Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 150218
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
818 PM MDT TUE APR 14 2015

.UPDATE...
ISSUED AT 754 PM MDT TUE APR 14 2015

THANKS TO OUR MIDNIGHT AND DAY SHIFT SHORT TERM METEOROLOGISTS...
OUR OVERNIGHT SHORT TERM FORECAST IS QUITE ON TRACK. PLEASE SEE
THE FIRE WEATHER SECTION FOR CANCELLATION OF RED FLAG WARNING.

NICE CALL ON THE WIND ADVISORY FOR ALL NEBRASKA PANHANDLE COUNTIES
...EXCEPT FOR DAWES COUNTY...WHERE WILL LET THE HIGH WIND WARNING
CONTINUE AS KINGS CANYON CONTINUING TO SEE SUSTAINED SOUTHEAST
WINDS OF 30 TO 35 MPH WITH GUSTS NEAR 50 MPH...AND THE 00Z UPPER
AIR ANALYSIS AND 00Z NAM PROGS THE LOW LEVEL JET TO CRANK UP
OVERNIGHT...AND AS OUR SHORT TERM DAY SHIFT FORECASTER CORRECTLY
ASSESSED...WINDS TEND TO PICK UP AT CHADRON IN THE EARLY EVENING
HOURS...WELL DEPICTED BY THE GFS LAMP GUIDANCE SHOWING 35 TO 41
KNOT WINDS AT CHADRON FROM 9 PM TO 1 AM.

HAVING WORKED AT GOODLAND AND AMARILLO NATIONAL WEATHER SERVICE
OFFICES AS WELL AS AT CHEYENNE...THE MODELS SOMETIMES HAVE
TROUBLE ASSESSING HOW MUCH LOW LEVEL MOISTURE WILL QUICKLY
RETURN OVERNIGHT WITH BRISK SOUTH WINDS IN THE LOW LEVELS...AND
THUS WITH THE 15/00Z NAM SHOWING BOUNDARY LAYER HUMIDITIES FROM
60 TO 80 PERCENT BY DAWN WEDNESDAY...HAVE ADDED MENTION OF FOG
OVER OUR SOUTHEASTERN NEBRASKA PANHANDLE COUNTIES...THOUGH WE
MAY ONLY SEE SOME LOW CLOUDS ADVECTING IN FROM THE SOUTH AND
SOUTHEAST.

POWERHOUSE UPPER TROUGH MOVES INTO NORTHEAST UTAH BY DAWN
WEDNESDAY AND THE 00Z NAM CONTINUING TREND OF MOISTENING LOW
AND MID LEVELS ACROSS OUR WESTERN COUNTIES WITH UPWARD VERTICAL
MOTION WORKING IN...THUS OUR POPS LOOK QUITE WARRANTED. PACIFIC
COLD FRONT MOVES INTO OUR WESTERN COUNTIES LATE TONIGHT AND
ACROSS THE REST OF OUR COUNTIES DURING THE WEDNESDAY DAYLIGHT
HOURS WITH THE 00Z NAM NOW SHOWING DECENT QPF WEDNESDAY AFTERNOON
ACROSS PORTIONS OF OUR COUNTIES AS A SHORTWAVE TROUGH ROTATES
NORTHWARD AND THE COLD FRONTAL BAROCLINIC BAND MOVES SLOWLY
EASTWARD OVER OUR COUNTIES.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 330 PM MDT TUE APR 14 2015

FAIRLY QUIET OVER THE CWA THIS AFTERNOON. SOME MODEST CUMULUS OVER
PARTS OF SE WY BUT DRY AIR HINDERING DEVELOPMENT. MEANWHILE UPPER
TROF CURRENTLY OVER THE PACIFIC NW WILL DIG SOUTH OVERNIGHT AND
CLOSE OFF A LOW OVER NORTHERN UTAH BY MORNING. GOOD SFC PRESSURE
GRADIENT OVER THE NEB PANHANDLE WILL KEEP WINDS UP THIS EVENING SO
WILL MAINTAIN WIND HIGHLIGHTS THERE. MOISTURE ASSOCIATED WITH THE
UPPER SYSTEM WILL SPREAD SLOWLY EAST AND SHOULD BRING A FEW
RAIN/SNOW SHOWERS TO FAR WESTERN PARTS OF THE CWA LATER TONIGHT.
OTHERWISE...A PACIFIC COLD FRONT WILL MOVE ACROSS THE CWA LATE
TONIGHT INTO WEDS MORNING WITH MUCH COOLER AIR MOVING IN BEHIND
IT. RAIN AND HIGHER ELEV SNOW STILL LOOKS TO SPREAD SLOWLY EAST
ACROSS THE CWA WEDS AS THE UPPER LOW DRIFTS SE ACROSS UTAH WITH
FAIRLY WIDESPREAD PCPN FOR WEDS NIGHT. ACCUMULATING SNOWS STILL
LOOK TO BE MAINLY OVER THE MTNS BUT SOME LIGHT ACCUMULATIONS
SHOULD OCCUR OVER ADJACENT AREAS OF THE PLAINS LATER WEDS NIGHT.
COOL THURSDAY AND THURSDAY NIGHT WITH PCPN MAINLY OVER THE SRN
PART OF THE CWA AS THE UPPER LOW MEANDERS AROUND THE 4 CORNERS
AREA. RAIN/SNOW LINE TRICKY AS NOT A LOT OF COLD AIR WITH THIS
SYSTEM. HOPEFULLY SOME DECENT PCPN AMOUNTS WILL FALL OVER MANY
AREAS TO ALLEVIATE THE DRY CONDITIONS SO FAR THIS SPRING.

.LONG TERM...(FRIDAY THROUGH TUESDAY)
ISSUED AT 330 PM MDT TUE APR 14 2015

THE FORECAST CHALLENGES WILL FOCUS THE FIRST HALF OF THE LONG TERM
WITH MODEL TIMING AND POSITION DIFFERENCES HANDLING THE SOUTHERN
STREAM UPPER LOW AND TROUGH. THE ECMWF...NAM AND CANADIAN MODELS
ARE SIMILAR WITH THE LOCATION OF THE CLOSED LOW OVER THE FOUR CORNERS
AT 12Z FRIDAY. THE GFS SHOWS A MORE ELONGATED LOW WITH ITS CENTER
OVER EAST CENTRAL COLORADO. THE GFS IS THE OUTLIER AS IT MOVES THE
LOW INTO THE CENTRAL/SOUTHERN PLAINS BY SATURDAY. THE OTHER MODELS
SLOWLY DRIFT THE SYSTEM EAST AND WEAKEN IT TO A OPEN WAVE. MEANWHILE...
THE NORTHERN STREAM WILL BE PROGRESSIVE DEPICTING ONE TROUGH PASSAGE
BYPASSING TO THE NORTH FRIDAY...TRANSITORY RIDGE OVERHEAD SATURDAY...
FOLLOWED BY A STRONGER TROUGH IMPACTING THE NORTHERN PLAINS AND UPPER
MIDWEST LATE SUNDAY AND MONDAY. WILL PUT MORE EMPHASIS ON THE
ECMWF/CANADIAN AND ENSEMBLES.

WITH REGARDS TO SENSIBLE WEATHER...WILL HOLD ONTO CHANCES FOR LOWER
ELEVATION RAIN/MOUNTAIN SNOW MOST OF THE CWA THIS WEEKEND. GENERALLY
LOOKING AT LIGHT QPF AMOUNTS...WITH BETWEEN 0.10 AND 0.50 INCHES.
TEMPERATURES WILL AVERAGE BELOW SEASONAL NORMALS FRIDAY...WITH
NEAR NORMAL VALUES SATURDAY. A COLD FRONT WILL PUSH THROUGH THE
CWA EARLY SUNDAY...RESULTING IN BELOW AVERAGE TEMPERATURES ONCE
AGAIN. EARLY NEXT WEEK...THE CWA WILL BE POSITIONED BETWEEN A
TROUGH TO THE NORTHEAST AND RIDGE OVER THE GREAT BASIN. THE RESULT
WILL BE DRY WEST TO NORTHWEST FLOW ALOFT AND MILDER TEMPERATURES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 634 PM MDT TUE APR 14 2015

NEBRASKA TAFS...THROUGH 03Z...STRONG SOUTH TO SOUTHEAST WINDS
GUSTING 40 TO 50 KNOTS...THEN WINDS DECREASING AT ALL SITES
EXCEPT CHADRON...WHERE THE LOW LEVEL JET PREVAILS ALL NIGHT WITH
GUSTS TO 45 KNOTS THROUGH 09Z.

VFR PREVAILS...EXCEPT FOR IFR CEILINGS AND VISIBILITIES AT SIDNEY
BETWEEN 10Z AND 15Z. PACIFIC COLD FRONT PASSES NEBRASKA TAF SITES
AFTER 15Z WITH WINDS BECOMING NORTHWEST AND THEN NORTH IN THE
AFTERNOON. CEILINGS LOWERING IN THE AFTERNOON WITH ISOLATED TO
SCATTERED SHOWERS DEVELOPING WEDNESDAY AFTERNOON...WITH ISOLATED
THUNDERSTORMS AT SIDNEY AFTER 21Z.

WYOMING TAFS...SOUTHWEST WINDS GUSTING NEAR 30 TO 40 KNOTS AT
RAWLINS THROUGH 15Z WITH VFR PREVAILING AND CEILINGS JUST ABOVE
MVFR FROM 06Z TO 15Z. PACIFIC COLD FRONTAL PASSAGE AFTER 15Z AT
RAWLINS WITH WINDS VEERING TO NORTHWEST AND GUSTING NEAR 30 KNOTS
AND ISOLATED TO SCATTERED SHOWERS DEVELOPING WITH CEILINGS
LOWERING TO NEAR 4500 FEET AGL ALONG WITH MOUNTAIN OBSCUREMENT
AFTER 20Z.

AT LARAMIE AND CHEYENNE...SOUTH TO SOUTHEAST WINDS GUSTING TO
33 KNOTS THROUGH 03Z...THEN WINDS DECREASING. WINDS BECOMING
WEST AFTER 06Z...THEN WEST AND NORTHWEST AFTER 15Z WITH PACIFIC
COLD FRONTAL PASSAGE WITH GUSTS TO 33 KNOTS. WINDS BECOMING NORTH
WEDNESDAY AFTERNOON...GUSTING TO 25 KNOTS...WITH CEILINGS
LOWERING TO 3500 TO 4500 FEET...MOUNTAIN OBSCUREMENT AND ISOLATED
TO SCATTERED SHOWERS DEVELOPING ALONG WITH VISIBILITIES IN
SHOWERS FROM 3 TO 5 MILES.


&&

.FIRE WEATHER...
ISSUED AT 754 PM MDT TUE APR 14 2015

RED FLAG WARNING EXPIRED AT 800 PM MDT AS HUMIDITIES CONTINUE
TO SLOWLY RECOVER AND WIDESPREAD CRITICAL FIRE WEATHER CONDITIONS
WILL CONTINUE TO ALLEVIATE THROUGH THE EVENING HOURS.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...WIND ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR NEZ003-019>021-054-
     055-095-096.

     HIGH WIND WARNING UNTIL MIDNIGHT MDT TONIGHT FOR NEZ002.

&&

$$

UPDATE...RUBIN
SHORT TERM...RE
LONG TERM...MJ
AVIATION...RUBIN
FIRE WEATHER...RUBIN



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