Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 202033
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
233 PM MDT SAT SEP 20 2014

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 220 PM MDT SAT SEP 20 2014

REX BLOCK OVR WRN NOAM SLOWING DOWNSTREAM PATTERN PROGRESSION.
EARLY AFTERNOON SATELLITE PIX SHOW JUST A FEW SHALLOW CU
DEVELOPING OVR MTNS IN ADDITION TO LARAMIE CO. 19Z SFC ANALYSIS
SHOWS 1024MB SFC HI PUSHING LAST NIGHTS COLD FRONT INTO THE TX/OK
PANHANDLES. TEMPERATURES ARE RUNNING 5-10F COOLER IN THE COOLER
POST FRONTAL AIR MASS COMPARED TO THIS TIME YESTERDAY. SUBSIDENCE
FROM THE SFC HI WILL COMBINE WITH THE DRY AIR MASS TO KEEP
CONDITIONS DRY TONIGHT.

UPPER LOW OVR THE SW CONUS WILL LIFT NE THRU THE GREAT BASIN
SUNDAY AS IT BEGINS TO PHASE WITH THE NRN STREAM. SHOULD BEGIN TO
SEE MOISTURE/CLOUDS ADVECT NORTHEAST INTO SRN CARBON/ALBANY
COUNTIES AS EARLY AS SUNDAY MORNING...BUT MORE SO SUNDAY
AFTERNOON. MOIST ASCENT AHEAD OF THE LOW PRESSURE WILL COMBINE
WITH COOLING MID-LEVEL TEMPS TO BEGIN TO PRODUCE SHOWERS AND A FEW
EMBEDDED THUNDERSTORMS PRIMARILY ACROSS AREAS WEST OF INTERSTATE
25 DURING THE AFTERNOON HOURS. PROGD SBCAPES OF AROUND 500 J/KG
WILL SUPPORT ONLY GARDEN VARIETY CONVECTION. THIS CONVECTION WILL
CONTINUE TO LIFT NORTHEAST ACROSS THE REST OF THE CWFA SUNDAY
NIGHT AND DURING THE DAY ON MONDAY A PRE-FRONTAL SFC TROF MOVES
THRU. PRECIPITATION CHANCES WILL DECREASE W-E ON MONDAY NIGHT AS
THE FILLING UPPER LOW PASSES THRU THE CWFA.

THE PACIFIC ORIGIN OF THE APPROACHING SYSTEM WILL HAVE LITTLE
EFFECT ON TEMPERATURES AS PROGD H7 TEMPS OF 8-10C YIELD AFTERNOON
HIGHS THAT WILL REACH THE 70S AT MOST LOCALES.

.LONG TERM...(TUESDAY THROUGH FRIDAY)
ISSUED AT 220 PM MDT SAT SEP 20 2014

MAINLY DRY CONDITIONS THROUGH THE LONG TERM WITH TEMPERATURES
SLIGHTLY ABOVE SEASONAL NORMS. SHORTWAVE RESPONSIBLE FOR THE
UNSETTLED WEATHER ON MON WILL HAVE MOVED EASTWARD INTO
NEBRASKA/SOUTH DAKOTA BY TUES WITH LARGE SCALE SUBSIDENCE OVER THE
CWA. NORTHWEST WINDS WILL BE BREEZY THROUGH THE EARLY AFTN WITH
THE SFC TROUGH LOCATED OVER WESTERN NEBRASKA. ISOLATED SHOWERS
WILL STILL BE POSSIBLE OVER THE NEBRASKA PANHANDLE THROUGH THE
DAY. UPPER LEVEL RIDGE IS QUICK TO BUILD OVER COLORADO AND WYOMING
BY WED AND THURS. WHILE TEMPS WILL BE SLIGHTLY ABOVE
NORMAL...GENERALLY 70S TO THE EAST OF THE LARAMIE RANGE...THE LACK
OF DOWNSLOPING WILL KEEP TEMPS FROM GETTING TOO WARM. WINDS WILL
BE LIGHT WITH THE WEAK FLOW ALOFT. SOME MODEL DISAGREEMENT
EMERGES BY FRI WITH REGARD TO EASTWARD MOVEMENT OF THE BIG WESTERN
TROUGH. THE GFS IS MORE PROGRESSIVE AND WOULD BRING INCREASED
MOISTURE AND CLOUD COVER BY LATE FRI IN THE DEEP LAYERED SOUTHERLY
FLOW. THE ECMWF KEEPS THE TROUGH OFF THE WEST COAST WITH THE RIDGE
REMAINING ENTRENCHED OVER WYOMING.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING)
ISSUED AT 1133 AM MDT SAT SEP 20 2014

VFR CONDITIONS THROUGH THE TAF PERIOD. CLOUD COVER WILL BE LIMITED
TO A FEW AFTERNOON CUMULUS. NORTH-TO-NORTHEAST WINDS WILL
GENERALLY BE LESS THAN 15 KTS THROUGH THE AFTERNOON.

&&

.FIRE WEATHER...
ISSUED AT 230 PM MDT SAT SEP 20 2014

A UNSETTLED PERIOD THRU EARLY NEXT WEEK WILL KEEP ANY CRITICAL
FIRE WEATHER CONCERNS AT BAY. AN AREA OF LOW PRESSURE WILL BRING
FAIRLY DECENT CHANCES OF WETTING RAINS TO THE DISTRICTS BEGINNING
SUNDAY AFTERNOON AND CONTINUING INTO MONDAY EVENING. DO NOT
ANTICIPATE SIGNIFICANT RAINFALL TOTALS...HOWEVER A FEW TENTHS OF
AN INCH WILL BE A POSSIBILITY IN THE HEAVIEST SHOWERS/STORMS.
DRIER AND WARMER CONDITIONS WILL RETURN TUE-FRI. EVEN SO MINIMUM
RELATIVE HUMIDITIES ARE STILL ONLY EXPECTED TO REACH 20 TO 30
PERCENT.

&&

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

&&

$$

SHORT TERM...HAHN
LONG TERM...FINCH
AVIATION...FINCH
FIRE WEATHER...HAHN



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