Area Forecast Discussion
Issued by NWS Cheyenne, WY

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KCYS 291716
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1116 AM MDT MON JUN 29 2015

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 342 AM MDT MON JUN 29 2015

ONGOING EARLY MORNING CONVECTION WILL CONTINUE TO SLIDE
SOUTH/SOUTHEAST ACROSS THE ERN PLAINS THROUGH SUNRISE. THESE
SHOWERS/WEAK THUNDERSTORMS FORMED ALONG A N-S LLVL CONVERGENCE
AXIS AHEAD OF SHORTWAVE ENERGY DIVING SOUTHEAST THRU NE WYOMING
AND WRN SOUTH DAKOTA. ALTHOUGH SOME OF THIS CONVECTION MAY LINGER
SHORTLY AFTER SUNRISE...RADAR TRENDS AND MODEL PROGS CARRY THE
BULK OF THE ACTIVITY OUT OF THE CWFA BY SUNRISE. OTHERWISE...
EXPECT A DRY/HOT DAY AS THE EASTWARD PUSH OF THE UPPER HIGH
COMBINES WITH SUBSIDENCE BEHIND THE AFOREMENTIONED MID-LEVEL
SHORTWAVE. THERE MAY BE JUST ENOUGH MOISTURE FOR SOME SHALLOW
CONVECTIVE BUILD-UPS OVR THE MED BOWS...BUT CONFIDENCE IS LOW IN
ITS OCCURRENCE. H7 TEMPERATURE PROGS PEAK AROUND 17C WEST AND 12C
EAST. THIS WILL YIELD AFTERNOON HIGHS THAT WILL CLIMB WELL INTO
THE 80S ACROSS SE WYOMING WITH UPPER 80S/LOW 90S OVR WRN NEBRASKA.

NEXT SHORTWAVE WILL DIVE SOUTHEAST FROM ALBERTA INTO THE NRN
PLAINS ON TUESDAY. LEE-SIDE SFC PRESSURE FALLS WILL SPIN UP A LOW
PRESSURE AREA IN NE WYOMING/WRN SOUTH DAKOTA ON TUESDAY. THIS LOW
ALONG WITH SOUTHWARD MOVING SFC BOUNDARY AND GRADUALLY FALLING
HEIGHTS WILL SET THE STAGE FOR MORE WIDESPREAD CONVECTION TUESDAY
AFTERNOON/EVENING. MODELS PROG 800-1500 J/KG OF SBCAPE AND 30-40
KNOTS OF 0-6KM SHEAR LATE IN THE DAY. SO...SO LONG AS THE WARM
MID-LEVEL TEMPERATURES ARE UNABLE TO CAP THE ENVIRONMENT...WOULD
EXPECT CONVECTION TO BECOME SCATTERED. ALTHOUGH DONT ANTICIPATE AN
OUTBREAK...WOULD EXPECT AT LEAST A FEW STRONG STORMS ESPECIALLY
TUESDAY EVENING. COMPRESSIONAL WARMING AHEAD OF THE BOUNDARY WILL
CONTRIBUTE TO HOT CONDITIONS TUESDAY AS HIGHS CLIMB INTO THE 90S
MOST PLACES. SHOULD CONVECTION GET GOING EARLIER THAN CURRENTLY
FORECASTED...FORECAST HIGH TEMPERATURES MAY BE A FEW DEGREES TOO
WARM.

ACTIVE NORTHWEST FLOW WILL CONTINUE FOR WEDNESDAY. ALTHOUGH
CONVECTIVE COVERAGE SHOULD BE LESS COMPARED TO TUESDAY...STILL
EXPECT AFTERNOON/EVENING THUNDERSTORMS AS LLVL CONVERGENCE ALONG
THE TERRAIN COMBINES WITH ANY PRESENT MID-LEVEL SHORTWAVE ENERGY.
0-6KM SHEAR WILL STILL BE IN THE 30-40 KNOT RANGE...ESPECIALLY
ACROSS EXTREME SOUTHEAST WYOMING. HOWEVER...COOLER TEMPERATURES
BEHIND TUESDAYS WEAK BOUNDARY WILL ONLY YIELD AROUND 800-1000 J/KG
OF AVAILABLE SBCAPE. IF REALIZED THIS WOULD LIMIT THUNDERSTORM
ORGANIZATION AND COVERAGE SOMEWHAT.

.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 342 AM MDT MON JUN 29 2015

THERE IS GENERAL MODEL AGREEMENT PROGGING SLOW WESTWARD RETROGRESSION
OF THE UPPER RIDGE TOWARD UT/CA LATE THIS WEEK. THE CWFA WILL BE UNDER
THE INFLUENCE OF NORTHWEST FLOW ALOFT...WITH A SERIES OF SHORTWAVES
MOVING SOUTHEAST FROM THE CANADIAN ROCKIES INTO THE NORTHERN GREAT
PLAINS AND UPPER MIDWEST. THE BEST CHANCE FOR WETTING RAINFALL WILL
BE EARLY IN THE PERIOD AS A COUPLE OF THESE WAVES INTERACT WITH UPSLOPE
AND MOISTURE. TEMPERATURES THURSDAY AND FRIDAY WILL BE MODERATED BY
CONVECTION AND NORTHEASTERLY LOW LEVEL FLOW. THERE ARE INDICATIONS
THAT THE CENTER OF THE UPPER RIDGE WILL MIGRATE EASTWARD TOWARD
THE FOUR CORNERS LATE THIS WEEKEND. CONSEQUENTLY...WARMER TEMPERATURES
ALOFT WILL LIMIT AFTERNOON CONVECTION TO THE SOUTHEAST WY MOUNTAINS.
SATURDAY LOOKS TO BE THE WARMEST DAY WITH HIGHS IN THE 80S AND LOWER
90S. A WEAK DISTURBANCE AND FRONTAL PASSAGE WILL COOL TEMPERATURES
ABOUT 5 DEGREES SUNDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY MORNING)
ISSUED AT 1116 AM MDT MON JUN 29 2015

VFR EXPECTED OVER ALL TERMINALS THROUGH TUESDAY MORNING WITH
NORTHERLY FLOW ALOFT OVER THE REGION.

&&

.FIRE WEATHER...
ISSUED AT 342 AM MDT MON JUN 29 2015

STRONG HIGH PRESSURE ACROSS THE WESTERN UNITED STATES
WILL RESULT IN SEASONABLY WARM TEMPERATURES AND VIRTUALLY NO
PRECIPITATION CHANCES TODAY. THIS STRONG AREA OF HIGH PRESSURE
WILL GRADUALLY WEAKEN THROUGH THE MIDDLE OF NEXT WEEK RESULTING IN
AN INCREASING CHANCE OF THUNDERSTORMS AND WETTING RAINFALL TUESDAY
THROUGH THURSDAY ACROSS THE REGION. A FEW STORMS ON TUESDAY MAY
BECOME STRONG LATE IN THE DAY.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

$$

SHORT TERM...CAH
LONG TERM...MJ
AVIATION...MJ
FIRE WEATHER...CAH



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.