Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 242157
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
357 PM CST MON NOV 24 2014

.SYNOPSIS...
ISSUED AT 352 PM CST MON NOV 24 2014

AT 20Z WATER VAPOR IMAGERY SHOWED AN AMPLIFIED UPPER LEVEL
PATTERN OVER THE CONUS WITH RIDGING IMPACTING BOTH THE WEST AND
EAST COASTS AND A DEEP TROUGH ACROSS THE CENTRAL PART OF THE
COUNTRY ANCHORED TO AN UPPER LOW OVER ONTARIO. AT THE SURFACE AND
WITH VISIBLE SATELLITE COULD SEE THE SURFACE LOW TO THE EAST ALSO
OVER ONTARIO WITH THE COLD FRONT EXTENDING INTO THE DEEP SOUTH.
IT WAS A VERY WRAPPED UP SYSTEM WITH A TIGHT PRESSURE GRADIENT
EXTENDING AS FAR WEST AS NEBRASKA THROUGH THE DAY TODAY. BOUNDARY
LAYER MIXING ACROSS THE AREA...VARYING FROM 850-750MB THIS
AFTERNOON BROUGHT BREEZY WINDS TO THE SURFACE AS READINGS HAVE
BEEN GENERALLY AT 25-30KTS THROUGH THE AFTERNOON.
ADDITIONALLY...A FEW WAVES OF WEAK ENERGY WERE CURRENTLY MOVING
ACROSS THE PANHANDLE AND WESTERN NEBRASKA THIS AFTERNOON. SOME
ENHANCED LIFT ASSOCIATED WITH THE SHORTWAVES ALONG WITH THE STEEP
LOW LEVEL LAPSE RATES WAS CONTRIBUTING TO THE DEVELOPMENT OF SNOW
SHOWERS OVER THE WESTERN PART OF THE FORECAST AREA. GENERALLY
THIS WAS FALLING AS SNOW DUE TO A LARGE T/TD SPREAD REGARDLESS OF
TEMPERATURES BEING IN THE UPPER 30S AND LOW 40S. SNOW WASN/T
AMOUNTING TO MUCH...BUT HIGHER ELEVATIONS ARE POSSIBLY SEEING SOME
LIGHT ACCUMULATIONS. THE EXCEPTION MAY BE OVER THE PINE RIDGE.
HAVE HAD NO REPORTS BUT RADAR ECHOES HAVE PERSISTED LONGEST IN
THAT AREA AND WITH THE ADDED OROGRAPHIC LIFT IN THE AREA WOULDN/T
BE SURPRISED IF AN INCH OR TWO HAS ACCUMULATED.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 352 PM CST MON NOV 24 2014

THE LAST OF THE TRAIN OF WEAK SHORTWAVES MOVING ACROSS WESTERN
NEBRASKA WILL MOVE THROUGH THIS EVENING. THIS WILL BRING AN END
TO THE LIFT OVER THE AREA...AND AS THE BOUNDARY LAYER BECOMES
DECOUPLED...THE LOSS OF THE STEEP LOW LEVEL LAPSE RATES WILL
BRING AN END TO THE SHOWERS. MAY SEE THE SNOW PERSIST OVER
NORTHERN SHERIDAN COUNTY INTO THE EVENING /OUT TO 02Z OR SO/ WITH
OTHER AREAS SEEING AN END TO THE SHOWERS BY 00Z.

THE PRESSURE GRADIENT RELAXES TONIGHT AS THE SYSTEM OVER ONTARIO
CONTINUES TO MOVE EASTWARD. THIS WILL ALLOW THE BOUNDARY LAYER TO
DECOUPLE TONIGHT SO EXPECTING WINDS TO BECOME LIGHT. A WEAK
PACIFIC FRONT WILL MOVE ACROSS NEBRASKA TONIGHT ASSOCIATED WITH
THE PREVIOUSLY MENTIONED SHORTWAVE TROUGH. THIS WILL ALSO BRING
INTERMITTENT CLOUD COVER TONIGHT. THE CLOUDS SHOULD KEEP
RADIATIONAL COOLING LIMITED AND WITH THE WARMER AIR MOVING IN
DON/T EXPECT AN EXTREME DROP IN LOWS TONIGHT. THE FRONT WILL
BRING A SHIFT IN THE WINDS TO THE WEST/SOUTHWEST WHICH WILL
PERSIST THROUGH THE DAY TUESDAY. LOW PRESSURE ASSOCIATED WITH
ANOTHER UPPER LEVEL SYSTEM MOVING OVER THE WESTERN CONUS RIDGE
WILL MOVE INTO EASTERN MONTANA AND WESTERN NORTH DAKOTA ON
TUESDAY. WARM AIR ADVECTION AHEAD OF THIS SYSTEM WILL RAISE 850MB
TEMPERATURES BY UP TO 5 DEGREES FROM THE CURRENT TIME. WITH THE
WEST-SOUTHWEST DOWNSLOPE FLOW IN THE LOW LEVELS AND FORECAST
SOUNDINGS AGAIN SHOWING DECENT BOUNDARY LAYER MIXING...FELT THE
TEMPERATURE FORECAST WAS A BIT COOL AND INCREASED HIGHS A FEW
DEGREES...ESPECIALLY OVER SOUTHWEST NEBRASKA. THE FORECAST IS NOW
A BIT ABOVE THE STATISTICAL GUIDANCE BUT THE TREND OVER THE PAST
FEW DAYS HAS BEEN WARMER SO AM FAIRLY CONFIDENT WITH THIS CHANGE.
BY THE END OF THE DAY TUESDAY THE FRONT ASSOCIATED WITH THE
NORTHERN PLAINS SURFACE LOW WILL HAVE MOVED EAST AND BE THROUGH
CENTRAL NEBRASKA. CROSS-SECTIONS ARE INDICATING SOME DEEPER
MOISTURE ALONG THE FRONT OVER SOUTH DAKOTA AND NORTHERN NEBRASKA
WHICH COULD GENERATE SOME LIGHT SHOWERS SO WILL CONTINUE WITH
THAT MENTION FOR LATER TUESDAY AFTERNOON.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 352 PM CST MON NOV 24 2014

TUESDAY NIGHT THROUGH WED NIGHT NORTHWEST FLOW WILL DOMINATE THE
AREA AS RIDGE AXIS IS ACROSS THE WESTERN CONUS AND TROUGH DIGS
TOWARDS THE MID ATLANTIC STATES. WITH THE COLD FRONT SE OF THE
AREA...EXPECT SOME CAA TUESDAY NIGHT. THE BULK OF THE COLD AIR
WILL REMAIN TO THE NORTH AND EAST...HOWEVER WILL SEE A SLIGHT COOL
DOWN FOR WED. POST FRONT COLD AIR RESULTS IN ABOUT 1000 METER
LAYER OF FAVORED DENDRITIC GROWTH ZONE. LIFT IN THE COLUMN IS
MARGINAL ALTHOUGH MOISTURE IS INITIALLY GOOD...HOWEVER MODELS
QUICKLY CREATE A DRY POCKET AROUND 650MB TO 750MB. THIS DRY POCKET
SHOULD BE ENOUGH TO LIMIT SNOW REACHING THE GROUND...ESPECIALLY
ACROSS SW NEB WHERE MODELS SHOW THE GREATEST DRYING OF THE LAYER.
THE HIGHER TERRAIN AND SOME ENHANCEMENT DOWNWIND OF THE BLACK
HILLS IS EXPECTED TO LINGER LIGHT SNOW ACROSS THE NW ZONES. DURING
THE DAY ON WEDNESDAY A WARM FRONT WILL BEGIN TO LIFT NE ACROSS THE
AREA. THIS WAA ALONG AND AHEAD OF THE BOUNDARY WILL RESULT IN
MOSTLY CLOUDY SKIES...ALTHOUGH THE DRY LL POCKET REMAINS. CANNOT
RULE OUT A FEW FLURRIES/SPRINKLES ACROSS SW INTO N
CENTRAL...ALTHOUGH WILL KEEP FORECAST DRY AT THIS TIME. THE NW
ZONES WILL HAVE LESS OF A DRY POCKET AND COULD SEE SOME LIGHT
SNOW REACHING THE GROUND.

AFTER HIGHS WED IN THE 30S AND 40S...A SOUTHERLY WIND KICKS UP
THURSDAY. DECOUPLING AND DECREASING SKIES /IN THE WAKE OF THE
WARM FRONT/ IN THE MORNING WILL ALLOW FOR A COOL START /TEENS TO
AROUND 20/ THEN A NICE WARM UP FOR THE HOLIDAY...ESPECIALLY
ACROSS SW NEB. THURSDAY SKIES WILL BE DECREASING FROM SW TO NE
AIDING IN TEMPS WARM INTO THE 50S ACROSS SW NEB...WHILE STILL
HOLDING ON TO SOME MID AND UPPER 30S ACROSS N CENTRAL. BY FRIDAY
50S AND 60S WILL BE COMMON. THE FORECAST TRENDED UP...BUT WITH A
FEW OF THE MODELS SHOWING 850 MB TEMPS SURGING TO 17C ACROSS SW
NEB...A HIGH NEAR OR EVEN TOPPING 70 IS POSSIBLE.

SATURDAY WILL SEE THE NEXT COLD FRONT MOVE DOWN ACROSS THE
NORTHERN PLAINS. MODELS HAVE SLOWED DOWN THE ARRIVAL TIME...AND
FORECAST FOLLOWS THE TREND...WARMER. WITH THE RECENT STRUGGLES
WITH THE EXTENDED MODELS...CONFIDENCE IS LOW ON TIMING AND WOULD
NOT BE SURPRISED TO SEE ADDITIONAL MODEL ADJUSTMENTS. FOR NOW
LOOKS LIKE SATURDAY WILL BE CLOSE TO FRIDAY AS THE FRONT HAS
TRENDED LATER IN THE DAY ON SATURDAY. IF THE TREND
CONTINUES...SATURDAY COULD END UP JUST AS WARM...IF NOT
WARMER...THAN FRIDAY.

COLD FRONT SHOULD BE THROUGH THE AREA BY SUNDAY MORNING. MODELS
IN GOOD AGREEMENT DROPPING 850 MB TEMPS BACK TO AROUND -10C
BEHIND THE FRONT DURING THE DAY SUNDAY. THIS WILL BRING A RETURN
OF NOTICEABLY COOLER TEMPS...HIGHS IN THE 20S AND LOWER TO MID
30S. NOT MUCH MOISTURE TO WORK WITH DURING FRONTAL PASSAGE AND
POST FRONTAL AND FORECAST IS DRY AT THIS TIME. THE COLD AIR IS
ONLY A GLANCING BLOW...WITH TEMPS QUICKLY REBOUNDING. BY MONDAY
GUIDANCE IS BACK ON AN UPWARD TREND....HIGHS GENERALLY IN THE 30S
WITH SW NEB IN THE 40S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1214 PM CST MON NOV 24 2014

A SURFACE LOW OVER THE GREAT LAKES IS KEEPING THE PRESSURE
GRADIENT ACROSS NEBRASKA FAIRLY TIGHT TODAY AND WITH GOOD LOW
LEVEL MIXING BREEZY WINDS WILL PERSIST THROUGH THIS AFTERNOON. THE
PRESSURE GRADIENT WILL RELAX TONIGHT...ALLOWING THE BOUNDARY LAYER
TO DECOUPLE AND WINDS TO DECREASE TO BELOW 10KTS. AN AREA OF LOW
PRESSURE WILL MOVE OUT OF THE NORTHERN ROCKIES ON TUESDAY WHICH WILL
LEAD TO WINDS SWITCHING TO THE SOUTHWEST BY TUESDAY MORNING. THERE
WILL BE SNOW CONFINED TO THE NORTHERN PANHANDLE THIS AFTERNOON
WHICH WILL END BY MID EVENING. OTHER PARTS OF THE AREA WILL SEE
DRY CONDITIONS. THERE IS SOME INDICATION OF MVFR CEILINGS MOVING
INTO NORTHERN NEBRASKA OVERNIGHT SO HAVE INCLUDED THIS IN THE KVTN
FORECAST. CEILINGS WILL IMPROVE TO IFR BY 12Z.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...BROOKS
SHORT TERM...BROOKS
LONG TERM...MASEK
AVIATION...BROOKS




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