925 FXUS65 KPUB 021001 AFDPUB SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO COLORADO 355 AM MDT WED MAY 2 2001 ...CHALLENGING FORECAST THIS MORNING WITH POTENTIAL WINTER STORM... QUESTIONS RIGHT NOW REGARDING ACTUAL TRACK OF UPPER LOW NEXT FEW DAYS. AVN AND MOST OTHER MODELS HAVE BEEN CONSISTENT ON HAVING A CLOSED...SLOWER MOVING CIRCULATION ACROSS THE GREAT BASIN...WHILE THE ETA...WHICH WAS INITIALLY OPEN AND VERY PROGRESSIVE WITH THE WAVE...IS NOW TRENDING TOWARD THE AVN ET AL. THINKING IS...SYSTEM WILL TEND TO FOLLOW THE TIMING OF THE SLOWER MODELS MORE CLOSELY AND...IN FACT MAY END UP MOVING EVEN SLOWER. PRESENTLY...SYSTEM IS STILL DIGGING...WELL WEST OF HERE...OVER NEVADA. WHILE I WILL FOLLOW THE AVN MORE CLOSELY FOR TIMING...I WILL FOLLOW THE ETA MORE CLOSELY FOR THE SURFACE DETAILS...JUST PUSHED BACK IN TIME A LITTLE. ETA SOUNDINGS/CROSS SECTIONS PAINT A WET PICTURE FOR SOUTHEAST COLORADO TONIGHT THROUGH FRIDAY. LOOKS LIKE SFC-H7 NORTHEAST UPSLOPE FLOW WILL BE ONGOING FOR A WHILE TODAY THROUGH FRIDAY...WITH THE STRONGEST UPSLOPE INDICATED FOR LATE THURSDAY INTO EARLY FRIDAY...AS THE UPPER LOW MOVES NEARER THE FOUR CORNERS REGION. THIS IS ALSO WHEN THE UPPER LEVEL DYNAMICS FINALLY GET HERE. FEEL THAT LATE THURSDAY INTO EARLY FRIDAY MAY BE THE BEST OPPORTUNITY FOR SIGNIFICANT PRECIPITATION IN SOUTHEAST COLORADO. UNTIL THEN...UPPER LEVEL DYNAMICS KIND OF HOLD BACK AND SFC-H7 UPSLOPE IS NOT ALL THAT STRONG. WITH RELATIVELY WEAK UPSLOPE...AND WEAK DYNAMICS TO WORK WITH...PRECIPITATION LATER TODAY THROUGH EARLY THURSDAY MAY NOT BE ALL THAT IMPRESSIVE. AS FOR SNOWFALL POTENTIAL...A LOOK AT ETA FORECAST SOUNDINGS CLEARLY SHOWS SNOWFALL FOR ELEVATIONS ABOVE ROUGHLY 5000 FEET BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. HOWEVER...THE AVN IS CONSIDERABLY WARMER...HOLDING SNOWFALL TO PROBABLY 7000 FEET AND ABOVE. THE AVN IS PROBABLY TOO WARM...BUT THEN THE ETA IS PROBABLY TOO COLD. WILL USE SOMEWHAT OF A COMPROMISE WHEN DECIDING ON THERMAL FIELDS WITH THIS EVENT...BUT WILL LEAN CLOSER TO THE ETA. BASED ON THE 20 DEGREE DEWPOINTS UP IN WYOMING THAT ARE APPARENTLY HEADED OUR WAY...THERE IS CERTAINLY A LOT OF EVAPORATIVE/DIABATIC COOLING POTENTIAL OVER SOUTHERN COLORADO TONIGHT THROUGH FRIDAY UNDER THE RIGHT CONDITIONS OF MODERATE OR HEAVY PRECIPITATION. FOR NOW...THE ONLY HIGHLIGHT WILL BE A WINTER STORM WATCH FOR ZONE 67 FOR TONIGHT THROUGH THURSDAY NIGHT. THIS AREA WILL SEE ENOUGH COLD AIR FOR ACCUMULATING SNOWS BEGINNING TONIGHT. SNOW MODEL YIELDED 8 INCHES ACCUMULATIONS FOR THE OVERNIGHT 12 HOUR PERIOD...WITH ADDITIONAL SIMILAR ACCUMULATIONS FOR THE THURSDAY 12 HOUR PERIOD WITH EVEN GREATER ACCUMULATIONS FOR THE THURSDAY NIGHT PERIOD. FOR THE REMAINDER OF SOUTHERN COLORADO...IT WILL TAKE A BIT LONGER TO COOL DOWN...WITH THE MAIN THREAT FOR ACCUMULATING SNOWS HOLDING OFF UNTIL THURSDAY OR THURSDAY NIGHT. FOR THE SOUTHEAST MOUNTAINS THE SNOW MODEL INDICATED SIMILAR ACCUMULATIONS AS THOSE FOR ZONE 67, BUT BEGINNING THURSDAY INSTEAD OF TONIGHT. FOR THE SOUTHWEST AND CENTRAL MOUNTAINS...ACCUMULATIONS WERE NOT ALL THAT HIGH...AS THE FLOW IS NOT RIGHT FOR THESE AREAS. A NOTE ON ZONE 72, IT MAY BE ON THE EDGE TONIGHT AS FAR AS ACCUMULATING SNOWFALL...BUT PER COORDINATION WITH BOULDER WILL HOLD OFF ON ANY WATCH THERE AS THEY WILL HOLD OFF FOR ZONE 41. IF THE SNOW DID START ACCUMULATING THESE AREAS...IT WOULD PROBABLY NOT BE UNTIL LATE TONIGHT...ANYWAY...SO THERE WILL STILL BE TIME TO ALERT FOR THESE AREAS TODAY. THE REST OF SOUTHERN COLORADO...ROUGHLY ABOVE 5000 FEET...COULD SEE SOME ACCUMULATING SNOWFALL TOO...BUT THIS THREAT WOULD LIKELY NOT COME UNTIL LATE THURSDAY/THURSDAY NIGHT WHEN THE ATMOSPHERE COOLS...THE UPSLOPE INCREASES AND THE DYNAMICS MOVE OVERHEAD...SO TOO EARLY FOR ANY HIGHLIGHTS. THIS DOES NOT OUTRULE SOME HEAVY WET SNOW AT ELEVATIONS ROUGHLY ABOVE 5000 FEET FOR TONIGHT AND EARLY THURSDAY...IT'S JUST THAT IT WILL PROBABLY HAVE A HARD TIME ACCUMULATING INITIALLY. WILL MAKE NO CHANGES TO THE EXTENDED. DEALING WITH SHORT TERM ISSUES HAS LEFT ME NO TIME TO LOOK AT THAT RANGE. .PUB...NONE.  336 FXUS65 KPUB 021002 CCA AFDPUB SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION...CORRECTION NATIONAL WEATHER SERVICE PUEBLO COLORADO 355 AM MDT WED MAY 2 2001 ...CHALLENGING FORECAST THIS MORNING WITH POTENTIAL WINTER STORM... QUESTIONS RIGHT NOW REGARDING ACTUAL TRACK OF UPPER LOW NEXT FEW DAYS. AVN AND MOST OTHER MODELS HAVE BEEN CONSISTENT ON HAVING A CLOSED...SLOWER MOVING CIRCULATION ACROSS THE GREAT BASIN...WHILE THE ETA...WHICH WAS INITIALLY OPEN AND VERY PROGRESSIVE WITH THE WAVE...IS NOW TRENDING TOWARD THE AVN ET AL. THINKING IS...SYSTEM WILL TEND TO FOLLOW THE TIMING OF THE SLOWER MODELS MORE CLOSELY AND...IN FACT MAY END UP MOVING EVEN SLOWER. PRESENTLY...SYSTEM IS STILL DIGGING...WELL WEST OF HERE...OVER NEVADA. WHILE I WILL FOLLOW THE AVN MORE CLOSELY FOR TIMING...I WILL FOLLOW THE ETA MORE CLOSELY FOR THE SURFACE DETAILS...JUST PUSHED BACK IN TIME A LITTLE. ETA SOUNDINGS/CROSS SECTIONS PAINT A WET PICTURE FOR SOUTHEAST COLORADO TONIGHT THROUGH FRIDAY. LOOKS LIKE SFC-H7 NORTHEAST UPSLOPE FLOW WILL BE ONGOING FOR A WHILE TODAY THROUGH FRIDAY...WITH THE STRONGEST UPSLOPE INDICATED FOR LATE THURSDAY INTO EARLY FRIDAY...AS THE UPPER LOW MOVES NEARER THE FOUR CORNERS REGION. THIS IS ALSO WHEN THE UPPER LEVEL DYNAMICS FINALLY GET HERE. FEEL THAT LATE THURSDAY INTO EARLY FRIDAY MAY BE THE BEST OPPORTUNITY FOR SIGNIFICANT PRECIPITATION IN SOUTHEAST COLORADO. UNTIL THEN...UPPER LEVEL DYNAMICS KIND OF HOLD BACK AND SFC-H7 UPSLOPE IS NOT ALL THAT STRONG. WITH RELATIVELY WEAK UPSLOPE...AND WEAK DYNAMICS TO WORK WITH...PRECIPITATION LATER TODAY THROUGH EARLY THURSDAY MAY NOT BE ALL THAT IMPRESSIVE. AS FOR SNOWFALL POTENTIAL...A LOOK AT ETA FORECAST SOUNDINGS CLEARLY SHOWS SNOWFALL FOR ELEVATIONS ABOVE ROUGHLY 5000 FEET BEGINNING TONIGHT AND CONTINUING THROUGH FRIDAY. HOWEVER...THE AVN IS CONSIDERABLY WARMER...HOLDING SNOWFALL TO PROBABLY 7000 FEET AND ABOVE. THE AVN IS PROBABLY TOO WARM...BUT THEN THE ETA IS PROBABLY TOO COLD. WILL USE SOMEWHAT OF A COMPROMISE WHEN DECIDING ON THERMAL FIELDS WITH THIS EVENT...BUT WILL LEAN CLOSER TO THE ETA. BASED ON THE 20 DEGREE DEWPOINTS UP IN WYOMING THAT ARE APPARENTLY HEADED OUR WAY...THERE IS CERTAINLY A LOT OF EVAPORATIVE/DIABATIC COOLING POTENTIAL OVER SOUTHERN COLORADO TONIGHT THROUGH FRIDAY UNDER THE RIGHT CONDITIONS OF MODERATE OR HEAVY PRECIPITATION. FOR NOW...THE ONLY HIGHLIGHT WILL BE A WINTER STORM WATCH FOR ZONE 67 FOR TONIGHT THROUGH THURSDAY NIGHT. THIS AREA WILL SEE ENOUGH COLD AIR FOR ACCUMULATING SNOWS BEGINNING TONIGHT. SNOW MODEL YIELDED 8 INCHES ACCUMULATIONS FOR THE OVERNIGHT 12 HOUR PERIOD...WITH ADDITIONAL SIMILAR ACCUMULATIONS FOR THE THURSDAY 12 HOUR PERIOD WITH EVEN GREATER ACCUMULATIONS FOR THE THURSDAY NIGHT PERIOD. FOR THE REMAINDER OF SOUTHERN COLORADO...IT WILL TAKE A BIT LONGER TO COOL DOWN...WITH THE MAIN THREAT FOR ACCUMULATING SNOWS HOLDING OFF UNTIL THURSDAY OR THURSDAY NIGHT. FOR THE SOUTHEAST MOUNTAINS THE SNOW MODEL INDICATED SIMILAR ACCUMULATIONS AS THOSE FOR ZONE 67, BUT BEGINNING THURSDAY INSTEAD OF TONIGHT. FOR THE SOUTHWEST AND CENTRAL MOUNTAINS...ACCUMULATIONS WERE NOT ALL THAT HIGH...AS THE FLOW IS NOT RIGHT FOR THESE AREAS. A NOTE ON ZONE 72, IT MAY BE ON THE EDGE TONIGHT AS FAR AS ACCUMULATING SNOWFALL...BUT PER COORDINATION WITH BOULDER WILL HOLD OFF ON ANY WATCH THERE AS THEY WILL HOLD OFF FOR ZONE 41. IF THE SNOW DID START ACCUMULATING THESE AREAS...IT WOULD PROBABLY NOT BE UNTIL LATE TONIGHT...ANYWAY...SO THERE WILL STILL BE TIME TO ALERT FOR THESE AREAS TODAY. THE REST OF SOUTHERN COLORADO...ROUGHLY ABOVE 5000 FEET...COULD SEE SOME ACCUMULATING SNOWFALL TOO...BUT THIS THREAT WOULD LIKELY NOT COME UNTIL LATE THURSDAY/THURSDAY NIGHT WHEN THE ATMOSPHERE COOLS...THE UPSLOPE INCREASES AND THE DYNAMICS MOVE OVERHEAD...SO TOO EARLY FOR ANY HIGHLIGHTS. THIS DOES NOT OUTRULE SOME HEAVY WET SNOW AT ELEVATIONS ROUGHLY ABOVE 5000 FEET FOR TONIGHT AND EARLY THURSDAY...IT'S JUST THAT IT WILL PROBABLY HAVE A HARD TIME ACCUMULATING INITIALLY. WILL MAKE NO CHANGES TO THE EXTENDED. DEALING WITH SHORT TERM ISSUES HAS LEFT ME NO TIME TO LOOK AT THAT RANGE. .PUB...WINTER STORM WATCH TONIGHT THROUGH THURSDAY NIGHT ZONE 67