOWERS. KMTJ MAY BE AFFECTED AT
TIMES AS THIS STORM SYSTEM BEGINS TO LIFT NORTHEAST. SHOWERS
EXPAND ACROSS MOST AREAS THIS AFTERNOON AND EVENING, SCATTERED
IN COVERAGE AFFECTING SOME TERMINALS AT TIMES WITH BRIEF
MVFR/IFR CONDITIONS AND ILS BREAKPOINTS BEING REACHED. OUTSIDE
OF SHOWERS, EXPECT VFR CONDITIONS WITH SCT TO BKN CLOUD COVER.
SNOW WILL CONTINUE AT ELEVATIONS ABOVE 8500 FEET. SHOWERS WILL
LESSEN IN COVERAGE AFTER 06Z WITH SOME LINGERING OVER THE
NORTHERN AND CENTRAL DIVIDE THROUGH 12Z MONDAY.
GJT WATCHES/WARNINGS/ADVISORIES
CO...WINTER WEATHER ADVISORY UNTIL 9 PM MDT THIS EVENING FOR COZ018.
WINTER STORM WARNING UNTIL 9 PM MDT THIS EVENING FOR COZ019.
UT...NONE.
SHORT TERM...MDA
LONG TERM...MDA/DB
AVIATION...TGJT
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