Area Forecast Discussion
Issued by NWS North Platte, NE

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000
FXUS63 KLBF 191155
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
655 AM CDT SAT JUL 19 2014

.SYNOPSIS...
ISSUED AT 333 AM CDT SAT JUL 19 2014

AT THE SURFACE...LOW PRESSURE WAS CENTERED OVER CENTRAL WYOMING WITH
A WEAK BOUNDARY EXTENDING EAST INTO SOUTH DAKOTA AND SOUTH INTO
EASTERN COLORADO. DEWPOINTS AT OR ABOVE 60F HAD SQUEEZED BETWEEN THE
BOUNDARIES TO NORTHWEST NEBRASKA. ALSO...INDICATING LOW LEVEL
MOISTURE...STRATUS HAD PUSHED INTO CENTRAL AND SOUTH CENTRAL
NEBRASKA EXTENDING NORTHWARD AND WESTWARD TO NORTH OF BROKEN BOW AND
NORTH PLATTE AND EAST OF IMPERIAL AND OGALLALA. SATELLITE DERIVED
PRECIPITABLE WATER FROM GOES AND LOW ORBITER MICROWAVE SENSORS
(AMSU) WAS 25-30MM OVER SOUTHERN NEBRASKA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 333 AM CDT SAT JUL 19 2014

HEAT IS ON IN WESTERN NEBRASKA TODAY WITH HIGHS EXPECTED IN THE
LOWER 90S. ALSO...WITH DEWPOINTS OF 60-65...IT WILL BE HUMID.
OTHERWISE...MOISTURE AND WIND CONVERGENCE ALONG THE SURFACE
BOUNDARIES WILL PROVIDE A FOCUS FOR THUNDERSTORMS TO DEVELOP THIS
AFTERNOON AND EVENING. THE CONVERGENCE ZONE WILL MAKE ITS WAY
EASTWARD TO CENTRAL NEBRASKA DURING THE EVENING. THOUGH THE COVERAGE
IS LIKELY TO BE LIMITED...ANY THUNDERSTORMS THAT DEVELOP HAVE
POTENTIAL FOR LARGE HAIL. CONDITIONS COULD BECOME VERY UNSTABLE
ACCORDING TO THE STRONGEST OF THE SHORT RANGE MODELS (THE NAM12)
WITH SURFACE BASED POTENTIAL CONVECTIVE ENERGY POSSIBLE EXCEEDING
4000J/KG AND 800MB BASED POTENTIAL ENERGY APPROACHING 3000J/KG.
ALSO...THE 0-6KM  BULK SHEAR IS EXPECTED TO BE 35-40KT WHICH COULD
PROVIDE ENOUGH OFFSET OF THE UPDRAFT FOR LARGE HAIL TO REACH THE
GROUND. OTHER MODELS...SUCH AS THE HRRR13 AND THE GFS40 INDICATE
WEAKER SHEAR AND CONVECTIVE POTENTIAL SO THERE REALLY IS NOT A
STRONG CONSENSUS AMONG THE SHORT RANGE PROJECTIONS REGARDING THE
POTENTIAL CONVECTIVE ENERGY OR THE 0-6KM BULK SHEAR...SO WE WILL NOT
INCLUDE SEVERE IN THE FORECAST AT THIS TIME.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 333 AM CDT SAT JUL 19 2014

MAIN FORECAST CONCERNS IN THE EXTENDED PERIODS CENTER ON A
BUILDING SUBTROPICAL RIDGE ATOP THE CENTRAL AND NORTHERN PLAINS.
TRIPLE DIGIT HIGHS WILL BE POSSIBLE SUNDAY AND AGAIN MONDAY FOR
PORTIONS OF THE COUNTY WARNING AREA...WITH THE POSSIBILITY OF HEAT
HEADLINES NEEDED. LARGE SCALE SUBSIDENCE ASSOCIATED WITH THE
BUILDING HIGH WILL BE GREATLY SUPPRESS PRECIPITATION
CHANCES...ESPECIALLY SINCE WARMING TEMPERATURES ALOFT WILL CAP
MUCH OF THE REGION...BUT PRECIP CHANCE ARE NOT NIL AS PERIODIC
WEAK DISTURBANCES MAY FOCUS STORMS ALONG A WEAK BOUNDARY OR TWO.

THE UPPER RIDGE IS SHOWN TO BUILD AND STRENGTHEN NORTHEAST ATOP THE
PLAINS ON SUNDAY.  H85 TEMPERATURES WILL RESPOND BY WARMING TO NEAR
OR ABOVE 30C.  NUMERICAL GUIDANCE IS PEGGING TRIPLE DIGIT HEAT
ACROSS MUCH OF SOUTHWEST NEBRASKA AND THE I80 CORRIDOR SUNDAY
AFTERNOON.  SOMEWHAT CONCERNING IS THE HIGH RH...LEADING TO HEAT
INDICES OF GREATER THAN 100F FOR MOST LOCATIONS SOUTH OF THE
INTERSTATE AND NORTHEAST THROUGH CUSTER AND WHEELER COUNTIES.  WE
FULLY ANTICIPATE THE NEED FOR A HEAR RELATED HEADLINE...BUT WILL
HOLD OFF UNTIL THE AFTERNOON FORECAST PACKAGE SO THAT WE CAN FURTHER
DEFINE THE LOCATION OF SAID HEADLINE.  THE HEAT AND HUMIDITY WILL
LEAD TO UNSTABLE ATMOSPHERIC CONDITIONS...BUT WITH WIDESPREAD H7
TEMPERATURES OF 15C OR WARMER...THE ATMOSPHERE IS ANTICIPATED TO BE
CAPPED.  WILL LEAVE THE FORECAST DRY FOR SUNDAY.  MORE OF THE SAME
ON MONDAY...EXCEPT THE WARMEST TEMPERATURES SHOULD SHIFT EAST AND
NORTH A BIT.  HEAT RELATED HEADLINES MAY BE NEEDED ACROSS NORTH
CENTRAL NEBRASKA AS SFC HIGH TEMPERATURES ARE EXPECTED TO ECLIPSE
100F.  THE EC AND THE NAM ARE GENERATING CONVECTION TO THE WEST OF
THE CWA MONDAY AFTERNOON AND SUGGESTING THE ACTIVITY TO SPREAD EAST
INTO THE EVENING.  NOT TOO EXCITED WITH THE CONVECTIVE PROSPECTS AT
THIS TIME...AS ONCE AGAIN THE ATMOSPHERE WILL BE STRONGLY
CAPPED...AND A LLJ IS SHOWN TO SHIFT EAST OF THE AREA....BUT WILL
NEED TO WATCH AS THERE IS SLIGHTLY BETTER FORCING INDICATED WITH A
WEAK DISTURBANCE AND SFC TROUGH IN THE REGION. IF STORMS
GO...INVERTED T/TD PROFILES FAVOR EXTREME WIND GUSTS.

COOL FRONT TO CROSS WESTERN NEBRASKA EARLY TUESDAY WITH A
NORTHEASTERLY TO EASTERLY COMPONENT OF THE LOWER TROPOSPHERIC WIND
TO FOLLOW.  TEMPERATURES WILL COOL CLOSER TO NEAR SEASONAL NORMS FOR
MIDWEEK.  DEPENDING ON THE VARIOUS MODEL OF CHOICE...PERTURBATIONS
AND/OR WEAK UPSLOPE FLOW TO BRING A SLIGHT CHANCE OF STORMS THROUGH
THE EXTENDED...HOWEVER THESE POPS WERE SCALED BACK AS THE REGION
WILL BE UNDER THE INFLUENCE OF THE EXPANSIVE UPPER RIDGE THROUGH
LATE WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 654 AM CDT SAT JUL 19 2014

OUTFLOW FROM THE THUNDERSTORMS IN NORTHERN NEBRASKA IS SCOURING
OUT THE LOW STRATUS. THE LOW CEILINGS SHOULD SCATTERED OUT AT
BBW...LBF AND OGA BY 14Z. SHOWERS AND THUNDERSTORMS IN NORTHERN
NEBRASKA ARE EXPECTED TO WEAKEN AND DISSIPATE BY LATE THIS MORNING
OR EARLY AFTERNOON. THEY HAVE CLEARED VTN AND WILL CLEAR ANW BY
13Z. THUNDERSTORMS MAY MOVE OVER ONL BETWEEN 12Z AND 15Z IF THEY
CAN HOLD TOGETHER.

OTHERWISE...THUNDERSTORMS ARE EXPECTED TO REDEVELOP THIS AFTERNOON
IN WESTERN NEBRASKA. HOWEVER...THE COVERAGE WILL BE LESS THAN 30
PERCENT AND THE PROBABILITY OF THUNDER AT ANY ONE SITE IS LOW.

&&

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

$$

SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...JACOBS
AVIATION...SPRINGER





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