Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 261204
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
704 AM CDT TUE AUG 26 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 455 AM CDT TUE AUG 26 2014

THE PRIMARY ISSUE THROUGH THE NEXT 24 HOURS CONTINUES MUCH THE
SAME AS THE PAST 24...AS THE OVERALL EXPECTATION IS OF THE SAME
GENERAL SCENARIO...AS LINGERING MORNING SHOWERS/STORMS ACROSS
PARTS OF THE AREA GRADUALLY GIVE WAY TO A MOSTLY DRY
DAY...FOLLOWED BY A LIKELY UPSWING IN PRECIPITATION COVERAGE THIS
EVENING/TONIGHT AS A MODEST SOUTHERLY LOW LEVEL JET PICKS UP.
ONCE AGAIN...AT LEAST A BRIEF WINDOW OF OPPORTUNITY WILL LIKELY
EXIST FOR A FEW STRONG TO SEVERE STORMS DURING THE LATE
AFTERNOON-EVENING TIME FRAME...WITH THE MAIN ISSUE GRADUALLY
TRANSITIONING TO ANOTHER ROUND OF LOCALLY HEAVY RAIN...WITH THE
MILLION DOLLAR QUESTION BEING EXACTLY WHERE THE MAIN RAIN AXIS
SETS UP THIS TIME AROUND. PRELIMINARY INDICATIONS ARE THAT IT
COULD BE A GENERALLY WEST-SOUTHWEST TO EAST-NORTHEAST SWATH ACROSS
THE HEART OF THE CWA...INCLUDING THE TRI-CITIES AREA.

STARTING OFF HERE AT 09Z/4AM...THINGS HAVE SETTLED DOWN QUITE A
BIT FROM THE EARLY OVERNIGHT TIME FRAME...BUT ONGOING AREAS OF
SHOWERS/FAIRLY WEAK THUNDERSTORMS ARE NOTED MAINLY WITHIN THE FAR
NORTHERN AND SOUTHERN CWA...WITH THE MAJORITY OF THE AREA IN
BETWEEN VOID OF PRECIP AT LEAST FOR NOW. EARLIER IN THE NIGHT...A
CORRIDOR OF STRONG TO SEVERE ELEVATED STORMS WITH HAIL AND HEAVY
RAINFALL RAPIDLY DEVELOPED ALONG AN AXIS FROM THE ADAMS/HALL
COUNTY AREAS EAST-NORTHEAST INTO THE YORK/POLK COUNTY AREAS. WHILE
RADAR ESTIMATIONS AND LIMITED GROUND TRUTH SUGGEST THAT MANY OF
THESE AFFECTED AREAS RECEIVED RAINFALL IN THE 0.50-1.00 INCH
RANGE...BY FAR AND AWAY THE BIG STORY OVERNIGHT WAS IN YORK
COUNTY...WHERE TRAINING CONVECTION DUMPED AN AREA OF 3-5 INCHES OF
RAIN IN A 1-2 HOUR TIME FRAME...CENTERED RIGHT OVER THE CITY OF
YORK ITSELF. ALTHOUGH MAINLY URBAN/STREET FLASH FLOODING SITUATION
HAS SINCE ABATED...A FLOOD ADVISORY REMAINS IN EFFECT FOR THAT
AREA THROUGH 845 AM AS RUNOFF CONTINUES. IN THE MID-UPPER
LEVELS...SOUTHWEST FLOW ALOFT REMAINS IN PLACE OVER THE CENTRAL
PLAINS PER WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA...AS THE
LOCAL AREA REMAINS DOWNSTREAM OF A LARGE SCALE WESTERN CONUS
TROUGH ANCHORED OVER THE NV AREA...AND TO THE NORTHWEST OF A BROAD
RIDGE CENTERED FROM THE SOUTHERN PLAINS INTO THE EAST-CENTRAL
CONUS. AT THE SURFACE...THE CWA LIES AT LEAST SLIGHTLY NORTH OF A
SOMEWHAT CONVECTIVELY-MASKED WEST-EAST ORIENTED QUASI-STATIONARY
FRONT DRAPED ACROSS CENTRAL/SOUTHERN KS...WITH PREVAILING BREEZES
LOCALLY GENERALLY SOME VARIATION OF NORTH/NORTHEASTERLY AROUND 10
MPH OR LESS. LOW TEMPS EARLY THIS MORNING ARE ON TRACK TO BOTTOM
OUT IN THE 60-64 RANGE MOST AREAS.

LOOKING AHEAD FORECAST WISE...IT GOES WITHOUT SAYING THAT THERE IS
PLENTY OF UNCERTAINTY IN THE HOURLY TRENDS...BUT AM GENERALLY
EXPECTING ONGOING NON-SEVERE CONVECTION THIS MORNING TO GRADUALLY
DECREASE IN COVERAGE...WITH A DECENT MAJORITY OF THE CWA LIKELY
EXPERIENCING DRY CONDITIONS BETWEEN THE MID-LATE MORNING AND LATE
AFTERNOON HOURS. THAT BEING SAID...THERE IS ENOUGH SUBTLE FORCING
OVER THE AREA FROM PASSING LOW-AMPLITUDE MID LEVEL WAVES...THAT
ITS ALMOST IMPOSSIBLE TO STRIP POPS COMPLETELY...AND OTHER THAN A
BRIEF PERIOD THIS AFTERNOON WITHIN THE SOUTHERN CWA...HELD ONTO AT
LEAST A TOKEN 20 PERCENT POP IN ALL AREAS THROUGH THE DAY...BUT
WITH THE HIGHEST CONCENTRATION OF 30-60 POPS FOCUSED PRIOR TO
15Z/10AM. ALTHOUGH A FEW STRONGER STORM CORES POTENTIALLY YIELDING
SMALL HAIL CANNOT BE RULED OUT HEADING INTO TODAY...ODDS ARE
FAIRLY GOOD THAT ANY SEVERE STORM RISK WOULD HOLD OFF UNTIL LATE
AFTERNOON OR EARLY EVENING. IN THE MID-UPPER LEVELS...MODELS SUCH
AS THE NAM/GFS GENERALLY SUGGEST THAT THE CWA SPENDS MUCH OF THE
DAY/EARLY EVENING IN BETWEEN LOW-AMPLITUDE DISTURBANCES...BEFORE
THE NEXT SOMEWHAT MORE ORGANIZED DISTURBANCE LIFTS EAST-NORTHEAST
INTO THE LOCAL AREA OUT OF THE CENTRAL ROCKIES LATER THIS
EVENING/OVERNIGHT OUT AHEAD OF THE PARENT 500 MILLIBAR LOW
TRACKING ACROSS UTAH. AS THIS OCCURS...AT LEAST A MODEST INCREASE
IN THE 850 MILLIBAR LOW LEVEL JET WILL TAKE PLACE...LEADING TO
INCREASING AREAL COVERAGE OF CONVECTION MUCH LIKE THIS PAST
NIGHT...WITH LOCALLY HEAVY RAIN OF 2+ INCHES AGAIN QUITE POSSIBLE
GIVEN THAT PRECIPITABLE WATER VALUES WILL CONTINUE TO AVERAGE
GENERALLY IN THE 1.50-1.80 INCH RANGE.

ALTHOUGH THE DETAILS ARE FAR FROM CLEAR...HAVE GEARED THE
CONVECTIVE TRENDS OVER THE NEXT 24 HOURS TOWARD THE SIMULATED
REFLECTIVITY PROGS OFFERED BY THE 00Z RUNS OF THE 4KM WRF-NMM AND
4KM-NSSL WRF. THIS GENERALLY SPELLS THAT THE MAJORITY OF THE CWA
SHOULD STAY DRY THROUGH EARLY EVENING...WITH THE BEST CHANCES FOR
PRE-SUNSET CONVECTION FOCUSED WITHIN SOUTHERN/SOUTHWEST COUNTIES
IN CLOSEST PROXIMITY TO THE SURFACE FRONT AND THE HOTTER/MORE
DEEPLY-MIXED AIRMASS TO THE SOUTH OF IT. AS A RESULT...MUCH LIKE
YESTERDAY COULD SEE SOME PULSY STRONG TO POSSIBLY SEVERE
CONVECTION FLARE UP IN OR NEAR OUR KS ZONES DURING THE LATE
AFTERNOON/EARLY EVENING IN AN ENVIRONMENT CHARACTERIZED BY AROUND
2000 J/KG MIXED LAYER CAPE BUT ONLY AROUND 20KT OF DEEP LAYER
SHEAR. THEN LATER IN THE EVENING...LARGELY AFTER NIGHTFALL...THE
EJECTING WAVE AND INCREASING LOW LEVEL JET SHOULD FOCUS INCREASING
COVERAGE OF SHOWERS/STORMS ACROSS MUCH OF THE CWA...BUT PROBABLY
FOCUSED MORE ACROSS THE CENTRAL/NORTH IN NEB AND LESS SO THE FAR
SOUTHEAST ZONES. EVEN AFTER DARK...A FEW STRONG TO SEVERE STORMS
CANNOT BE RULED OUT ESPECIALLY BEFORE 06Z/1AM. AS FOR RAIN
POTENTIAL...WON/T BE A BIT SURPRISED IF SOME AREAS EXCEED 2 INCHES
OF RAIN THIS EVENING/TONIGHT...AND AT LEAST BRIEFLY PONDERED
WHETHER SOME VARIETY OF FLOOD WATCH MAY BE WARRANTED.
HOWEVER...GIVEN THAT ESSENTIALLY ONLY ONE COUNTY (YORK) RECEIVED
SIGNIFICANT 3+ INCH RAINFALL FROM LAST NIGHTS ROUND...FEEL THAT
THE MAJORITY OF THE CWA WILL PROBABLY GET THROUGH TONIGHT WITHOUT
WIDESPREAD/MAJOR ISSUES. THAT BEING SAID...AT LEAST ONE OR TWO
LOCALIZED AREAS OF SHORT-TERM FLASH FLOODING CANNOT BE RULED
OUT...BUT JUST NOT THINKING WIDESPREAD ENOUGH COVERAGE AT THIS
TIME TO WARRANT HEADLINES. DEPENDING ON WHAT HAPPENS TONIGHT
THOUGH...THE STAGE COULD CERTAINLY BE SET FOR SOMEWHAT GREATER
FLOODING CONCERNS HEADING INTO THE WED-THURS TIME FRAME DESCRIBED
BELOW.

BRIEFLY TURNING TO TEMPERATURES...CONFIDENCE IN HIGHS TODAY IS
AGAIN BELOW AVERAGE ESPECIALLY FOR THIS TIME OF YEAR...AS THE
CURRENT FORECAST ASSUMES THAT NORTHERN COUNTIES REMAIN MOSTLY
CLOUDY WELL INTO THE DAY...WHILE SOUTHERN AREAS SEE AT LEAST A
MODEST AMOUNT OF SUNSHINE AS THE SURFACE FRONT OVER KS STARTS
LIFTING BACK NORTH CLOSER TO THE NEB BORDER BY LATE IN THE DAY.
THE NET RESULT IS A SEASONABLY SHARP 15+ DEGREE FORECAST HIGH
TEMP GRADIENT RANGING FROM ONLY THE MID 70S NORTH OF I-80...TO THE
80S ALONG/NEAR THE STATE LINE...TO THE LOW AND POSSIBLY MID 90S
ESPECIALLY WITHIN THE BOTTOM ROW OF NORTH CENTRAL KS COUNTIES.
MADE LITTLE CHANGE TO LOWS TONIGHT...AIMING MOST AREAS INTO THE
63-67 RANGE.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 450 AM CDT TUE AUG 26 2014

THE WEATHER PATTERN WILL REMAIN ACTIVE THROUGH THE REMAINDER OF THE
WORKWEEK IN SOUTHWEST FLOW ALOFT AHEAD OF AN UPPER TROUGH OVER THE
CENTRAL ROCKIES AND THIS TROUGH WILL GRADUALLY SHIFT EAST ACROSS THE
PLAINS STATES LATE THURSDAY THRU LATE FRIDAY.  THE NAM IS A QUICKER
WITH THE TROUGH PROGRESSION THAN OTHER MODELS AND FOLLOWED CLOSER TO
GFS/ECMWF/ENSEMBLES FOR TIMING. WITH THE TROUGH TO THE WEST..ENERGY
LIFTING OUT OF THE TROUGH COMBINED WITH A MEANDERING FRONTAL
BOUNDARY WILL GENERATE CONVECTION EACH DAY UNTIL THE UPPER TROUGH
AXIS PASSES TO THE EAST EARLY THIS WEEKEND.  ABUNDANT MOISTURE IS
AVAILABLE TO WORK WITH PRECIPITABLE WATER VALUES CURRENTLY 130
PERCENT OF NORMAL AND AVERAGE AN INCH AND A HALF TO TWO INCHES THRU
FRIDAY. THE POTENTIAL FOR HEAVY RAINFALL EXISTS THRU THE WORKWEEK
AND AS THE GROUND SATURATES...AREAS OF FLOODING WILL BE POSSIBLE
WITH ADDITIONAL RAINFALL. CANNOT RULE OUT THE POTENTIAL FOR A
STRONG TO SEVERE STORM WITH DECENT INSTABILITY AND MARGINAL SHEAR
AND WILL CONTINUE MENTION IN HWO.

THE FORECAST DRIES OUT FOR THE FIRST PART OF THE LABOR DAY HOLIDAY
WEEKEND...THEN PRECIPITATION CHANCES RETURN TO THE FORECAST SUNDAY
NIGHT IN WAA AHEAD OF YET ANOTHER TROUGH TRANSLATING ACROSS THE
NORTHERN CONUS.  DEPENDING ON COLD FRONTAL TIMING...LABOR DAY OR
MONDAY NIGHT COULD ALSO SEE CONVECTION.

&&

.AVIATION...(FOR THE 12Z KGRI/KEAR TAFS THROUGH 12Z WEDNESDAY)
ISSUED AT 704 AM CDT TUE AUG 26 2014

THIS IS A SOMEWHAT LOW-CONFIDENCE FORECAST...ESPECIALLY WITH
REGARD TO CEILING TRENDS. ALTHOUGH THE CURRENT FORECAST REFLECTS
THE THINKING THAT ANY MVFR CEILING TODAY WOULD BE FAIRLY SHORT-
LIVED AND CONFINED TO THE INITIAL FEW HOURS THIS MORNING...THERE
IS SOME MODEL GUIDANCE SUGGESTING THAT THERE COULD IN FACT BE
SEVERAL HOURS OF MVFR CEILING IN THE CARDS DURING THE NEXT 24
HOURS...SO THIS SCENARIO BEARS CLOSE WATCHING. OTHERWISE...THERE
ARE AT LEAST TWO DISTINCT CHANCES FOR SHOWERS/THUNDERSTORMS DURING
THE PERIOD...ONE MAINLY FOCUSED DURING THE FIRST SEVERAL
HOURS...AND THEN AGAIN THIS EVENING/TONIGHT. GIVEN THAT COVERAGE
OF PRECIPITATION THIS MORNING IS NOT OVERLY WIDESPREAD...AND THAT
CONFIDENCE IN TIMING FOR THE EVENING/OVERNIGHT EVENT IS STILL A
BIT SHAKY GIVEN IT IS BEYOND THE FIRST 12 HOURS...HAVE SIMPLY GONE
WITH A GENERIC VICINITY THUNDERSTORM (VCTS) MENTION TO COVER THE
CHANCES...AND WILL DEFER TO LATER FORECASTS TO PINPOINT ANY
POTENTIAL PREVAILING/TEMPO GROUPS. IT IS WORTH NOTING HOWEVER THAT
SOME STORMS THIS EVENING/TONIGHT COULD CONTAIN HAIL AND LOCALLY
HEAVY RAINFALL. AS FOR SURFACE WINDS...THEY SHOULD GENERALLY
PREVAIL FROM SOME SORT OF EASTERLY DIRECTION THROUGH MOST OF THE
PERIOD AT SPEEDS LARGELY UNDER 12KT.

&&

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

$$

SHORT TERM...PFANNKUCH
LONG TERM...FAY
AVIATION...PFANNKUCH


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