National Weather Service Raw Text Product

416 
FXUS65 KCYS 280015
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
615 PM MDT SUN MAY 27 2012


.AVIATION...
IFR ACROSS THE FORECAST AREA THROUGH TONIGHT AND TOMORROW. 
GUSTY WINDS WILL DECREASE THIS EVENING DROPPING TO 10 TO 15 MPH
EAST OF THE LARAMIE RANGE. WEST OF THE LARAMIE RANGE WIND 
SPEEDS WILL REMAIN ELEVATED...WITH GUSTS TO 40 MPH LIKELY. WIND
PRONE AREAS SUCH AS ARLINGTON...WINDS SPEEDS OF 50 MPH ARE 
POSSIBLE THROUGH TONIGHT. WINDS WILL INCREASE AROUND SUNRISE
MEMORIAL DAY ACROSS THE FORECAST AREA WITH GUSTS OVER 30 MPH
COMMON. 


&&

.PREV DISCUSSION... /ISSUED 334 PM MDT SUN MAY 27 2012/ 

SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...
WELL-DEFINED CLOSED MID/UPPER-LEVEL LOW PRESSURE AREA SPINNING
ACROSS ERN MONTANA THIS AFTERNOON. ITS ASSOCIATED SFC LOW WAS
LOCATED ACROSS ERN NORTH DAKOTA. THE CWA HAS BEEN INFLUENCED BY A
VERY DRY AIR MASS THROUGH MUCH OF THE DAY...BUT LATEST SATELLITE
PIX SHOWS MID-LEVEL MOISTURE ADVECTING EAST. LATEST MODEL GUIDANCE
SHOWS THIS INCREASING MID-LEVEL MOISTURE AND RESULTANT WEAK
INSTABILITY SPREADING EAST THROUGH EARLY EVENING. HOWEVER THE
INVERTED-V PROFILE WILL MAKE IT DIFFICULT FOR ANY PRECIPITATION
TO REACH THE GROUND ESPECIALLY OUT ON THE ERN PLAINS. EVEN
SO...ANY PRECIPITATION WILL REMAIN EXTREMELY LIGHT. CONFIDENCE IS
WANING ON THE HIGH WINDS ACROSS PORTIONS OF SOUTHEAST WYOMING THIS
AFTERNOON. WIND GUSTS HAVE BEEN STEADY IN THE 40 TO 50 MPH RANGE
THUS FAR. THE LOWEST GATE OF MEDICINE BOW HAS HELD BETWEEN 35 AND
40 KNOTS AS WELL OVER THE RECENT HOURS. AM ALSO CONCERNED ABOUT
OUTFLOW ENHANCED WIND GUSTS ASSOCIATED WITH THESE LIGHT AND/OR
VIRGA SHOWERS THRU EARLY EVENING. SO WILL KEEP THE HIGH WIND
WARNING GOING FOR THE SAME AREAS THROUGH 9 PM.

ANY PRECIPITATION CHANCES WILL FADE QUICKLY BY SUNSET AS
INSOLATION AND INSTABILITY WANE. SKIES WILL BECOME MOSTLY CLEAR
OVERNIGHT AS DRIER AIR WORKS INTO THE CWA. WINDS WILL CONTINUE TO
BE BREEZY TO LOCALLY WINDY FOR WIND PRONE AREAS TONIGHT AS MODELS
PROG A POCKET OF 50 KNOT H7 WINDS OVERNIGHT. DID KEEP THE WINDS
HIGHER FOR WIND PRONE AREAS...BUT IN THE ABSENCE OF A LOWERING
STABLE LAYER DO NOT ANTICIPATE THAT THESE WILL REACH HIGH WIND
CRITERIA.

FOR MEMORIAL DAY AND TUESDAY...THE LOW PRESSURE AREA WILL
ACCELERATE EAST FROM NORTH DAKOTA TOWARDS THE GREAT LAKES. TIGHT
LLVL HEIGHT GRADIENT WILL CONTINUE FOR MEMORIAL DAY. SO EXPECT
ANOTHER DAY OF BREEZY WINDS. WINDS MAY APPROACH ADVISORY CRITERIA
IN THE WESTERN NEBRASKA PANHANDLE AGAIN DURING THE AFTERNOON
HOURS...BUT EXPECT THEM TO REMAIN JUST BELOW. EXPECT DRY
CONDITIONS ON BOTH MEMORIAL DAY AND TUESDAY AS SFC HIGH MOVES
THRU. MODELS BRING A SHORTWAVE INTO MONTANA BY TUESDAY NIGHT. DO
THINK THAT THE LIFT ASSOCIATED WITH THE DEVELOPING LEE-SIDE SFC
LOW WILL BE SUFFICIENT FOR AT LEAST SLIGHT CHANCE POPS AT THAT
TIME.

ONE MORE DAY OF BELOW NORMAL TEMPERATURES FOR MEMORIAL DAY AS H7
TEMPERATURES CLIMB TO AROUND 2-4C. THIS WILL RESULT IN HIGH
TEMPERATURES THAT WILL CLIMB INTO THE 60S WITH LOW 70S OVER THE
SRN PANHANDLE AND NORTH PLATTE RIVER VALLEY. H7 TEMPERATURES WILL
CLIMB TO AROUND 8C FOR TUESDAY YIELDING HIGH TEMPERATURES THAT
WILL RETURN TO THE 70S ACROSS MOST LOWER ELEVATIONS.

LONG TERM...WEDNESDAY THROUGH SUNDAY

MAIN FORECAST IMPACT ON WED AND THU WILL BE NORTHWEST UPPER
FLOW PATTERN AND SHORTWAVES PASSING BY TO THE NORTHEAST OF 
THE AREA. ON WED THE FIRST SHORTWAVE EJECTS SE THROUGH SOUTH
DAKOTA WITH GFS FARTHER SOUTH THAN ECMWF. THIS MOVES A FAIRLY
STRONG SURFACE LOW ACROSS CNTRL WY INTO NEBR WITH BEST MOISTURE
CONVERGENCE IN PANHANDLE FOR PCPN CHCS. ON THU...THE MODELS DIVERGE
WITH ECMWF TRAILING A SHORTWAVE INTO BLACK HILLS AND CNTRL NEBR WHILE
GFS HAS WEAK ENERGY NORTH INTO MONTANA. THIS DIFFERENCE PUTS MORE
PCPN IN UPSLOPE FLOW INTO SE WYOMING INTO FRI MORNING ON THE
ECMWF SOLUTION VS GFS. HAVE ELECTED TO KEEP LOWER POPS WITH PREV
GFS SOLUTION INTO THU NIGHT. ON FRI AFTN BOTH MODELS SHOW BROAD
WEST TO NORTHWEST FLOW ALOFT WITH GENERAL FLAT RIDGE. UPSLOPE AND
CONVERGENCE SHIFTS FARTHER SOUTH OF THE AREA AS UPPER RIDGE AXIS
BUILDS OVER WYOMING. BOTH MODELS INDICATE REMNANTS OF SUBTROPICAL
PACIFIC SYSTEM SOUTH OF FOUR CORNERS AREA WITH SOME MOISTURE
POSSIBLY INTERACTING WITH APPROACHING JET AND NRN STREAM SHORTWAVE
ENERGY. THIS SHOULD KEEP UNSETTLED CONVECTIVE PATTERN ACROSS
HIGHER TERRAIN INTO SUNDAY. TEMPS THROUGH THE PERIOD WILL BE
SLIGHTLY COOLER INTO THU WITH WARMING BUILDING FROM THE SOUTHWEST
FRI INTO SUNDAY. BY SUNDAY THE 700MB TEMPS WILL BE 10-14C FOR 80S
TO 90S POSSIBLE.

AVIATION...18Z TAF ISSUANCE

EXPECT GUSTY WEST SURFACE WINDS TO BE MAIN IMPACT ACROSS
THE AREA THROUGH 00Z 25-35KTS WITH 35-45KTS FROM LAR-RWL.
LARGE UPPER TROUGH MOVING EAST WILL BRING IN SOME MID LEVEL 
CIGS 060-080 LAR-RWL FROM 18-00Z AND 090-100 21Z-02Z FROM CYS
INTO NEBR PANHANDLE. MAY SEE SOME VIRGA AND OCNL DRY MICROBURST
WINDS DUE TO DRY SUBCLOUD LAYER. CIGS WILL BECOME SCT AFTER 02Z
ACROSS THE AREA WITH SFC WINDS DROPPING TO 15-25KTS BY 09Z.

FIRE WEATHER...
CRITICAL CONDITIONS WILL IMPROVE ACROSS THE SOUTHERN AND CENTRAL
NEBRASKA PANHANDLE AS TEMPERATURES COOL AROUND MID-EVENING. A RED
FLAG WARNING WILL CONTINUE FOR THESE AREAS THROUGH 7 PM. A FEW
ISOLATED SHOWERS WILL BE POSSIBLE AS WELL MAINLY WEST OF THE
LARAMIE RANGE THROUGH EARLY EVENING. NOT EXPECTING MUCH IF ANY
PRECIPITATION FROM THIS ACTIVITY. HOWEVER GUSTY WINDY WILL
BE A POSSIBILITY IN AND AROUND THIS SHOWER ACTIVITY. WINDS WILL
DECREASE SOMEWHAT OVERNIGHT BUT REMAIN BREEZY ESPECIALLY OVER THE
WIND PRONE AREAS OF SOUTHEAST WYOMING. EXPECT ANOTHER BREEZY DAY
ACROSS THE DISTRICT FOR MEMORIAL DAY. HOWEVER...MINIMUM RELATIVE
HUMIDITIES WILL ONLY DROP INTO THE UPPER TEENS AS SURFACE MOISTURE
WILL BE HIGHER THAN TODAY. DRY CONDITIONS WILL PREVAIL ON MONDAY
AND TUESDAY AS HIGH PRESSURE BUILDS ACROSS THE AREA. A WEAK
DISTURBANCE WILL PUSH TOWARDS THE DISTRICT TUESDAY NIGHT AND
WEDNESDAY...SO EXPECT SMALL PRECIPITATION CHANCES TO RETURN AT
THAT TIME.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...HIGH WIND WARNING UNTIL 9 PM SUNDAY FOR WYZ101-WYZ104-WYZ105-
     WYZ106-WYZ107-WYZ109-WYZ110-WYZ115-WYZ116-WYZ117.
NE...RED FLAG WARNING UNTIL 7 PM SUNDAY FOR NEZ003-NEZ019-NEZ020-
     NEZ021-NEZ054-NEZ055-NEZ096.

&&

$$

SHORT TERM/FIRE WEATHER...HAHN
LONG TERM/AVIATION...SLA