NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NWS DENVER COLORADO
AFDDEN 1140 AM MST MON JAN 21 2002 ...UPDATE
SHORT TERM DISCUSSION: 88D SHOWING DISAPPEARANCE OF MTN WAVE
SIGNATURE DURING THE LAST HOUR...AND AS A RESULT WINDS IN MOST SPOTS
ARE ON THE DECREASE. THIS CONICIDES WITH LASTEST ACARS DATA SHOWING
THE STRONG MTN TOP INVERSION HAS WEAKENED CONSIDERABLY. PLATTEVILLE
PROFILER ALSO SHOWING SPEEDS DECREASING AS FLOW BACKS MORE TO THE
SW. STILL SOME GUSTS UP AROUND 50-60 MPH UP HIGH BUT OVERALL WINDS
SPEEDS WILL STAY BLOW HI WIND CRITERIA THIS AFTN. WILL ALLOW ALL
WARNINGS TO EXPIRE PER FCST.
STILL A LITTLE CONCERNED ABOUT THE WINDS TNT OVER THE HIR FOOTHILLS
AS WNDS AT MEDICINE BLOW ARE BACK UP AGAIN TO 60KT AT LOWEST GATES.
HOWEVER...WITH THE SHEAR INCREASING A LITTLE AND THE SW
FLOW...SPEEDS SHOULD STAY BLO HI WND TNT. WILL TAKE A CLOSER LOOK
FOR THE AFTN AFD/ZONES. ENTREKIN
.DEN...NONE.
AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 915 AM PST MON JAN 21 2002
.SYNOPSIS...SHOWERS AND COOL ONSHORE FLOW WILL CONTINUE OVER THE AREA
THROUGH TUESDAY NIGHT...AS AN UPPER LEVEL TROUGH OF LOW PRESSURE IN
THE SOUTHEAST GULF OF ALASKA DROPS INTO THE AREA. SNOW LEVELS WILL
GENERALLY RANGE FROM 500 TO 1000 FEET. A WARM FRONT WILL APPROACH THE
AREA FROM THE WEST ON WEDNESDAY...BRINGING STEADIER PRECIPITATION.
PRECIPITATION MAY BEGIN AS SNOW IN THE INTERIOR. A WARMER AND MUCH
WETTER SYSTEM WILL MOVE INTO THE AREA ON THURSDAY.
.DISCUSSION...SATELLITE IMAGERY SHOWS COLD UPPER LEVEL TROUGH
OFFSHORE WITH THE TROUGH AXIS NEAR 128W. WSR-88D SHOWS THE RAIN
SHADOW EFFECT OF THE OLYMPICS WELL WITH BANDS OF SHOWERS OVER THE
NORTHERN INTERIOR AND SOUTH OF THE SEATTLE METRO AREA. NWS EMPLOYEE
REPORTED SNOW IN ENUMCLAW AS ENHANCED ECHO MOVED OVER THE AREA. TWO
ACARS SOUNDINGS OVER WESTERN WASHINGTON HAVE 500 MB TEMPS -35 AND
-37C. MODEL SOUNDINGS HAVE THE CONVECTIVE TEMPERATURES IN THE MID 30S
TO LOWER 40S ALL THE WAY THROUGH TOMORROW AFTERNOON WITH LIFTED
INDEXES NEAR 0. WILL ADD ISOLATED THUNDERSTORMS TO THE FORECAST FOR
THROUGH TUESDAY. UPPER LEVEL TROUGH AXIS MOVES THROUGH WESTERN
WASHINGTON TUESDAY AFTERNOON WITH LOW SNOW LEVELS CONTINUING. TIME OF
DAY AND INTENSITY OF THE SHOWER WILL EFFECT THE SNOW LEVEL WITH
CURRENT WORDING IN THE ZONES LOOKING GOOD. 12Z MODELS CONTINUE TO
INDICATE COLD TEMPS OVER THE AREA WEDNESDAY MORNING WITH THE ONSET OF
PRECIPITATION OVER THE INTER 12Z-15Z. WITH COLD AIR IN PLACE AND
SURFACE GRADIENTS GOING OFFSHORE AHEAD OF THE FRONT PRECIPITATION
COULD START OUT AS SNOW BUT WILL CHANGE OVER TO RAIN IN MOST PLACES
FAIRLY QUICKLY. WILL NOT MENTION AMOUNTS AT THIS TIME BUT KITSAP
PENINSULA COULD SEE SOME ACCUMULATIONS BEFORE THE CHANGE OVER. THIS
ALREADY COVERED IN THE FORECAST. FIRST LOOK AT THE 12Z AVN HAS
TRANSITION TO WARMER PATTERN STILL INTACT. WILL PROBABLY ISSUE ESF
THIS AFTERNOON BUT WITH THE 850 MB PROGGED TO BE NEAR 0 EXTENDED OF
THE FLOODING PROBLEMS COULD BE LIMITED. OTHER THAN ADDING
THUNDERSTORMS LITTLE CHANGE TO THE FORECAST. felton
UIL ++7 SEA 776 OLM 976
.SEW...HIGH SURF ADVISORY TODAY AND TONIGHT.
.SMALL CRAFT ADVISORY COAST...CAMANO ISLAND TO POINT ROBERTS
AND PUGET SOUND AND HOOD CANAL.
.KATX...VCP21/CSR21...OPERATIONAL.