Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 250343
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
843 PM MST SAT JAN 24 2015

.UPDATE...
ISSUED AT 843 PM MST SAT JAN 24 2015

SHOWERS CONTINUE TO MAKE SOUTHWARD ADVANCEMENT ACROSS THE PLAINS
THIS EVENING. UPSTREAM OBS OVER THE NEBRASKA PANHANDLE AND
SOUTHEAST WYOMING INDICATE A MIX OF RAIN AND SNOW SHOWERS...AND
PATCHES OF MEASURABLE PRECIP. HAVE BOOSTED POPS A BIT MORE OVER
THE NEXT COUPLE HOURS BUT SHOWERS SHOULD BE DECREASING BY
MIDNIGHT OR SHORTLY THEREAFTER AS UPPER LEVEL SPEED MAX SHIFTS
EASTWARD AND LARGE SCALE SUBSIDENCE TAKES OVER.

OTHER AREA OF CONCERN TONIGHT IS WINDS. LATEST CROSS SECTIONS SHOW
A MEAN STATE CRITICAL LAYER IN PLACE THROUGH THE NIGHT AND STRONG
30-40 KNOT NW FLOW NEAR MOUNTAIN TOP. COULD SEE MOUNTAIN WAVE
DEFLECTION WITH THE MEAN STATE CRITICAL LAYER IN PLACE...SO WILL
KEEP GUSTY WINDS IN/NEAR THE FRONT RANGE MOUNTAINS AND FOOTHILLS
THROUGH THE NIGHT. THIS ALSO INCLUDES PARK COUNTY SO WILL KEEP
SOME BLOWING SNOW IN THAT AREA OVERNIGHT WHERE IT HAS CAUSED
TROUBLES ON A STRETCH OF HIGHWAY 285 BETWEEN KENOSHA PASS AND
ANTERO JUNCTION.

UPDATE ISSUED AT 601 PM MST SAT JAN 24 2015

A FAIRLY WELL ORGANIZED BAND OF SHOWERS IS MOVING SOUTH ACROSS
THE NEBRASKA PANHANDLE AND EASTERN WYOMING EARLY THIS EVENING.
LOOKS LIKE THESE WILL MOVE INTO NORTHEAST COLORADO BEFORE
DISSIPATING LATER IN THE EVENING. AT THIS TIME LOOKS LIKE
TEMPERATURES MAY COOL JUST ENOUGH FOR A MIX OF LIGHT RAIN OR
SNOW...BUT NO ACCUMULATION. HAVE UPDATED POPS JUST A BIT FOR THE
NORTHEAST PLAINS.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 108 PM MST SAT JAN 24 2015

WEAK SHORTWAVE TROUGH DROPPING ACROSS NEBRASKA AT THIS TIME. THERE
ARE A FEW WEAK SHOWERS DEVELOPING IN THE NORTHEAST CORNER OF
COLORADO AND IN THE NORTHERN MOUNTAINS...BUT THE BEST BATCH OF
THESE HAS ALREADY PASSED THE CORNER AND IS HEADED INTO KANSAS.
EXISTING LOW POPS ARE ENOUGH TO COVER THIS ACTIVITY. WINDS SHOULD
ALSO BE PEAKING AS CONDITIONS FOR WAVE AMPLIFICATION AROUND
BOULDER FADE AND GRADIENT WIND ALSO STARTS TO DIMINISH. THERE WILL
STILL BE LOTS OF CLOUD COVER THIS EVENING AND ENOUGH WIND TO KEEP
LOW LEVELS FAIRLY WELL MIXED OVERNIGHT SO LOWS TONIGHT WILL BE
MILD. ON SUNDAY TEMPERATURES WILL WARM WITH MORE SUNSHINE AND
STILL SOME WIND...THOUGH THERE WILL LIKELY STILL BE SOME CLOUDS.
PREFERRED THE WARMER GFS GUIDANCE...MAIN CHANGE WAS TO WARM THE
MOUNTAINS.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 108 PM MST SAT JAN 24 2015

AN UPPER LEVEL RIDGE WILL BUILD OVER THE AREA ON MON WITH DRY
CONDITIONS AND MUCH ABV NORMAL TEMPS OVER NERN CO. 850-700 MB
TEMPS WOULD SUPPORT HIGHS IN THE MID 60S TO NR 70. BY TUE A WK
UPPER LEVEL LOW WEST OF BAJA WILL BEGIN TO MOVE NE WHICH WILL
ALLOW FOR SOME MID AND HIGHER LEVEL MOISTURE TO AFFECT THE AREA
ESPECIALLY BY AFTN. THERE COULD BE A FEW -SHSN OVER THE HIGHER
PEAKS BY LATE AFTN MAINLY IN ZN 31 OTHERWISE IT WILL REMAIN DRY.
850-700 MB TEMPS DO NOT CHANGE MUCH ON TUE HOWEVER INCREASE IN MID
LVL CLOUD COVER COULD KEEP TEMPS A FEW DEGREES COOLER THAN MON
OVER NERN CO HOWEVER READINGS WILL STILL BE WELL ABV NORMAL.

BY WED THE REMNANTS OF THE WK UPPER LEVEL LOW WILL MOVE ACROSS NRN
CO ALONG WITH SOME INCREASE IN MOISTURE WHICH WILL LEAD TO A CHC OF
SNOW IN THE MTNS.  OVER NERN CO A COOL FNT WILL MOVE ACROSS THE
PLAINS WHICH WILL DROP HIGHS BACK INTO THE LOWER TO MID 50S.  FOR
WED NIGHT ANOTHER SURGE OF COOLER AIR WILL MOVE INTO NERN CO WITH
UPSLOPE FLOW AND SOME LOW LVL MOISTURE.  BOTH THE ECMWF AND GFS SHOW
SOME POTENTIAL FOR LIGHT PCPN OVERNIGHT ALONG THE FRONT RANGE.
PREVIOUS RUNS DID NOT SHOW THIS SO WILL KEEP A DRY FCST FOR NOW.

ON THU AN UPPER LEVEL RIDGE WILL REBUILD BACK INTO THE AREA WITH
CROSS-SECTIONS SHOWING ONLY LIMITED MOISTURE.  THUS WILL ONLY
MENTION A SLIGHT CHC OF -SHSN IN THE MTNS.  AS FOR HIGHS 850-700 MB
TEMPS DROP FM 7 TO 8 DEGREES C ON THU SO HIGHS WILL FALL BACK TO
NEAR SEASONAL LEVELS OVER NERN CO.

FOR FRI INTO SAT THE ECMWF AND GFS HAVE DIFFERING SOULTIONS.  THE
GFS DIGS AN UPPER LEVEL TROUGH FM THE PACIFIC NW INTO THE GREAT
BASIN FRI NIGHT INTO SAT WITH A STG CDFNT MOVING INTO NERN CO.  AS A
RESULT THIS LEADS TO COLDER TEMPS ALONG WITH A CHC OF SNOW.
MEANWHILE THE ECMWF DOES NOT HAVE AN UPPER LEVEL TROUGH DIGGING INTO
THE GREAT BASIN AS IT HAS AN UPPER LEVEL RIDGE IN THE SAME AREA.
HOWEVER IT DOES SHOW A CDFNT MOVING INTO NERN CO ON SAT.  THE LATEST
GEM MODEL IS MORE LIKE THE GFS ALTHOUGH IT HAS THE TROUGH MORE OVER
COLORADO THAN THE GREAT BASIN. AT THIS POINT HARD TO SAY WHICH
SOLUTION WILL END UP BEING RIGHT. FOR NOW WILL JUST MENTION SOME
LOW POPS FRI NIGHT INTO SAT AND TREND TOWARDS COOLER TEMPS.

&&

.AVIATION...(FOR THE TAFS THROUGH 06Z SUNDAY EVENING)
ISSUED AT 843 PM MST SAT JAN 24 2015

VFR CONDITIONS WILL PERSIST. OCCASIONAL SCT-BKN MID LEVEL CLOUD
DECK NEAR 10 THOUSAND FEET WILL DISSIPATE FULLY BY 08Z-10Z. WINDS
WILL BE MORE TRICKY OVERNIGHT. CURRENT NORTHWEST WINDS WILL LIKELY
REMAIN IN PLACE TIL AROUND 06Z WITH SURFACE PRESSURE SURGE MOVING
DOWN THIS SIDE OF THE ROCKIES. HOWEVER...VARIOUS SHORT RANGE
MODELS SUGGEST WINDS COULD THEN GO ANTICYCLONIC TO A WEAK
EASTERLY COMPONENT...OR BACK TO WEST/SOUTHWEST AS GRADIENT SLOWLY
WEAKENS. THIS WILL HAVE TO BE MONITORED OVERNIGHT AS WINDS COULD
BE QUITE VARIABLE.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...BARJENBRUCH
SHORT TERM...GIMMESTAD
LONG TERM...RPK
AVIATION...BARJENBRUCH



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