National Weather Service Forecast Discussion

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FXUS65 KBOU 260315
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
915 PM MDT SAT MAY 25 2013

.UPDATE...

&&

.SHORT TERM...THREAT OF THUNDERSTORMS APPEARS TO BE OVER. THERE
ARE OUTFLOW BOUNDARIES COMING BACK INTO FAR EASTERN COLORADO...BUT
THE AIR HAS COOLED AND IT APPEARS THAT THERE IS NOT ENOUGH
INSTABILITY TO TRIGGER NEW STORMS IN OUR AREA. WE DO HAVE A
SUBSTANTIAL AMOUNT OF HIGH CLOUDINESS MOVING IN FROM THE SOUTHWEST
WHICH SHOULD BE AROUND MOST OF THE NIGHT...SO UPDATED THE FORECAST
FOR THIS.

.AVIATION...VFR CONDITIONS THROUGH SUNDAY. WINDS AT KDEN STILL
EXPECTED TO TURN AROUND TO THE NORTHWEST LATER TONIGHT AS THE
DENVER CYCLONE CIRCULATION MOVES EASTWARD...THEN SOUTHWEST LATE
TONIGHT. KAPA SHOULD GO NORTHWEST WITHIN THE HOUR...THEN BACK TO
SOUTHWEST LATER AS WELL.

&&

.PREV DISCUSSION... /ISSUED 245 PM MDT SAT MAY 25 2013/

SHORT TERM...THE LOW LEVEL MOISTURE HAS HELD ACROSS MOST OF THE
NORTHEAST PLAINS WITH SLIGHTLY DEEPER EASTERLY FLOW IN PLACE.
MEANWHILE...A DRYLINE WAS BECOMING MORE DEFINED FROM THE
ARAPAHOE/ELBERT COUNTY LINE EASTWARD INTO FAR SOUTHERN WASHINGTON
COUNTY. CUMULUS TOWERS WERE DEVELOPING ALONG THIS LINE...WITH THE
BEST CHANCE OF CONVECTIVE INITIATION THROUGH EARLY EVENING ALONG
AND JUST AHEAD OF THIS FEATURE AS IT MOVES NORTHEAST. THERE WAS A
LITTLE CUMULUS EXTENDING NORTHWARD INTO SOUTHEAST WELD
COUNTY...BUT INITIATION IN THIS AREA WILL BE MORE DIFFICULT WITH
CIRRUS SHIELD SPREADING ACROSS THE TOP. SURFACE CAPES 2500-3000
J/KG WHERE DEWPOINTS HAVE HELD IN THE LOWER 50S SO IF CONVECTION
CAN POP WE WILL LIKELY SEE A COUPLE SEVERE STORMS WITH LARGE HAIL
AND DAMAGING WINDS THE PRIMARY THREATS. MIXED LAYER CAPES SHOULD
BE CLOSER TO 1000-2000 J/KG. AT THIS TIME...SEE THIS THREAT JUST A
SHADE WEST OF EARLIER FORECAST...POSSIBLY AS FAR BACK AS FORT
MORGAN.

SKIES WILL CLEAR LATER THIS EVENING WITH THE LOSS OF CONVECTION
AND CIRRUS SHIELD SHIFTING EASTWARD. DEPENDING ON LOCATION AND
STRENGTH OF MESOSCALE CONVECTIVE SYSTEMS DEVELOPING IN THE CENTRAL
PLAINS...COULD SEE ANOTHER PUSH OF LOW LEVEL MOISTURE AND POSSIBLE
STRATUS INTO THE NORTHEAST CORNER AGAIN OVERNIGHT.

ON SUNDAY...LOOKS PRETTY MUCH LIKE A REPEAT OF TODAY WITH VERY
WARM TEMPERATURES ALOFT...DRY AIRMASS OVER MOST OF THE FORECAST
AREA...AND CONVECTION INITIATING ALONG DRYLINE FORMATION IN THE
AFTERNOON. AT THIS TIME...WILL BACK THINGS UP JUST ABOUT ANOTHER
COUNTY WESTWARD FROM PREVIOUS FORECAST BASED ON MODEL BIASES AND
POTENTIAL SURGES FROM CENTRAL PLAINS CONVECTION. COULD SEE A
COUPLE SEVERE STORMS OVER THE NORTHEAST CORNER AGAIN DUE TO AMOUNT
OF INSTABILITY NEAR 2000-3000 J/KG.

LONG TERM...ASIDE FROM SOME LINGERING THUNDERSTORMS OVER THE
NORTHEAST PLAINS IN THE EVENING...IT WILL BE DRY AND MOSTLY CLEAR.
ON MONDAY....ANOTHER UNSEASONABLY WARM DAY WITH A DRY
SOUTHWESTERLY FLOW OVER MUCH OF THE CWFA. THE ONLY EXCEPTION WILL
CONTINUE TO BE THE FAR NORTHEAST CORNER WHERE THE BEST LOW LEVEL
MOISTURE WILL BE...BUT EVEN THERE THE COVERAGE WILL BE ISOLATED.
MONDAY NIGHT INTO TUESDAY...THE NEXT UPPER TROUGH WILL MAKE ITS
WAY INTO THE GREAT BASIN. THERE WILL BE SOME INCREASE IN MID AND
UPPER LEVEL MOISTURE AHEAD OF THE SYSTEM. THERE WILL BE A BETTER
CHANCE OF SOME HIGH BASED THUNDERSTORMS IN THE FOOTHILLS AND URBAN
CORRIDOR IN THE AFTN AND EVENING WITH GUSTY OUTFLOW WINDS AND
LIGHT RAIN POSSIBLE. FURTHER TO THE NORTH AND EAST...BETTER LOW
LEVEL MOISTURE WITH A BETTER CHANCE OF THUNDERSTORMS...A FEW OF
WHICH COULD BE SEVERE. THE TROUGH ITSELF IS PROGGED TO MOVE ACROSS
COLORADO WEDNESDAY INTO THURSDAY. THE TROUGH HAS A STRONG
NEGATIVE TILT INTO THE PAC NW ON WEDNESDAY AND WEDNESDAY NIGHT.
ON THURSDAY A BROAD CLOSED UPPER LOW BREAKS OFF AND MOVE ACROSS
THE NORTHERN ROCKIES. THE SYSTEM IS NOT VERY WELL ORGANIZED BUT
IT WILL BE COOL AND UNSETTLED BOTH DAYS. AS A RESULT...BEST CHANCE
OF SHOWERS AND TSTMS IN THE MOUNTAINS WILL BE AT THIS TIME...WITH
COOLER TEMPERATURES AND A BETTER CHANCE OF SHOWERS AND STORMS FOR
THE NORTHEAST PLAINS AS WELL. COULD EVEN SEE SOME LIGHT SNOW
DEVELOP IN THE HIGH COUNTRY AS WELL AS THE SYSTEM PASSES ACROSS
THE REGION. TIMING OF THE MDLS GETS ERRATIC BEYOND WEDNESDAY...BUT
TEMPERATURES WILL BE NEAR NORMAL WITH SOME DRYING BY THE END OF
THE WEEK AS AN UPPER RIDGE BUILDS IN FM THE NORTHWEST.

AVIATION...VFR CONDITIONS WILL PREVAIL. SURFACE WINDS WILL BE A
LITTLE TRICKY AGAIN WITH POTENTIAL FOR DENVER CYCLONE INDUCED MORE
NORTHERLY FLOW THIS EVENING VERSUS POSSIBLE NORMAL TRANSITION TO
DRAINAGE. EVENTUAL DRAINAGE WINDS SHOULD PREVAIL BY 06Z WITH
RETURN TO NORMAL DIURNAL EASTERLIES BY 17Z-19Z SUNDAY.

HYDROLOGY...NO CONCERNS.

&&

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

$$

SHORT TERM...BARJENBRUCH
LONG TERM....COOPER
AVIATION/UPDATE...GIMMESTAD

NWS BOU Office Area Forecast Discussion