Damaging Wind in Colorado, September 27, 2002

WESTERN COLORADO & EASTERN UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
226 PM MDT FRI SEP 27 2002

SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON SUPPORTED BY
SUFFICIENT MID LEVEL MOISTURE...UPPER JET DYNAMICS AND MARGINAL
INSTABILITY. RELATIVELY DRY LOW LEVELS (DEWPTS IN THE 30S) AND RAPID
PROGRESSION OF STORMS RESULTING IN GENERAL RAINFALL AMOUNTS OF LESS
THAN A TENTH INCH. BRIEF STRONG WIND GUSTS WILL BE PRIMARY THREAT
WITH STORMS THROUGH THIS EVENING.

UPPER LEVEL LOW CIRCULATION OVER IDAHO WILL CONTINUE TO SLIDE SOUTH
OVER THE GREAT BASIN TONIGHT. SHEARING MID LEVEL ENERGY AND NOSE OF
SUB-TROPICAL JET (OVER SOUTHWEST COLORADO) WILL SUPPORT SHOWERS AND
THUNDERSTORMS THROUGH AT LEAST MIDNIGHT. SEPARATE SHORTWAVE OVER
SOUTHERN CALIFORNIA WILL APPROACH FOUR CORNERS AREA LATE TONIGHT.
THIS WILL BRING A SURGE OF DEEPER PACIFIC MOISTURE AND MID LEVEL
DYNAMICS...AND WILL BE FOCUS FOR ADDITIONAL SHOWERS AND THUNDERSTORMS
AFFECTING SE UTAH AND SW COLORADO SATURDAY MORNING. EXPECT SCATTERED
PRECIPITATION TO SPREAD NORTH ACROSS THE FCST AREA SATURDAY.
MEANWHILE...MAIN TROUGH WILL DROP ACROSS SOUTHERN GREAT BASIN WITH
ENERGY SHEARING EAST. TROUGH BEGINS TO LIFT EAST ACROSS UTAH
AND COLORADO SUNDAY WITH ANOTHER THREAT OF SHOWERS AND THUNDERSTORMS.
BREEZY TO WINDY CONDITIONS POSSIBLE SUNDAY AFTERNOON AS WEST-TO-EAST
PGRAD STRENGTHENS. NOT LOOKING AT MAJOR COLD SURGE WITH THIS
SYSTEM...SO EXPECT ANY SNOWFALL TO BE CONFINED TO HIGHEST MOUNTAIN
PEAKS (>11K) THROUGH SUNDAY.

AREA REMAINS IN PROGRESSIVE WESTERLY FLOW SUNDAY NIGHT AND MONDAY
AS ANOTHER TROUGH DROPS ACROSS PACIFIC NORTHWEST. THREAT OF
PRECIPITATION WILL DIMINISH AS DRIER AIR MOVES IN FROM SOUTHWEST.
BREEZY CONDITIONS WILL PERSIST INTO MONDAY. WILL BE WATCHING NEXT
SYSTEM AS SIGNIFICANT COLD FRONT DROPS INTO NORTHWEST UTAH MONDAY
AFTERNOON.  NADLER.83

TUESDAY THROUGH FRIDAY: MODELS CONTINUE TO STRUGGLE WITH THIS
ACTIVE TRANSITIONAL PATTERN. GOOD AGREEMENT WITH GENERAL PATTERN
OF A CLOSED LOW DIGGING AND DEEPENING OVER THE SW. THE EC FURTHER
WEST/LESS PROGRESSIVE SOLUTION IS GENERALLY FOLLOWED AS IT HAS BEEN
PERFORMING BETTER LATELY AND IS SUPERIOR HANDLING COOL-SEASON CUTOFF
LOWS. THE ONLY ADDED DETAIL TO THIS PACKAGE WILL BE COOLER TEMPS
ACROSS THE NORTH ON TUESDAY AS THE LOW DIVES AND DEEPENS INTO THE
WESTERN GREAT BASIN. THE MRF TROPA ON THURSDAY REJECTED FOR NOW.
GENERALLY WILL KEEP UNSETTLED MOIST SW FLOW WITH BREEZES AND SNOW
LEVEL REMAINING IN THE MTNS.   RAMEY

.GJT...NONE.