Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 241123
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
623 AM CDT FRI APR 24 2015

.SYNOPSIS...
ISSUED AT 349 AM CDT FRI APR 24 2015

HAND ANALYSIS OF THE 07Z MSL DATA SHOWED LOW PRESSURE CENTERED IN
SOUTHEAST MONTANA AND WESTERN SOUTH DAKOTA WITH A QUASI- STATIONARY
FRONT ACROSS NORTHERN NEBRASKA INTO CENTRAL MONTANA. THERE WAS ALSO
A SHARP DEWPOINT GRADIENT INDICATING A DRY LINE ALONG THE WYOMING
NEBRASKA BORDER INTO EAST CENTRAL COLORADO. ANOTHER FRONT WAS
STRETCHED ACROSS SOUTHEAST COLORADO AND SOUTHWEST KANSAS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT FRI APR 24 2015

WITH SEVERAL POTENTIAL FOCUSING MECHANISMS AROUND THE PLAINS...THE
BIG CHALLENGE WITH THE FORECAST TODAY AND TONIGHT IS THE TIMING...
COVERAGE AND INTENSITY OF CONVECTION TODAY AND TONIGHT. FOR THIS
AFTERNOON...IT APPEARS THAT CONVECTION WILL DEVELOP ALONG THE DRY
LINE EARLY AFTERNOON AND MAKE IT INTO CENTRAL AND SOUTHWEST NEBRASKA
BY EARLY AFTERNOON. SURFACE-BASED CONVECTIVE POTENTIAL ENERGY IS
LIKELY TO BE 1000-2000J/KG...SO STRONG UPDRAFTS ARE LIKELY IN THE
STORMS THAT DO DEVELOP. HOWEVER...THE DEEP LAYER BULK SHEAR IS NOT
REALLY STRONG ENOUGH TO CREATE A SUFFICIENT OFFSET BETWEEN THE
UPDRAFT AND THE PRECIPITATION SHAFT. THUS LARGE HAIL IS NOT LIKELY.
AS WAS THE CASE YESTERDAY...DRY AIR IN THE SURFACE BASED MIXED LAYER
COULD ENHANCE DOWNDRAFTS AND PRODUCE STRONG DOWNBURSTS AND
OUTFLOW.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 349 AM CDT FRI APR 24 2015

RIDGING ALOFT WILL BUILD ACROSS THE CENTRAL PLAINS SATURDAY AHEAD OF
AN APPROACHING LONG WAVE TROUGH MOVING ONTO THE WEST COAST. THE LONG
WAVE TROUGH WILL MOVE INTO THE ROCKIES REGION SATURDAY NIGHT INTO
SUNDAY...WITH A STRONG CLOSED LOW TAKING SHAPE SUNDAY MORNING ACROSS
WESTERN COLORADO. WINDS TURN SOUTH ALOFT ACROSS WESTERN NEBRASKA
AHEAD OF THIS FEATURE LATER SATURDAY INTO SUNDAY. EXPECTING A CLOUDY
DAY ACROSS WESTERN NEBRASKA SATURDAY AS ISENTROPIC LIFT AND MOISTURE
TRANSPORT PERSISTS THROUGH THE DAY. AS LARGE SCALE LIFT INCREASES
DURING THE AFTERNOON AND EVENING HOURS SATURDAY...EXPECT SHOWERS AND
A FEW  THUNDERSTORMS TO DEVELOP. INSTABILITY IS MARGINAL AND WILL
KEEP THE THUNDERSTORM MENTION TO ISOLATED. PRECIPITATION WILL HAVE A
HARD TIME MAKING IT VERY FAR EAST SATURDAY NIGHT...AS SOUTHERLY FLOW
ALOFT CARRIES MOST OF THE SHOWER ACTIVITY NORTH INTO WESTERN SOUTH
DAKOTA. ALSO RIDGING ALOFT PERSISTS FARTHER EAST...HAMPERING MUCH
EASTWARD MOVEMENT TO THE PRECIPITATION. WILL GENERALLY KEEP THE RAIN
CHANCES ALONG AND WEST OF HIGHWAY 83 SATURDAY NIGHT...WITH THE
HIGHEST CHANCES ACROSS THE PANHANDLE. AS THE CLOSED UPPER LOW TAKES
SHAPE SUNDAY MORNING ACROSS WESTERN COLORADO...BOTH THE GFS AND NAM
MODELS INDICATE A DISTURBANCE ROTATING NORTHWARD ACROSS EASTERN
COLORADO INTO WESTERN NEBRASKA TO THE EAST OF THE UPPER LOW CENTER.
THIS WILL ENHANCE LIFT AND SHOWERS/RAIN LOOKING QUITE LIKELY LATE
SATURDAY NIGHT THROUGH AT LEAST THE FIRST HALF OF THE DAY SUNDAY.
AGAIN...PRECIPITATION WILL HAVE A HARD TIME MOVING VERY FAR TO THE
EAST...AND AREAS FROM AROUND ONE ILL SOUTH THROUGH BROKEN BOW WILL
LIKELY REMAIN MOSTLY DRY. AS FAR AS PRECIPITATION AMOUNTS SATURDAY
THROUGH SUNDAY NIGHT...THINKING AROUND THREE QUARTERS OF AN INCH
WILL BE FAIRLY COMMON ACROSS THE PANHANDLE. AMOUNTS WILL QUICKLY
DIMINISH FARTHER TO THE EAST...WITH A QUARTER OF AN INCH OR LESS
ALONG HIGHWAY 83 FROM VALENTINE TO NORTH PLATTE...AND LESS THAN THAT
OR PERHAPS NOTHING EAST OF THIS LINE.

ENSEMBLE MEAN AND OPERATIONAL MODELS AGREE THAT THE CLOSED LOW WILL
TRACK SOUTHEAST FROM WESTERN COLORADO INTO THE SOUTHERN PLAINS
MONDAY INTO TUESDAY. THERE MAY BE SOME LINGERING LIGHT SHOWERS
ACROSS THE PANHANDLE MONDAY...BUT THE MAIN PRECIPITATION SHOULD
REMAIN WELL SOUTH OF THE AREA IN CLOSER PROXIMITY TO THE UPPER LEVEL
LOW. UPPER LEVEL RIDGING WILL BUILD EAST ACROSS THE CENTRAL PLAINS
BY MIDWEEK WITH A WARNING TREND. HIGH TEMPERATURES BY WEDNESDAY
AND THURSDAY SHOULD BE WELL INTO THE 70S. DRY WEATHER EXPECTED
WITH THE RIDGING ALOFT.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 620 AM CDT FRI APR 24 2015

THUNDERSTORMS ARE EXPECTED AGAIN TODAY WITH MORE OF THE AREA
AFFECTED THAN IT WAS YESTERDAY. SCATTERED THUNDERSTORMS FROM
COLORADO AND EXTREME WESTERN NEBRASKA ARE EXPECTED TO MOVE OVER A
LARGE PART OF WESTERN NEBRASKA AS EARLY AS 20Z ALONG AND WEST OF
AN IEN-IML LINE AND REACHING VTN-MHN BY 21Z AND ONL-BBW-LBF BY
23Z. HAIL UP TO 1/2 INCH IN DIAMETER CAN BE EXPECTED WITH GUSTY
WIND VRB15-20G25-30KT. THERE IS SOME POTENTIAL THAT DOWNBURSTS
COULD PRODUCE HIGHER WIND.

&&

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

$$

SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...TAYLOR
AVIATION...SPRINGER







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