National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS65 KCYS 121040
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
440 AM MDT WED MAR 12 2014

.SHORT TERM...(TODAY THROUGH FRIDAY NIGHT)
ISSUED AT 440 AM MDT WED MAR 12 2014

CLOSED LOW OVR THE SW CONUS HAS DETACHED FROM THE PROGRESSIVE NRN
STREAM THIS MORNING. THIS PATTERN WILL CONTINUE UNTIL THE CLOSED
LOW FILLS AND PHASES BACK INTO THE NRN STREAM THURSDAY NIGHT AND
FRIDAY. CLOSER TO HOME...SUBSIDENCE ASSOCIATED WITH A PERSISTENT
SFC HIGH WILL BRING DRY AND WARMING CONDITIONS THROUGH THE END OF
THE WEEK. RISING HEIGHTS TODAY WILL BOOST H7 TEMPERATURES FROM
AROUND -10C THIS MORNING TO -5C BY THIS AFTERNOON. NEARLY FULL
INSOLATION TODAY WILL YIELD AFTERNOON HIGHS 10-15F WARMER THAN
YESTERDAY...NR 40 WEST AND 40S TO NR 50 EAST. DRY SHORTWAVE WILL
APPROACH THE REGION THURSDAY AND WILL BE THE KICKER SYSTEM TO OPEN
THE SOUTHWEST CONUS CLOSED LOW. ASIDE FROM A BRIEF PERIOD OF MID
/HIGH-LEVEL CLOUDS AND BREEZY SOUTHWEST WINDS ALONG AND WEST OF
THE LARAMIE RANGE...IMPACTS WITH THIS WAVE WILL BE MINIMAL.
TEMPERATURES WILL BE WARMER THURSDAY HOWEVER AS H7 TEMPS BOOST TO
NEAR -2C. THIS WILL WARM HIGHS WEST INTO THE 40S WEST AND 50S TO
NR 60 EAST. A WEAK FROPA ASSOCIATED WITH ANOTHER DRY SHORTWAVE
EMBEDDED WITHIN ACTIVE NORTHWEST FLOW WILL PUSH THRU THURSDAY
NIGHT. AGAIN...LITTLE TO NO IMPACT ASSOCIATED WITH THIS WAVE ASIDE
FROM A BIT MORE CLOUD-COVER AND SLIGHTLY COOLER HIGH TEMPS FOR
FRIDAY.

.LONG TERM...(FRIDAY NIGHT THROUGH TUESDAY)
ISSUED AT 440 AM MDT WED MAR 12 2014

SYNOPTICALLY...MODERATE TO HIGH CONFIDENCE IN MODEL SOLUTIONS
SATURDAY AND SUNDAY WITH DOMINANT RIDGING ALOFT INFLUENCING THE
WESTERN UNITED STATES. ON MONDAY...RIDGING ALOFT BEGINS TO BE
ERODED AS A SERIES OF SHORTWAVE TROUGHS ALOFT CARVE OUT OVER
MONTANA...MORE AMPLITUDE ON THE ECMWF VERSUS THE GFS. ON
TUESDAY...THE GFS AND ECMWF ARE TOTALLY OUT OF PHASE...WITH THE
12/00Z GFS SHOWING RIDGING OVER THE GREAT BASIN STATES AND THE
12/00Z ECMWF SHOWING TROUGHINESS OVER THE ROCKIES...WITH GFS
SHOWING THE 5640 METER 500 MB HEIGHT CONTOUR OVER WYOMING...AND
THE ECMWF THE 5460 METER CONTOUR AT THE SAME LOCATION...THUS LOW
CONFIDENCE IN MODEL SOLUTIONS BY TUESDAY.

SATURDAY...PROGRESSIVE POSITIVELY TILTED SHORTWAVE TROUGH ALOFT
MOVES ACROSS OUR COUNTIES...AND FROM THE LOOKS OF THE LOW AND MID
LEVEL MOISTURE...MOST LOCALES SHOULD AT LEAST SEE MEASURABLE
PRECIPITATION THROUGH WITH MINIMAL SNOWFALL ACCUMULATION DUE TO
THE FAST MOVEMENT OF THE SHORTWAVE. OUR NORTHERN LARAMIE...SNOWY
AND SIERRA MADRE RANGES SHOULD SEE DECENT OROGRAPHIC SNOWS...THUS
HAVE PAINTED POPS THERE NEAR 100 PERCENT.

SUNDAY...WINDY DAY PER DEEP UNIDIRECTIONAL FLOW ALOFT AND PROGGED
SURFACE THROUGH 500 MB GRADIENTS. NORTH AND NORTHWEST FLOW ALOFT
WILL RETARD AND LIMIT THE WARMING TREND. DRY DUE TO
PAUCITY...LACK... OF LOW AND MID LEVEL MOISTURE.

MONDAY...WARMING TREND CONTINUES AS THE FLOW ALOFT BACKS TO WEST
NORTHWEST...INDUCING LOW LEVEL THERMAL WARMING DUE TO
STRENGTHENING SURFACE LEE TROUGHING. BREEZY TO WINDY PER PROGGED
SURFACE THROUGH 700 MB GRADIENTS.

TUESDAY...CONFIDENCE IN MODEL SOLUTIONS IS QUITE MINIMAL DUE TO
ECMWF AND GFS OUT OF PHASE WITH EACH OTHER. SINCE OUR RIVERTON
NEIGHBORS ARE SIDING CLOSER TO THE WETTER AND COOLER ECMWF
SOLUTION...WILL BLEND WITH THEM FOR NOW...PAINTING 20 TO 50 PERCENT
POPS GENERALLY ALONG AND WEST OF INTERSTATE 25 IN THE
AFTERNOON...WITH 70 TO 100 PERCENT POPS OVER OUR NORTHERN LARAMIE
RANGE DUE TO OROGRAPHICS. PLUS...THE ECMWF TYPICALLY HAS BEEN DOING
BETTER THAN THE GFS WITH RESPECT TO SHORTWAVE TROUGH TRACKS IN THE
EXTENDED PERIOD. THE GFS SOLUTION SHOWS DRY...NON DESCRIPT
FLOW...WHICH SEEMS UNLIKELY SINCE WE HAVE BEEN SEEING PERIODIC 2 TO
3 DAY SHORTWAVE TROUGH PASSAGES THE PAST WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 440 AM MDT WED MAR 12 2014

VFR. SCATTERED TO BROKEN CLOUDS AT OR ABOVE 12000 FEET AGL.

&&

.FIRE WEATHER...
ISSUED AT 440 AM MDT WED MAR 12 2014

MINIMAL FIRE WEATHER CONCERNS. A DRY AND WARMER PERIOD IN STORE
ACROSS THE DISTRICT THROUGH THE END OF THE WEEK. AFTERNOON HIGHS
WILL RETURN TO THE 40S AND 50S BY THURSDAY AND FRIDAY. MINIMUM
RELATIVE HUMIDITIES WILL FALL GENERALLY 20S WITH PERHAPS A FEW
UPPER TEENS OVR THE SOUTHERN NEBRASKA PANHANDLE ON THURSDAY.
WEST/SOUTHWEST WINDS WILL INCREASE ALONG AND WEST OF I-25 ON
THURSDAY AS WELL...WITH GUSTS TO AROUND 40 MPH. THE NEXT CHANCE
FOR PRECIPITATION WILL WAIT TO RETURN UNTIL SATURDAY.

&&

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

$$

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