Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 052055
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
355 PM CDT TUE MAY 5 2015

.SYNOPSIS...
ISSUED AT 354 PM CDT TUE MAY 5 2015

H5 ANALYSIS FROM THIS MORNING HAD A CLOSED LOW IN THE
VICINITY OF THE FOUR CORNERS. A SECOND SHORTWAVE TROUGH WAS NOTED
OFF THE COAST OF NRN CALIFORNIA WITH A THIRD FEATURE OVER SWRN
BRITISH COLUMBIA. DOWNSTREAM OF THE FIRST SYSTEM...RIDGING EXTENDED
FROM THE SERN STATES INTO THE MID MISSISSIPPI VALLEY. WV IMAGERY
THIS AFTERNOON HAD THE FOUR CORNERS SYSTEM...SLIGHTLY FURTHER EAST
OVER N CENTRAL NM ATTM. AT THE SURFACE...LOW PRESSURE WAS PRESENT
OVER SERN COLORADO. A WARM FRONTAL BOUNDARY EXTENDED TO THE ENE FROM
THIS FEATURE ACROSS WESTERN KS...INTO SERN NEBRASKA. NORTH OF THE
FRONT...DEEP EASTERLIES AND ABUNDANT LOW LEVEL MOISTURE WAS PRESENT
ACROSS THE FORECAST AREA THIS AFTERNOON. DEW POINTS HAVE SURGED WELL
INTO THE MID TO UPPER 50S AS AIR TEMPERATURES WERE IN THE UPPER 50S
TO AROUND 60. MOISTURE EXTENDED WELL ABOVE THE SURFACE TDY AS THE
12Z LBF RAOB SOUNDING HAD 1.04 INCHES OF PW IN THE SOUNDING WHICH
WAS WELL ABOVE NORMAL FOR THIS TIME OF YEAR. THIS MORNING...WE WERE
FAIRLY DRY ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...UNDER A THICK
VEIL OF LOW CLOUDS...FOG AND DRIZZLE. JUST OVER THE PAST COUPLE OF
HRS...A LEAD DISTURBANCE HAS PUSHED INTO NWRN KS AND SWRN NEBRASKA.
THIS HAS BEGUN TO MOISTEN UP THE MID LEVELS ACROSS THE FORECAST
AREA...AND HAS LED TO INCREASED COVERAGE OF SHRAS OVER THE PAST
COUPLE OF HRS. COVERAGE OF SHRAS WILL CONTINUE TO EXPAND INTO THE
EVENING HOURS AS CONVECTION OVER NORTHERN KS IN THE WARM
SECTOR...LIFTS NORTH INTO THE FORECAST AREA.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 354 PM CDT TUE MAY 5 2015

UPPER LEVEL LOW WILL CONTINUES TO SLOWLY LIFT NE FROM COLORADO OVER
THE HIGH PLAINS OVER THE NEXT 24 HOURS. MEANWHILE THE SFC LOW SLOWLY
LIFTS INTO EASTERN CO. SFC SOUTHEASTERLY FLOW HAS CONTINUES TO BRING
GULF MOISTURE TO THE REGION...WITH DEW PTS WELL INTO THE 50S TO NEAR
60. MORNING PRECIP WATER FOR THE KLBF SOUNDING WAS 1.04 INCHES...AND
MODELS HAVE ONLY INCREASED MOISTURE. GENERALLY CLOSE TO ONE INCH TO
1.25 INCHES ACROSS THE AREA. GOOD ISENTROPIC LIFT HAS SET UP A LARGE
AREA OF SHOWERS WHICH WILL ROTATE OVER THE AREA OVERNIGHT. THERE ARE
A FEW BREAKS IN THE PRECIP SHIELD SO INTENSITY IS EXPECTED TO
FLUCTUATION AND VARYING QPF AMOUNTS LIKELY. SHOWERS COULD EASILY
PRODUCE A QUICK TENTH TO A QUARTER...WITH LOCALLY HALF AN INCH OR
MORE POSSIBLE. SLIGHTLY NEG LI VALUES AND MU CAPES ARE LOW
/GENERALLY AROUND 500 J/KG OR LESS/ ACROSS THE AREA. THUS THINKING
PRIMARY ACTIVITY TO BE SHOWERS WITH SOME EMBEDDED THUNDER...WHICH IS
WHAT HAS BEEN OCCURRING.

FORECAST FOR TOMORROW FOLLOWS A LOWERING OF POPS ACROSS PORTIONS OF
SW NEB INTO THE CENTRAL SANDHILLS AS A DRY SLOT IS DEVELOPING. SOME
CONCERN ON HOW EXPANSIVE THE DRY SLOT WILL BE...AS MODELS ALL
DIFFERENT IN HANDLING THE DRY AIR FROM THE SW. THIS COULD BE
ADJUSTED SIGNIFICANTLY AS IT DEVELOPS AND MODELS GET A BETTER HANDLE
ON IT. AS FOR TEMPS...WARM FRONT TO THE SOUTH AND EAST SHOULD LIFT
INTO THE AREA AS THE SFC LOW LIFTS INTO CO. THIS WILL ALLOW TEMPS TO
WARM INTO THE 60S TO AROUND 70.

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 354 PM CDT TUE MAY 5 2015

WEDNESDAY NIGHT THROUGH FRIDAY...IN THE MID RANGE
PERIODS...RAIN CHANCES ARE THE MAIN FORECAST CHALLENGE. THE UPPER
LEVEL SYSTEM...CURRENTLY OVER THE FOUR CORNERS...WILL CROSS THROUGH
EASTERN COLORADO INTO NRN NEBRASKA BY 12Z THURSDAY. LIFT IN
ASSOCIATION WITH THIS FEATURE...WILL TRACK FROM SWRN NEBRASKA INTO
NORTHERN NEBRASKA WEDS NIGHT. HAVE TAPERED POPS FROM THE SWRN CWA TO
THE NERN CWA WEDS NIGHT...WITH DRY CONDS EXPECTED OVERNIGHT IN THE
SWRN CWA. BY THURSDAY MORNING...SOME LIGHT RAIN SHOWERS WILL LINGER
OVER NRN NEBRASKA AS THE UPPER LEVEL DISTURBANCE LIFTS FROM NORTH
CENTRAL INTO NERN NEBRASKA. ON THURSDAY...LOW AMPLITUDE RIDGING WILL
PUSH INTO THE CENTRAL PLAINS IN ADVANCE OF DEEPENING CLOSED LOW OVER
SRN CALIFORNIA. MAINLY DRY CONDS ARE EXPECTED...HOWEVER...HAVE
CONTINUED TO MENTION SLIGHT CHANCES FOR PCPN DUE TO STEEP MID LEVEL
LAPSE RATES AND ELEVATED INSTABILITY THURSDAY NIGHT...FOR THE ENTIRE
FORECAST AREA AND ON FRIDAY AND THE SRN CWA. WITH DRIER AIR PUSHING
INTO THE REGION THURSDAY NIGHT AND FRIDAY...CONFIDENCE IN WIDESPREAD
PCPN CONTINUES TO WANE ATTM AND HAVE TRIMMED POPS BACK TO SLIGHT
CHANCES FOR THUS NITE AND FRIDAY.

LONG RANGE...FRIDAY NIGHT THROUGH TUESDAY...A DEEP UPPER LEVEL LOW
AND TROUGH OF LOW PRESSURE WILL LIFT FROM SO CAL INTO THE FOUR
CORNERS FRIDAY NIGHT INTO SATURDAY. A LEAD DISTURBANCE WILL LIFT
NORTH INTO THE CENTRAL PLAINS FRIDAY NIGHT. KEPT POPS FAIRLY LOW FOR
THE PERIOD AS BOUNDARY LAYER MOISTURE WILL REMAIN LIMITED THROUGH
FRIDAY NIGHT. BY SATURDAY...LOW LEVEL MOISTURE WILL BEGIN TO
INCREASE AS WINDS SHIFT TO THE EAST AND SOUTHEAST SATURDAY. THE MAIN
UPPER LEVEL SYSTEM WILL LIFT ACROSS COLORADO SAT NIGHT INTO SUNDAY.
PRECIPITATION CHANCES WILL INCREASE TO LIKELY SATURDAY INTO SATURDAY
NIGHT. DEEP ISENTROPIC LIFT WILL BE PRESENT ACROSS THE FORECAST AREA
IN ADVANCE OF THE UPPER LEVEL LOW SATURDAY NIGHT INTO EARLY SUNDAY.
WITH PWATS OF BETTER THAN AN INCH IN SWRN NEBRASKA SAT EVENING...WE
COULD SEE SOME HEAVY RAIN. BY SUNDAY...PRECIP CHANCES MAY DIMINISH
SOME IN SRN NEBRASKA AS THE UPPER LEVEL LOW LIFTS INTO FAR NERN
COLORADO OR SWRN NEBRASKA. THE GFS IS SOMEWHAT SLOWER IN LIFTING
THE LOW OUT OF COLORADO SUNDAY...AND THUS DEVELOPS A DRY SLOT
ACROSS SWRN NEBRASKA SUNDAY MORNING INTO EARLY SUNDAY AFTERNOON.
THE ECMWF IS MORE AGGRESSIVE WITH THE LOW AND THUS THE
PRECIPITATION FREE AREA IS OVER SOUTH CENTRAL NEBRASKA. GIVEN THE
MODEL DIFFERENCES...CHOSE NOT TO DEVIATE FROM THE CRINIT
GRIDS...WHICH HAS CHANCE POPS IN THE SOUTH AND LIKELY POPS IN THE
NORTH FOR SUNDAY. ON SUNDAY NIGHT INTO MONDAY...THE UPPER LEVEL
TROUGH AND LOW WILL LIFT INTO EASTERN NEBRASKA. THERMAL PROFILES
ON THE BACK SIDE OF THE EXITING LOW ARE FAVORABLE FOR SNOW ACROSS
THE BLACK HILLS SWD TO THE CHEYENNE RIDGE MONDAY MORNING INTO
MONDAY AFTERNOON. BASED ON H85 TEMPS AND THICKNESSES....SNOW IS
NOT EXPECTED ACROSS THE NORTHWESTERN CWA FOR MONDAY MORNING AND
MONDAY AFTN.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1247 PM CDT TUE MAY 5 2015

GENERALLY IFR CONDITIONS THE NEXT 24 HOURS DUE TO LOW CIGS AND LOW
VISIBILITIES FROM FOG AND SHOWERS. THERE WILL BE A FEW BREAKS FROM
SHOWERS AND FOG WHEN CONDITIONS MAY LIFT TO MVFR FOR A SHORT
TIME...HOWEVER EXPECT THESE CONDITIONS TO BE SHORT LIVED.

A SHIELD OF SHOWERS WILL ROTATE INTO THE REGION THIS
AFTERNOON/EVENING AND PRODUCE A FEW HOURS OF SHOWERS...ESPECIALLY
ACROSS SW NEB AND THE KLBF TERMINAL. STILL HAVE ENOUGH CONFIDENCE
THAT KVTN WILL SEE SOME OF THE RAINFALL AND DID INCLUDE IN TAF.
SOME CONCERN OVERNIGHT IS THE REDEVELOPMENT OF FOG...ALTHOUGH THE
SHOWERS COULD CONTINUE AND KEEP CONDITIONS FROM FALLING TO LIFR.

THERE IS ALSO A CHANCE FOR THUNDER ALTHOUGH NOT AS CONFIDENT AS
EARLIER AND DID NOT INCLUDE IN LATEST TAF. WILL AMEND IF LIGHTNING
STRIKES LOOK BETTER TO REACH THE TERMINALS.


&&

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

$$

SYNOPSIS...CLB
SHORT TERM...MASEK
LONG TERM...CLB
AVIATION...MASEK





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