FXUS65 KCYS 050528
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1028 PM MST SAT FEB 4 2012

.AVIATION...06Z TAF ISSUANCE...
OTHER THAN PATCHY FOG POSSIBLE INTO LOW LYING AND VALLEY
AREAS...VFR TONIGHT THROUGH SUNDAY AFTERNOON. MAIN TAF SITES WITH
FOG POTENTIAL TONIGHT WILL BE LAR AND RWL. UNCERTAIN IF FOG WILL
FORM AT THESE LOCATIONS...BUT IF IT DOES IT COULD PRODUCE IFR TO
LIFR TYPE CEILINGS AND VISIBILITIES. MAIN FOG THREAT TIME WILL BE
LATE TONIGHT AND TOWARD SUNRISE SUNDAY MORNING. ANY FOG THAT DOES
DEVELOP TONIGHT WILL BE SHALLOW AND WILL RAPIDLY DISSIPATE AFTER
SUNRISE. WINDS WILL GENERALLY BE LIGHT ACROSS THE AREA THROUGH THE
REMAINDER OF THE WEEKEND.

&&

.PREV DISCUSSION... /ISSUED 823 PM MST SAT FEB 4 2012/

UPDATE...
FORECAST PRETTY WELL ON TRACK THIS EVENING. SOME MID TO HIGH
CLOUDS REMAIN IN PLACE ACROSS SOUTHERN PORTIONS OF THE FORECAST
AREA IN ASSOCIATION WITH UPPER LEVEL ENERGY SPINNING OVER THE
INTERMOUNTAIN WEST. CLEAR SKIES OVER THE NORTHERN FORECAST AREA
WHICH IS BEING INFLUENCED MORE BY UPPER LEVEL HIGH PRESSURE. COULD
SEE SOME PATCHY FOG TONIGHT IN LOW LYING LOCATIONS.

AVIATION...00Z TAF ISSUANCE...
OTHER THAN PATCHY FOG POSSIBLE INTO LOW LYING AND VALLEY
AREAS...VFR TONIGHT THROUGH TOMORROW. WINDS WILL GENERALLY BE
LIGHT ACROSS THE AREA THROUGH THE REMAINDER OF THE WEEKEND.

PREV DISCUSSION... /ISSUED 240 PM MST SAT FEB 4 2012/

SHORT TERM...TODAY THROUGH MONDAY NIGHT...CURRENT VISIBLE
SATELLITE LOOP SHOWS DECREASING CLOUDS ACROSS MOST OF THE AREA
WITH SOME CLOUDS LINGERING NEAR THE COLORADO BORDER AS THE POTENT
STORM SYSTEM...WHICH BROUGHT HEAVY SNOW TO PORTIONS OF THE
ROCKIES...CONTINUES TO DRIFT EAST ACROSS FAR EASTERN NEBRASKA.
COLD TEMPERATURES AND LIGHT WINDS ARE EXPECTED THROUGH THE DAY
INTO TONIGHT...AND EXPECT THIS PATTERN TO CONTINUE THROUGH EARLY
NEXT WEEK AS A REX BLOCK ESTABLISHES ITSELF OVER THE ROCKY
MOUNTAIN REGION...WITH HIGH PRESSURE ALOFT NEAR THE CANADIAN
BORDER...AND A WEAK UPPER LEVEL LOW OVER UTAH AND SOUTHWEST
WYOMING. OUTSIDE OF SOME PATCHY VALLEY FOG WEST OF THE LARAMIE
RANGE...EXPECT PARTLY CLOUDY SKIES AND COLD TEMPERATURES IN THE
SINGLE DIGITS TO NEAR ZERO.

MODELS IN VERY GOOD AGREEMENT SUNDAY THROUGH MONDAY...SHOWING THE
WEAK UPPER LEVEL LOW GRADUALLY DRIFTING EAST AS THE REX BLOCK
BEGINS TO BREAK DOWN AND A POLAR COLD FRONT DIGS SOUTHWARD ACROSS
THE HIGH PLAINS MONDAY NIGHT. DO NOT EXPECT MUCH PRECIPITATION
WITH EITHER OF THESE SYSTEMS...BUT SOME LIGHT SNOW FLURRIES OR
SNOW SHOWERS ARE NOT OUT OF THE QUESTION FOR MOST OF SOUTHEAST
WYOMING ON MONDAY AS THE UPPER LEVEL LOW DRIFTS EASTWARD AND
COMBINES WITH THE POLAR COLD FRONT TO PRODUCE SOME INSTABILITY AND
LLVL CONVERGENCE. LITTLE SNOW ACCUMULATION IS EXPECTED WITH
PERHAPS A DUSTING OR UP TO AN INCH OF SNOW POSSIBLE ALONG
INTERSTATE 80 AND THE MOUNTAINS. DO NOT EXPECT TEMPERATURES TO
WARM TOO MUCH OVER THE NEXT FEW DAYS WITH HIGHS REMAINING IN THE
20S AND 30S WITH VERY COLD OVERNIGHT LOWS IN THE SINGLE DIGITS AND
TEENS. SOME OF THE MORE SHELTERED VALLEYS MAY SEE LOW TEMPERATURES
A FEW DEGREES BELOW ZERO EACH MORNING THROUGH LATE MONDAY NIGHT.

LONG TERM...TUESDAY THROUGH SATURDAY...12Z MEDIUM RANGE MODELS
REMAIN CONSISTENT DEPICTING A PREVAILING NORTHWEST FLOW ALOFT
BETWEEN A DEEP VORTEX OVER HUDSON BAY CANADA AND HIGH AMPLITUDE
RIDGE OVER THE INTERMOUNTAIN WEST BY WEEK/S END. WEAK SURFACE
BOUNDARY ALONG THE LARAMIE RANGE TUESDAY GIVES WAY TO A RIDGE
WEDNESDAY AND THURSDAY. BOTH DAYS WILL BE DRY WITH BREEZY
WESTERLY WINDS DEVELOPING WEDNESDAY AFTERNOON ALONG AND WEST OF
THE LARAMIE RANGE. SHORTWAVE DIVING SOUTHEAST FROM SOUTH CENTRAL
CANADA INTO THE NORTHERN PLAINS THURSDAY WILL BRING A WEAK
REINFORCEMENT OF COOLER AIR THURSDAY AND THURSDAY NIGHT. MODELS
CONTINUE TO PAINT LIGHT QPF AMOUNTS OVER THE SNOWY AND SIERRA
MADRE MOUNTAINS...WITH DRY CONDITIONS ELSEWHERE. WINDS WILL BE
LIGHTER THURSDAY...BUT BECOME BREEZY OVER SOUTHEAST WYOMING BOTH
FRIDAY AND SATURDAY AFTERNOON AS ANOTHER WEAK SURFACE BOUNDARY
STALLS TO THE LEE OF THE LARAMIE RANGE. TEMPERATURES WILL BE 10
TO 15 DEGREES BELOW NORMAL TUESDAY...NEAR NORMAL WEDNESDAY AND
THURSDAY...AND 5 DEGREES ABOVE NORMAL FRIDAY AND SATURDAY.

AVIATION...18Z TAF ISSUANCE...VFR CEILINGS ABOVE 15000 FT...BECOMING
SCATTERED THIS EVENING AS DRIER AIR ALOFT FILTERS INTO THE REGION.
WEST TO NORTHWEST WINDS 5 TO 10 KT WILL BECOME LIGHT AND VARIABLE
BY THIS EVENING.

FIRE WEATHER...DRY AND SEASONALLY COOL WEATHER IS EXPECTED OVER
SOUTHEAST WYOMING AND WESTERN NEBRASKA THROUGH THE MID PART OF
NEXT WEEK ALONG WITH FAIRLY LIGHT WINDS. TEMPERATURES WILL CLIMB
BACK TO ABOVE NORMAL TOWARD THE END OF NEXT WEEK.

&&

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

&&

$$

UPDATE...LIEBL
SHORT TERM/FIRE WEATHER...TJT
LONG TERM...JAMSKI
AVIATION...LIEBL


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