Area Forecast Discussion
Issued by NWS Cheyenne, WY

Home | 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 091718
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1118 AM MDT WED JUL 9 2014

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 440 AM MDT WED JUL 9 2014

PRETTY QUIET NIGHT WITH JUST SOME SCT MIDLVL CLOUDS PASSING ACROSS
THE REGION. THE MONSOONAL RIDGE IS LOCATED NEAR THE FOUR CORNERS
REGION WITH THE BEST SUBTROPICAL MOISTURE ACROSS ARIZONA AND
NEVADA. STORM CHANCES THIS AFTN WILL BE BETTER THAN YESTERDAY BUT
NOT AS GOOD AS THE FOLLOWING DAYS (THURS AND FRI). SFC WINDS WILL
BE SOUTH-TO-SOUTHEAST THIS AFTN ACROSS THE PLAINS WITH GOOD LLVL
MOISTURE...ESPECIALLY OVER THE NEBRASKA PANHANDLE WHERE DEWPOINTS
WILL BE IN THE 55-60F RANGE. THIS RESULTS IN LI VALUES AROUND -5C
ACROSS THE PANHANDLE. A WEAK SHORTWAVE MOVING OVER THE NORTHERN
PLAINS DURING THE AFTN WILL SERVE TO STRENGTHEN THE FLOW ALOFT SUCH
THAT BULK SHEAR WILL BE 40-45 KTS. WITH THESE CONVECTIVE
PARAMETERS...A BIT CONCERNED ABOUT A STRONG TO SVR STORM IN THE
PANHANDLE. SPC HAS THE DAY1 SLIGHT RISK GRAZING CHEYENNE COUNTY
BUT MAINLY TO THE SOUTHEAST OF THE CWA. THINKING THAT COVERAGE OF
STORMS WILL BE ISOLATED DUE TO RISING HEIGHTS ALOFT OVER THE
COURSE OF THE DAY.

MIDLVL RIDGE SHIFTS EASTWARD INTO NEW MEXICO ON THURS. THIS
MOVEMENT CAUSES THE MIDLVL FLOW TO HAVE A MORE WEST TO SOUTHWEST
COMPONENT WITH INCREASING SUBTROPICAL MOISTURE. IT IS THE MOISTURE
PLUME CURRENTLY OVER NEVADA THAT PUSHES ACROSS THE CWA ON THURS
AFTN. THE GFS SHOWS PW VALUES RISING TO AROUND 1 INCH EVEN FOR
AREAS TO THE WEST OF THE LARAMIE RANGE...SO HAVE MORE OF A SCT
COVERAGE OF STORMS. MIDLVL FLOW IS WEAKER ON THURS AND COMBINED
WITH LESS SFC INSTABILITY...THE SVR RISK IS QUITE SMALL. THE
MODELS CONTINUE TO INDICATE THAT FRI SHOULD SEE THE GREATEST
COVERAGE OF STORMS. PW VALUES RISE FURTHER WITH MOST LOCATIONS AT
1-1.3 INCHES. IN ADDITION...A WEAK COOL FRONT/SFC BOUNDARY WILL
MOVE OVER THE PLAINS IN THE MORNING WITH LLVL WINDS BECOMING
INCREASING EASTERLY AND UPSLOPE. HEAVY RAIN WILL PROBABLY BE THE
PRIMARY THREAT WITH THE STORMS ON FRI...ALTHOUGH SMALL HAIL WILL
BE POSSIBLE ALSO.

.LONG TERM...(SATURDAY THROUGH WEDNESDAY)
ISSUED AT 440 AM MDT WED JUL 9 2014

AN INCREASINGLY ACTIVE PERIOD TAKING SHAPE FOR THE UPCOMING WEEKEND
AND INTO EARLY NEXT WEEK. THE SRN PLAINS HIGH PRESSURE WILL
RETROGRADE WEST TOWARDS THE FOUR CORNERS/GREAT BASIN BY EARLY NEXT
WEEK. A SERIES OF SHORTWAVES WILL ROTATE AROUND ITS PERIPHERY AND
INTERACT WITH A FAIRLY PERSISTENT INSTABILITY AXIS THAT WILL EXIST
ALONG THE FRONT RANGE. MEDIUM RANGE GUIDANCE ARE CONSISTENT IN
MOVING THE FIRST SHORTWAVE AND ASSOCIATED WK FRONT THRU THE REGION
ON SATURDAY. NORTHEASTERLY UPSLOPE FLOW WILL FOLLOW IN THE LLVLS
AIDING CONVECTIVE COVERAGE. MODELS ALSO SHOW THE RRQ OF A H3 JET
STREAK SAGGING SOUTH LATE IN THE DAY...WHICH WILL ELEVATE DEEP LAYER
SHEAR TO AROUND 40 KNOTS. WOULD SUSPECT AT A MINIMUM A FEW STRONG
STORMS ON SATURDAY...WHICH PERHAPS SOME MARGINALLY SEVERE ACTIVITY.
CONVECTION WILL LIKELY BECOME ELEVATED AND LINGER SATURDAY NIGHT AND
SUNDAY MORNING AS WELL. CONVECTIVE COVERAGE LOOKS A BIT LESS ON
SUNDAY...BUT STILL CANT RULE IT OUT GIVEN ACTIVE NORTHWEST FLOW.
HIGH PRESSURE CENTER WILL RE-ESTABLISH ITSELF NR THE FOUR CORNERS/
GREAT BASIN MON-TUE. NORTHWEST FLOW WILL BE THE RESULT...ALLOWING
FOR A STRONGER FROPA SOMETIME ON MONDAY. THE ECMWF IS THE QUICKEST
IN DRIVING IT THRU DURING THE DAYTIME HOURS...WHILE THE GFS HOLDS
IT BACK UNTIL MONDAY NIGHT. IN EITHER CASE...CONVECTIVE CHANCES
WILL INCREASE AGAIN FOR BOTH MONDAY/TUESDAY. SHOWER/THUNDERSTORM
COVERAGE AND ORGANIZATION WILL AGAIN BE AIDED BY THE RRQ OF A H3
JET STREAK DIVING INTO THE CENTER OF THE COUNTRY. HAVE COOLED
TEMPERATURES SOME FOR TUE AND WED...BUT STILL LIKELY NOT ENOUGH IF
THE STRONGER FROPA IS REALIZED. WEDNESDAY LOOKS TO TURN A BIT
DRIER...BUT STEERED THE FORECAST TOWARD CLIMATOLOGY GIVEN TIMING
UNCERTAINTIES AT THE FAR RANGES OF THE PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY MORNING)
ISSUED AT 1118 AM MDT WED JUL 9 2014

VFR EXPECTED OVERALL THROUGH THE PERIOD WITH WNW FLOW ALOFT OVER THE
REGION.  A FEW SHOWERS OR TSTMS MAY DEVELOP THIS AFTERNOON THEN END
THIS EVENING.

&&

.FIRE WEATHER...
ISSUED AT 440 AM MDT WED JUL 9 2014

MINIMAL FIRE WEATHER CONCERNS THROUGH FRIDAY. HUMIDITY VALUES THIS
AFTERNOON WILL BE IN THE 15-20 PERCENT RANGE FOR AREAS TO THE WEST
OF THE LARAMIE RANGE...HOWEVER WIND GUSTS WILL GENERALLY BE BELOW
20 MPH. ISOLATED THUNDERSTORMS WILL BE POSSIBLE DURING THE
AFTERNOON AND EVENING. MOISTURE WILL INCREASE ON THURSDAY AND
FRIDAY AND MINIMUM HUMIDITY VALUES WILL RISE TO ABOVE 25 PERCENT.
THE INCREASE IN MOISTURE WILL RESULT IN A MORE WIDESPREAD COVERAGE
OF SHOWERS AND THUNDERSTORMS ON THESE DAYS.

&&

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

$$

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








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