Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 182041
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
341 PM CDT MON AUG 18 2014

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014

THE MAIN FORECAST ISSUE WILL BE THE POSSIBILITY OF SOME
THUNDERSTORM ACTIVITY IN THE FAR SOUTHERN CWA OVERNIGHT.

WEST NORTHWEST FLOW ALOFT IS FAIRLY WEAK AND A NEARLY STALLED
BOUNDARY ACROSS THE CWA CONTINUES TO DRIFT SOUTH TODAY. LITTLE IF
ANY DEVELOPMENT SHOULD DEVELOP ALONG THIS BOUNDARY TODAY INTO THIS
EVENING AS A FAIRLY HEALTHY CAP KEEPS THINGS QUIET...DESPITE
MODERATE INSTABILITY IN THE 1500 TO 2000 J/KG RANGE FOR CONVECTIVE
AVAILABLE POTENTIAL ENERGY. SOME SMALL POP-UPS ARE SHOWING UP JUST
NORTH OF THE CWA...BUT THERE SHOULD BE ENOUGH OF A CAP TO TAMP
MUCH FURTHER DEVELOPMENT IN THE NORTH.

LATER ON TONIGHT...A HEALTHY 40 TO 45 KT JET WILL DEVELOP OVER
KANSAS AND WILL CURVE EAST...MOSTLY LIKELY OVER NORTH CENTRAL
KANSAS. THIS WILL SET THE STAGE FOR SOME POTENTIAL LOW-LEVEL
CONVERGENCE ACROSS OUR SOUTHERN CWA IN NORTH CENTRAL KANSAS AND
FAR SOUTHERN NEBRASKA NEAR THE AFOREMENTIONED SURFACE BOUNDARY.
THIS COULD BE JUST ENOUGH SUPPORT FOR SOME SMALL HAIL AND GUSTY
WIND IN OUR FAR SOUTH AS WELL. THE HRRR IS TRENDING STRONGER WITH
SOME DEVELOPMENT OVER THE HIGH PLAINS THIS AFTERNOON...SUPPORTED
BY ANOTHER LOW-AMPLITUDE SHORTWAVE TROUGH. THIS COULD BE ENHANCED
BY THE DEVELOPING LOW-LEVEL JET IN KANSAS AS THIS POTENTIAL
CONVECTION HEADS SOUTH. THE NAM HAS BEEN ADVERTISING SOME ACTIVITY
IN THIS VICINITY FOR THE PAST COUPLE OF DAYS. THE PRUDENT ACTION
WOULD BE TO PUT A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS BACK
INTO THE FORECAST IN OUR SOUTH. OUR CHANCES OF RAIN ARE LARGELY
DEPENDENT ON INITIAL CONVECTION IN THE HIGH PLAINS WITHIN THE
STRONGLY UNSTABLE...YET STILL CAPPED ENVIRONMENT TO THE WEST AS
THE AFOREMENTIONED TROUGH ENTERS THE CENTRAL PLAINS. THE SREF
SOLUTIONS ARE ALSO COMING IN WITH STRONGER SIGNALS TOWARD
CONVECTION IN OUR SOUTH AS WELL.

FOR TUESDAY...KEEPING IT QUIET WITH THE THINKING THAT THERE
SHOULD BE ENOUGH OF A CAP FROM PRECLUDING DEVELOPMENT UNTIL THE
EVENING HOURS. HIGH PLAINS CONVECTION COULD DEVELOP DURING THE
DAY...BUT SHOULD HOLD OFF MAKING IT HERE UNTIL EVENING...WHEN A
LOW-LEVEL JET AXIS DEVELOPS JUST TO THE WEST OF THE CWA.

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 341 PM CDT MON AUG 18 2014

GUIDANCE SUGGESTS UPPER TROPOSPHERIC RIDGING WILL EXIST OVER THE
CENTRAL CONUS TO START THE LONG TERM FORECAST PERIOD. THE RIDGE
AXIS IS EXPECTED TO SHIFT EAST SOMEWHAT BY THURSDAY OR FRIDAY
HOWEVER...ALLOWING FOR MORE OF A SOUTHWESTERLY UPPER TROPOSPHERIC
FLOW OVER OUR AREA LATE THIS WEEK INTO EARLY NEXT WEEK.

THE AXIS OF A 35-40KT LOWER TROPOSPHERIC JET STREAK...JUST ABOVE
THE BOUNDARY LAYER...IS EXPECTED DEVELOP FROM WESTERN KANSAS INTO
SOUTH CENTRAL NEBRASKA TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
THERMAL ADVECTION ALONG THIS AXIS APPEARS AS THOUGH IT WILL BE
SUFFICIENT FOR PRECIPITATION PRODUCTION ACROSS NORTHEASTERN
PORTIONS OF OUR CWA...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND EC. WENT AHEAD WITH 20-30% POPS ACROSS
OUR NORTHEAST TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING AS A
RESULT.

ON OVERALL LACK IN OMEGA SHOULD THEN PROVIDE DRY CONDITIONS TO
OUR AREA THROUGH MUCH OF THE DAY WEDNESDAY. BY LATE WEDNESDAY
AFTERNOON HOWEVER...THE NAM AND OPERATIONAL GFS BOTH SUGGEST
CONVECTION WILL INITIATE OVER THE CENTRAL HIGH PLAINS...AND THEN
MOVE EAST INTO OUR AREA WEDNESDAY EVENING AND OVERNIGHT. GIVEN
THIS...WENT AHEAD WITH 20-30% POPS ACROSS MUCH OF THE CWA
WEDNESDAY EVENING AND NIGHT.

ALTHOUGH OMEGA IS EXPECTED TO REMAIN WEAK THROUGH THE DAY
THURSDAY AS WELL...FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE
CWA...PER THE NAM AND OPERATIONAL GFS...SUGGEST A NEARLY DRY
ADIABATIC TEMPERATURE PROFILE WILL BE REALIZED FROM THE SURFACE TO
JUST ABOVE 700MB ACROSS MUCH OF THE CWA...THUS ALLOWING CONVECTIVE
TEMPERATURE READINGS TO BE REACH AND PROVIDING FOR ISOLATED
THUNDERSTORM DEVELOPMENT. THIS IS A SOLUTION ALSO SUPPORTED BY QPF
FIELDS FROM THE NAM...OPERATIONAL GFS AND EC. GIVEN ALL
THIS...WENT AHEAD WITH ~20% POPS ACROSS MUCH OF THE CWA THURSDAY
AFTERNOON AND EVENING.

HEADING INTO THURSDAY NIGHT AND BEYOND...GUIDANCE SUGGESTS
MULTIPLE UPPER TROPOSPHERIC PERTURBATIONS COULD MOVE OVER THE
CENTRAL PLAINS AS THE SOUTHWESTERLY UPPER TROPOSPHERIC FLOW
INTENSIFIES. ALLBLEND RESPONDED BY PROVIDING 20-50% POPS TO MANY
AREAS ACROSS THE CWA THURSDAY NIGHT THROUGH MONDAY...AND THESE
POPS WERE LEFT UNCHANGED FOR THE MOST PART.

FORECAST PROXIMITY SOUNDINGS FROM THE NORTHEASTERN CWA...PER THE
NAM AND OPERATIONAL GFS...SUGGEST STORM-ACCESSIBLE POTENTIAL
ENERGY WILL NOT EXCEED 200-300J/KG TUESDAY NIGHT INTO EARLY
WEDNESDAY MORNING AND THUS...WILL HOLD OFF FROM ANY MENTION OF
SEVERE WEATHER TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING.
CONVECTION ALONG THE CENTRAL HIGH PLAINS WEDNESDAY AFTERNOON AND
EVENING WILL LIKELY HAVE THE CAPABILITY TO BE STRONG...BUT THERE
IS CONSIDERABLE UNCERTAINTY AS TO HOW LONG THIS CONVECTION WILL BE
ABLE TO MAINTAIN ITS INTENSITY AS IT MOVES EAST INTO OUR AREA.
GIVEN THIS UNCERTAINTY...WILL HOLD OFF FROM ANY MENTION OF SEVERE
WEATHER ACROSS OUR AREA WEDNESDAY EVENING AND LET FUTURE SHIFTS
REEVALUATE. BEYOND WEDNESDAY EVENING...AT THIS TIME THERE ARE NO
OVERWHELMING SIGNALS OF A SIGNIFICANT SEVERE WEATHER OUTBREAK.
ALTHOUGH A FEW HIT AND MISS STRONG TO SEVERE STORMS PROBABLY
CANNOT BE RULED OUT...DUE TO THE UNCERTAINTY WILL LEAVE OUT ANY
MENTION OF SEVERE WEATHER WEDNESDAY NIGHT AND BEYOND.

LITTLE CHANGE IN THE LOWER TROPOSPHERIC AIR MASS SHOULD PROMOTE
SIMILAR TEMPERATURE READINGS FROM DAY TO DAY WEDNESDAY THROUGH
SATURDAY...WITH AFTERNOON HIGHS IN THE UPPER 80S AND 90S AND
OVERNIGHT LOWS IN THE 60S AND LOWER 70S EXPECTED FOR THE MOST
PART. BEYOND SATURDAY...GUIDANCE DOES SUGGEST A LOWER TROPOSPHERIC
BAROCLINIC ZONE WILL MOVE ACROSS THE AREA...THUS ALLOWING A COOLER
LOWER TROPOSPHERIC AIR MASS INTO THE REGION. AFTERNOON HIGHS IN
THE UPPER 70S TO MID 80S AND LOWS GENERALLY IN THE 60S ARE
CURRENTLY EXPECTED TO FINISH THE LONG TERM FORECAST PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1243 PM CDT MON AUG 18 2014

WITH WEAK WEATHER FEATURES AT THE SURFACE AND LIGHT FLOW
ALOFT...WEATHER WILL BE RATHER BENIGN FOR THIS FORECAST.


&&

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

$$

SHORT TERM...HEINLEIN
LONG TERM...BRYANT
AVIATION...HEINLEIN



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