Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 191755
AFDBOU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1155 AM MDT TUE AUG 19 2014

.UPDATE...
ISSUED AT 1155 AM MDT TUE AUG 19 2014

MINOR CHANGES FOR CONVECTIVE DETAILS. TWO SHORTWAVES APPARENTLY
ORGANIZING SHOWERS UPSTREAM...ONE WILL PASS OVER DENVER IN THE MID
TO LATE AFTERNOON HOURS...THE OTHER WILL COME INTO WESTERN
COLORADO THIS EVENING AND WILL LIKELY KEEP SOME SHOWERS GOING IN
THE MOUNTAINS OVERNIGHT. OVERALL RAISED POPS A LITTLE BIT AND
TRENDED THEM TOWARD THE TIMING OF THESE WAVES. STILL LOOKING
SOMEWHAT UNFAVORABLE IN THE AREA JUST EAST OF THE MOUNTAINS.
WARMING ALOFT AND A LACK OF LOW LEVEL MOISTURE WILL LIMIT
CAPES...AND WESTERLY FLOW ALOFT WILL INCREASE SO THERE WILL BE
SOME DOWNSLOPING OFF THE GROUND BEHIND THE FIRST WAVE OF STORMS.
SO CONVECTIVE BANDS WILL LIKELY WEAKEN AS THEY COME
DOWNHILL...THEN FILL IN AGAIN AS THEY MOVE ACROSS THE PLAINS.
STILL A LITTLE SEVERE THREAT ON THE EASTERN PORTION OF THE PLAINS
WHERE CAPES WILL BE MORE LIKE 1000-1500 J/KG. GIVEN THE LIKELY
LINEAR NATURE OF THE CONVECTION...MAIN THREAT WILL BE WIND BUT
STRONG PULSES COULD HAVE SOME HAIL. HARD TO TELL HOW MUCH OF THE
SECOND WAVE WILL MAKE IT EAST OF THE MOUNTAINS...SOME OF THE
MESOSCALE MODELS BRING A SUBSTANTIAL AREAS OF LIGHT SHOWERS ACROSS
THE NORTHEAST...MOST ARE DRY.

&&

.SHORT TERM...(TODAY THROUGH TONIGHT )
ISSUED AT 223 AM MDT TUE AUG 19 2014

RADAR INDICATED STILL SOME LINGERING LIGHT SHOWERS OVER THE FAR
NORTHEAST PLAINS IN THE VICINITY OF JET STREAK ACROSS NEBRASKA
PANHANDLE. EXPECT THESE SHOWERS TO DIMINISH BY SUNRISE. ALSO SOME
LIGHT SHOWERS OVER WESTERN COLORADO AND EXPECT SOME OF THIS
ACTIVITY TO MOVE INTO WESTERN CWA DURING THE MORNING HOURS.

THE HIGH PRESSURE RIDGE ALOFT WILL SHIFT EASTWARD INTO THE
CENTRAL PLAINS TONIGHT AS AN UPPER LEVEL DISTURBANCE ROUNDS THE
RIDGE INTO NW COLORADO LATER TODAY. OVERALL...THE FLOW ALOFT WILL
SHIFT MORE SOUTHWEST BY AFTERNOON AS MOISTURE LEVELS CONTINUE TO
SLOWLY INCREASE. INTEGRATED PRECIPITABLE WATER VALUES FROM GPS
ALREADY REFLECTING THIS WITH VALUES UP A COUPLE OF TENTHS IN THE
PAST 18 HOURS. PW VALUES EXPECTED TO INCREASE EVEN MORE TO NEAR AN
INCH BY LATER THIS AFTERNOON. INITIALLY...MUCH OF THIS MOISTURE TO
COME IN THE WAY OF HIGHS CLOUDS THIS MORNING. THIS WILL DELAY SOME
OF THE HEATING AND REDUCE OVERALL INSTABILITY. THE MOUNTAINS WILL
BENEFIT THE MOST FROM THIS MOISTURE WITH THE BEST CHANCE FOR
SHOWERS GIVEN CLOSER PROXIMITY TO WAVE AND NOTED ASCENT. STORMS
WILL BE MOVING FAIRLY GOOD TODAY IN THE ORDER OF 10-15KT SO
OVERALL FLASH FLOOD THREAT ON THE LOW SIDE DESPITE INCREASE
MOISTURE LEVELS.

WILL ALSO EXPECT AN INCREASE IN SHOWER COVERAGE OVER LOWER
ELEVATIONS BUT INSTABILITY APPEARS MARGINAL...ESPECIALLY OVER THE
FRONT RANGE. CAN`T COMPLETELY RULE AN ISOLATED SEVERE STORM OVER
THE FAR NORTHEAST PLAINS GIVEN HIGHER LOW LEVEL MOISTURE.
TEMPERATURES TODAY WILL BE SLIGHTLY COOLER GIVEN INCREASED CLOUD
COVER FROM THIS AM AND EARLY AFTERNOON...BUT STILL CLOSE TO
SEASONAL NORMALS. OVERALL CURRENT FORECAST PACKAGE LOOKS GOOD WITH
ONLY MINOR CHANGES NEEDED.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 223 AM MDT TUE AUG 19 2014

ON WEDNESDAY...THE FLOW ALOFT WILL BE SOUTHWESTERLY WITH A TROUGH
OVER SRN CA AND AN UPPER RIDGE OVER THE SERN U.S. A WEAK UPPER
LEVEL DISTURBANCE EMBEDDED IN THE FLOW WILL PASS TO THE NORTH OF
COLORADO EARLY WEDNESDAY. THE BEST CHC OF PCPN WILL BE IN THE HIGH
COUNTRY IN THE MORNING...WITH A SLGT CHC SPILLING INTO THE NERN
PLAINS IN THE AFTN. PW VALUES STILL AROUND 0.9 INCHES BUT MINIMAL
CAPE OF 200-300 J/KG. ON THURSDAY...THE FLOW ALOFT WILL REMAIN
SWLY BUT A BIT MORE SUBSIDENT IN THE MID LEVELS AS THE RIDGE
BUILDS IN SLIGHTLY FM THE SE. THE UPPER TROUGH WILL MOVE FM SRN CA
INTO THE GREAT BASIN REGION BY 00Z FRIDAY IF THE GFS IS CORRECT.
IF THE NAM IS CORRECT...THEN THE TROUGH WILL STILL BE OVER SRN CA.
IN GENERAL...WL GO WITH CHC POPS IN THE HIGH COUNTRY WITH LESSER
POPS OVER THE NERN PLAINS THURSDAY AFTN/EVNG. ON FRIDAY...MDLS
STILL DO NOT HAVE A CONSISTENT HANDLE ON THE MOVEMENT OF THE
TROUGH OVER THE SWRN U.S. THE GFS LIFTS THE TROUGH AXIS NORTH AND
EAST INTO CO WHILE THE ECMWF KEEPS THE TROUGH HUNG UP OVER SRN CA.
FOR NOW WL GO WITH PERSISTENCE...A CHANCE OVR THE MTNS WITH LESSER
POPS OVER THE NERN PLAINS. TOO MUCH UNCERTAINTY TO CHANGE MUCH AT
THIS POINT. THE WEEKEND COULD BE DRIER OR NOT...IT IS ALL
DEPENDENT ON WHERE THE SUBTROPICAL MOISTURE ORIENTS ITSELF WHICH
WILL BE PREDICATED ON THE FLOW ALOFT. IF IT IS MORE WLY LIKE THE
GFS IT WILL BE DRIER...IF ITS MORE SLY LIKE THE ECMWF THEN THERE
WILL BE A BETTER CHANCE OF TSTMS.

&&

.AVIATION...(FOR THE TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 223 AM MDT TUE AUG 19 2014

VFR TODAY WITH SCATTERED THUNDERSTORMS AT TIMES OVER THE DENVER
AREA. EXPECT CONVECTIVE OUTFLOW WINDS TO DOMINATE TODAY...WITH
WINDS GOING SOUTHWEST TO WEST WITH MID AFTERNOON CONVECTION...THEN
POSSIBLY BACK TO SOUTHEAST OR EAST AS STORMS DEVELOP ON THE
PLAINS. A SECOND WIND SHIFT IS LIKELY SOMETIME THIS EVENING. GUSTS
TO 40 KNOTS ARE POSSIBLE THIS AFTERNOON...GUSTS THIS EVENING WILL
BE LIGHTER.

&&

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

$$

UPDATE...GIMMESTAD
SHORT TERM...ENTREKIN
LONG TERM...COOPER
AVIATION...GIMMESTAD



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