Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 032104
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
404 PM CDT SUN MAY 3 2015

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 401 PM CDT SUN MAY 3 2015

TONIGHT AND MONDAY...SPLIT CYCLONIC FLOW WILL ENCOMPASS THE WESTERN
CONUS THROUGH THE SHORT TERM PERIOD.  THIS EFFECTIVELY PLACES THE
CENTRAL PLAINS UNDER THE INFLUENCE OF SOUTHWEST FLOW ALOFT.  AT THE
SURFACE...BEHIND THE PASSAGE OF A COLD FRONT...MOIST EASTERLY
UPSLOPE FLOW WILL PREVAIL ACROSS THE SANDHILLS REGION AS HIGH
PRESSURE AND A INVERTED SFC RIDGE SITS ATOP THE WESTERN GREAT LAKES
REGION.  WITH THE EASTERLY UPSLOPE...COOL...CLOUDY AND POSSIBLY WET
CONDITIONS ARE ANTICIPATED BEGINNING LATE TONIGHT AND CONTINUING
THROUGH THE SHORT TERM FOR THE ENTIRE FORECAST AREA.

THE PRECIPITATION FORECAST WAS DERIVED FROM A GENERAL BLEND OF
AVAILABLE DATA AS THE MODELS HAVE SHOWN SOME CONSISTENCY. THE BLEND
FAVORS INCREASING PRECIPITATION CHANCES FROM SOUTH TO NORTH
OVERNIGHT AND INTO TOMORROW.  THE HIGHEST POPS ARRIVE MONDAY ACROSS
THE WESTERN SANDHILLS...THEN TRANSITION EAST ACROSS NORTH CENTRAL
NEBRASKA THROUGH THE LATE AFTERNOON HOURS.  THIS GENERALLY FOLLOWS
THE GUIDANCE OF THE NAM AND GFS.  FOR NOW...A WIDESPREAD HIGH END
CHANCE MENTION WAS USED FOR MUCH OF THE FORECAST AREA /TO ACCOUNT
FOR THE EASTERLY UPSLOPE/...HOWEVER FOLLOWING THE NAM AND GFS...LOWER
END LIKELY WERE RE-INTRODUCED WHERE MID LEVEL DEFORMATION FOCUSES
PRECIP /WESTERN SANDHILLS TO NORTH CENTRAL NEBRASKA/.

PROXIMITY SOUNDINGS SHOW LIMITED INSTABILITY BEYOND THIS
EVENING...BUT WASN/T READY TO TOTALLY ABANDON THUNDER MENTION JUST
YET.  THUS BEYOND 06Z THE PRIMARY PRECIPITATION MODE WILL BE
SHOWERS...WITH ISOLATED THUNDER MENTION.  WITH THE LESSER CONVECTIVE
NATURE OF THE STORMS...FORECAST QPF WAS DECREASED SLIGHTLY...MOST
LOCATIONS WOULD SEE A FEW TENTHS OF AN INCH OF RAIN...TO POSSIBLY A
HALF INCH.

TEMPERATURES UNDER CLOUDY SKIES AND WITHIN A POST FRONTAL REGIME
WILL BE COOL ON MONDAY...HIGHS IN THE 50S TO LOWER 60S SHOULD
PREVAIL.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 401 PM CDT SUN MAY 3 2015

A LARGE UPPER LEVEL LOW WILL BE DROPPING SOUTHEAST INTO THE PACIFIC
NORTHWEST AT THE START OF THE PERIOD. A STRONG PV ANOMALY WILL EJECT
NORTHEAST AHEAD OF THIS FEATURE MONDAY NIGHT THROUGH WEDNESDAY
ACROSS THE CENTRAL AND NORTHERN PLAINS. AS THIS OCCURS...STRONG
SOUTHERLY FLOW WILL INCREASE WITH RAPID MOISTURE TRANSPORT NORTHWARD
INTO THE REGION FROM THE GULF OF MEXICO.

AT THE SURFACE A COLD FRONT WILL STALL MONDAY NIGHT ACROSS NORTHERN
KANSAS...THEN AS SURFACE LOW PRESSURE DEEPENS ACROSS NORTHEAST
COLORADO IN RESPONSE TO THE APPROACHING STRONG PV ANOMALY...EXPECT
THE FRONT TO BEGIN LIFTING NORTHWARD THROUGH THE AREA AS A WARM
FRONT TUESDAY. THIS WILL ALLOW BETTER MOISTURE/HUMIDITY TO SURGE
INTO THE AREA FROM THE SOUTH. THE INCREASE IN MOISTURE WILL COINCIDE
WITH STRONG LIFT/GOOD DYNAMICS...RESULTING IN RAIN LATE MONDAY NIGHT
THROUGH TUESDAY. HAVE CUT BACK ON THE THUNDER MENTION TO JUST
ISOLATED WORDING MONDAY NIGHT DUE TO ONLY MARGINAL INSTABILITY. AS
FAR AS THE SEVERE POTENTIAL TUESDAY AS THE WARM FRONT MOVES
NORTH...IT IS LOOKING LOW. DESPITE BACKED LOW LEVEL FLOW TO THE
NORTH OF THE BOUNDARY...SUCH STRONG NORTHWARD MOISTURE ADVECTION
INTO THE AREA WILL LIMIT MUCH IF ANY HEATING DUE TO LOW STRATUS
CLOUDS REMAINING LOCKED IN PLACE. TUESDAY NIGHT INTO
WEDNESDAY...EXPECT ISENTROPIC LIFT AND STRONG MOISTURE ADVECTION TO
KEEP CLOUD COVER IN PLACE. ALTHOUGH NOT AS ROBUST AS DURING THE DAY
TUESDAY...LIFT CONTINUES AND SHOWERS AND SOME THUNDER WILL REMAIN
LIKELY.

STILL APPEARS THAT LATE WEDNESDAY NIGHT THROUGH THURSDAY WILL HAVE A
LULL IN PRECIPITATION. THE PV ANOMALY WILL BE MOVING NORTHEAST AWAY
FROM THE AREA...BUT APPROACHING FROM THE WEST WILL BE THE LARGE CUT
OFF LOW THAT WILL HAVE SETTLED FROM THE PACIFIC NORTHWEST INTO THE
CENTRAL GREAT BASIN. THE ECMWF AND GEFS ARE IN VERY GOOD AGREEMENT
WITH THIS SYSTEM AS IT MOVES EASTWARD INTO THE CENTRAL GREAT PLAINS
FRIDAY THROUGH SATURDAY. BY SATURDAY NIGHT THE H700MB LOW SHOULD BE
CENTERED IN EASTERN COLORADO...WITH ABUNDANT MOISTURE FLOWING NORTH
INTO THE AREA AHEAD OF THE LOW CENTER. WITH SUCH GOOD AGREEMENT
BETWEEN THE ECMWF AND GEFS...WILL INCLUDE SOME LIKELY POPS FOR
PORTIONS OF THE AREA SATURDAY DUE TO THE HIGH DEGREE OF CONFIDENCE
AND MODEL AGREEMENT.

ALL IN ALL APPEARS TO BE A WET WEEK AHEAD...WITH A GENERAL ONE TO
TWO INCHES OF RAINFALL LIKELY BY WEEKS END.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1225 PM CDT SUN MAY 3 2015

ALTHOUGH VFR CONDITIONS WILL CONTINUE THROUGH THIS EVENING...GUSTY NORTH
WINDS ARE EXPECTED IN THE WAKE OF A PASSING COLD FRONT. CEILINGS
WILL LOWER OVERNIGHT INTO MONDAY MORNING AS THE NEXT SYSTEM MOVES
INTO THE AREA. ONE ROUND OF SHOWERS OR THUNDERSTORMS MAY
AFFECT SOUTHWEST NEBRASKA...INCLUDING KLBF...AROUND 04/06Z. RAIN
CHANCES INCREASE AGAIN TOWARD MID MORNING...AND SPREAD NORTH
THROUGHOUT THE DAY...AFFECTING KVTN AROUND OR AFTER 04/18Z.

&&

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

$$

SHORT TERM...JACOBS
LONG TERM...TAYLOR
AVIATION...DS




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