452
FXUS65 KPUB 202158
AFDPUB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
258 PM MST FRI NOV 20 2009
SHORT TERM
(TONIGHT AND SATURDAY)
..INCREASING CLOUDINESS SATURDAY
THE RIDGE OF HIGH PRESSURE ALOFT WILL CONTINUE MOVING EAST...AS A
WEAK STORM MOVES THROUGH WYOMING AND INTO THE PLAINS BY LATE
SATURDAY. USED THE WRF AS A BASIS OF THE FORECAST...AS WINDS
APPEARED CONSISTENT...AND THE SYSTEM KEPT ANY PRECIPITATION NORTH OF
OUR CWA THROUGH SATURDAY AFTERNOON. WINDS ALSO APPEARED TO BE
REASONABLE...WITH SOME DOWNSLOPE WINDS ALONG THE MOUNTAINS WEST OF
THE I-25 CORRIDOR OVERNIGHT...WHICH WILL KEEP TEMPERATURES WARMER
THAN THOSE EXPECTED IN THE LOWER AREAS OF THE ARKANSAS RIVER VALLEY.
WITH MAINLY CLEAR SKIES EXPECTED OVERNIGHT...THE HIGH MOUNTAIN
VALLEYS WILL AGAIN COOL INTO THE SINGLE DIGITS TO LOW TEENS. CLOUDS
WILL INCREASE SATURDAY AS THE SYSTEM MOVES A WEAK COLD FRONT ACROSS
MAINLY THE CENTRAL MOUNTAINS...BUT...SINCE THE LOWER LEVELS ARE
DRY...NO PRECIPITATION IS EXPECTED THROUGH THE DAY. THE MAIN PROBLEM
WILL BE INCREASING WINDS ACROSS THE HIGHER MOUNTAINS AND ALONG THE
EASTERN SLOPES AHEAD OF AND WITH THE COLD FRONT. --JKH--
LONG TERM
(SATURDAY NIGHT THROUGH FRIDAY)
FIRST SHORTWAVE WILL CROSS THE CO ROCKIES SAT NIGHT. THIS SYSTEM
LOOKS RELATIVELY DRY...BRINGING A BRIEF SHOT OF SNOW TO THE CENTRAL
MOUNTAINS AND DRAGGING A DRY COLD FRONT THROUGH THE REMAINDER OF THE
AREA BY EARLY SUNDAY MORNING. THIS SYSTEM IS FAIRLY
PROGRESSIVE...WHICH SHOULD KEEP SNOWFALL AMOUNTS ON THE LIGHT SIDE
ACROSS THE SAWATCH AND MOSQUITO RANGES. MOISTURE SHALLOWS OUT
QUICKLY ALONG THE CONTDVD ON SUNDAY BEHIND THE SYSTEM...THOUGH THERE
WILL BE ENOUGH MOISTURE FOR SOME ISOLATED OROGRAPHIC SNOW SHOWERS
ACROSS THE HIGHER PEAKS. TEMPS SHOULD BE AROUND 5 TO 10 DEGREES COOLER
THAN THE DAY BEFORE...ESPECIALLY ACROSS THE PLAINS.
THE NEXT UPPER TROF WHICH DROPS IN SUNDAY NIGHT/MONDAY HAS THE
POTENTIAL TO BE THE STRONGEST OF THE WEEK. THERE IS STILL SOME
VARIABILITY BETWEEN THE MODELS WITH 12Z NAM AND GFS DROPPING THE
OPEN TROF THROUGH WY/NRN CO INTO THE CENTRAL PLAINS...GIVING
SOUTHERN CO MORE OF A GLANCING BLOW BEFORE IT CLOSES OFF AND HEADS
TOWARDS THE UPPER MID WEST. THE 00Z AND 12Z ECMWF AND NOW THE 18Z
NAM ARE STRONGER AND FARTHER WEST WITH THE SOUTHEASTWARD TRACK OF
THIS SYSTEM...WITH ECMWF THE STRONGEST AND SLOWEST OF THE BUNCH...
CLOSING OFF THE UPPER LOW ACROSS WRN KS/ERN CO BY MON AFTN. EVEN
WITH THE STRONGER SOLN...MOST OF THE FORECAST AREA WILL BE UNDER
THE DRY DOWNSLOPE PORTION OF THE STORM...HOWEVER NRN PORTIONS OF
THE PLAINS...PALMER DIVIDE AND ALONG WITH THE CENTRAL MOUNTAINS
COULD SEE SOME ACCUMULATING SNOWS UNDER THE DEVELOPING TROWAL ON
MONDAY. GIVEN THE UNCERTAINTIES...WILL LEAVE THE LOW GRADE
ISOLATED POPS IN FOR THE SOUTHEAST PLAINS SUNDAY NIGHT/MONDAY. THE
CENTRAL MOUNTAINS COULD SEE A FEW INCHES OF ACCUMULATION WITH THIS
SYSTEM AS WELL.
REGARDLESS OF THE MODEL...THE SYSTEM SHOULD WELL EAST OF THE AREA BY
TUES WITH A RETURN OF DRY WEATHER AND REBOUNDING TEMPERATURES.
GFS HAS TRENDED WESTWARD WITH THE NEXT ROUND OF ENERGY DROPPING DOWN THE
EAST SIDE OF THE UPPER RIDGE THROUGH THE CENTRAL PLAINS TUES
NIGHT/EARLY WED. THIS SYSTEM WILL SEND ANOTHER FRONT THROUGH THE SE
PLAINS...AND WHICH IF LATEST GFS IS CORRECT COULD BE ACCOMPANIED BY
SOME ISOLATED LIGHT SNOW SHOWERS. FOR NOW WILL KEEP FORECAST DRY
FOR THE PLAINS AS PREVIOUS RUNS AND ECMWF KEEPS THE TRACK OF THIS
SYSTEM FARTHER OFF TO THE EAST. THIS SHOULD AT LEAST BRING SOME
DEGREE OF A COOL DOWN FOR WEDNESDAY. UPPER RIDGE WILL TRANSLATE IN
ALOFT FOR THURS BEFORE GETTING CUT DOWN AND TRANSITIONING TO ZONAL
FLOW FOR FRI AS NEXT SYSTEM ENTERS THE PACIFIC NORTHWEST. THIS
SHOULD BRING WARMER TEMPERATURES AND A TREND TOWARDS BREEZY/WINDY
CONDITIONS TO THE AREA THROUGH LATE NEXT WEEK. -KT
AVIATION
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES THROUGH THE
PERIOD. GUSTY WINDS MAY DEVELOP ALONG THE EASTERN MOUNTAIN SLOPES
LATE TONIGHT AND EARLY SATURDAY AS A DRY COLD FRONT MOVES THROUGH
THE AREA FROM WEST TO EAST. THE GUSTY WINDS ARE NOT EXPECTED TO
AFFECT THE TAF SITES...BUT COULD CAUSE PROBLEMS FOR GENERAL AVIATION
TRYING TO FLY FROM THE PLAINS INTO THE MOUNTAINS. --JKH--
PUB WATCHES/WARNINGS/ADVISORIES
NONE.
51/31
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