Alert archive / Wyoming / Winter Weather Advisories in 2009

Winter Weather Advisory 21, NWS Cheyenne, WY

April 25, 2009

NWS Cheyenne, WY issued this winter weather advisory at Apr 25, 2009, 4:05 PM MDT. It took effect at Apr 25, 2009, 8:00 PM MDT. It was in force for 13 hr.

The area

The counties it named.

The facts

Issued
Apr 25, 2009, 4:05 PM MDT (22:05 UTC)
In effect from
Apr 25, 2009, 8:00 PM MDT
Expired
Apr 26, 2009, 9:10 AM MDT
In force
13 hr
Issued by
NWS Cheyenne, WY

What forecasters said that day

The local office's own words before this winter weather advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Cheyenne, WY wrote its last area forecast discussion before this winter weather advisory went out at Apr 25, 3:51 PM MDT, 14 minutes earlier.

Area forecast discussion, Apr 25, 3:51 PM MDT, 14 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
351 PM MDT SAT APR 25 2009

.SHORT TERM...TONIGHT THROUGH MONDAY...
MODELS ARE IN FAIRLY GOOD AGREEMENT...EXCEPT THAT GFS IS A BIT
FASTER...IN MOVING WEAK UPPER LOW INTO CENTRAL UT THIS EVENING
AND NORTHEAST FROM THERE REACHING NERN WY AREA SUNDAY MORNING.
THICKENING AND COOLING CLOUD TOPS OVER NERN UT/SW WY ALONG WITH
INCREASING LIGHTNING STRIKES ALL TESTIFY TO THE INCREASING UPPER
DYNAMICS THAT WILL BE MOVING ACROSS MUCH OF WY TONIGHT. LEFT FRONT
QUAD OF UPPER JET WILL ALSO BE COMING INTO PLAY THIS EVENING. BOTH
NAM AND GFS HAVE IMPRESSIVE QPF AMOUNTS ESPECIALLY OVER WESTERN
AND NORTHERN PARTS OF OUR CWA FROM MID EVENING INTO EARLY SUN
MORNING. DECIDED TO HOIST A WINTER WX ADVISORY FOR MOST OF OUR
MOUNTAINS EXCLUDING THE SOUTHERN LARAMIE RANGE 02Z TO 15Z. LOWER
ELEVATIONS FROM KRWL-KDGW WILL ALSO PICK UP A COUPLE OF INCHES
THOUGH TEMPS WILL NOT BE GETTING MUCH BELOW 31-33 DEGREES THERE.
LIKELY TO UNQUALIFIED POPS ARE BASICALLY IN ORDER OVER ENTIRE CWA
TONIGHT FOR RAIN/SNOW SHOWERS AND SOME EVENING TSTMS. RAIN/SNOW
SHOWERS WILL DECREASE AFTER MID MORNING SUNDAY AS STRONG DOWNSLOPE
WINDS RETURN BEHIND THE EXITING UPPER SYSTEM. SHOWERS WILL BE
INCREASING AGAIN OVER WESTERN CWA SUNDAY AFTERNOON AHEAD OF NEXT
SYSTEM MOVING ACROSS SOUTHERN ID. THIS LATTER SYSTEM WILL IMPACT
THE WEST AND SOUTH PARTS OF THE CWA SUNDAY NIGHT INTO MON MORNING
...AND HAVE BOOSTED POPS IN THESE AREAS FROM WEST TO EAST. SHOWERS
WILL BEGIN TO DECREASE MONDAY AFTERNOON AS THE LATTER UPPER SYSTEM
SHIFTS ON TO THE EAST AND WEAKENS.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY.
BY MONDAY EVENING THE SHORTWAVE IMPACTING THE AREA WILL BE SLOWLY
SHIFTING EAST...WITH DECREASING CHANCES OF PRECIPITATION THROUGH
THE EVENING. THE UPPER LEVEL FLOW BECOMES SOUTHWEST AS AN UPPER
LEVEL LOW DEVELOPS OVER THE WESTERN PORTIONS OF THE UNITED STATES.
TEMPERATURES ON TUESDAY SHOULD REBOUND RATHER QUICKLY COMPARED TO
MONDAY WITH HIGHS IN THE UPPER 50S TO LOW 60S. SHOULD SEE SOME
ISOLATED THUNDERSTORMS DEVELOPING IN THE AFTERNOON ON TUESDAY...
MAINLY WEST AND ALONG INTERSTATE 25. IT DOES NOT APPEAR THAT
THESE STORMS WILL BE SEVERE. AS THE SHORTWAVE EXISTS THE AREA...
THERE COULD BE POTENTIAL FOR STRONG AND GUSTY WINDS ACROSS THE
NEBRASKA PANHANDLE TUESDAY AFTERNOON. THE GFS AND THE ECMWF MODELS
APPEAR TO BE FAIRLY CONSISTENT UP UNTIL WEDNESDAY. HOWEVER...THEY
START TO DIVERGE FROM HOW THEY ARE BOTH HANDLING THE MOVEMENT AND
STRENGTH OF THE UPPER LEVEL LOW OVER THE WESTERN UNITED STATES.
BASICALLY THE ECMWF WEAKENS THE UPPER LEVEL LOW AND SLIDES IT
NORTHWARD ACROSS WYOMING WITH LESS IMPACT TO SOUTHEAST WYOMING.
ALTHOUGH THE 12Z MODEL RUN IS CONSISTENT WITH YESTERDAY EVENINGS
MODEL RUN...IT IS STILL A CHANGE FROM WHAT IT HAD SHOWN PREVIOUSLY.
THE GFS MODEL KEEPS THE UPPER LEVEL LOW CLOSED OFF AS IT MOVES
ACROSS CENTRAL WYOMING ON WEDNESDAY THROUGH FRIDAY MORNING. IN
EITHER CASE...THERE IS SHOULD BE ENOUGH INSTABILITY FOR SCATTERED
THUNDERSTORMS TO DEVELOP MAINLY ACROSS EASTERN PORTIONS OF THE CWA
ON WEDNESDAY AFTERNOON INTO THE EVENING. THIS POTENTIALLY COULD BE
OUR FIRST DAY FOR SEVERE WEATHER...BUT SREFS PROBABILISTIC
GRAPHICS INDICATE IT COULD BE MARGINAL. STILL SOME TIME OUT IN THE
FORECAST...SO WILL JUST MENTION THUNDERSTORMS WITH THE FORECAST.
THURSDAY WILL BE COOLER AND CONTINUE TO HAVE CHANCE OF SHOWERS
ACROSS ENTIRE CWA AS THE UPPER LEVEL FEATURES MOVES OVER WYOMING.

&&

.AVIATION...WIDESPREAD MVFR CEILINGS AND VSBYS IN RAIN AND SNOW
SHOWERS/SOME TSTMS AND EVEN PATCHY FOG WILL OCCASIONALLY LOWER
INTO IFR CATEGORY TONIGHT AND EARLY SUNDAY MORNING. CONDITIONS
WILL IMPROVE RAPIDLY TO VFR DURING THE MID TO LATE MORNING HOURS
OF SUNDAY AS DOWNSLOPE WINDS DEVELOP. MVFR CEILINGS WILL RETURN TO
KSAA AND KRWL TERMINALS LATE SUNDAY AFTERNOON AND EVENING.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...WINTER WEATHER ADVISORY FROM 8 PM SATURDAY TO 9 AM SUNDAY FOR
     WYZ063-WYZ064.
NE...NONE.

&&

SHORT TERM/AVIATION...JLH
LONG TERM....MG
Hazardous weather outlook, Apr 25, 11:06 AM MDT, 4 hours 59 minutes before
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In the hours before

Local storm report, Apr 25, 3:14 PM MDT, 51 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
314 PM MDT SAT APR 25 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0150 PM     HAIL             RAWLINS                 41.78N 107.23W
04/25/2009  E0.50 INCH       CARBON             WY   TRAINED SPOTTER

            HAIL ARRIVED WITH A SHORT SHOWER LASTING ABOUT 5 MINUTES.
            NO DAMAGE WITH STORM.

&&

DDEAL

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 25, 5:11 PM MDTSevere Thunderstorm WarningCYSCarbon37 min

Nearby

Winter Weather Advisories in Wyoming, 2009Every winter weather advisory in 2009

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.