My weather nerds may appreciate this. I should release this AFD more often. I have not changed my mind.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
532 PM MDT SAT MAR 30 2019
SHORT TERM
(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 338 PM MDT SAT MAR 30 2019
A COUPLET OF LARGE HEIGHT ANOMALIES ACROSS THE HIGH LATITUDES OF
NOAM SEEM HAVE PUT THE MODELS IN A TAILSPIN THE PAST 24 HOURS.
THE INTEGRATED REX PATTERN DEVELOPING OVER THE INTERMOUNTAIN WEST
THIS AFTERNOON IS ALSO WAY OFF BASE AS FAR AS PATTERN RECOGNITION
GOES SO CONFIDENCE IS LOW GOING INTO THIS FORECAST. THE
ANTICYCLONIC CIRCULATION OVER THE N.ROCKIES SEEMS TO BE IN CONTROL
OF THE FLOW WITH GOES IMAGERY SHOWING AN EASTWARD DRIFT TO THE
DEVELOPING MODCU FIELDS OVER OUR CWA. THERE IS CHANNELIZED
VORTICITY STRETCHING FROM THE GREAT LAKES THROUGH CENTRAL COLORADO
AND BACK INTO THE PACNW. A CYCLONIC CIRCULATION IS DEVELOPING
OVER OUR CWA IN THE AREA OF SHEAR THAT IS RETROGRADING WESTWARD
ON THE SOUTHERN PERIPHERY OF THE ABOVE MENTIONED HIGH PRESSURE
CELL. THIS LOW WILL STALL OVER EASTERN UTAH THIS EVENING BEFORE
AN UPSTREAM RIDGE MOVING ONSHORE GIVES THE WHOLE PATTERN A SHOVE
EASTWARD. COLD...AIR IN THIS VORTICITY CHANNEL IS AND WILL AID
INSTABILITY AS THIS COMPACT SYSTEM ACCELERATES ACROSS THE 4
CORNERS LATE TONIGHT INTO TOMORROW. ASCENT WILL INCREASE
DRAMATICALLY NEAR SUNRISE AS UPPER JET SUPPORT ARRIVES. THIS
ASCENT WILL ALSO TRIGGER A LOW LEVEL RESPONSE WHICH SHOULD HELP
PULL MOISTURE NORTHWARD. AT THE MOMENT MOISTURE AVAILABILITY IS
CONCERNING AS LOW LEVEL DEWPOINT DEPRESSIONS ARE VERY LARGE ACROSS
THE SOUTHERN VALLEYS AND MOUNTAINS. I HAVE NO DESIRE TO CHANGE
MUCH BASED ON CONFIDENCE ALONE BUT THE RAPID DECREASE IN
PRECIPITATION AMOUNTS AND THE SOUTHERN SHIFT OF THE PRECIPITATION
TRACK IS WORRYING. HIGH MOUNTAIN PRECIPITATION WILL PERSIST
THROUGH THE NIGHT ON OROGRAPHICS AND INSTABILITY ALONE BUT IT MAY
NOT COME TOGETHER FOR THE MUCH OF THE LOWER ELEVATIONS UNTIL
SUNRISE AND BEYOND. THE INGREDIENTS ARE DEFINITELY THERE FOR HEAVY
SNOWFALL RATES IN CONVECTIVE SHOWERS THROUGH THE DAY AS THE COLD
AIR ALOFT SHIFTS OVERHEAD THEN TO THE EAST. THIS SHOULD ALLOW FOR
A RATHER QUICK DOWNTURN AFTER SUNSET TOMORROW WITH LAPSE RATES
ALSO RELAXING BY A TRANSITORY RIDGE AND WARMER AIR BUILDING IN
ALOFT.
LONG TERM
(MONDAY THROUGH SATURDAY)
ISSUED AT 338 PM MDT SAT MAR 30 2019
WARMER CONDITIONS MOVE IN FOR THE FIRST FEW DAYS OF THE NEW WEEK
AS THIS RIDGE WORKS THROUGH THE GREAT BASIN AS IS REPLACED BY THE
NEXT UPSTREAM KICKER TROUGH. MOISTURE MOVING IN AHEAD OF THIS
SYSTEM AND THE DOWNSTREAM CONFLUENT FLOW OVER OUR REGION WILL LEAD
TO SOME ISOLATED SHOWERS MONDAY NIGHT WITH THE SHOWERS BECOMING
MORE WIDESPREAD ON THE TERRAIN THROUGH THE DAY TUESDAY AS DAYTIME
HEATING KICKS IN. THE ACTUAL TROUGH MOVES THROUGH ON WEDNESDAY
AND EXPECT MORE SHOWERS ACROSS THE LOWER ELEVATIONS. THIS TROUGH
IS NOT AS COLD AS THE CURRENT ONE AND SNOW LEVELS WILL BE HIGHER
WITH RAIN EXPECTED MOST AREAS BELOW 9000 FEET. BY WEDNESDAY
EVENING COOLER AIR FILTERS IN ON THE BACKSIDE OF THE TROUGH AND
SNOW LEVELS WILL DROP THROUGH DRIER AIR IS ALREADY FILTERING IN.
THE SAME PATTERN REPEATS FOR THE END OF THE WEEK AS THE FLOW STAYS
PROGRESSIVE. DRY THROUGH THURSDAY WITH HEIGHTS BUILDING ALOFT
LEADS TO INCREASING SHOWERS FRIDAY AFTERNOON INTO SATURDAY AS THE
NEXT SYSTEM WORKS INTO THE GREAT BASIN. OVERALL TEMPERATURES
REMAIN BELOW NORMAL THROUGH THESE PERIODS OF RAINFALL AND DRIER
DAYS.
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