Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 302001
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
301 PM CDT TUE SEP 30 2014

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT)
ISSUED AT 258 PM CDT TUE SEP 30 2014

MAP ANALYSIS INDICATES UPPER TROPOSPHERIC RIDGING OVER THE CENTRAL
CONUS...AS WELL AS AN UPPER TROPOSPHERIC CLOSED LOW OVER THE
CENTRAL TO NORTHERN HIGH PLAINS. ENHANCED UPPER TROPOSPHERIC
FLOW EXTENDS FROM THE SOUTHWESTERN CONUS...EAST INTO THE SOUTHERN
HIGH PLAINS...THEN NORTH ACROSS MUCH OF THE PLAINS AND INTO
CANADA. UPPER TROPOSPHERIC FLOW OVER OUR AREA MAXES OUT AROUND
60KTS NEAR 37000FT AGL PER 12Z SOUNDING DATA FROM KLBF AND KOAX.
WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED UPPER
TROPOSPHERIC RIDGE OVER THE CENTRAL CONUS AS WELL AS THE CLOSED
UPPER TROPOSPHERIC LOW OVER THE CENTRAL TO NORTHERN HIGH PLAINS.
WATER VAPOR IMAGERY ALSO SHOWS ENHANCED UPPER TROPOSPHERIC
MOISTURE EXTENDING ALONG THE PRIMARY BAND OF THERMAL ADVECTION
FROM SOUTH CENTRAL KANSAS INTO EAST/SOUTHEASTERN NEBRASKA. AN
UPPER TROPOSPHERIC DRY-INTRUSION IS ALSO NOTED EXTENDING FROM
NORTHWESTERN KANSAS INTO CENTRAL NEBRASKA. AT THE SURFACE...AN
AREA OF LOW BAROMETRIC PRESSURE EXISTS OVER WESTERN SOUTH DAKOTA.
A COLD FRONT EXTENDS SOUTHWEST FROM THE LOW INTO WESTERN NEBRASKA
AND NORTHEASTERN COLORADO...AND A WARM FRONT/ STATIONARY BOUNDARY
EXTENDS EAST/SOUTHEAST ACROSS SOUTH DAKOTA...NORTHEASTERN NEBRASKA
AND WESTERN IOWA. BOUNDARY-LAYER FLOW ACROSS OUR AREA REMAINS FROM
THE SOUTH AS A RESULT.

GUIDANCE FROM THE NAM...OPERATIONAL GFS AND EC SUGGESTS THE CLOSED
UPPER TROPOSPHERIC LOW...CURRENTLY OVER THE CENTRAL TO NORTHERN
HIGH PLAINS...WILL MOVE NORTHEAST AND WEAKEN INTO A SHORT WAVE
THROUGH THE NEXT 36 HOURS...LIKELY MOVING INTO SOUTH CENTRAL
CANADA BY 12Z WEDNESDAY AND ADVANCING FARTHER NORTHEAST INTO
CANADA WEDNESDAY INTO WEDNESDAY NIGHT. SOUTHWESTERLY UPPER
TROPOSPHERIC FLOW IS THEN EXPECTED TO OVERTAKE THE CENTRAL PLAINS
WEDNESDAY INTO WEDNESDAY NIGHT AS AN UPPER TROPOSPHERIC TROUGH
STRENGTHENS OVER THE ROCKIES. ALONG WITH THIS APPROACHING TROUGH
AXIS...AN UPPER TROPOSPHERIC JET STREAK OF ~70KTS IS ALSO EXPECTED
TO DEVELOP FROM NORTH TEXAS INTO NORTHWESTERN MISSOURI. AT THE
SURFACE...THE AREA OF LOW BAROMETRIC PRESSURE OVER WESTERN SOUTH
DAKOTA IS EXPECTED TO MOVE NORTHEAST...ALONG WITH THE UPPER
TROPOSPHERIC LOW/SHORT WAVE...THROUGH THE NEXT 36 HOURS. THIS LOW
WILL LIKELY MOVE INTO SOUTH CENTRAL CANADA BY 12Z WEDNESDAY...AND
FARTHER INTO CANADA WEDNESDAY INTO WEDNESDAY NIGHT. THIS SHOULD
ALLOW THE BOUNDARY-LAYER BAROCLINIC ZONE...CURRENTLY ACROSS
WESTERN NEBRASKA...TO MOVE EAST AND CLEAR PORTIONS OF OUR CWA
TONIGHT. THAT SAID...THIS BAROCLINIC ZONE SHOULD WILL NOT LIKELY
CLEAR THE ENTIRE CWA BEFORE IT STALLS OUT ACROSS CENTRAL OR
SOUTHEASTERN PORTIONS OF THE CWA DURING THE DAY WEDNESDAY AS
ANOTHER AREA OF LOW BAROMETRIC PRESSURE STRENGTHENS OVER
SOUTHWESTERN KANSAS. THIS SECONDARY AREA OF LOW BAROMETRIC
PRESSURE OVER SOUTHWESTERN KANSAS SHOULD THEN MOVE EAST ACROSS
SOUTHERN KANSAS WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING...THUS
ALLOWING THE BOUNDARY-LAYER BAROCLINIC ZONE TO COMPLETELY CLEAR
OUR AREA BY EARLY THURSDAY MORNING. GIVEN ALL THIS...THE BOUNDARY-
LAYER FLOW ACROSS OUR AREA SHOULD REMAIN FROM THE SOUTH THIS
AFTERNOON AND EVENING...BEFORE BECOMING MORE NORTHERLY ACROSS OUR
NORTH/NORTHWEST TONIGHT INTO WEDNESDAY. THE BOUNDARY-LAYER FLOW
SHOULD THEN BECOME NORTHERLY ACROSS THE ENTIRE CWA BY EARLY
THURSDAY MORNING.

THE EVOLUTION OF WEATHER LATE THIS AFTERNOON THROUGH THIS EVENING
REMAINS A BIT OF A MYSTERY FOR ROUGHLY THE EAST/SOUTHEASTERN HALF
OF THE CWA. FARTHER WEST/NORTHWEST ACROSS THE AREA...THE
CONTINUED INFILTRATION OF THE UPPER TROPOSPHERIC DRY INTRUSION AND
A RESULTANT LACK IN OVERALL OMEGA SHOULD PROVIDE DRY CONDITIONS TO
THAT AREA AND SUCH HAS BEEN PRESENTED IN THE FORECAST. FARTHER
EAST/SOUTHEAST HOWEVER...UPPER TROPOSPHERIC THERMAL ADVECTION WILL
LIKELY PERSIST AND SEVERAL DETERMINISTIC MODELS RESPOND BY
PROVIDING PRECIPITATION TO THE AREA. WHILE THESE SOLUTIONS ARE NOT
OUT OF THE REALM OF POSSIBILITY...IT IS INTERESTING TO NOTE THAT
RESULTANT OMEGA WITHIN THE PRIMARY AXIS OF UPPER TROPOSPHERIC
THERMAL ADVECTION DOES NOT APPEAR OVERLY STRONG...AND WITH THE
BOUNDARY-LAYER BAROCLINIC ZONE NOT EXPECTED TO MOVE INTO THE CWA
UNTIL LATER TONIGHT...ITS DIFFICULT TO FIND ANY SUBSTANTIAL FORM
OF LIFT THAT WOULD PROVIDE WIDESPREAD RAINFALL ACROSS OUR
EAST/SOUTHEAST LATE THIS AFTERNOON THROUGH THIS EVENING. ADD TO
THAT...SIMULATED REFLECTIVITY FROM 1KM WRF-ARW...1KM WRF-NMM...AND
HRRR ALL SUGGEST THE VAST MAJORITY OF PRECIPITATION LATE THIS
AFTERNOON INTO THIS EVENING WILL ACTUALLY REMAIN SOUTHEAST OF OUR
AREA. ALL THAT SAID...IT IS ALSO WORTH NOTING THAT MORNING CLOUD
COVER AND PRECIPITATION HAVE PROVIDED A DIFFERENTIAL HEATING
BOUNDARY FROM NEAR SMITH CENTER TO AURORA AND ALBION. BOUNDARY-
LAYER CONVERGENCE AND RESULTANT LIFT ALONG THIS BOUNDARY COULD
SERVE AS AN INITIATION POINT FOR CONVECTION LATE THIS AFTERNOON
AND EVENING AND GIVEN THIS...OPTED TO PLAY IT SAFE AND KEEP POPS
GOING ACROSS OUR EAST/SOUTHEASTERN CWA LATE THIS AFTERNOON THROUGH
THIS EVENING. DUE TO THE AFOREMENTIONED UNCERTAINTY OF THE
EVOLVING SITUATION HOWEVER...OPTED TO GO NO HIGHER THAN A 30% POP
ACROSS OUR EAST/SOUTHEAST UNTIL AFTER SUNSET.

HEADING INTO THE OVERNIGHT HOURS TONIGHT...THE AXIS OF A ~40KT JET
STREAK JUST ABOVE THE BOUNDARY LAYER IS EXPECTED TO DEVELOP FROM
SOUTH CENTRAL KANSAS INTO SOUTHEASTERN NEBRASKA...WITH THE
NORTHWESTERN PERIPHERY OF THIS JET STREAK CLIPPING OUR
SOUTHEASTERN CWA. THERMAL ADVECTION ALONG THIS AXIS APPEARS AS
THOUGH IT WILL BE SUFFICIENT FOR PRECIPITATION PRODUCTION ACROSS
OUR SOUTHEAST...A SOLUTION SUPPORTED BY QPF FIELDS FROM THE
NAM...OPERATIONAL GFS AND EC. THAT SAID...SIMULATED REFLECTIVITY
FROM SEVERAL MODELS REMAIN VERY PESSIMISTIC WITH RESPECT TO
PRECIPITATION PRODUCTION ACROSS OUR AREA TONIGHT AND WITH THE
PRIMARY JET STREAK AXIS REMAINING TO OUR SOUTHEAST...IT CERTAINLY
SEEMS TO BE A FAIR ARGUMENT. THAT SAID...OF ANY TIME PERIOD
BETWEEN LATE THIS AFTERNOON AND 12Z WEDNESDAY...THE 03-09Z TIME
PERIOD SEEMS TO HOLD THE HIGHEST PROBABILITY OF PRECIPITATION
PRODUCTION ACROSS OUR EAST/SOUTHEAST AND AS A RESULT...WENT AHEAD
AND RELEGATED THE HIGHEST POPS...~50%...TO OUR SOUTHEAST 03-09Z
TONIGHT.

THE MORNING HOURS ON WEDNESDAY...POST-SUNRISE...WILL LIKELY
PRESENT A DRY PERIOD TO THE AREA AS THE AFOREMENTIONED LOWER
TROPOSPHERIC JET AXIS WEAKENS AND SHIFTS EAST OF THE AREA. DRY
CONDITIONS ARE FORECAST 12-18Z AS A RESULT. HEADING INTO WEDNESDAY
AFTERNOON AND EVENING HOWEVER...INCREASING UPPER TROPOSPHERIC
THERMAL ADVECTION AHEAD OF THE APPROACHING TROUGH AXIS TO OUR
WEST...WORKING IN CONCERT WITH THE THERMALLY-INDIRECT CIRCULATION
WITHIN THE LEFT- FRONT QUADRANT OF THE AFOREMENTIONED UPPER
TROPOSPHERIC JET STREAK...COULD BE ENOUGH TO PROMOTE PRECIPITATION
PRODUCTION MOST ANYWHERE ACROSS THE AREA. GIVEN ALL THIS...WENT
AHEAD WITH 20-40% POPS ACROSS MUCH OF THE CWA WEDNESDAY AFTERNOON
AND EVENING...WITH POPS INCREASING TO AROUND 70% AFTER 06Z
THURSDAY FOR MANY LOCATIONS AS THE UPPER TROPOSPHERIC TROUGH AXIS
DRAWS CLOSER TO THE AREA THUS RESULTING IN INCREASING OMEGA.

UPPER TROPOSPHERIC LAPSE RATES ARE NOT OVERLY IMPRESSIVE THIS
AFTERNOON AND EVENING WITH THE CLOSED LOW/SHORT WAVE REMAINING
WELL NORTHWEST OF OUR AREA. THAT SAID...AFTERNOON SURFACE DEW
POINT READINGS IN THE UPPER 50S TO LOWER 60S ARE HELPING PROMOTE
POTENTIAL ENERGY VALUES OF 1000-1500J/KG ACROSS OUR EAST
SOUTHEAST. DEEP-LAYER BULK SHEAR VALUES ON THE ORDER OF 40KTS ARE
ALSO IN EXISTENCE. GIVEN ALL THIS...IT CERTAINLY SEEMS
POSSIBLE...SHOULD CONVECTION BE REALIZED LATE THIS AFTERNOON AND
EVENING...THAT A FEW STRONG TO PERHAPS SEVERE STORMS COULD BE
REALIZED AND WILL CONTINUE SUCH MENTION IN THE HWO. LOOKING AHEAD
TO WEDNESDAY AFTERNOON AND EVENING...THE BOUNDARY-LAYER AIR MASS
SHOULD NOT CHANGE ALL THAT MUCH WHEN COMPARED TO TODAY...BUT UPPER
TROPOSPHERIC LAPSE RATES WILL BE ON THE INCREASE WITH THE TROUGH
AXIS APPROACHING FROM THE WEST AND AS A RESULT...WEDNESDAY
AFTERNOON/EVENING POTENTIAL ENERGY VALUES TO BE CLOSER TO
2000J/KG. IN ADDITION...INCREASING UPPER TROPOSPHERIC JET ENERGY
SHOULD ALSO RESULT IN INCREASING DEEP-LAYER BULK SHEAR...WITH
VALUES CLOSER TO 45 OR 50KTS EXPECTED ACROSS OUR SOUTHEASTERN CWA
ON WEDNESDAY. FINALLY...A BACKED BOUNDARY-LAYER WIND FIELD TO THE
SOUTH OF THE BAROCLINIC ZONE MAY ALSO PROMOTE LOCALLY ENHANCED
BOUNDARY-LAYER SRH VALUES THUS PROMOTING THE POSSIBILITY OF
TORNADIC ACTIVITY. GIVEN ALL THIS...WILL CONTINUE THE MENTION OF
SEVERE WEATHER...INCLUDING TORNADIC ACTIVITY...IN THE HWO FOR FOR
MUCH OF THE AREA ON WEDNESDAY AFTERNOON AND EVENING.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 258 PM CDT TUE SEP 30 2014

PRIMARY FORECAST CONCERNS THROUGH THE LONG TERM PERIOD LIE WITH
PRECIPITATION CHANCES RIGHT OFF THE BAT...THEN TEMPERATURES.

THE START OF THE PERIOD HAS MODELS IN PRETTY GOOD AGREEMENT WITH
THE OVERALL PATTERN ACROSS THE CONUS...WITH THE LATEST UPPER
LEVEL DISTURBANCE MAKING ITS WAY EAST INTO THE REGION. THIS
SHORTWAVE TROUGH AXIS IS SET UP JUST WEST OF THE CWA AT SUNRISE
THURSDAY...WITH THE INCREASED MID/UPPER LEVEL LIFT OUT AHEAD OF
THE AXIS BRINGING CONTINUED PRECIPITATION CHANCES TO MAINLY THE
EASTERN HALF OF THE CWA. AT THE SURFACE...TIMING/LOCATION OF THE
ACCOMPANYING COLD FRONT MATCHES UP FAIRLY WELL BETWEEN
MODELS...SHOWING IT EITHER RIGHT OVER THE SERN CORNER OF THE
CWA...OR JUST OUTSIDE THE CWA BOUNDARY. THROUGH THE DAYTIME
HOURS...THE MAIN STORY LIES WITH PRECIPITATION COMING TO AN
END...AND COOLER AIR BUILDING INTO THE REGION. DID INCREASE POPS
DURING THE MORNING HOURS WITH MODELS IN GOOD AGREEMENT SHOWING
THINGS HANGING A BIT LONGER...BUT TRENDED THINGS DOWN FOR THE
AFTERNOON HOURS. SOME UNCERTAINTY IN PLACE WITH HOW MUCH
INSTABILITY MAY LINGER...SO HAVE SOME SCATTERED THUNDER MENTION IN
THE EAST...WITH JUST SHOWERS IN THE AFTERNOON. SHOULD SEE
DIMINISHING SKY COVER WITH TIME...BUT GUSTY NORTHWEST WINDS LOOK
TO HANG ON FOR A GOOD CHUNK OF THE DAY. NO SIGNIFICANT CHANGES
WERE MADE TO HIGH TEMPS FOR THURSDAY...WHICH REMAIN IN THE
MID/UPPER 60S.

THURSDAY NIGHT...MORE AMPLIFIED NORTHWESTERLY FLOW IS EXPECTED TO
SET UP ACROSS THE CENTRAL CONUS...AS THE LATEST DISTURBANCE KEEPS
SHIFTING EAST AND RIDGING IS BUILDING ALONG THE WEST COAST. KEPT
THE DRY FORECAST GOING...BUT CONFIDENCE IS A LITTLE LOWER.
MODELS SHOWING THE AREA BEING IN THE EXIT REGION OF A HEFTY 120+KT
UPPER LEVEL JET STREAK NOSING IN FROM CENTRAL CANADA...THINKING
THAT THE ATMOSPHERE WILL REMAIN DRY ENOUGH TO KEEP THINGS
DRY...BUT THE LATEST ECMWF TRIES BRINGING ANOTHER SHORTWAVE
DISTURBANCE SOUTH INTO THE AREA...ALONG WITH ITS RESULTANT QPF.
WANT TO SEE IF THAT FEATURE REMAINS IN UPCOMING RUNS BEFORE
JUMPING ON BOARD. THE GFS KEEPS THAT DISTURBANCE WELL TO THE
NORTH...AND ANY PRECIP WOULD BE JET STREAK DRIVEN.

AS WE GET INTO FRIDAY...THAT NEXT DISTURBANCE MOVING THROUGH THE
MAIN FLOW WILL BRING A REINFORCING COLD FRONT THROUGH THE
REGION...AND LOOKS TO RESULT IN FRIDAY BEING THE COOLEST DAY OF
THE 7 DAY FORECAST PERIOD. SURFACE HIGH PRESSURE WILL SETTLE
INTO THE REGION FROM THE NW THROUGH THE DAY...BRINGING ANOTHER
SURGE OF COOLER AIR. EXPECTING MOSTLY CLEAR SKIES...AND ANOTHER
ROUND OF GUSTY NW WINDS...THOUGH THEY SHOULD START DIMINISHING
LATER IN THE AFTERNOON WITH THE SFC HIGH BECOMING MORE OF A
PLAYER. DID LOWER HIGHS A FEW DEGREES...WITH THE FORECAST NOW
RANGING FROM THE UPPER 50S IN THE NORTHEAST TO MID 60S IN THE SW.
BIGGEST CHANGE MADE TO FRIDAY WAS TO KNOCK DOWN DEWPOINTS. MODELS
ARE IN GOOD AGREEMENT SHOWING NOTABLY DRIER AIR WORKING IN...AND
FORECAST DEWPOINTS IN SOME LOCATIONS WERE DECREASED BY AROUND 10
DEGREES.

LOOKING AHEAD TO THE UPCOMING WEEKEND AND EARLY PART OF NEXT
WEEK...ANY NOTABLE CHANGES OCCURRED WITH TEMPERATURES...AS THE DRY
FORECAST REMAINS IN PLACE. MODELS REMAIN IN GOOD AGREEMENT
SHOWING THE UPPER LEVEL PATTERN REMAINING A WELL AMPLIFIED WITH
NWRLY FLOW IN PLACE ACROSS THE REGION AND ANY DISTURBANCES
EXPECTED TO REMAIN TO THE N/NE OF THE CWA. THE COOLEST PART OF THE
AIR MASS WHICH BUILDS IN AT THE END OF THE WEEK STARTS TO SHIFT
OFF TO THE EAST...BUT THROUGH THE WEEKEND THERE LOOKS TO BE ENOUGH
OF AN INFLUENCE OVER THE CWA TO KEEP HIGHS FOR SAT IN THE
MID/UPPER 60S...WITH ANOTHER BUMP UP INTO THE UPPER 60S TO MID 70S
FOR SUN. A PRETTY NICE WEEKEND...NOT A WHOLE LOT IN THE WAY OF
CLOUDS EXPECTED...AND WHILE SUNDAY MAY BE A TOUCH BREEZIER...SAT
WIND LOOK TO TOP OUT ARND 10 MPH. NO NOTABLE CHANGES EXPECTED AS
WE GET INTO MON/TUE...WITH HIGHS CLIMBING BACK INTO THE LOWER/MID
70S.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1234 PM CDT TUE SEP 30 2014

VFR CONDITIONS ARE FORECAST THROUGH THE NEXT 24 HOURS.

OCCASIONAL CLOUD COVER NEAR 15000FT AGL WILL REMAIN POSSIBLE
DURING THE TAF PERIOD. SHOWER AND THUNDERSTORM ACTIVITY WILL BE
POSSIBLE ACROSS PORTIONS OF THE REGION THROUGH THE NEXT 24
HOURS...BUT AT THIS TIME IT APPEARS ANY SUCH ACTIVITY SHOULD
REMAIN SOUTHEAST OF GRI AND EAR THROUGH 18Z WEDNESDAY. THE SURFACE
WIND WILL REMAIN FROM THE SOUTH FOR THE MOST PART TODAY AND THIS
EVENING...BUT BECOME LIGHT AND VARIABLE TONIGHT INTO WEDNESDAY AS
A BOUNDARY-LAYER BAROCLINIC ZONE MOVES INTO THE AREA. IT IS WORTH
MENTIONING THAT SOME SETS OF GUIDANCE SUGGEST A PERIOD OF
VISIBILITY RESTRICTION IN FOG COULD BE REALIZED AT BOTH TAF SITES
AROUND SUNRISE WEDNESDAY...BUT AT THIS TIME CONFIDENCE IN SUCH
ACTIVITY BEING REALIZED IS TOO LOW FOR INSERTION INTO THE TAFS.

&&

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

$$

SHORT TERM...BRYANT
LONG TERM...ADP
AVIATION...BRYANT


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