National Weather Service Forecast Discussion

000
FXUS65 KBOU 170833
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
233 AM MDT THU MAY 17 2012

.SHORT TERM...UPPER LEVEL LOW CURRENTLY OVER WESTERN COLORADO WILL
SLOWLY MOVE EAST ACROSS THE STATE TODAY. SIMILAR SET UP AS YESTERDAY
WHERE THE LOWER LEVELS OF THE AIRMASS ARE DRY WITH SOME MOISTURE
ALOFT. CAPES WILL BE LESS THAN 500 J/KG AND DEW POINTS WILL BE IN
THE MID 20S AND 30S. THESE LOW DEW POINTS COMBINED WITH HIGHS IN
THE 80S WILL RESULT IN HIGH BASED SHOWERS AND THUNDERSTORMS TODAY.
WIND GUSTS UP TO 50 MPH WILL AGAIN BE POSSIBLE...BUT MOST OF THE
OUTFLOW WINDS WILL BE IN THE 25 TO 40 MPH RANGE. BEST CHANCE WILL
BE FROM NOON TO 5 PM. COVERAGE WILL AGAIN BE SCATTERED TO
ISOLATED. MEASURABLE PRECIPITATION WILL BE VERY ISOLATED AND
MAINLY LIMITED TO THE HIGHER TERRAIN. THE RAIN THAT FALLS WILL BE
LIGHT AND SHORT LIVED. A SURFACE TROUGH ALONG THE FRONT RANGE WILL
SHIFT EAST TODAY AND CAUSE THE WINDS TO TURN NORTHWESTERLY ACROSS
NORTHEAST COLORADO.

EXPECT THE CONVECTION TO DIE OFF QUICKLY EARLY THIS EVENING AS
SUBSIDENCE MOVES IN BEHIND THE LOW. BY MIDNIGHT...EXPECT SKIES TO
BE MOSTLY CLEAR.

.LONG TERM...SOUTHWESTERLY WINDS AT THE SURFACE AND ALOFT ARE
EXPECTED TO DEVELOP OVER THE CWFA BY FRIDAY AFTERNOON...AHEAD OF
THE NEXT UPPER LEVEL TROUGH. THE TROUGH WILL BE OVER WESTERN UTAH
BY MIDDAY FRIDAY. AHEAD OF IT...INCREASING MID AND UPPER LEVEL
MOISTURE WILL DEVELOP AOA 500 MB. NAM12/GFS BUFFER SOUNDINGS FOR
FRIDAY AFTERNOON AGAIN DEPICT THE DREADED INVERTED-V PROFILE
WHICH IS INDICATIVE OF MORE WIND VS PCPN WITH THE STORMS. WILL
MENTION DRY THUNDERSTORMS IN THE GRIDS FOR FRIDAY AFTN. FCST CAPES
FRIDAY AFTN RANGE FROM 500 J/KG IN THE MTNS TO 700 J/KG OVER THE
URBAN CORRIDOR AND NORTHEAST PLAINS. IN ADDITION...VERY WARM
TEMPERATURES IN THE MID TO UPPER 80S ALONG WITH RELATIVE
HUMIDITIES OF 10-15 PERCENT WILL AGAIN INCREASE THE FIRE DANGER.
THE COMBINATION OF THESE FACTORS WILL BE GREATEST ALONG THE PALMER
DIVIDE AND NORTHEASTERN PLAINS. AS A RESULT...A FIRE WEATHER WATCH
WILL LIKELY BE NECESSARY FOR THOSE AREAS AT SOME POINT. FRIDAY
NIGHT INTO SATURDAY...WEAK MID AND UPPER LEVEL QG ASCENT WILL
DEVELOP AS THE UPPER TROUGH CONTINUES TO SHIFT EASTWARD. AT THE
SURFACE...DOWNSLOPE SOUTHWESTERLY WINDS WILL KEEP THE LOWER LEVELS
DRY FRIDAY NIGHT...FROM THE FRONT RANGE FOOTHILLS EASTWARD. ON
SATURDAY MORNING THE TROUGH AXIS WILL BE OVER EASTERN COLORADO.
DECREASING MID AND UPPER LEVEL QG ASCENT WILL OCCUR THROUGH THE
DAY. AT THE LOWER LEVELS HOWEVER... ANTICYCLONIC UPSLOPE FOLLOWING
THE PASSAGE OF A COLD FRONT SATURDAY MORNING WILL DEVELOP.
SOUNDINGS AND SPATIAL CROSS- SECTIONS GRADUALLY INCREASE THE
NORTH/NORTHEASTERLY WINDS TO AROUND 700 MB BY LATE SATURDAY AFTN.
SO ALTHOUGH THE UPPER LEVEL QG SUPPORT WILL BE DECREASING
SATURDAY...THE QG ASCENT WILL BE INCREASING IN THE LOWER LEVELS
THROUGH THE DAY. THE BEST CHANCE OF ANY RAINFALL WILL BE SATURDAY
AFTN/EARLY EVENING IN AND NEAR THE FOOTHILLS AND PALMER DIVIDE.
THE THUNDERSTORMS WILL INITIATE OVER THE HIGHER TERRAIN THEN
GRADUALLY WEAKEN AS THEY MIGRATE INTO THE MORE STABLE AMS OVER THE
NORTHEAST PLAINS. AS A RESULT...WL HIT THE SHOWERS VS TSTMS
HARDEST OVER THE NORTHEAST PLAINS. FCST CAPES SATURDAY AFTN ONLY
IN THE 250-350 J/KG RANGE. ON SUNDAY...IT WILL BE DRIER BUT STILL
RELATIVELY COOL WITH A RIDGE OF HIGH PRESSURE BUILDING OVER THE
WEST. THERE MAY STILL BE ENOUGH MOISTURE TO PRODUCE A FEW STORMS
NEAR THE HIGHER TERRAIN DURING THE AFTN/EARLY EVENING TIME FRAME.
THE ROLLER COASTER WILL HEAD TOWARD DRIER AND WARMER CONDITIONS
FOR MONDAY AND TUESDAY THIS WEEK. THE SOUTHWESTERLY FLOW MAY AGAIN
INCREASE TUESDAY AHEAD OF YET ANOTHER SYSTEM THAT COULD BRUSH
ACROSS COLORADO ON WEDNESDAY.

&&

.AVIATION...SOUTHERLY WINDS WILL TURN WEST TO NORTHWEST BY MID
MORNING...15Z AS A SURFACE TROUGH MOVES EAST ACROSS NORTHEAST
COLORADO. BY AFTERNOON...THERE IS CHANCE WINDS COULD TURN TO THE
NORTHEAST. HIGH BASED SHOWERS AND THUNDERSTORMS ARE AGAIN EXPECTED
THIS AFTERNOON. MAIN CONCERN WITH THESE WILL BE OUTFLOW WINDS UP
TO 40 KNOTS. AIRMASS WILL QUICKLY STABILIZE EARLY THIS EVENING AND
BY MID NIGHT MOSTLY CLEAR SKIES WILL PREVAIL.

&&

.HYDROLOGY...NO HYDROLOGY CONCERNS TODAY WITH ONLY LIGHT RAIN OR
SPRINKLES FROM THE SHOWERS AND THUNDERSTORMS.

&&

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

$$

SHORT TERM...MEIER
LONG TERM....COOPER
AVIATION...MEIER

NWS BOU Office Area Forecast Discussion