Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 240008
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
708 PM CDT WED APR 23 2014

.SYNOPSIS...
ISSUED AT 342 PM CDT WED APR 23 2014

A STRONG UPPER LEVEL DISTURBANCE WILL EXIT THE FORECAST AREA TONIGHT
AND BE REPLACED BY ANOTHER STRONGER UPPER LEVEL LOW SUNDAY. THIS LOW
IS EXPECTED TO MOVE VERY SLOWLY EAST THROUGH THE CNTL PLAINS SUNDAY
THROUGH TUESDAY AND PRODUCE RAIN AND STRONG WINDS WITH SEVERE
THUNDERSTORMS POSSIBLE SUNDAY AS A WARM FRONT LIFTS NORTH THROUGH
THE FCST AREA.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 342 PM CDT WED APR 23 2014

AT 19Z...WATER VAPOR IMAGERY SHOWED AN EXTENSIVELY LARGE NEGATIVELY
TILTED UPPER LEVEL TROUGH ACROSS THE WESTERN HALF OF THE
COUNTRY...WITH RIDGING THROUGH THE MISSISSIPPI RIVER VALLEY INTO THE
NORTHERN PLAINS AND INTO THE YUKON TERRITORY IN CANADA. THERE ARE
TWO MAIN PV ANOMALIES AMONGST THE TROUGH...THE FIRST HAD MOVED OUT
OF COLORADO AND INTO THE DAKOTAS THROUGH THE DAY...WHILE THE SECOND
WAS SEEN OVER ARIZONA THIS AFTERNOON. AT THE SURFACE...A COLD FRONT
HAD PASSED THROUGH MUCH OF THE LOCAL FORECAST AREA AND AT 20Z WAS
ROUGHLY FROM K9V9 TO KBBW TO KMCK...THEN EXTENDING INTO EAST CENTRAL
COLORADO. HAVE BEEN SEEING CUMULUS ALONG THE FRONT IN KANSAS AND A
FEW CUMULUS IN THE FAR NORTHEASTERN PARTS OF THE FORECAST AREA ALONG
THE FRONT OVER THE LAST SEVERAL HOURS. JUST NOT GETTING ENOUGH
CONVERGENCE AND LIFT AT THE TIME TO BE GETTING PRECIPITATION TO
DEVELOP YET AS RADAR IS STILL QUIET ALONG THE FRONT. FURTHER TO THE
WEST OVER THE PANHANDLE AND WESTERN SANDHILLS...VERY NEAR CRITICAL
FIRE WEATHER CONDITIONS WERE BEING OBSERVED WITH RELATIVE HUMIDITY
IN THE TEENS AND BREEZY NORTHWEST WINDS GUSTING TO 35 MPH.

FOR THE REMAINDER OF THE AFTERNOON AND THIS EVENING...INSTABILITY
AND MOISTURE CONVERGENCE ALONG THE FRONT HAS BEEN SLOWING INCREASING
OVER THE PAST SEVERAL HOURS AND AS THAT CONTINUES THIS AFTERNOON
EXPECT CONVECTION TO DEVELOP ALONG THE FRONT BY 00Z. THERE IS GOOD
DEEP LAYER SHEAR IN THE AREA...SO WHATEVER DOES DEVELOP WILL HAVE
THE POTENTIAL TO BECOME ORGANIZED WITH SUPERCELLS POSSIBLE...BUT
WITH THE MOVEMENT OF THE FRONT...THIS WILL LIKELY BE JUST EAST OF
THE FORECAST AREA. AS THE UPPER LEVEL PV ANOMALY PUSHES EAST THROUGH
THE EVENING...PRECIPITATION CHANCES WILL INCREASE ACROSS CENTRAL AND
EASTERN NEBRASKA AS THE LARGE SCALE LIFT INCREASES. THERE WILL BE
SOME INSTABILITY EVEN THOUGH THE AREA IS BEHIND THE FRONT...SO WILL
KEEP CHANCES FOR THUNDERSTORMS IN THE SOUTHEAST PORTIONS OF THE
FORECAST AREA THROUGH THE EVENING. BY 06Z...THE PRIMARY FOCUS FOR
STORMS WILL HAVE SHIFTED EAST OF THE LOCAL AREA SO PRECIPITATION
CHANCES END SHORTLY AFTER 06Z. THERE WILL BE A SECONDARY COLD FRONT
THAT WILL MOVE THROUGH THE AREA THIS EVENING WHICH WILL BRING SOME
STRONG WINDS...PRIMARILY TO SOUTHWEST NEBRASKA WHERE PRESSURE RISES
WILL BE THE HIGHEST. COULD SEE AN HOUR OR SO OF SUSTAINED WINDS
AROUND 30 MPH WITH GUSTS TO 40 MPH...BUT BELIEVE THIS WILL BE FAIRLY
SHORT LIVED...SO WILL NOT PUT ANY WIND HEADLINES OUT AT THIS TIME.

FOR THURSDAY...DRY AIR WILL BE THE MAIN STORY WITH SUNNY SKIES AND
NEAR CRITICAL FIRE WEATHER CONDITIONS. FURTHER DISCUSSION ON FIRE
CONDITIONS IN THE FIRE WEATHER SECTION. OTHERWISE...WESTERLY
DOWNSLOPE WINDS SHOULD ALLOW FOR GOOD WARMING DESPITE TEMPERATURES
ALOFT BEING SLIGHTLY COOLER THAN HAS BEEN OVER THE AREA THE LAST FEW
DAYS. WITH STEEP LAPSE RATES TO 700MB...HIGHS ARE LOOKING TO BE FROM
THE MID 60S TO THE LOW 70S. IN ADDITION...WITH THE DOWNSLOPE FLOW
AND DEEP MIXING...COULD GET SOME BREEZY CONDITIONS THROUGH THE DAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 342 PM CDT WED APR 23 2014

AN ELONGATED AREA OF WEAK LOW PRESSURE STRETCHING ACROSS THE NRN
PLAINS INTO THE MIDWEST WILL COALESCE ACROSS THE UPPER GREAT LAKES
THURSDAY NIGHT AND BEGIN PULLING A LATE SEASON ARCTIC FRONT SOUTH
INTO THE NRN PLAINS. THIS FRONT SHOULD REMAIN NORTH OF THE FCST
AREA FRIDAY BUT DROP INTO NERN NEBRASKA SATURDAY. LOW PRESSURE
AROUND 990 MB OR PERHAPS DEEPER WILL SET UP ACROSS NERN COLO/ERN
WY/ERN MT SATURDAY POTENTIALLY SETTING UP A LARGE TEMPERATURE
GRADIENT ACROSS THE FCST AREA. THE GEM...NAM...ECM AND GFS ALL
SHOW 80S FOR HIGH SATURDAY ACROSS THE SOUTHWEST FALLING TO 60S AND
70S ACROSS THE NORTHEAST AND LITTLE IN THE WAY OF CLOUD COVER. THE
TEMPERATURE FORECAST FOR SATURDAY CALLS FOR HIGHS IN THE UPPER 70S
SOUTHWEST TO LOWER 60S NORTHEAST WHICH IS COOLER THAN ALL OF THE
MODEL FORECAST.

THE NAM AND THE ECM INDICATE ELEVATED INSTABILITY ACROSS THE
NORTHWEST AND LIGHT QPF SATURDAY AFTN SO ISOLATED POPS ARE IN PLACE
ACROSS NORTHWEST NEB. A CORRIDOR OF STRONG SOUTHEAST WINDS DEVELOP
ACROSS THE NORTH IN RESPONSE TO DEEPENING LOW PRESSURE OVER COLO.
THE WINDS BECOME SOUTH SATURDAY NIGHT AS A WARM FRONT LIFTS NORTH
THROUGH THE FCST AREA.

THE WEATHER FRIDAY IS VERY TRANQUIL. WEAK PACIFIC HIGH PRESSURE
REMAINS ACROSS THE FCST AREA AND WINDS SHOULD GRADUALLY SHIFT AROUND
TO THE SOUTHEAST LATE IN THE DAY AS LOW PRESSURE MOVES INTO THE CNTL
ROCKIES. TEMPERATURE ADVECTION IS NEARLY NEUTRAL WHICH SUPPORTS
HIGHS IN THE 70S WITH H850MB TEMPERATURES IN THE MID TO UPPER TEENS.

SATURDAY NIGHT THROUGH WEDNESDAY...
LOW PRESSURE DEEPENS TO AROUND 985 MB ACROSS NORTHEAST COLORADO
SATURDAY NIGHT WITH THE APPROACH OF A VERY DEEP 4 CORNERS UPPER
LEVEL LOW. THE UPPER LEVEL LOW IS PROGGED TO TRACK SLOWLY EAST
ACROSS KS SUNDAY AND MONDAY. THE MODELS SHOW VERY STRONG WARM AIR
ADVECTION SUNDAY AND A LARGE AMOUNT OF DRY AIR GETTING DRAWN INTO
THIS SYSTEM WHICH WOULD SEND THE MOISTURE NORTH INTO THE DAKOTAS AND
INTO ERN NEB. HOWEVER THIS PROCESS...A WARM FRONT LIFTING THROUGH
THE FCST AREA SUNDAY...COULD BECOME THE FOCUS FOR SFC BASED SEVERE
THUNDERSTORMS. THE 12Z GFS SHOWS 1000 TO 1500 J/KG CAPE...A WEAK CAP
AND 45 KT OF BULK SHEAR ALONG THE FRONT WHICH IS CONSISTENT WITH THE
SPC DAY 5 SEVERE OUTLOOK ACROSS NCNTL NEB.

AS THE UPPER LOW MOVES EAST MONDAY...STRONG NORTHWEST WINDS SHOULD
DEVELOP WITH WIND SPEEDS INCREASING TO AROUND 30 MPH. H850MB WINDS
INCREASE TO 40 TO 45 KTS MONDAY AFTN. THE MODEL CONSENSUS SUGGESTS
STRONG WINDS COULD CONTINUE AGAIN ON TUESDAY AS THE UPPER LOW MOVES
SLOWLY INTO MISSOURI.

THE RAIN CHANCES ARE CONFINED TO THE WARM FRONT LIFTING NORTH
SATURDAY NIGHT AND SUNDAY...AND WRAP AROUND RAIN OR SHOWERS SUNDAY
NIGHT...MONDAY AND TUESDAY. THE RAIN COULD EVEN CHANGE TO WET SNOW
ACROSS THE NORTHWEST MONDAY NIGHT THROUGH TUESDAY MORNING. A 3 WAY
BLEND OF THE GEM...GFS AND ECM SUGGESTED AROUND AN INCH OF RAIN
COVERING ALL OF THE FCST AREA BUT SOME MODELS WERE WETTER OR DRIER
IN THE SOUTHWEST VS THE NORTHEAST SO AMOUNTS WILL VARY. THE HPC FCST
PREDICTS 1/4 TO 1/2 INCH IN THE SOUTHWEST TO NEAR 1 INCH IN THE
NORTHEAST WHICH IS CLOSE TO THE GFS OPERATIONAL MODEL.

THE ECM STALLS THIS UPPER LOW ACROSS THE MIDWEST WEDNESDAY. THIS
PLACES THE FCST AREA IN NORTH WINDS AND COOL CONDITIONS. HIGHS
SUNDAY IN THE SHOULD RISE INTO THE 60S BUT A 3 WAY BLEND OF THE
GEM...GFS AND ECM INDICATED 70S AS THE WARM FRONT WOULD BE LIFTING
NORTH THROUGH THE FCST AREA. THE OFFICIAL FORECAST IS FOR 60S SO AN
UPWARD ADJUSTMENT IS POSSIBLE WITH LATER FORECASTS. THE MODELS ARE
CONSISTENT WITH HIGHS IN THE 50S MONDAY THROUGH WEDNESDAY BUT WE
WILL BE WATCHING THE AMOUNT OF COLD AIR MOVING SOUTH FROM AN ARCTIC
HIGH ACROSS CANADA WHICH COULD PRODUCE HIGHS IN THE UPPER 40 TUESDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 707 PM CDT WED APR 23 2014

AN UPPER LEVEL TROUGH PASSAGE WILL BRING CONSIDERABLE MID AND HIGH
CLOUDINESS TO KLBF AND KVTN THIS EVENING. SHOWER ACTIVITY IS
UNLIKELY HOWEVER. SKIES TO BECOME MOSTLY CLEAR AFTER 06Z. WINDS
NEAR 33015G25KT TO DIMINISH LATE EVENING...THEN INCREASE BY
15Z/24TH TO 31017G26KT THROUGH THE REMAINDER OF THE TAF PERIOD.

&&

.FIRE WEATHER...
ISSUED AT 342 PM CDT WED APR 23 2014

NEAR CRITICAL FIRE DANGER IS EXPECTED ON THURSDAY. DEWPOINTS ARE
LIKELY TO DROP INTO THE TEENS AS THE BOUNDARY LAYER SEES DEEP MIXING
TO AROUND 700MB. ALTHOUGH TEMPERATURES WILL BE SLIGHTLY COOLER THAN
TODAY...HIGHS IN THE UPPER 60S AND LOW 70S WILL DROP RELATIVE
HUMIDITY DOWN AROUND 15 PERCENT. WHAT IS MORE QUESTIONABLE WILL BE
THE WINDS. THE GFS DOES HAVE WINDS OF 30KTS AT THE TOP OF THE MIXED
LAYER...WHILE THE NAM IS LESS ROBUST WITH SPEEDS OF 20KTS. WITH
DOWNSLOPE FLOW...BELIEVE THE FASTER WIND SPEEDS WILL HAPPEN...BUT
WILL WAIT TO SEE IF MODELS GET ON BOARD WITH HIGHER WINDS BEFORE
ISSUING ANY FIRE HEADLINES. FOR FRIDAY...RELATIVE HUMIDITY WILL BE
LOW AGAIN...BUT FAIRLY LIGHT WINDS ARE EXPECTED SO FIRE DANGER IS
NOT LIKELY TO BE ELEVATED. THEN LOOKING TO THE WEEKEND...A LARGE
STORM SYSTEM WILL IMPACT THE CENTRAL PART OF THE COUNTRY. AN
INCREASE IN MOISTURE IS EXPECTED...SO CRITICAL FIRE DANGER IS NOT
CURRENTLY EXPECTED. HOWEVER...THERE WILL BE CHANCES FOR SHOWERS AND
STORMS THROUGH THE WEEKEND.

&&

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

$$

SYNOPSIS...CDC
SHORT TERM...BROOKS
LONG TERM...CDC
AVIATION...ROBERG
FIRE WEATHER...BROOKS







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