Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 251526
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
926 AM MDT WED MAR 25 2015

.UPDATE...
ISSUED AT 926 AM MDT WED MAR 25 2015

AN UPPER LEVEL SYSTEM COMBINED WITH UPSLOPE BEHIND A COLD FRONT
ARE PRODUCING SNOW SHOWERS ACROSS THE METRO AREA. THE BAND OF
HEAVIER SNOW IS PUSHING SOUTH. SO EXPECT AN HOUR OR TWO PERIOD OF
MODERATE TO HEAVY SNOW THIS MORNING. IT WILL REMAIN UNSTABLE THIS
AFTERNOON UNDER A NORTHWEST FLOW ALOFT. MODELS SHOW MOST OF THE
ACTIVITY THIS AFTERNOON ALONG AND WEST OF I-25. HAVE ALREADY
INCREASED POPS FOR THIS TODAY. ALSO LOWERED TEMPERATURES A FEW
DEGREES TOO. EXPECT TEMPERATURES TO REMAIN AT OR ABOVE FREEZING
THROUGH THE DAY...SO ANY SNOW ACCUMULATION IS EXPECTED TO BE
LIGHT...LESS THAN 2 INCHES WITH MOST AREAS SEEING LESS THAN 1
INCH.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 350 AM MDT WED MAR 25 2015

A DISTURBANCE IN NW FLOW ALOFT WILL MOVE ACROSS THE AREA TODAY.
THIS FEATURE HAS FAVORABLE MID LVL ASCENT AND LAPSE RATES WITH IT
THRU LATE AFTN.  AT LOWER ELEVATIONS A CDFNT WILL MOVE ACROSS NERN
CO WITH THE LOW LVL FLOW MAINLY NLY BEHIND THE FNT.

IN THE MTNS WILL SEE PERIODS OF SNOW THRU MIDDAY HOWEVER BY AFTN
SOME DRIER AIR WILL SPREAD ACROSS AS MID LVL DESCENT DVLPS.  THUS
SNOW SHOULD BEGIN TO DECREASE THRU THE AFTN HOURS.

OVER NERN CO FCST IS MORE COMPLICATED.  WITH NLY LOW LVL FLOW AREAS
CLOSER TO THE WY BORDER MAY NOT SEE MUCH PCPN LATER THIS MORNING
THRU THE AFTN HOURS WHILE AREAS FM DENVER SOUTH TO THE PALMER DIVIDE
SEE THE BEST CHC. WITH STEEP LAPSE RATES THERE COULD BE SOME
ISOLD TSTMS AS WELL IN THE AFTN. ONE POTENTIAL ISSUE IS LYR OF DRY
AIR IN THE LOWER LEVELS AND HOW LONG IT WILL TAKE TO ERODE AS
THERE COULD BE QUITE A BIT OF VIRGA INITIALLY BEFORE SATURATION
OCCURS. MEANWHILE WET BULB ZEROS SUGGEST PCPN MAY FALL MOSTLY AS
SNOW AT LOWER ELEVATIONS WITH A MIX OVER THE FAR NERN PLAINS.
DEPENDING ON HOW THINGS EVOLVE COULD SEE AN INCH OR SO OVER THE
SRN AND WESTERN SUBURBS OF DENVER WITH SLIGHTLY HIGHER AMOUNTS
OVER THE PALMER DIVIDE. THE HRRR AND RAP HAVE NOT BEEN MUCH HELP
TONIGHT DUE TO HOUR TO HOUR INCONSISTENCIES WITH WITH REGARDS TO
PCPN POTENTIAL.

AS FOR HIGHS WILL KEEP READINGS MAINLY IN THE 40S OVER NERN CO
HOWEVER THE FAR NERN CORNER COULD RISE INTO THE LOWER 50S WHERE PCPN
POTENTIAL AND CLOUD COVER WILL BE LESS.

FOR TONIGHT PCPN SHOULD GRADUALLY END BY EARLY EVENING IN THE
MTNS...SRN FOOTHILLS AND ACROSS THE PALMER DIVIDE WITH CLEARING
SKIES OVERNIGHT.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 350 AM MDT WED MAR 25 2015

STRONG NORTHERLY FLOW ALOFT THURSDAY MORNING GIVES WAY TO
DECREASING NORTHWESTERLY FLOW ALOFT LATER THURSDAY THROUGH FRIDAY
NIGHT. AND UPPER RIDGE APPROACHING SLOWLY FROM THE WEST IS THE
CAUSE. THERE IS WEAK DOWNWARD SYNOPTIC SCALE ENERGY PROGGED FOR
THE CWA THURSDAY THROUGH FRIDAY NIGHT. THE BOUNDARY LAYER FLOW IS
DOWNSLOPING NORTHWESTERLY ON THURSDAY...THEN NORMAL PATTERNS
THURSDAY NIGHT. THERE IS WEAK NORTHWESTERLY DOWNSLOPING ON FRIDAY
THAN NORMAL DRAINAGE AGAIN FRIDAY NIGHT. FOR MOISTURE...THERE IS
SOME AROUND ON THURSDAY AND THURSDAY EVENING...THEN IT DRIES OUT
FOR THE REST OF THURSDAY NIGHT THROUGH FRIDAY NIGHT. THERE IS NO
CAPE PROGGED OVER THE CWA ALL FOUR PERIODS. THE QPF FIELDS SHOW
THAT THERE IS A TINY BIT OF MEASURABLE PRECIPITATION ONLY ON THE
GFS FOR LATE DAY THURSDAY. WILL GO WITH "SLIGHT CHANCE"S IN THE
MOUNTAINS FOR LATE DAY RAIN/SNOW ON THURSDAY ONLY. FOR
TEMPERATURES...THURSDAY`S HIGHS WARM UP 4-7 C OVER TODAY`S HIGHS.
FRIDAY`S READINGS ARE ANOTHER 3-6 C WARMER THAN THURSDAY`S. FOR
THE LATER DAYS...SATURDAY THROUGH TUESDAY...THE UPPER RIDGE IS
MOVING OVER COLORADO AND WEAKENING ON SATURDAY. THE ECMWF HAS A
VERY WEAK UPPER TROUGH ON SATURDAY NIGHT...THE GFS KEEPS RIDGING.
ON SUNDAY...THERE IS EITHER ZONAL FLOW OR NORTHWESTERLY FLOW
ALOFT...WITH A WEAK CLOSED LOW/TROUGH TO OUR SOUTHWEST. THIS
THING PUSHES EAST ON MONDAY...WITH MORE RIDGING AND WEAK ZONAL
FLOW ON TUESDAY. THE GFS HAS WAY MORE MID AND UPPER LEVEL
MOISTURE ALL FOUR DAYS COMPARED TO THE MUCH DRIER ECMWF. REALLY
THERE IS LITTLE GOING ON AND GFS HAS SOME MINOR MEASURABLE
PRECIPITATION HERE AND THERE WITH NOTHING ON THE ECMWF. WILL GO
WITH LITTLE TO NO POPS.

&&

.AVIATION...(FOR THE TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 926 AM MDT WED MAR 25 2015

HEAVY SNOW AND LOW CEILINGS ARE EXPECTED TO LINGER THROUGH 17Z TO
18Z AND THEN IMPROVE. IT WILL REMAIN UNSTABLE THIS AFTERNOON WHICH
SHOULD PRODUCE SNOW SHOWERS. A BRIEF THUNDERSTORM ALSO CAN`T BE
RULED OUT. CEILINGS WILL FALL BELOW 2000 FEET UNDER THE SNOW
SHOWERS WITH VISIBILITY UNDER A MILE FOR A SHORT TIME. WINDS WILL
BE NORTHERLY THROUGH 00Z AND THEN SWITCH SOUTHERLY BETWEEN 00Z AND
06Z.

&&

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

$$

UPDATE...MEIER
SHORT TERM...RPK
LONG TERM...RJK
AVIATION...MEIER



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