000
FXUS63 KLBF 192010
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
310 PM CDT WED JUN 19 2013

.SYNOPSIS...
ISSUED AT 310 PM CDT WED JUN 19 2013

UPPER LEVEL LOW IS COMING ONSHORE IN THE PACIFIC NORTHWEST. A WEAK
RIDGE REMAINS ACROSS THE SOUTHERN PLAINS...WHILE THERE IS A BROAD
TROUGH ACROSS THE NORTHEAST CONUS/SOUTHEAST CANADA. A SURFACE LOW IS
OVER THE NORTHERN ROCKIES...WHILE A TROUGH TRAILS SOUTH ALONG THE
FRONT RANGE. ACROSS MUCH OF THE HIGH PLAINS...WINDS THIS AFTERNOON
HAVE BEEN GUSTY OUT OF THE SOUTH. SO FAR NO ECHOES HAVE DEVELOPED ON
THE LOCAL RADAR...ALTHOUGH SOME MID/HIGH CLOUDS DRIFT ACROSS THE
AREA. TEMPS HAVE WARMED NICELY INTO THE 80S.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 310 PM CDT WED JUN 19 2013

TROUGH WILL BE ONE OF THE FOCUS POINTS FOR POSSIBLE THUNDERSTORM
DEVELOP LATE THIS AFTERNOON INTO THIS EVENING. FLOW IS NEARLY ZONAL
AND ANY DEVELOP ALONG THE HIGHER TERRAIN TO THE WEST SHOULD DRIFT
EAST OVERNIGHT. ALSO A STRONG LL JET WILL KICK IN LATE THIS EVENING
AND WILL SUSTAIN OR ENHANCE CONVECTION ACROSS WESTERN
NEBRASKA...SHIFTING OVER CENTRAL NEBRASKA OVERNIGHT. WHILE DECENT
ELEVATED INSTABILITY...MARGINAL SHEAR ENVIRONMENT SHOULD KEEP
ACTIVITY COVERAGE GENERALLY ISOLATED...THUS FORECAST IS LOW POPS.
EXPECT ACTIVITY TO MOVE EAST BY THE MORNING HOURS.

AS THE UPPER LOW PUSHES TOWARDS THE NORTHERN ROCKIES
TOMORROW...RIDGE AMPLIFIES SLIGHTLY WHICH WILL HELP WARM TEMPS UP
A COUPLE OF DEGREES...ESPECIALLY ACROSS THE SOUTH. HIGHS INTO THE
LOWER 90S ACROSS SW NEB...MID TO UPPER 80S ELSEWHERE. ALSO WITH THE
RIDGE EXPANDING...WARMER TEMPS ALOFT SHOULD PROVIDE A STRONG ENOUGH
CAP TO KEEP DEVELOPMENT AT BAY THRU THE AFTERNOON HOURS. AT THE
SURFACE...THE LOW WILL PUSH INTO CANADA...WITH A SECONDARY LOW
DEVELOPING OVER S DAKOTA. FROM THE SECONDARY LOW...EXPECT A
TROUGH/DRY LINE TO CONTINUE SOUTH ACROSS THE CWA...INTO WESTERN
KANSAS. WILL HAVE TO MONITOR CLOSELY THE CAP AS THUNDERSTORM DEVELOP
IS POSSIBLE BEFORE 00Z.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 310 PM CDT WED JUN 19 2013

FOR THURSDAY NIGHT...FRONTAL BOUNDARY IS EXPECTED TO BE STALLED
ACROSS SOUTHERN NEBRASKA. AHEAD OF THIS FRONT...ELEVATED MIXED
LAYER WILL ADVECT ACROSS THE CENTRAL PLAINS REGION WITH THE
SOUTHWESTERLY FLOW AHEAD OF THE APPROACHING LONG WAVE TROUGH
MOVING ACROSS THE NORTHERN ROCKIES. WHILE THIS MAY CONTRIBUTE TO
SUBSTAINTIAL CAPPING DURING THE DAYLIGHT HOURS THU...AS THE PLAINS
LOW LEVEL JET STRENGTHS AFTER SUNSET AND AN UPPER PV ANOMALY
APPROACHES...SHOULD BE A MID LEVEL CONVERGENT REGION LOCATED NORTH
OF SFC STATIONARY FRONT. THE MID LEVEL INSTABILITY COMBINED WITH
THE AFOREMENTIONED FORCING SHOULD ALLOW SUFFICIENT LIFT TO
GENERATE NOCTURNAL THUNDERSTORMS IN THE EASTERN PORTION OF THE
CWA. ANY DEVELOPMENT SHOULD MOVE NORTHEAST AFTER MIDNIGHT AND
SHOULD GENERALLY BE OUT OF THE AREA TOWARD DAYBREAK...FAIRLY
TYPICAL OF NOCTURNAL EVENTS IN WRN NEBRASKA. WOULD EXPECT THAT
WITH THE DEGREE OF ELEVATED INSTABILITY THERE IS MODERATE
CONFIDENCE IN THE POTENTIAL FOR SEVERE HAIL OVERNIGHT.

FRIDAY UPPER HEIGHTS BUILD ACROSS THE MIDWEST AS THE UPPER LOW MOVES
OUT ONTO THE NORTHERN PLAINS. THIS KEEPS THE FORECAST AREA IN
SOUTHWEST FLOW ALOFT AND FORCES A COLD FRONT SOUTHWARD ACROSS THE
AREA AS THE AFOREMENTIONED PV ANOMALY SHIFTS NORTHEASTWARD
ASSOCIATED WITH THE EASTWARD PROPAGATING UPPER LOW. IN ADDITION...A
MORE DEFINITIVE DEW POINT GRADIENT DEVELOPS AS THE HIGHER TERRAIN
HEATS UP AND THE ATMOSPHERE MIXES MORE DEEPLY FURTHER WEST. AHEAD OF
THE COLD FRONT TEMPS SHOULD RISE QUICKLY IN THE DRIER AIR...TYPICAL
FOR THIS PATTERN...AND MAY REACH TRIPLE DIGITS IN THE SOUTHWEST.
ALSO...THIS SHOULD SET THE STAGE FRIDAY AFTERNOON FOR A BETTER
CHANCE FOR SURFACE BASED CONVECTIVE DEVELOPMENT NEAR THE FRONT/DRY
LINE INTERACTION. IN ADDITION...DEEP LAYER SHEAR WILL BE BETTER WITH
THE INCREASED FLOW ALOFT SO STORM ORGANIZATION SHOULD BE BETTER AS
WELL. ANY STORMS SHOULD PROGRESS ACROSS THE AREA SUSTAINED BY THE
DIURNALLY DRIVEN LLJ. AS THE FRONT MOVES SOUTH IT WILL STALL AS IT
ENCOUNTERS THE STRONGER LLJ.

FOR THE WEEKEND /SATURDAY THRU SUNDAY NIGHT/ THERE WILL BE ADDITIONAL
ITERATIONS OF A SIMILAR SETUP AS THE UPPER LOW PROGRESSES SLOWLY
ACROSS THE NORTHERN PLAINS. AHEAD OF EACH APPROACHING PIECE OF THE
TROUGH WINDS SHOULD BECOME SOUTH AND PUSH THE BOUNDARY
NORTHWARD...AND THEN THE SUBSEQUENT PUSH OF COOLER AIR DRAGS THE
FRONT BACK SOUTH. IN EACH CASE THUNDERSTORM DEVELOPMENT WILL BE A
POSSIBILITY...AUGMENTED BY WHATEVER OUTFLOW BOUNDARIES REMAIN ACROSS
THE AREA FROM PREVIOUS CONVECTION. HOWEVER...SOUTHWEST NEBRASKA MAY
NOT GET AS MUCH AS PORTIONS OF THE SANDHILLS AND NORTHERN NEBRASKA
IN THIS TYPE OF SETUP SO IN GENERAL PRECIP CHANCES REFLECT THIS LINE
OF THINKING WHICH MODELS SEEMS TOGET THE IDEA OF AS WELL.

IN THE OUTER PERIODS MODELS GENERALLY AGREE ON BUILDING THE UPPER
RIDGE ACROSS THE PLAINS WHICH SEEMS TO MAKE SENSE GIVEN A MORE
ACTIVE ERN PACIFIC IN LATER PERIODS AS THE MJO AND ASSOCIATED
EFFECTS PROPAGATE EWD. THIS WILL MEAN A TREND TWD ABOVE AVERAGE
TEMPS AND LESSENING CHANCES FOR PRECIPITATION. MONDAY IS THE
TRANSITION DAY HOWEVER AS MODELS SUGGEST A WEAK SHORT WAVE MOVING
INTO THE NORTHERN HIGH PLAINS. CONFIDENCE AT THIS TIME IS LACKING SO
PRECIPITATION CHANCES FOR MONDAY AND MONDAY NIGHT ARE NOT INCLUDED
AT THIS POINT.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 102 PM CDT WED JUN 19 2013

VFR CONDITIONS THIS AFTERNOON...ALTHOUGH WILL SEE SOME MID/HIGH
CLOUDS ON THE INCREASE. SOUTHERLY WINDS WILL ALSO GUST AT TIMES
ABOVE 20 KTS. OVERNIGHT A FEW MODELS HINT AT SOME LOWER STRATUS
DEVELOPING. CONFIDENCE IS LOW ON DEVELOPMENT...HOWEVER DID
INCLUDE A SCT LOW DECK AT TIME. STRATUS IS LIKELY DEPENDENT ON
CONVECTION OVERNIGHT...WHICH IS ISOLD AND MAINLY TO THE WEST AND
EAST OF THE TERMINAL SITES...AND ANY OUTFLOW BOUNDARIES THAT MAY
DEVELOP. ANY LOWER CLOUDS THAT DO DEVELOP WILL QUICKLY BURN OFF
IN THE MORNING.


&&

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

$$

SYNOPSIS...MASEK
SHORT TERM...MASEK
LONG TERM...JWS
AVIATION...MASEK