National Weather Service Weather Forecast Office

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

000
FXUS65 KCYS 081302
AFDCYS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
602 AM MST SAT MAR 8 2014

.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 445 AM MST SAT MAR 8 2014

TODAY WILL SEE A WELCOME BREAK IN THE RECENT ACTIVE WEATHER PATTERN
AS THE UPPER LEVEL LOW THAT BROUGHT SNOW AND RAIN YESTERDAY DIVES
SOUTHWARD...AND AN UPPER LEVEL RIDGE BEGINS TO BUILD OVERHEAD. FOG
HAS SETTLED IN MAINLY FOR THE NEBRASKA PANHANDLE EARLY THIS
MORNING...WITH SOME AREAS OF DENSE FOG ALONG THE CHEYENNE RIDGE FROM
PINE BLUFFS TO SIDNEY...AND UP NEAR ALLIANCE. A LOOK AT AREA SFC
OBS SHOWS A WEAK LEESIDE TROUGH DEVELOPING EARLY THIS MORNING WITH
WINDS SHIFTING TO A MORE WESTERLY COMPONENT. THIS SHOULD ADVECT
THE FOG ESE THROUGH THE EARLY MORNING HOURS...WITH EVENTUAL
CLEARING EXPECTED SHORTLY AFTER SUNRISE. A MUCH DRIER AIRMASS WILL
MOVE INTO THE CWA TODAY WITH SKIES EXPECTED TO BE MOSTLY CLEAR.
FORECAST SOUNDINGS SHOW THE ATMOS COLUMN WILL WARM TODAY WITH
FAIRLY GOOD LLVL MIXING ACROSS THE AREA. AS A RESULT...MAX TEMPS
WILL WARM A BIT AS COMPARED TO YESTERDAY...AVERAGING ABOUT 5 TO
10F HIGHER...WITH SLIGHTLY WARMER READINGS IN THE PANHANDLE.

A STRONG UPPER SYSTEM MOVING INTO THE PAC NW TONIGHT AND SUNDAY
WILL FURTHER DEEPEN THE LEESIDE PRESSURE TROUGH WITH A THERMAL
RIDGE MOVING OVERHEAD. MOS GUIDANCE STILL SHOWS SIGNIFICANT
DIFFERENCES IN THE TEMPERATURE FORECAST FOR SUNDAY...AND THINK
THAT WITH THE DOWNSLOPE WARMING COMPONENT FROM WINDY CONDITIONS
DEVELOPING THROUGH THE DAY SHOULD FAVOR THE WARMER GUIDANCE.
SO...MAINTAINED THE TREND FOR HIGH TEMPS IN THE 60S AND 70S ACROSS
THE EASTERN PLAINS WITH 50S IN THE WEST. REGARDING THE WINDS...THE
SFC PRESSURE GRADIENT LOOKS TO STRENGTHEN THROUGH THE MORNING AS
PRESSURE FALLS DEEPEN AND SHIFT TO THE EAST ACROSS THE NORTHERN
PLAINS EARLY SUNDAY MORNING. HOWEVER...THE PRESSURE PATTERN IS
NOT INCREDIBLY FAVORABLE FOR A HIGH WIND EVENT AS THE DEEPEST
PRESSURE FALLS LOOK TO BE TOO FAR TO THE EAST TO HAVE A
SUBSTANTIAL EFFECT ON THE SFC PRESSURE GRADIENT. WITH THAT
SAID...THE WRKHGT PRODUCT SHOWS THE LLVL GRADIENT INCREASING TO
AROUND 60 DAM DURING THE TIME OF STRONGEST WAA EARLY SUNDAY
MORNING...WHICH LOOKS TO DEVELOP A CAPPING INVERSION AROUND MOUNTAIN
TOP. THIS SETUP WILL NO DOUBT BRING WINDY CONDITIONS TO THE WIND
PRONE REGIONS ALONG AND WEST OF INTERSTATE 25 SUNDAY MORNING...BUT
700 MB WINDS LOOK TO INCREASE TO JUST AROUND 50 KTS AND DEEP
SUBSIDENCE WILL BE LACKING OVERALL...SO NOT THINKING WINDS WILL
BECOME ALL THAT STRONG TO WARRANT A HIGH WIND WATCH AT THIS TIME.
HAVE SUSTAINED 30 TO 40 MPH IN THE FORECAST FOR THE WIND PRONE
AREAS WITH GUSTS TO AROUND 55 MPH FOR NOW THROUGH SUNDAY
AFTERNOON. THE GRADIENT WILL WEAKEN SUNDAY EVENING AS THE LEESIDE
TROUGH SHIFTS EAST WITH THE SHORTWAVE MOVING QUICKLY INTO THE
UPPER MIDWEST. DRY CONDITIONS WILL PERSIST THROUGH THE PERIOD WITH
MAINLY ONLY MID AND HIGH CLOUDS MOVING OVERHEAD WITHIN
ANTICYCLONIC FLOW ALOFT.

.LONG TERM...(MONDAY THROUGH FRIDAY)
ISSUED AT 445 AM MST SAT MAR 8 2014

THE MAIN CONCERN WITH THIS PORTION OF THE FORECAST IS THE TIMING
OF THE WAVE CURRENTLY IN THE EAST PACIFIC AND HOW THIS WAVE WILL
IMPACT OUR FORECAST AREA MONDAY NIGHT AND TUESDAY.

MONDAY:
LATEST WATER VAPOR LOOP WAS SHOWING A WELL DEFINED VORT LOBE
MOVING THROUGH THE EASTERN PACIFIC. AHEAD OF THIS FEATURE...WE
SHOULD SEE ANOTHER FAIRLY NICE DAY SETTING UP FOR MONDAY.
ALTHOUGH...IT WILL BE A BIT BREEZY AND MORE CLOUD COVER THAN
SUNDAY. STANDARDIZED 700MB TEMPERATURE ANOMALIES FROM THE GEFS ARE
SHOWING STANDARD DEVIATION VALUES BETWEEN 1 AND 1.5 WHICH WILL
ALLOW US TO BE WELL ABOVE NORMAL FOR HIGH TEMPERATURES...BUT WE
WOULD NOT EXPECT THEM TO REACH RECORD VALUES. WE DID BACK OFF ON
HIGHS A BIT FROM THE PREVIOUS FORECAST. WE MAY HAVE TO KEEP AN EYE
ON THE POTENTIAL FOR HIGHER WIND SPEEDS ON MONDAY...ESPECIALLY
SINCE THIS SYSTEM DOES HAVE SOME NEGATIVE TILT ALONG WITH A
DIGGING JET.

MONDAY NIGHT-TUESDAY:
THE ECMWF/GEM APPEARS TO BE THE MOST AGGRESSIVE WITH THIS WAVE AND
SHOWS THE GREATEST AMOUNT OF QUASIGEOSTROPHIC FORCING ACROSS
SOUTHERN WYOMING ON MONDAY NIGHT INTO TUESDAY. MEANWHILE...THE GFS
KEEPS THE BULK OF THE FORCING FURTHER NORTH. THIS WILL ALL BE
HIGHLY DEPENDENT WHERE THE JET ENERGY FOCUSES AT. ALL OF THESE
SOLUTIONS DUE BRING SNOW TO THE ENTIRE REGION BEGINNING MONDAY
NIGHT ACROSS THE NORTH AND SPREADING SOUTH ON TUESDAY MORNING
BEHIND THE PACIFIC FRONTAL BOUNDARY. NOT REAL CONFIDENT ON AMOUNTS
AT THIS TIME...SINCE THERE IS LIMITED FRONTOGENESIS...BUT THERE IS
SYNOPTIC SCALE FORCING ALONG WITH THE SOME POTENTIAL INSTABILITY
FOR A SHORT TIME PERIOD MONDAY NIGHT INTO EARLY TUESDAY MORNING.
HIGH TEMPERATURES WILL MOST LIKELY OCCUR BEFORE 12Z ACROSS THE
NORTH HALF OF THE AREA AND BEFORE 18Z IN THE SOUTHERN HALF.

THE SNOW SHOULD BEGIN TO TAPER OFF TO FLURRIES BY TUESDAY EVENING
ACROSS THE ENTIRE AREA AS THE SYNOPTIC LIFT WEAKENS IN RESPONSE TO
THE UPPER JET MOVING OUT OF THE REGION.

WEDNESDAY-SATURDAY:
THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THIS SHORTWAVE
CUTTING OFF ACROSS THE SOUTHERN ROCKIES WEDNESDAY AND THURSDAY
BEFORE SHIFTING INTO THE PLAINS ON FRIDAY. THIS WILL ALLOW FOR
SOME UPPER LEVEL RIDGING TO TAKE PLACE ACROSS OUR FORECAST AREA
AND MILDER TEMPERATURES. NOT EXPECTING A BIG WARM UP AT THIS TIME...BUT
IF THIS SHORTWAVE KICKS OUT A LITTLE SOONER THINGS MAY WARM UP A
BIT QUICKER. FOR NOW...WE ARE EXPECTING TEMPERATURES TO CLIMB ABOVE
NORMAL HIGHS WHICH COULD SPELL 50S FOR AREAS EAST OF THE LARAMIE
RANGE WITH 40S TO THE WEST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 457 AM MST SAT MAR 8 2014

LATEST FOG IMAGERY WAS SHOWING DENSE FOG DEVELOPING IN THE NORTH
PLATTE RIVER VALLEY FROM SCOTTSBLUFF SOUTHEAST TOWARDS SIDNEY.
MICROPHYSICS FROM THE VIIRS IMAGERY IS SHOWING THE BACK EDGE OF
A WELL DEFINED BAND OF LOW CLOUDS/FOG STRETCHING FROM DIA TO
ALLIANCE TERMINAL. CURRENTLY...ALLIANCE IS RECEIVING SOME FOG AS WELL.
SURFACE FLOW IS FAIRLY LIGHT AT SCOTTSBLUFF WHICH IS A GOOD
INDICATION THAT A FAIRLY GOOD INVERSION IS TAKING SHAPE.
MEANWHILE...SIDNEY HAS SOMEWHAT OF A DOWNSLOPE COMPONENT WHICH
SHOULD HELP ERODE THE FOG BY AROUND 15Z OR SO. THE LATEST HRRR IS
SHOWING THE FOG ERODING AROUND THAT TIME AS WELL. NOT REAL
CONFIDENT ABOUT SCOTTSBLUFF ERODING THAT SOON...BUT IF THE SUN CAN
PENETRATE THE STRATUS DECK IT MAY BE ABLE TO ERODE BY MID MORNING.
AFTER THE FOG ERODES WE SHOULD HAVE VFR CONDITIONS BY MIDDAY.


&&

.FIRE WEATHER...
ISSUED AT 445 AM MST SAT MAR 8 2014

DRY...WARM AND WINDY CONDITIONS WILL PREVAIL ACROSS THE DISTRICT
THROUGH THE WEEKEND. WESTERLY WIND GUSTS OF 45 TO 55 MPH ARE
EXPECTED ACROSS SOUTHEAST WYOMING SUNDAY AND MONDAY WITH LESS WIND
IN THE PANHANDLE. THE WARMEST DAY LOOKS TO BE SUNDAY WITH
WIDESPREAD 60 DEGREE READINGS AND A FEW 70S LIKELY ACROSS THE
EASTERN PLAINS...WHERE HUMIDITIES WILL ALSO DROP INTO THE UPPER
TEENS TO MID 20S. FURTHER WEST...HIGHS IN THE 50S WILL COINCIDE
WITH HUMIDITIES REMAINING 25 PERCENT OR HIGHER. THE NEXT CHANCE
FOR PRECIP WILL BE TUESDAY AS A PACIFIC STORM SYSTEM MOVES ACROSS
THE ROCKIES.

&&

.HYDROLOGY...
ISSUED AT 601 AM MST SAT MAR 8 2014

LOCALIZED FLOODING CONTINUES TO BE AN ISSUE THIS MORNING FOR
SOUTHERN AND EASTERN PORTIONS OF NIOBRARA COUNTY...AND HIGHWAY 20
REMAINS CLOSED FROM LUSK TO THE NEBRASKA STATE LINE. THE FLOOD
ADVISORY FOR THIS AREA HAS BEEN EXTENDED THROUGH 530 PM THIS
EVENING. SEVERAL COUNTY ROADS IN KIMBALL COUNTY REMAIN CLOSED THIS
MORNING DUE TO FLOODING...AND THE FLOOD ADVISORY HAS BEEN EXTENDED TO
330 PM FOR THIS AREA. KIMBALL COUNTY OFFICIALS WILL VISIT THE AREA
EARLY THIS AFTERNOON TO REASSESS THE EXTENT OF FLOODING AND ROAD
CLOSURES.

&&

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

$$

SHORT TERM...RJM
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...RJM
HYDROLOGY...RJM