Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 232356
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
656 PM CDT WED JUL 23 2014

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 253 PM CDT WED JUL 23 2014

MAP ANALYSIS INDICATES UPPER TROPOSPHERIC RIDGING OVER THE
WESTERN HALF OF THE CONUS...WITH ZONAL FLOW OVER OVER THE EAST.
ENHANCED UPPER TROPOSPHERIC FLOW EXTENDS FROM THE WESTERN
CONUS...NORTHEAST INTO THE NORTHERN HIGH PLAINS...AND THEN
EAST/SOUTHEAST INTO THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES
REGION...THUS RESULTING IN FAIRLY WEAK UPPER TROPOSPHERIC FLOW
OVER OUR AREA. AT THE SURFACE A RIDGE OF HIGH BAROMETRIC PRESSURE
EXTENDS FROM THE NORTHERN PLAINS AND UPPER MISSISSIPPI
VALLEY...SOUTH/SOUTHWEST INTO PORTIONS OF THE CENTRAL PLAINS...BUT
THIS RIDGE AXIS HAS MOVED JUST EAST OF OUR AREA THUS ALLOWING THE
LOWER TROPOSPHERIC WIND FIELD ACROSS OUR AREA TO BECOME MORE
SOUTHEASTERLY.

LOWER TROPOSPHERIC THERMAL ADVECTION AND RESULTANT ISENTROPIC
UPGLIDE...PRIMARILY WITHIN THE 305-310K SURFACES...HAS PROMOTED
CONTINUED PRECIPITATION PRODUCTION ACROSS WESTERN AND SOUTHERN
PORTIONS OF OUR CWA THROUGH MUCH OF TODAY. AS OF THIS WRITING
HOWEVER...KUEX INDICATES THIS ACTIVITY IS DIMINISHING AS IT MOVES
SOUTH OUT OF OUR AREA.

ONCE THE CURRENT PRECIPITATION MOVES OUT OF OUR AREA...GUIDANCE
SUGGESTS AN OVERALL LACK IN OMEGA WILL PRESENT DRY CONDITIONS TO
OUR AREA THROUGH THIS EVENING. LATER TONIGHT HOWEVER...A 40-50KT
LOWER TROPOSPHERIC JET STREAK AXIS JUST ABOVE THE BOUNDARY LAYER
IS EXPECTED TO DEVELOP FROM SOUTHWESTERN NEBRASKA INTO SOUTH
CENTRAL SOUTH DAKOTA. THIS AXIS IS THEN EXPECTED TO SHIFT
EAST/NORTHEAST MORE INTO NORTHEASTERN NEBRASKA AND SOUTHEASTERN
SOUTH DAKOTA THURSDAY MORNING. ALTHOUGH THE PRIMARY AXIS OF
THERMAL ADVECTION IN ASSOCIATION WITH THIS JET STREAK IS EXPECTED
TO REMAIN NORTH AND NORTHEAST OF OUR AREA...QPF FIELDS FROM
VARIOUS DETERMINISTIC MODELS SUGGEST THE SOUTHWESTERN PERIPHERY OF
THE PRIMARY THERMAL ADVECTION AXIS COULD CLIP OUR NORTHEASTERN
CWA...THUS RESULTING IN SOME PRECIPITATION PRODUCTION. SIMULATED
REFLECTIVITY FROM VARIOUS MODELS IS NOT NEARLY AS CONFIDENT AS THE
AFOREMENTIONED QPF FIELDS...BUT THE INHERITED FORECAST ALREADY HAD
POPS IN OUR NORTHEAST FOR EARLY THURSDAY MORNING AND GIVEN THE
OUTPUT FROM THE DETERMINISTIC MODELS...FELT IT PRUDENT TO LEAVE
THE POPS IN FOR OUR EAST/NORTHEAST 06-18Z THURSDAY. AN OVERALL
LACK IN OMEGA IS THEN EXPECTED TO PROVIDE DRY CONDITIONS TO OUR
AREA THURSDAY AFTERNOON.

THE NAM AND OPERATIONAL GFS BOTH SUGGEST DEEP-LAYER MUCAPE VALUES
OF ~1000J/KG WILL BE IN EXISTENCE ACROSS OUR EAST/NORTHEAST
TONIGHT ...BUT AS USUAL THE BULK OF THIS POTENTIAL ENERGY WILL NOT
BE UTILIZED DUE TO THE NOCTURNAL INVERSION IN FACT...FORECAST
PROXIMITY SOUNDINGS FROM THE NAM AND OPERATIONAL GFS SUGGEST
PARCELS ROOTED AS HIGH AS 700MB OR 600MB WILL HAVE MORE THAN
100J/KG OF CIN TO OVERCOME ONLY TO ACHIEVE AROUND 500J/KG OF
ENERGY. GIVEN ALL THIS...SEVERE WEATHER DOES NOT SEEM LIKELY
TONIGHT...BUT PERHAPS WHAT LIMITED OMEGA THERE IS...AGAIN ON THE
SOUTHWESTERN PERIPHERY OF THE LOWER TROPOSPHERIC JET
STREAK...COULD PUSH PARCELS ENOUGH TO ALLOW ~500J/KG OF POTENTIAL
ENERGY TO BE UTILIZED. GIVEN THIS...WILL GO AHEAD AND OUTLOOK THE
POTENTIAL FOR SUB-SEVERE HAIL IN THE HWO FOR TONIGHT INTO THURSDAY
MORNING.

LITTLE IF ANY CHANGE IN THE LOWER TROPOSPHERIC AIR MASS SHOULD
PROMOTE SIMILAR OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS
MORNING...WITH LOWS IN THE 60S TO NEAR 70 CURRENTLY FORECAST FOR
TONIGHT. HIGHS IN THE MID 80S TO MID 90S ARE THEN FORECAST FOR
THURSDAY.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 253 PM CDT WED JUL 23 2014

MAIN FORECAST CONCERNS WILL BE CHANCES FOR THUNDERSTORMS THURSDAY
NIGHT AND SATURDAY AND TEMPERATURES THROUGH THE PERIOD.

THE UPPER RIDGE BREAKS DOWN AS AN UPPER LEVEL WAVE MOVES INTO THE
AREA THURSDAY NIGHT. A SURFACE LOW AND COLD FRONT DEVELOPING ON
THE HIGH PLAINS APPROACHES THE AREA DURING THE NIGHT. AS THE UPPER
WAVE MOVES INTO THE AREA THERE COULD BE A FEW SHOWERS AND
THUNDERSTORMS IN THE NORTHWESTERN PART OF THE FORECAST AREA DURING
THE EVENING. LATE THURSDAY NIGHT INTO FRIDAY...THE SURFACE LOW AND
COLD FRONT MOVE THROUGH THE AREA. AHEAD OF THE FRONT THE
TEMPERATURES WILL SOAR INTO THE 90S AND EVEN THE 100 TO 105 DEGREE
RANGE. DEW POINT TEMPERATURES WILL LIKELY BE IN THE MID 60S TO
AROUND 70 DEGREES AS WELL. THIS WILL CREATE HEAT INDICES OVER 100
DEGREES FOR THE SOUTH AND EASTERN PARTS OF THE FORECAST AREA.

DESPITE THE COLD FRONT MOVING THROUGH...TEMPERATURES ON SATURDAY
WILL REMAIN ON THE WARM SIDE WITH READINGS IN THE 90S FOR THE MOST
PART. A FEW DEGREES COOLER...BUT NOT COOL. SATURDAY AFTERNOON
THERE IS ANOTHER UPPER LEVEL WAVE THAT MOVES THROUGH THE AREA.
THIS COULD BRING A FEW THUNDERSTORMS TO THE NORTHEAST PART OF THE
FORECAST AREA.

SATURDAY NIGHT THROUGH TUESDAY THERE WILL BE NORTHWEST FLOW WITH
VERY FEW WAVES THAT MOVE THROUGH...AND THOSE THAT DO ARE FAIRLY
WEAK. COOLER AIR IS EXPECTED TO PUSH INTO THE AREA WITH
TEMPERATURES FALLING BACK BELOW NORMAL FOR THIS TIME OF YEAR FOR
MONDAY AND TUESDAY.

THE NEXT WAVE THAT WILL AFFECT THE AREA WILL MOVE INTO THE AREA
TUESDAY NIGHT INTO WEDNESDAY. EXPECT THERE COULD BE SOME
THUNDERSTORMS AROUND...BUT THERE ARE A FEW DIFFERENCES IN THE
MODELS SO WILL HAVE TO WATCH THIS PERIOD TO SEE WHAT HAPPENS.
TEMPERATURES WILL REMAIN ON THE COOLER SIDE.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 651 PM CDT WED JUL 23 2014

PREVAILING VFR CONDITIONS EXPECTED AT THE TERMINALS FOR THE NEXT
24 HOURS. THAT SAID...EXPECT THE POSSIBILITY FOR SOME LOW LEVEL
WIND SHEAR AT BOTH TERMINALS OVERNIGHT AS THE LOW LEVEL JET SETS
UP OVER WESTERN AND CENTRAL NEBRASKA...WHICH MAY ALSO RESULT IN
THE CHANCE FOR A VCTS NEAR KGRI DURING THE EARLY MORNING HOURS
THURSDAY. OTHERWISE...EXPECT A MOSTLY CLEAR AND BREEZY DAY ON
THURSDAY...WITH SOUTHERLY WINDS GUSTING TO NEAR 25 KTS OR GREATER
DURING THE LATE MORNING THROUGH AFTERNOON HOURS.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&

$$

SHORT TERM...BRYANT
LONG TERM...JCB
AVIATION...ROSSI


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