Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 142335
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
535 PM MDT TUE APR 14 2015

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 225 PM MDT TUE APR 14 2015

FOR TONIGHT...THE FLOW ALOFT WILL INCREASE FROM THE SOUTHWEST AS
THE STORM SYSTEM APPROACHES FM THE PACIFIC NORTHWEST. THE MDLS
STILL SHOW ENOUGH MOISTURE AND INSTBY FOR SOME SHOWERS EARLY THIS
EVENING IN THE HIGH COUNTRY. ACROSS THE NORTHEAST PLAINS...GUSTY
SLY WINDS WILL PERSIST INTO THE EARLY EVENING HOURS OVER THE
NORTHEASTERN PLAINS. WL CONTINUE TO RED FLAG WARNING FOR THE
PALMER DIVIDE AND NORTHEAST PLAINS THROUGH 8 PM MDT. ALTHOUGH THE
GUSTY WINDS WILL PERSIST THROUGH MUCH OF THE EVENING THE RELATIVE
HUMIDITIES WILL START TO RECOVER IN THE MID 20S BY MID EVENING. BY
12Z WEDNESDAY...THE UPPER TROUGH WL BE CENTERED OVER NORTHERN UT
WITH INCREASING QG ASCENT FROM WEST TO EAST ACROSS NORTHERN
COLORADO. THE CENTER OF THE TROUGH IS PROGGED TO BE OVER CENTRAL
COLORADO WITH A BULLSEYE OF SUBSIDENCE OVER EASTERN COLORADO IN
THE AFTN. SOME MIXED SIGNALS IN THE AFTN. PLENTY OF MOISTURE AND
MID LEVEL INSTABILITY WITH GUSTY NORTHERLY WINDS IN THE AFTN.
FORECAST SOUNDINGS SHOW INVERTED V TYPE SOUNDINGS SO LIGHT RAIN
AND GUSTY WINDS WITH ANY DEVELOPING STORMS. WL STICK WITH CHC
POPS WITH ISOLD THUNDERSTORM COVERAGE THROUGH FOR WEDNESDAY AFTN.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 225 PM MDT TUE APR 14 2015

MAIN CONCERN DURING THE LONG TERM PERIOD CONTINUES TO BE THE
POTENTIAL FOR SIGNIFICANT PRECIPITATION AND SNOW.

THE SREF 15Z PLUMES FOR DIA SHOW ANYWHERE FROM 0.04 INCHES OF
PRECIPITATION TO 4.28. ONE THING TO KEY ON IS THAT...ALL BUT 5
MEMBERS SHOW MORE THAN THREE-QUARTERS OF AN INCH PRECIPITATION
THROUGH FRIDAY EVENING. THE MEAN OF ALL THE MEMBERS IS 1.87
INCHES...AND ABOUT HALF HAVE OVER 2 INCHES. THE FAVORED GEM AND
ECMWF ARE CONTINUING TO SHOW 2 TO 3 INCHES OF PRECIPITATION WITH
THIS STORM. THE LAST 7 RUNS OF THE ECMWF HAVE HAD THE CLOSED LOW
SOMEWHERE OVER NEW MEXICO AT 00Z FRIDAY. THE PREVIOUS 5 RUNS HAVE
HAD THE CLOSED LOW OVER WESTERN NEW MEXICO AT 00Z FRIDAY WITH EACH
RUN CREEPING A LITTLE MORE NORTH. WITH THE ECMWF BEING MUCH MORE
CONSISTENT THAN MOST OF THE OTHERS...WILL LEAN THE FORECAST
TOWARDS IT. THE GFS MODEL RUNS CONTINUE TO FLIP FLOP AND HAVE
LITTLE FAITH IN THE 12Z RUN. OTHER THAN THE GFS AND SOME OF IT
ENSEMBLE MEMBERS...MOST MODELS ARE TRENDING TOWARDS A WET PATTERN
FOR EASTERN COLORADO. HOWEVER UNCERTAINLY IS STILL HIGHER THAN
USUALLY.

A BIG CONCERN WILL BE THE POTENTIAL FOR HEAVY SNOW. THIS WILL DEPEND
ON THE TEMPERATURES. BEST CHANCE FOR HEAVY SNOW WILL BE OVER THE
HIGHER TERRAIN WHERE IT WILL BE COLDER. SNOW RATIOS WILL LOW...BUT
IF 2 OR MORE INCHES OF LIQUID FALLS...1 TO 2 FEET OF SNOW WILL BE
POSSIBLE WITH EVEN HIGHER AMOUNTS POSSIBLE IN THE MOUNTAINS AND
HIGHER FOOTHILLS. THE ECMWF AND GEM ARE GENERALLY WARMER...WHICH
COULD LEAD TO RAIN FOR THE LOWER ELEVATIONS.

FORECAST WISE WILL TREND POPS HIGHER...ESPECIALLY THURSDAY NIGHT AND
FRIDAY WHEN THE ECMWF AND GEM SHOW A GOOD AMOUNT OF PRECIPITATION.
IF MODELS CONTINUE TO TREND TOWARDS THE ECMWF AND GEM SOLUTION WILL
NEED TO ISSUE WINTER STORM WATCHES SOMETIME IN THE NEXT 24 HOURS FOR
AT LEAST THE HIGHER TERRAIN. STILL A LOT OF UNCERTAINTY TEMPERATURE
WISE WHEN AND IF RAIN WILL CHANGE TO SNOW.

WITH THE UPPER LEVEL LOW POSSIBLY REMAINING IN THE AREA THIS
WEEKEND... WILL INCREASE POPS SOME AND KEEP TEMPERATURES COOL. THE
WEEKEND WEATHER AND THE WEATHER NEXT WEEK WILL DEPEND ON THE
EVOLUTION OF THE CLOSED LOW. BY EARLY NEXT WEEK...MODELS ARE SHOWING
A NORTHWEST FLOW A LOFT WITH A RIDGE OVER THE WESTERN U.S. THERE
COULD BE A WEAK WAVE EMBEDDED IN THE NORTHWEST FLOW...SO WILL KEEP
LOW POPS IN THE FORECAST WITH TEMPERATURES NEAR NORMAL.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z WEDNESDAY LATE AFTERNOON)
ISSUED AT 535 PM MDT TUE APR 14 2015

HIGH BASED CONVECTIVE SHOWERS CONTINUE TO FORM OVER THE HIGH
TERRAIN AND MOVE NORTHEAST OVER THE FOOTHILLS THEN DRY OUT OVER
THE PLAINS. AT THIS TIME...NO EFFECT IS EXPECTED AT THE AREA
AIRPORTS...HOWEVER WILL BE KEEPING AN EYE ON THE POTENTIAL FOR
GUSTY OUTFLOW WINDS FROM THE WEST FROM THESE. BEST CHANCE TO SEE
THE POSSIBLE WESTERLY GUSTS WOULD BE FROM 00Z-03Z.
OVERALL VFR CONDITIONS THROUGH WEDNESDAY AFTERNOON. SELY WINDS
15-25 KTS THROUGH THE EVENING WITH THE POTENTIAL OF SOME GUSTS TO
AROUND 30 KTS...THEN MORE SWLY TOWARS EARLY MORNING...BUT
REMAINING STRONGER THAN NORMAL DIURNAL SPEEDS AS A LOW INTENSIFIES
OVER EASTERN WYOMING. SURFACE LOW WILL DROP OVER NORTHEASTERN
COLORADO WEDNESDAY MORNING THEN DROP SOUTH INTO SOUTHEASTERN
COLORADO IN THE AFTERNOON. GUSTY NORTH- NORTHWESTERLY WINDS WILL
MOVE IN BEHIND THIS LOW...CURRENTLY EXPECTING AFTER 15Z. COULD SEE
SOME SHOWERS DEVELOPING BY THE AFTN WITH ENOUGH INSTABILITY TO
PRODUCE AN ISOLATED THUNDERSTORMS. SHOULD SEE PREVAILING ILS CIGS
IN THE AFTN BUT DO NOT EXPECTED ANYTHING MORE THAN LIGHT RAINFALL
IN THE SHOWERS. MORE PRECIPITATION AND POTENTIALLY IFR CEILINGS
EXPECTED WEDNESDAY NIGHT.

&&

.FIRE WEATHER...
ISSUED AT 225 PM MDT TUE APR 14 2015

WILL CONTINUE THE RED FLAG WARNING THROUGH 8 PM MDT THIS EVENING.
ALTHOUGH GUSTY WINDS WILL PERSIST THROUGH THE EVENING...THE
RELATIVE HUMIDITIES WILL RECOVER INTO THE MID 20S BY THAT TIME.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ241-242-
244>251.

&&

$$

SHORT TERM...COOPER
LONG TERM...MEIER
AVIATION...KRIEDERMAN
FIRE WEATHER...COOPER



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