Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 181806
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
106 PM CDT SAT APR 18 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SAT APR 18 2015

SPC SUGGESTED SIGNIFICANT SEVERE WEATHER POTENTIAL THIS AFTERNOON
AND EARLY THIS EVENING ACROSS PARTS OF SOUTHWEST AND NCNTL NEB. A
PORTION OF THE LOW PRESSURE ACROSS SWRN KS THIS MORNING IS
EXPECTED TO LIFT NORTHEAST THROUGH SCNTL AND ERN NEB THIS
AFTERNOON SETTING UP A UNSTABLE WARM SECTOR FROM ROUGHLY IMPERIAL
TO ONEILL.

ALTHOUGH THE RAP IS FAIRLY QUIET THE NAM AND HRRR SBN MODELS
SUGGEST REASONABLE POTENTIAL FOR CONVECTIVE DEVELOPMENT THIS AFTN
IF SKIES PARTIALLY CLEAR ALLOWING FOR TEMPERATURES TO RISE INTO
THE MID AND UPPER 60S. SATELLITE SHOWS CLEARING THIS MORNING
ACROSS CNTL HIGH PLAINS OF KS/COLO AND IT IS BELIEVED THIS
CLEARING WILL MOVE INTO SCNTL NEB THIS AFTN.

THE STORM ACTIVITY COULD BEGIN AS EARLY AS 18Z IN THE SOUTHWEST
WITH THE NAM SOLN OR AS LATE AS 21Z-00Z IN THE HRRR MODEL.
SATELLITE TIMING TOOLS INDICATE THE CLEARING ACROSS KS COULD
REACH SOUTHWEST NEB BY 13-15Z THIS MORNING WHICH WOULD PROVIDE A
GOOD START FOR MODEST HEATING GIVEN THAT THIS CLEARING AREA WOULD
TEND TO FILL IN WITH DEVELOPING CUMULUS.

ONE WEAKNESS ARE THE WIND FIELDS 500MB AND BELOW WHICH ARE LIGHT
PRODUCING BULK SHEAR VALUES OF 30KT OR LESS WHICH MIGHT SUPPORT
MORE OF HEAVY RAIN THREAT. STILL TEMPERATURES ALOFT WILL BE VERY
COLD AS THE H500MB LOW ACROSS COLO MOVES EAST TO NEAR
LIMON/SPRINGFIELD. WINDS AT 300MB ARE STRONG NEAR 65KT
POTENTIALLY ENHANCING UPDRAFTS AND PROVIDING VENTILATION.
FREEZING LEVELS ARE NEAR 5KFT SUPPORTING A LOW TOP STORM
ENVIRONMENT AND GOOD POTENTIAL FOR HAIL. THE NAM IS PRODUCING
AROUND 2000 J/KG OF CAPE AT NORTH PLATTE AND BROKEN BOW WHILE THE
RAP AND OTHER MODELS SHOW HALF OR LESS THAT VALUE.

NORTHWEST WINDS WILL SWEEP IN FROM THE WEST IN THE WAKE OF THE
DISTURBANCE TONIGHT. THIS SHOULD PRODUCE DRYING AND DECREASING
RAIN CHANCES FROM MIDNIGHT ONWARD.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 328 AM CDT SAT APR 18 2015

SUNDAY WILL SEE THE STRONG LOW PRESSURE WEAKENING AS IT PUSHES
EAST WHILE A TROUGH DIGS ACROSS THE CANADIAN PLAINS. SOME
LINGERING SUNDAY MORNING SHOWERS ARE POSSIBLE IN THE EASTERN
ZONES...HOWEVER THE BIGGER EVENTS OF THE DAY WILL BE THE CAA AND
INCREASING NW WINDS. AS THE LOW PUSHES ACROSS KS...DRY AIR WILL
QUICKLY FILL IN BEHIND...RESULTING IN DECREASING CLOUDS FROM WEST
TO EAST IN THE MORNING. BY AFTERNOON SHOULD SEE MOSTLY SUNNY
SKIES FOR ALL. THE SUN WILL COMBINE WITH THE STRONG NW WINDS
/GUSTING TO 30 TO 40 MPH/ TO PROMOTE GOOD MIXING OF THE BL AND
OFFSET THE CAA AND TEMPS PUSH INTO THE 50S.

EARLY IN THE WEEK THE TROUGH DIGS TOWARDS THE GREAT LAKES REGION
AND ABSORBS THE SOUTHERN LOW. ELONGATED SFC HIGH PRESSURE BUILDS
ACROSS THE HIGH PLAINS. THE ACTIVE WEATHER IS WELL TO THE NE
ALTHOUGH A FEW UPPER LEVEL DISTURBANCES WILL RIDE ALONG THE NW
FLOW OVERHEAD AND BRING SOME PASSING CLOUDS AT TIMES. LIMITED
MOISTURE IN THE LOWER LEVELS AND MODELS/FORECAST ARE DRY. TEMPS
TO START THE WEEK WILL BE CHILLY IN THE MORNING WITH MOST AREAS
NEAR OR BELOW THE FREEZING MARK. STILL A COUPLE OF WEEKS FROM
TYPICAL LAST FREEZE FOR MOST OF THE AREA...SO NO HEADLINES NEEDED
YET. HIGHS REBOUND NICELY WITH A WARMING TREND WITH 60S MAYBE 70
FOR WED AND THURS.

EYES THEN FOCUS ON A TROUGH AS IT DIGS ACROSS THE SOUTHWEST.
MODELS IN GOOD AGREEMENT DEVELOPING A CLOSED 500 MB LOW NEAR SRN
CAL BY THURS. THE LOW THEN LIFTS TOWARDS THE 4 CORNERS WHILE
BECOMING AN OPEN WAVE. THE WAVE WILL THEN PUSH ACROSS THE PLAINS
TO END THE WEEK. THIS WILL BRING A RETURN OF THE ACTIVE
WEATHER...AND WILL HAVE POPS TOWARDS THE END OF THE EXTENDED
PERIOD. STILL HAVE SOME LOCATION AND TIMING ISSUES TO IRON OUT
WHICH IS TYPICAL THIS FAR OUT SO POPS KEPT BELOW 50 PERCENT FOR
NOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1228 PM CDT SAT APR 18 2015

LARGE UPPER LEVEL LOW CONTINUES TO MOVE ONLY VERY SLOWLY ACROSS
EASTERN COLORADO. EXPECT ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS TO DEVELOP AS A RESULT THIS AFTERNOON AND TONIGHT.
THE BEST CONCENTRATION OF SHOWERS AND STORMS WILL BE ACROSS
CENTRAL AND SOUTHWEST NEBRASKA...INCLUDING THE KLBF TAF SITE. LATE
TONIGHT A COLD FRONT WILL QUICKLY MOVE SOUTHEAST THROUGH THE
AREA...THIS WILL BRING MVFR AND POSSIBLE IFR CEILINGS WITH IT FROM
AROUND 07Z TO 16Z SUNDAY.

&&

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

&&

$$

SHORT TERM...CDC
LONG TERM...MASEK
AVIATION...TAYLOR




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