Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 231143
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
643 AM CDT SAT AUG 23 2014

.SYNOPSIS...
ISSUED AT 408 AM CDT SAT AUG 23 2014

A SURFACE ANALYSIS AT 07Z INDICATED A FRONT DRAPED ACROSS SOUTHERN
SOUTH DAKOTA WHILE ANOTHER WAS DRAPED FROM WEST CENTRAL INTO
NORTHEAST KANSAS. A FAIRLY LARGE MCS WITH EMBEDDED MCVS CONTINUES TO
LIFT FROM EASTERN AND NORTHERN NEBRASKA INTO SOUTH DAKOTA. MOST IF
NOT ALL SHOWER ACTIVITY HAS ENDED FROM SOUTHWEST NEBRASKA INTO THE
CENTRAL SANDHILLS. TEMPERATURES AND DEWPOINTS RANGING IN THE 60S
ACROSS WRN AND NCTRL NEBR.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 408 AM CDT SAT AUG 23 2014

FOR TODAY...

MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PV ANOMALY AND MID LEVEL
DISTURBANCE LIFTING NORTHEAST FROM SOUTHERN UTAH CURRENTLY AND INTO
NORTHEAST COLORADO BY 00Z THIS EVENING. ALONG WITH PEAK
HEATING...THIS WILL PROVIDE AN INCREASE TO 30 POPS AFTER 21Z TODAY
ACROSS THE NWRN HALF OF FA AND A SLIGHT CHC TO SOUTHEAST AREAS. A
FAIRLY CLOUDY MORNING BASED ON RAP MODEL TIME SECTION AND LATEST
SATELLITE IMAGERY. AFTERNOON CLEARING TO PARTLY CLOUDY EXPECTED FOR
HIGHS FROM LOW 80S NORTHWEST TO UPPER 80S SOUTHWEST.

FOR TONIGHT...

THE ARW AND NMM MODELS FAVORED WHICH PERFORMED THE BEST WITH CURRENT
SYSTEM EXITING THE AREA. BEST OVERALL PRECIPITATION CHANCES THIS
EVENING WITH SYSTEM PASSAGE ARE 30-50 POPS WEST OF AN IML-ANW LINE
AND 20-30 POPS FOR AREAS EAST. STORM MOTION WILL BE TO THE NORTHEAST
AT 15 KTS. MUCH LESS RISK FOR LOCALLY HEAVY RAINFALL AS SOUNDINGS
INDICATE WARM RAIN PROCESSES NOT OPERATING. NEVERTHELESS AREAS
ACROSS THE WEST THIS EVENING MAY RECEIVE A TENTH TO QUARTER INCH OF
NEW RAINFALL. POPS LOWERING TO 20 PERCENT AFTER MIDNIGHT.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 408 AM CDT SAT AUG 23 2014

AN ACTIVE WEATHER PATTERN WILL BE IN PLACE THROUGH THIS PERIOD
WITH MULTIPLE CHANCES FOR RAIN AND COOLER TEMPERATURES EXPECTED
FOR MUCH OF THE WEEK.

THE UPPER LEVEL LOW NOW OVER IDAHO WILL CONTINUE TO IMPACT THE
FORECAST AREA THROUGH THE FIRST PART OF THIS PERIOD. THE CURRENT
FORECAST REMAINS DRY FOR SUNDAY AS THE MODELS SHOW A LACK OF
MOISTURE ACROSS THE AREA. SEVERAL MODELS ARE INDICATING A NARROW
BAND OF DEVELOPMENT MAINLY ACROSS CENTRAL NEBRASKA ALONG A COLD
FRONT THAT LOOKS TO PUSH ACROSS THE FORECAST AREA DURING THE MORNING
HOURS. THERE WILL BE SOME MID LEVEL SUPPORT AS THE UPPER LEVEL LOW
LIFTS INTO NORTHWEST NORTH DAKOTA...DRAGGING WEAK SHORTWAVE ENERGY
ACROSS THE CENTRAL PLAINS. WILL MONITOR FOR ANOTHER FORECAST CYCLE TO
SEE IF THIS TREND CONTINUES AND IF SO...MAY NEED TO ADD SOME
PRECIPITATION CHANCES FOR PART OF THE DAY SUNDAY. ALSO...A GOOD POOL
OF COLD AIR WILL BE CIRCULATING AROUND THE SYSTEM...WITH MUCH COOLER
AIR BEING DRAWN DOWN INTO NEBRASKA. BY 00Z TUESDAY THE MODELS ARE
LIFTING THE SYSTEM FURTHER NORTH...ALLOWING WARM AIR ADVECTION TO
BEGIN ACROSS THE SOUTH AND WESTERN PARTS OF THE AREA. WITH THE
COOLER TEMPERATURES AND EXPECTING AT LEAST PARTIAL CLOUD COVER THE
FORECAST HIGHS ARE NOW RANGING FROM THE MID 70S TO THE MID 80S.

AN UPPER LEVEL LOW NOW MOVING INTO NORTHWEST CANADA OUT OF THE GULF
OF ALASKA WILL DIG SOUTH INTO THE NORTHWEST PORTION OF THE CONUS BY
MONDAY WHILE THE UPPER LOW TO THE NORTH PUSHES FURTHER NORTH AND
EAST AWAY FROM THE AREA. THIS WILL KEEP THE CENTRAL PLAINS UNDER
SOUTHWEST FLOW TO HELP BRING MOISTURE UP INTO THE AREA THROUGH
MID-WEEK.

FOR SUNDAY NIGHT...THE MODELS CONTINUE TO DEVELOP CONVECTION OVER
NORTHEAST COLORADO...WHICH THEN SPREADS NORTHEAST INTO WESTERN
NEBRASKA. THE AREA WILL BE IN THE FAVORED RIGHT ENTRANCE REGION OF
THE JET AND WITH AN INCREASING LOW LEVEL JET /THOUGH NOT
PARTICULARLY STRONG/ INTO THE EVENING THERE MIGHT BE ENOUGH FORCING
TO KEEP THESE STORMS GOING OVERNIGHT INTO NEBRASKA SO MADE VERY
LITTLE CHANGES TO ONGOING PRECIPITATION FORECAST.

DURING THE DAY MONDAY...ATTEMPTED TO SHOW A TREND OF THIS ACTIVITY
MOVING NORTHEAST AND THROUGH THE FORECAST AREA. MODELS SEEM TO BE
SLOWING THE ADVANCEMENT OF THESE STORMS FROM PRIOR MODEL RUNS SO
DON/T HAVE A HIGH DEGREE OF CONFIDENCE ON THE TIMING NOR PLACEMENT
OF THESE STORM CHANCES.

KEPT LIKELY CHANCES FOR RAIN FOR PORTIONS OF THE FORECAST AREA FOR
MONDAY NIGHT. STILL LOOKS TO BE A SURFACE LOW SOMEWHERE OVER EASTERN
COLORADO/WESTERN KANSAS WITH WARM FRONT EXTENDING INTO CENTRAL AND
NORTHEAST NEBRASKA. THE MODELS ARE IN GOOD AGREEMENT WITH A WEAK
SHORTWAVE TROUGH MOVING OUT OF THE FOUR CORNERS AND ACROSS THE
CENTRAL PLAINS BY 12Z TUESDAY WHILE THE MAIN TROUGH REMAINS OFF TO
THE WEST OVER IDAHO AND NEVADA. THE COMBINATION OF FORCING FROM THE
SHORTWAVE TROUGH MOVING ACROSS THE AREA AND AN INCREASING LOW LEVEL
JET BEING FOCUSED INTO WESTERN NEBRASKA FEEL THAT MONDAY NIGHT HAS
THE HIGHEST CHANCES FOR RAINFALL. COULD BE ANOTHER DAY SIMILAR TO
YESTERDAY WHERE THERE IS ENOUGH SHEAR AND INSTABILITY TO AT LEAST
MENTION A THREAT FOR A FEW SEVERE STORMS...BUT THIS WILL DEPEND ON
CONVECTION DURING THE DAY MONDAY AND WITH PRECIPITABLE WATER VALUES
OVER 120 PERCENT OF NORMAL AND WARM CLOUD DEPTHS EXCEEDING 3500M
STORMS SHOULD BE EFFICIENT RAIN MAKERS SO MAY BE DEALING WITH MORE
OF A HEAVY RAIN THREAT.

TUESDAY THROUGH FRIDAY...THE LONG RANGE MODELS BEGIN TO DIVERGE WITH
HOW THEY HANDLE HOW THE TROUGH TO WEST BEHAVES. THE GFS QUICKLY
PUSHES IT EAST THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION BY
THURSDAY WHILE THE ECMWF AND GEM ARE SLOWER AND DON/T MOVE IT OUT OF
THE CENTRAL PLAINS UNTIL LATER IN THE WEEK. THIS WILL HAVE AN IMPACT
ON THE SENSIBLE WEATHER AS THE SLOWER SOLUTION WOULD LINGER
PRECIPITATION ACROSS THE AREA LONGER...AT LEAST THROUGH
THURSDAY...WHILE THE GFS HAS A DRY FORECAST BY WEDNESDAY MORNING.
HAVE NOT JUMPED ON THE SLOWER SOLUTION BUT DID LEAVE SOME SLIGHT
CHANCES IN THE FORECAST THROUGH THURSDAY. WHAT IS FAIRLY CERTAIN
EITHER WAY IS THAT TEMPERATURES WILL BE COOLER FOR THE WEEK. WITH
PRECIPITATION AND CLOUD COVER...SOME DAYS MAY SEE HIGHS STRUGGLE TO
GET INTO THE LOW AND MID 70S.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 642 AM CDT SAT AUG 23 2014

NEAR TERM AVIATION CONCERN IS DURATION OF MVFR CIGS. POTENTIAL FOR
CIGS BKN015-BKN020 FOR BOTH KLBF AND KVTN TERMINALS UNTIL 16Z.
THEREAFTER...ANY CIGS SHOULD LIFT TO VFR AND PERSIST FOR REMAINDER
OF THE PERIOD. DID NOT INCLUDE MENTION OF SHRA OR TSRA. EXPECT
MAIN AREA OF DEVELOPMENT TO BE WEST OF THE TERMINALS AFTER 00Z/24TH.

&&

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

$$

SYNOPSIS...ROBERG
SHORT TERM...ROBERG
LONG TERM...BROOKS
AVIATION...ROBERG






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