Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 220419 AAB
AFDLBF

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1119 PM CDT THU APR 21 2016

.SYNOPSIS...
ISSUED AT 333 PM CDT THU APR 21 2016

H5 ANALYSIS FROM EARLIER THIS MORNING HAD A CLOSED LOW
OVER WESTERN IOWA WITH A TROUGH OF LOW PRESSURE EXTENDING SOUTH INTO
THE ARKLATEX. HT FALLS OF 50 TO 70 METERS WERE NOTED FROM THE MID
MISSISSIPPI VALLEY NORTHWARD TO THE ARROWHEAD OF MINNESOTA. WEST OF
THE TROUGH AND CLOSED LOW...WAS A RIDGE OF HIGH PRESSURE WHICH
EXTENDED FROM THE FOUR CORNERS...NORTH TO NORTHERN MONTANA. WEST OF
THE RIDGE...A TROUGH OF LOW PRESSURE WAS PRESENT FROM THE
ALEUTIANS...SOUTH INTO THE EASTERN PACIFIC...AND WAS ROUGHLY 500
MILES WEST OF THE OREGON AND WASHINGTON COASTS. AT THE SURFACE...LOW
PRESSURE WAS LOCATED OVER CENTRAL IOWA WITH HIGH PRESSURE ANCHORED
ACROSS THE FRONT RANGE OF COLORADO AND WYOMING. ACROSS WESTERN AND
NORTH CENTRAL NEBRASKA...WINDS WERE NORTHERLY BETWEEN THESE TWO
SURFACE FEATURES...AND WERE BREEZY THIS AFTERNOON WITH SPEEDS OF 15
TO 25 MPH. UNDER PARTLY CLOUDY SKIES...TEMPERATURES WERE IN THE
UPPER 60S TO AROUND 70.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 333 PM CDT THU APR 21 2016

MAIN FORECAST CONCERNS ARE WIND AND TEMPERATURES. THE UPPER LOW
CONTINUES ITS SLOW EASTWARD TREK AND GETS ABSORBED WITH THE OVERALL
FLOW OVER THE GREAT LAKES. H5 RIDGE BUILDS OVER THE GREAT PLAINS
WHILE A SURFACE TROUGH APPROACHES THE PANHANDLE LATE FRIDAY.

THIS EVENING AND TONIGHT... EFFICIENT MIXING TO NEAR 750HPA AS
INDICATED BY RAP AND HRRR SOUNDINGS AND NEARLY UNIDIRECTIONAL FLOW
CREATING GUSTS TO 25MPH FOR MUCH OF THE AREA. SOUNDINGS ALSO
INDICATE LOW LEVEL LIFT... WHICH IS CONFIRMED BY A GROWING CUMULUS
FIELD OVER WESTERN NEBRASKA. LEFT PRECIP MENTION OUT AS ABUNDANT DRY
AIR EXISTS IN THE MID LEVELS AND SURFACE DEW POINT DEPRESSIONS REACH
30F WEST TO 20F EAST. CLOUDS WILL CLEAR TONIGHT WITH THE LOSS OF
DIURNAL HEATING AND WINDS RELAX WITH BOUNDARY LAYER DECOUPLING.
MADE LITTLE CHANGE TO MIN TEMPS AS MID/UPPER 30S SEEMED REASONABLE
GIVEN CLEAR SKIES... LIGHT WINDS... AND NEGLIGIBLE TEMP ADVECTION AT
H85.

FRIDAY... CONTINUED THE TREND OF FOLLOWING WARMER GUIDANCE OR GOING
SLIGHTLY ABOVE FOR MAX TEMPS. RETURN FLOW SWITCHES LOW LEVEL WINDS
TO SOUTHERLY... AND MODELS IN AGREEMENT WITH APPRECIABLE WAA. H85
TEMPS RANGE FROM NEAR 20C PANHANDLE TO 10C NORTH CENTRAL... ABOUT 5
TO 10C WARMER THAN THURSDAY. LOW LEVEL WINDS STRENGTHEN THROUGHOUT
THE DAY AS THE PRESSURE GRADIENT INCREASES AHEAD OF THE TROUGH. NAM
SHOWING AROUND 1MB/HR FALLS DURING THE AFTERNOON. COUPLED WITH
SUBSIDENCE AND MIXING TO NEAR 800HPA WHERE H85 WINDS APPROACH
30KTS... GUSTS MAY REACH 25 TO 30MPH AT THE SURFACE. DESPITE WARM
TEMPERATURES AND BREEZY WINDS... FIRE WEATHER DOES NOT APPEAR TO BE
A SIGNIFICANT ISSUE AT THIS TIME. NAM...GFS...AND EURO KEEP SFC DEW
POINTS IN THE 40S DURING THE AFTERNOON... AND MIXING RATIOS INCREASE
1-2G/KG SINCE THURSDAY. MINIMUM RH VALUES STAY ABOVE 25 PERCENT
PANHANDLE AND 30 PERCENT EAST.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 333 PM CDT THU APR 21 2016

MID RANGE...FRIDAY NIGHT THROUGH SUNDAY...A TROUGH OF
LOW PRESSURE ALOFT WILL COME ONSHORE ACROSS NRN CALIFORNIA/OREGON
LATE FRIDAY. THIS FEATURE WILL TRACK EAST INTO WYOMING OVER THE NEXT
24 HOURS...MAKING IT AS FAR EAST AS NWRN WYOMING BY 00Z SUNDAY.
DURING THIS PERIOD...A STRONG LEE SIDE SFC CYCLONE WILL DEVELOP OVER
EASTERN WYOMING AND NERN COLORADO. EAST OF THIS FEATURE...SRLY WINDS
WILL INCREASE FRIDAY AFTERNOON INTO FRIDAY NIGHT. SRLY FLOW WILL
PUSH LOW LEVEL MOISTURE NWD DURING THE NIGHT AND THIS COUPLED WITH
THE SRLY WINDS...WILL MAKE FOR MILD TEMPS FRIDAY NIGHT. FCST LOWS
WILL BE IN THE UPPER 40S TO AROUND 50...SOME 10 TO 15 DEGREES ABOVE
NORMAL. ON SATURDAY...STRONG LOW LEVEL WARM AIR ADVECTION WILL
CONTINUE WITH H85 TEMPS REACHING 25C IN THE WEST BY 00Z SUN. THE
LATEST GUIDANCE REFLECTED THESE WARMER TEMPS SHOWN IN THE GRAPHICAL
NAM AND GFS FCST MODELS FROM THIS MORNING...AND HAVE TRENDED UP
HIGHS FOR SAT AFTN. THIS RESULTED IN HIGHS IN THE LOWER 80S ACROSS
THE BOARD. WE EVEN MAY SEE SOME MIDDLE 80S IN THE NORTHWEST WHERE
DRIER AIR IS EXPECTED SAT AFTN. ON SATURDAY EVENING...A PACIFIC COLD
FRONT WILL APPROACH THE PANHANDLE SAT EVENING...AND A LEAD
DISTURBANCE WILL APPROACH SWRN NEBRASKA FROM NERN COLORADO.
THUNDERSTORM CHANCES WILL INCREASE DURING THE EVENING HOURS WITH THE
BEST CHANCES IN THE SOUTHWEST IN PROXIMITY TO THE UPPER LEVEL
WAVE...AND IN THE NORTHWESTERN CWA INVOF THE FRONT AND CLOSER
PROXIMITY TO THE H5 LOW. AS FOR THE THREAT FOR SEVERE STORMS...WAS
CONCERNED SOMEWHAT ABOUT THE 2000 J/KG CAPES DEPICTED IN THE 12Z
NAM SOLN THIS MORNING...ACROSS CENTRAL PORTIONS OF THE CWA.
HOWEVER...BULK SHEAR IS ONLY 15 TO 20 KTS SAT AFTN/EVE...SO THE
SEVERE THREAT APPEARS MINIMAL ATTM. ON SUNDAY...THE UPPER LEVEL LOW
WILL TRACK ALONG THE NEBR/SD BORDER. ATTM...THE MAIN THREAT FOR PCPN
WILL CONTINUE OVER NRN NEBRASKA WITH MAINLY DRY CONDS IN THE SOUTH.
IT WILL BE WINDY WITH DECENT NORTHWESTERLY WINDS BEHIND THE COLD
FRONT SUNDAY. TEMPERATURES WILL RANGE FROM AROUND 60 IN THE WEST TO
THE MID 70S IN THE FAR EAST.

LONG RANGE...SUNDAY NIGHT THROUGH THURSDAY...AN ACTIVE SWRLY FLOW
PATTERN WILL CONTINUE INTO NEXT WEEK. THE FIRST OF TWO UPPER LEVEL
LOWS WILL APPROACH THE FORECAST AREA MONDAY NIGHT WITH LIKELY PCPN
EXPECTED FOR TUESDAY INTO TUESDAY NIGHT. PCPN WILL LINGER IN THE
NORTH FOR WEDNESDAY...WITH DRY CONDS EXPECTED WEDS NIGHT INTO
THURSDAY. A SECOND SYSTEM WILL APPROACH THE REGION LATE THURSDAY
WITH ANOTHER ROUND OF PCPN ON TAP FOR FRIDAY INTO SATURDAY NEXT
WEEK. TEMPERATURES WILL BE COOL WITH HIGHS IN THE 50S WITH SOME 40S
POSSIBLE IN NRN NEBRASKA TUES/WEDS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1119 PM CDT THU APR 21 2016

VFR IS EXPECTED ALL AREAS OVERNIGHT THROUGH FRIDAY EVENING.

SFC LOW PRESSURE WILL ORGANIZE ACROSS THE NRN HIGH PLAINS BENEATH
AN UPPER LEVEL RIDGE OF HIGH PRESSURE. SKIES SHOULD REMAIN MOSTLY
CLEAR.

&&

.HYDROLOGY...
ISSUED AT 333 PM CDT THU APR 21 2016

RISES ON THE SOUTH PLATTE RIVER EXPECTED TO CONTINUE
OVER THE NEXT SEVERAL DAYS. UPSTREAM GAUGE AT JULESBURG STILL
SHOWING A SLOW RISE WITH AN EXPECTED CREST AT ROSCOE OF AROUND 7.3
FEET LATE FRIDAY/EARLY SATURDAY. ISSUED RVS THIS MORNING WITH
UPDATED FORECAST FROM MBRFC. SLIGHT UPTICK OBSERVED AT NORTH PLATTE
BUT STILL 1.5 FEET BELOW ACTION STAGE.

&&

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

$$

SYNOPSIS...BUTTLER
SHORT TERM...SNIVELY
LONG TERM...BUTTLER
AVIATION...CDC
HYDROLOGY...SNIVELY



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