Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 292108
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
308 PM MDT WED APR 29 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 308 PM MDT WED APR 29 2015

UPPER RIDGING REMAINING OVER COLORADO ON THURSDAY WILL BRING ONE
MORE VERY WARM DAY TO THE FORECAST AREA. HOWEVER...MID AND UPPER
LEVEL MOISTURE WILL BE INCREASING THROUGH THE DAY...LEADING TO
INCREASING CLOUDINESS AND THEN A CHANCE OF AFTERNOON SHOWERS AND
THUNDERSTORMS. MODEL SOUNDINGS INDICATE THAT AROUND 1000 J/KG OF
CAPE WILL BE PRESENT TO FUEL THUNDERSTORM GROWTH. EACH OF THE
MODELS SHOW PRECIPITATION STARTING IN THE MOUNTAINS AROUND NOON
AND THEN SPREADING TO THE ADJACENT PLAINS BY LATE AFTERNOON.
VERTICAL WIND PROFILES WILL BE WEAK...SO STRONGLY ORGANIZED
THUNDERSTORMS ARE NOT EXPECTED. MOST STORM MOTIONS WILL BE TO THE
SOUTHEAST. HEAVY RAINS AND SMALL HAIL WILL BE THE PRIMARY THREATS
FROM STORMS. BEFORE THE STORMS DEVELOP...HIGH TEMPERATURES ON THE
PLAINS WILL REACH THE MID AND UPPER 70S. WILL MENTION SCATTERED
THUNDERSTORMS IN THE MOUNTAINS AND FOOTHILLS...BUT ONLY ISOLATED
THUNDERSTORMS ON THE PLAINS. IT IS TOUGH TO TELL HOW FAR EAST THE
AFTERNOON CONVECTION EVENTUALLY TRAVELS...BUT SOUTHERLY LOW LEVEL
FLOW ON THE FAR EASTERN PLAINS MAY BE ENOUGH TO PRODUCE ADDITIONAL
CONVECTION OUT THERE LATE IN THE AFTERNOON.  A SURFACE COLD FRONT
WILL MOVE INTO NORTHEAST COLORADO TOMORROW EVENING...WHICH COULD
BECOME A FOCUSING MECHANISM FOR THUNDERSTORMS AT THAT TIME...OR
MORE LIKELY WILL BRING AN END TO THE SHOWER ACTIVITY. SEE
ADDITIONAL COMMENTS ON THIS IN THE NEXT SECTION.

OVERNIGHT...SKIES WILL REMAIN CLEAR WITH TEMPERATURES DROPPING TO
20S AND 30S IN THE MOUNTAINS AND THE 40S ACROSS THE PLAINS.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 308 PM MDT WED APR 29 2015

AN UPPER LEVEL DISTURBANCE MOVING OVER NORTHERN COLORADO AND
SOUTHERN WYOMING WILL PUSH A COLD FRONT ACROSS NORTHEASTERN COLORADO
LATE THURSDAY. INCREASED MOISTURE AND LIFT ASSOCIATED WITH THIS
SYSTEM SHOULD RESULT IN INCREASED PRECIPITATION CHANCES ACROSS NORTH
CENTRAL AND NORTHEASTERN COLORADO THURSDAY EVENING.

WE COULD SEE A FEW MORNING LOW CLOUDS EAST OF THE MOUNTAINS FRIDAY
MORNING ASSOCIATED WITH THE COOLER AIRMASS IN THE WAKE OF THE FRONT.
FRIDAY MAX TEMPS ARE EXPECTED TO BE A FEW DEGREES COOLER THAN
THURSDAYS READINGS. LINGERING MOISTURE COMBINED WITH DAYTIME HEATING
MAY RESULT IN ISOLATED TO SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS MOST NUMEROUS OVER THE MOUNTAINS AND FOOTHILLS. THERE
MAY BE THE POTENTIAL FOR SOME SEVERE STORMS ALONG THE FRONT RANGE
URBAN CORRIDOR AS BOTH THE GFS AND NAM SHOW CAPE VALUES NEAR OR
ABOVE 1500 J/KG.

OVER THE WEEKEND...AN UPPER LEVEL RIDGE COVERS THE SOUTHERN AND
CENTRAL ROCKIES...WITH A DRIER WESTERLY FLOW ALOFT OVER COLORADO.
TEMPERATURES ON THE PLAINS WILL RETURN TO 70S WITH ONLY A FEW
AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE. THE STORMS SHOULD BE
MAINLY HIGH BASED IN MOST AREAS...WITH THE EXCEPTION OF THE FAR
EASTERN PLAINS WHERE ADDITIONAL LOW LEVEL MOISTURE WILL BE PRESENT.

THE WEATHER BECOMES MORE INTERESTING DURING THE FIRST PART OF NEXT
WEEK AS AN UPPER LEVEL LOW PRESSURE SYSTEM EJECTS OUT OF THE
SOUTHWESTERN STATES AND ACROSS COLORADO. BY LATE MONDAY...THE GFS
AND ECMWF SHOW AN UPPER LEVEL LOW PRESSURE SYSTEM OVER NORTHERN
BAJA...WITH GULF MOISTURE INCREASING ACROSS EASTERN COLORADO.
MOISTURE AND INSTABILITY INCREASE ON TUESDAY AS THE UPPER LOW TRACKS
INTO THE FOUR CORNERS REGION. THE LOW THEN TRACKS ACROSS COLORADO ON
WEDNESDAY AND THEN MOVES INTO THE NORTHERN PLAINS STATES BY EARLY
THURSDAY MORNING. THE GFS IS STRONGER AND DEEPER WITH THIS SYSTEM
AND PRODUCES MORE PRECIPITATION ACROSS NORTH CENTRAL AND
NORTHEASTERN COLORADO. THIS PATTERN COULD PRODUCE SOME SEVERE
WEATHER AND HEAVY RAIN ACROSS EASTERN COLORADO ESPECIALLY ON
TUESDAY. THERE IS STILL UNCERTAINTY ON TRACK OF THIS
SYSTEM...HOWEVER IT DOES BEAR WATCHING.

&&

.AVIATION...(FOR THE TAFS THROUGH 00Z THURSDAY LATE AFTERNOON)
ISSUED AT 308 PM MDT WED APR 29 2015

CLEAR SKIES TONIGHT AND WINDS SWITCHING TO A LIGHT DRAINAGE AFTER
SUNSET. HIGH CLOUDS WILL BEGIN INCREASING THURSDAY MORNING AND
CONTINUE THROUGH THE AFTERNOON. CEILINGS WILL REMAIN ABOVE
6000 FT AGL THROUGH ABOUT 1 PM THURSDAY AFTERNOON. THURSDAY
AFTERNOON COULD SEE CEILINGS DROP TO 6000 FEET OR LOWER AS
THUNDERSTORMS DEVELOP OVER THE FOOTHILLS AND ISOLATED CELLS THEN
MOVE OVER THE DENVER METRO AREA. BRIEF HEAVY RAINFALL AND SMALL
HAIL WILL BE THE MAIN THREATS FROM THE THUNDERSTORMS.

&&

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

$$

SHORT TERM...DANKERS
LONG TERM...KALINA
AVIATION...DANKERS


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