000
FXUS63 KLBF 160900
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
400 AM CDT THU MAY 16 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 459 AM CDT THU MAY 16 2013

AT 08Z...RADAR RETURNS HAVE BEGUN IN GARDEN COUNTY WELL AHEAD OF AN
APPROACHING UPPER LEVEL LOW CIRCULATION CENTER JUST NORTHEAST OF
GRAND JUNCTION CO ALONG WITH AN ASSOCIATED PV ANOMALY. THIS FEATURE
WILL TRACK NORTHEAST TODAY INTO TONIGHT. AS SURFACE WINDS VEER TO
THE SOUTHEAST THIS MORNING...HIGHER DEWPOINTS IN THE LOWER TO MID
50S WILL BE DRAWN INTO MUCH OF WESTERN NEBRASKA TODAY. PRECIPITABLE
WATER VALUES ALSO INCREASE TO AROUND AN INCH TO 1.25 INCHES BY THIS
AFTERNOON. A WARM FRONT CURRENTLY LOCATED ACROSS FAR SOUTHERN
NEBRASKA NORTHWEST INTO EASTERN WYOMING WILL LIFT SLOWLY NORTH
TODAY. AS UPPER TROUGH LIFTS ACROSS THE REGION...CONVECTION WILL
CONTINUE TO DEVELOP AND SPREAD EAST ACROSS THE WESTERN SANDHILLS BY
MID MORNING AND OVER THE REMAINDER OF THE FA THIS AFTERNOON AND
EVENING. MODEL CONSENSUS IS FOR HIGHEST POPS ACROSS NORTH CENTRAL
NEBRASKA TODAY....WHERE 60 POPS FORECAST...FURTHER SOUTH TO NORTH
PLATTE AND BROKEN BOW 50 POPS. COVERAGE SHOULD MAINLY BE SCATTERED
TODAY. INSTABILITY WILL BE IN PLACE AS WELL...WITH SB CAPES RISING
AOA 500-1500 J/KG. DEEP CONVECTION THAT DEVELOPS WOULD HAVE THE
CAPABILITY TO PRODUCE HAIL UP TO ONE INCH IN DIAMETER AND STRONG
WIND GUSTS.  ALSO WITH THE INCREASING LOW LEVEL ATMOSPHERIC
MOISTURE...BENEFICIAL RAIN WILL OCCUR UNDER THE HEAVIEST OF
CELLS...BUT TOTAL OVERALL QPF AMOUNTS LOOK TO REMAIN LIGHT AT LESS
THAN A QUARTER INCH SOUTH AND A QUARTER TO HALF INCH NORTH
CENTRAL...EXCEPT UNDER THE HEAVIEST OF CELLS.

WITH THE EXPECTED INCREASE IN CLOUDS AND PRECIPITATION...HIGH
TEMPERATURES ARE GOING TO BE TRICKY THIS AFTERNOON. WENT NEAR A
MET/MAV BLEND IN TEMPERATURES FROM 76 TO 81 NCTRL TO 80 TO 85 SOUTH.

FOR TONIGHT...THE TROUGH AND ASSOCIATED SHOWERS AND THUNDERSTORMS
SHOULD EXIST MOST OF THE AREA BY 06Z...WITH ONLY A 30 POP NORTHEAST
AFTER 06Z. A FEW STRONG STORMS POSSIBLE THROUGH EARLY EVENING.
SOUTHERLY WINDS 5 TO 15 MPH WILL KEEP LOWS UP FROM NEAR 60 IN FAR
EASTERN AREAS TO THE MID 50S WESTERN SANDHILLS. A FAIRLY SUBSTANTIAL
UPPER TROUGH WILL DIG INTO THE WEST COAST REGION OVERNIGHT WITH
BROAD RIDGING PRESENT ACROSS THE CENTRAL CONUS.


.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 459 AM CDT THU MAY 16 2013

THIS FORECAST PERIOD DEALS WITH SHOWER AND THUNDERSTORM CHANCES
THROUGH MUCH OF THE PERIOD...ALONG WITH TEMPERATURES...AS ABOVE
NORMAL FOR THE WEEKEND TURNS TO BELOW NORMAL FOR THE FIRST HALF OF
NEXT WEEK.

IN GENERAL...THE PERIOD BEGINS WITH RIDGING OVER THE PLAINS AS THE
TROUGH CURRENTLY MOVING INTO THE PACIFIC NORTHWEST DIGS IN ACROSS
THE WESTERN PART OF THE CONUS THROUGH FRIDAY. THIS SYSTEM IS BEING
MODELED TO SPLIT...WITH ONE CIRCULATION PULLING NORTH INTO MONTANA
FOR SATURDAY WHILE A BROAD TROUGH SITS CENTERED OVER THE FOUR
CORNERS. THEN FOR THE FIRST HALF OF NEXT WEEK...TROUGHING /AND A
FAIRLY STRONG UPPER LOW/ WILL BE IN PLACE OVER THE NORTHERN AND
CENTRAL PLAINS...TO KEEP CHANCES FOR PRECIPITATION AND COOLER
TEMPERATURES IN THE FORECAST.

FRIDAY...EXPECTING A PRETTY WARM DAY ACROSS THE FORECAST AREA WITH
GOOD MIXING AND A WARM AIRMASS IN PLACE. 700MB TEMPERATURES WILL
BE 8-10C...WHICH WOULD BRING HIGHS INTO THE UPPER 80S TO LOW 90S.
DID INCREASE HIGHS BY A FEW DEGREES...BUT WITH MORE MOISTURE IN
PLACE THAN HAVE SEEN OVER THIS PAST WEEK TO INHIBIT MIXING DEPTH
FOR SOME OF THE AREA...DIDN/T GO AS HIGH AS SOME OF THE MODELS
WERE SUGGESTING. THE UPPER LEVEL TROUGH REMAINS WELL TO THE WEST
OF THE REGION...WHICH WILL KEEP THE SURFACE TROUGH ANCHORED OVER
THE LEE SIDE OF THE ROCKIES. COULD GET A DRY LINE TO PUSH INTO THE
PANHANDLE AND WITH INSTABILITY IN PLACE AND SLIGHT UPSLOPE
FLOW...COULD GET SOME STORMS TO DEVELOP OVER THE NORTHERN
PANHANDLE IN THE LATE AFTERNOON. DO THINK THERE IS A BETTER CHANCE
INTO THE EVENING AS THE LOW LEVEL JET STRENGTHENS AFTER
03Z...WITH THE FOCUS INTO NORTHWEST NEBRASKA AND SOUTH DAKOTA.
ONGOING FORECAST HAD THIS HANDLED WELL WITH SOME LOW CHANCES OVER
THE NORTHERN PANHANDLE AND FAR NORTHWEST NEBRASKA IN THE
AFTERNOON...WITH INCREASED CHANCES IN THESE SAME AREAS INTO THE
EVENING. UPPER LEVEL FLOW WOULD INDICATE ANY STORMS THAT DEVELOP
WILL MOVE NORTH-NORTHEAST SO SHOULDN/T IMPACT MUCH OF THE
FORECAST AREA. DEEP LAYER SHEAR THROUGH THIS TIME IS AROUND
30-35KTS SO COULD SEE A FEW ORGANIZED CELLS...BUT NOT CONCERNED
WITH WIDESPREAD SEVERE POTENTIAL.

ON SATURDAY...THE UPPER LOW MOVES CLOSER WITH A SURFACE LOW
DEVELOPING OVER NORTHWEST KANSAS. LOOKING FOR CONVECTION TO BECOME
FAIR LY WIDESPREAD IN THE AFTERNOON ACROSS THE WESTERN AND NORTH
CENTRAL NEBRASKA. THIS LOOKS TO BE THE DAY WITH THE BEST SETUP FOR
ANY SEVERE STORMS...WITH GOOD SHEAR IN PLACE FOR ORGANIZED
CONVECTION AND GOOD INSTABILITY OVER THE AREA. WHAT WILL NEED TO
MONITORED IS WHERE THE SURFACE LOW SETS UP AS BOUNDARIES OFF OF
THAT FEATURE WILL LIKELY BE THE FOCUS FOR STRONGER STORMS. THE LOW
LEVEL JET DOES INCREASE OVERNIGHT WITH SEVERAL MODELS SHOWING IT
FOCUSING INTO THE FORECAST AREA. SO THUNDERSTORM CHANCES INCREASE
AND CONTINUE THROUGH THE OVERNIGHT HOURS.

FOR NEXT WEEK...THE UPPER LEVEL TROUGH OVER THE FOUR CORNERS WILL
PULL NORTHEAST OVER THE CENTRAL PLAINS. AT THIS POINT...ANOTHER
UPPER LOW WILL DIG INTO THE LONGWAVE TROUGH WHILE STRONG RIDGING
REMAINS OVER THE EASTERN HALF OF THE COUNTRY. THIS PATTERN WILL
KEEP THIS UPPER LEVEL LOW FAIRLY STATIONARY FOR A TIME OVER THE
REGION. ALTHOUGH THERE IS SOME DIFFERENCES BETWEEN MODEL SOLUTIONS
ON HOW THIS WILL ALL PLAY OUT IN TERMS OF PRECIPITATION
CHANCES...THERE IS GOOD AGREEMENT IN THE GENERAL UPPER LEVEL
PATTERN THROUGH THIS PERIOD. AS WAS MENTIONED EARLIER...THERE
LOOKS TO BE A CIRCULATION THAT WILL EJECT OUT OF THE MAIN TROUGH
AND PUSH INTO MONTANA EARLY IN THIS PERIOD. BY LATE SUNDAY/MONDAY
THE MAIN LOW MAY INGEST THIS SECOND CIRCULATION...WHICH WOULD PULL
COOLER AIR INTO THE AREA.

WITH SHOWER/THUNDERSTORM CHANCES...AS THE UPPER LOW STAYS RIGHT
OVER THE FORECAST AREA THROUGH TUESDAY NIGHT...FELT THE NEED TO
KEEP CHANCES IN THE FORECAST THROUGH THIS TIME. IN ADDITION...WITH
THE COOLER AIR IN PLACE /ESPECIALLY ALOFT WITH 700MB TEMPERATURES
DROPPING BELOW 0C/ LAPSE RATES WILL STAY STEEP SO KEPT THUNDER IN
THROUGH ALL PERIODS.

IN TERMS OF TEMPERATURES...THE COOL AIR STARTS MOVING IN ON
SUNDAY AND WILL PERSIST THROUGH THE MIDDLE PART OF NEXT WEEK. IN
ADDITION...CLOUDS AND RAINS COULD TAKE PART IN KEEPING
TEMPERATURES DOWN A FEW OF THESE DAYS. LOOKING FOR HIGHS IN THE
60S TO LOW 70S THROUGH MUCH OF THE FIRST HALF OF NEXT WEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1207 AM CDT THU MAY 16 2013

THERE IS CONSIDERABLE DISAGREEMENT AMONG THE DIFFERENT SHORT RANGE
SIMULATIONS REGARDING THE POTENTIAL AND TIMING FOR THUNDERSTORMS
THROUGH THE NEXT 36 HOURS. THERE IS A WEAK SURFACE FRONT ACROSS
NORTHERN AND WESTERN KANSAS WHICH COULD PROVIDE A FOCUS FOR
THUNDERSTORM DEVELOPMENT TONIGHT. A TIME SECTION OVER LBF INDICATES
TWO PERIODS OF UPWARD MOTION AND HIGH RELATIVE HUMIDITY ALOFT.
HOWEVER...SHORT RANGE PROJECTIONS ALSO INDICATE THE HIGHEST CHANCES
OF THUNDERSTORMS 18Z OR LATER WHEN THE FRONT BEGINS TO MAKE ITS WAY
NORTHWARD INTO NEBRASKA. GOING WITH THE MOST LIKELY SCENARIO...WE
WILL BRING SHOWERS AND THUNDERSTORMS INTO CENTRAL AND WESTERN
NEBRASKA AFTER 18Z. THIS TIMING WOULD APPLY TO THE AREA SOUTH AND
EAST OF A VTN-OGA LINE. FOR THE AREA NORTH AND WEST OF THAT
LINE...AN EARLIER ONSET IS POSSIBLE.

&&

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

$$

SHORT TERM...ROBERG
LONG TERM...BROOKS
AVIATION...ROBERG