National Weather Service Forecast Discussion

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FXUS65 KBOU 080852
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER CO
251 AM MDT WED SEP 8 2010

.SHORT TERM...ONE DISTURBANCE HAS MOVED NORTHEAST OF THE AREA EARLY
THIS MORNING WHILE A SECOND FEATURE MAY MOVE ACROSS THE AREA BY MID
TO LATE AFTN IN SW FLOW ALOFT.  PRECIPITABLE WATER VALUES SO FAR ARE
ONLY AROUND .70 ON IPW SENSORS HOWEVER BOTH NAM AND GFS INCREASE
THESE VALUES TO AROUND AN INCH BY LATE AFTN ESPECIALLY OVER THE
PLAINS.  BEST INSTABILITY BY MID TO LATE AFTN WILL BE OVER THE
PLAINS WITH CAPES RANGING FM 500-1000 J/KG.  AT THIS POINT WILL
INCREASE POPS SOME INTO CHC CATEGORY IN AND NR THE FOOTHILLS FOR
THIS AFTN AND ACROSS THE NERN PLAINS FOR THIS EVENING.  IN THE MTNS
WILL KEEP SCT POPS FM PREVIOUS FCST.  WITH FAIRLY DECENT MID LVL
FLOW STORMS WILL MOVE RATHER QUICKLY AND WILL PRODUCE GUSTY WINDS
AND BRIEF MDT RAIN IN THE MTNS AND FOOTHILLS.  OVER THE NERN PLAINS
WHERE DEEPER LOW LEVEL MOISTURE WILL EXIST SOME BRIEF HEAVY RAINFALL
WILL BE POSSIBLE.  HIGHS TODAY WILL GENERALLY BE IN THE 80S ACROSS
NERN CO.  MEANWHILE WITH FAIRLY TIGHT SFC GRADIENT OVER THE PLAINS
EXPECT GUSTY SSE WINDS TO CONTINUE THRU THE AFTN HOURS INTO EARLY
EVENING.

FOR TONIGHT QUITE A BIT OF MID LVL DRYING WILL SPREAD FM WEST TO
EAST ACROSS THE AREA AS SUBTROPICAL MOISTURE BEGINS TO SHIFT EAST OF
THE AREA AS THE FLOW ALOFT BECOMES MORE WSW.  THUS PCPN CHANCES
SHOULD GRADUALLY END IN THE MTNS...FOOTHILLS BY EARLY EVENING AND
ACROSS THE PLAINS AROUND MIDNIGHT.


.LONG TERM...ON THURSDAY...AN INCREASING SOUTHWESTERLY FLOW ALOFT
WILL DEVELOP AHEAD OF THE NEXT UPPER TROF PROGGED TO BE OVER THE
SNAKE RIVER VALLEY REGION OF SRN ID AROUND 18Z THURSDAY.  AHEAD OF
THIS A 85+ KT JET MAX WILL BE ORIENTED SW TO NE...AS IT MIGRATES
EASTWARD INTO COLORADO THURSDAY NIGHT INTO FRIDAY MORNING.  THE TROF
AXIS IS PROGGED MOVE ACRS THE CNTRL ROCKIES AND EVENTUALLY BRUSH
ACROSS NORTHEASTERN COLORADO FRIDAY IN THE 12-18Z TIME FRAME.  NAM12
SPATIAL CROSS-SECTIONS INDICATE A 40KT CROSS-MOUNTAIN DOWNSLOPE WND
COMPONENT SPREADING INTO THE FOOTHILLS FM AROUND 06Z-15Z FRIDAY
MORNING AS A SHALLOW MOUNTAIN WAVE DEVELOPS. ALTHO HIGH WIND
CRITERIA IS NOT EXPECTED TO BE MET...THERE WILL STILL BE PLENTY OF
WIND TO FURTHER COMPOUND WILDFIRE CONDITIONS IN FOURMILE CANYON.
GUSTS AT THAT TIME WILL RANGE FM 45-55 MPH FOOTHILLS AND ERN MTN
SLOPES. NO FIRE WEATHER WATCH YET BUT IT MAY BE NECESSARY AT SOME
POINT FOR STRONG WINDS AND CONTINUED LOW RELATIVE HUMIDITIES.  WILL
SEE IF THE NEXT RUN ADVERTISES A SIMILAR SCENARIO.  THE NAM/GFS BOTH
INDICATE WEAK UPWARD QG ASCENT THURSDAY AFTN/EVNG.  THERE WILL BE
ENUF MSTR OVER THE NERN PLAINS FOR A SLIGHT CHANCE OF TSTMS AT THAT
TIME.  STRONGER DOWNWARD QG DESCENT (15-20 MB/HR) IS PROGGED TO
DEVELOP AFTER 12Z FRIDAY AOA 700 MB.  THE AMS WILL DRY OUT AND
STABILIZE AT THAT TIME WITH MORE OF A ZONAL WLY FLOW EXPECTED OVER
THE WEEKEND AND INTO THE START OF NEXT WEEK.  BREEZY-WINDY
CONDITIONS ALG THE FOOTHILLS WILL BE A BYPRODUCT OF THIS.
TEMPERATURES WILL GENERALLY REMAIN ABOVE NORMAL THROUGH THE
PERIOD.

.AVIATION...A DISTURBANCE IN SW FLOW ALOFT MAY TRACK ACROSS THE AREA
BETWEEN 21Z AND 00Z.  THIS FEATURE COULD BRIEFLY ENHANCE TSTM
ACTIVITY NE THE AIRPORT.  WITH RATHER DECENT MID LVL FLOW ANY STORM
COULD PRODUCE BRIEF WIND GUSTS OF 40-50 MPH ALONG WITH SOME BRIEF
MDT RAINFALL.  AT THIS POINT WL LEAVE VCTY IN THE TAF AND MENTION A
TEMPO GROUP FOR GUSTY OUTFLOW WIND BETWEEN 21Z AND 00Z.  ACTIVITY
SHOULD QUICKLY DECREASE AFTER 00Z.  WINDS TODAY WILL BE SLY EARLY
THIS MORNING AND THEN MORE SE BY 18Z AND THEN MORE SSW AFT 00Z.  NAM
SHOWS WINDS COULD INCREASE TO 15-20 MPH FM 20Z THRU 00Z.

&&

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


&&

RPK/COOPER

NWS BOU Office Area Forecast Discussion