Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 022040
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
340 PM CDT SAT MAY 2 2015

.SHORT TERM...(THIS EVENING THROUGH SUNDAY AFTERNOON)
ISSUED AT 340 PM CDT SAT MAY 2 2015

ALTHOUGH THE CHANCES FOR SHOWERS/THUNDERSTORMS BETWEEN NOW AND
LATE SUNDAY AFTERNOON APPEAR FAIRLY LIMITED FOR MOST OF THE LOCAL
AREA...BOTH LATE THIS AFTERNOON/EVENING AND ESPECIALLY LATE SUNDAY
AFTERNOON BEAR WATCHING FOR AT LEAST A MARGINAL RISK (TO USE THE
OFFICIAL SPC OUTLOOK TERMINOLOGY) FOR AT LEAST A FEW STRONG TO
SEVERE STORMS...ESPECIALLY WITHIN NORTHERN/WESTERN COUNTIES.
OTHERWISE...TODAY-SUNDAY CONTINUE TO LOOK LIKE HANDS-DOWN THE
WARMEST TWO DAYS OF THE UPCOMING WEEK...WITH ALL AREAS SUNDAY
EXPECTED TO CLIMB WELL INTO THE MID-80S (LOCALIZED UPPER 80S).

STARTING OFF THIS AFTERNOON AS OF 20Z/3PM...ALL IS QUIET...SUNNY
AND DRY CWA-WIDE...WITH ONLY SOME LIMITED FAIR WEATHER CUMULUS AND
WISPY CIRRUS. THE SCATTERED RAIN SHOWERS FROM THIS MORNING HAVE
LONG-SINCE DEPARTED EAST OF THE LOCAL AREA...AND AT LEAST FOR NOW
THE NEAREST UPSTREAM CONVECTION IS WELL-WEST NEAR THE NEB/CO/WY
BORDER. AS EXPECTED...TEMPERATURES ARE ON TRACK TO TOP OUT IN THE
81-85 DEGREE RANGE IN MOST AREAS...MARKING THE FIRST WIDESPREAD
80S FOR MOST OF THE CWA SINCE APRIL 1ST. IN THE MID-UPPER
LEVELS...WATER VAPOR SATELLITE IMAGERY AND SHORT TERM MODEL DATA
REVEAL A FAIRLY WEAKLY-FORCED...QUASI-ZONAL FLOW REGIME OVER THE
CENTRAL PLAINS...WITH VARIOUS WEAK/LOW AMPLITUDE DISTURBANCES
WORKING THEIR WAY FROM WEST-TO-EAST...WHILE THE PRIMARY
NORTHERN/SOUTHERN UPPER JET BRANCHES REMAIN WELL TO THE NORTH NEAR
THE CANADIAN BORDER...AND WELL TO THE SOUTH OVER
MEXICO...RESPECTIVELY. AT THE SURFACE...A MODEST LEE TROUGH
EXTENDS SOUTHWARD THROUGH WESTERN NEB AND ALONG THE KS/CO BORDER
AREA. EAST OF THIS TROUGH...BREEZES ACROSS THE CWA ARE AVERAGING
SUSTAINED SPEEDS OF 10-17 MPH WITH SEMI-FREQUENT GUSTS OVER 20
MPH.

NOW LOOKING AHEAD FORECAST-WISE...

LATE THIS AFTERNOON (THROUGH 00Z/7PM): WHILE THE VAST MAJORITY OF
THE CWA SHOULD STAY SHOWER/STORM FREE THROUGH THESE NEXT 3-4
HOURS...THERE ARE HINTS IN SOME MODELS INCLUDING THE LATEST HRRR
THAT AT LEAST THE WESTERN 1/4 OF THE CWA COULD SEE A FEW STORMS
ALREADY MOVE IN FROM THE WEST DURING THIS TIME. HOWEVER...BARRING
SOME RAPID CHANGES IN THE EXPECTED IMMINENCE OF CONVECTIVE
INITIATION WITHIN COUNTIES 50-100 MILES WEST OF THE CWA...FEEL
THAT SOME OF THESE MODELS MAY BE A BIT AGGRESSIVE BRINGING
ANYTHING INTO THE AREA BY THEN. LATEST VISIBLE SATELLITE IMAGERY
SURE DOESN/T LEND MUCH SUPPORT TO MUCH HAPPENING THROUGH 7PM. ALL
THIS BEING SAID...WILL MAINTAIN A NARROW STRIPE OF SLIGHT CHANCE
20 POPS ACROSS OUR FAR WESTERN ZONES FOR LATE THIS AFTERNOON JUST
IN CASE. SEE THE EVENING SECTION BELOW FOR A BIT MORE DETAIL ON
POTENTIAL STORM INTENSITY.

THIS EVENING/TONIGHT (00Z-12Z/7PM-7AM): THE UNCERTAINTY FROM LATE
THIS AFTERNOON CARRIES OVER INTO TONIGHT...AS THE MAIN BASIC
3 QUESTIONS ARE: 1) HOW MUCH SHOWER/STORM ACTIVITY WILL MOVE IN
FROM THE WEST? 2) HOW FAR EAST WILL ANY MEASURABLE RAIN POTENTIAL
SURVIVE BEFORE "LOSING STEAM" AND 3) WILL ESPECIALLY PARTS OF THE
WESTERN CWA SEE AT LEAST 1 OR 2 STRONG TO MARGINALLY SEVERE
STORMS? IN THE MID-UPPER LEVEL SCENE...THERE APPEARS TO BE A
DECENT CHANCE THAT A WEAK/LOW AMPLITUDE WAVE CURRENTLY TO OUR WEST
WILL PASS OVER THE LOCAL AREA AS THE NIGHT WEARS ON...WHICH ALSO
HELPS TO INDUCE THE DEVELOPMENT/INCREASE OF A MODEST 30-40KT
SOUTH-SOUTHWESTERLY LOW LEVEL JET EVIDENT AT THE 850MB LEVEL. AT
LEAST INITIALLY THIS EVENING...ALTHOUGH COVERAGE IS NOT EXPECTED
TO BE GREAT...CONFIDENCE IS FAIRLY HIGH THAT ESPECIALLY THE
NORTHWEST 1/2 OF THE CWA WILL SEE SOME STRONG TO POTENTIALLY
MARGINALLY SEVERE STORMS DRIFT INTO THE AREA OFF OF THE LEE TROUGH
TO THE WEST. AS A RESULT...WILL BRING AT LEAST 20 POPS AS FAR
EAST AS ROUGHLY AN OSCEOLA-OSBORNE LINE THIS EVENING...WITH THE
HIGHEST 30 POPS CONFINED TO SEVERAL FAR WESTERN COUNTIES PRIOR TO
03Z/10PM. ALTHOUGH INSTABILITY WILL BE DIURNALLY WANING WITH
TIME...AT LEAST THE EARLY EVENING HOURS SHOULD FEATURE AT LEAST
500-1000 J/KG MIXED LAYER CAPE...ALONG WITH DECENT 0-6 KM DEEP
LAYER SHEAR OF AT LEAST 30-35KT. THIS COULD EASILY SUPPORT A FEW
MARGINALLY SEVERE STORMS WITH HAIL UP TO AROUND QUARTER SIZE AND
WIND GUSTS TO AROUND 60 MPH...ESPECIALLY IF STORMS ARE ABLE TO
GENERATE A DECENT COLD POOL IN THE PRESENCE OF A STEEP LOW-MID
LEVEL LAPSE RATE ENVIRONMENT/INVERTED-V SOUNDINGS AS EVIDENCED BY
30+ DEGREE SPREADS LATE THIS AFTERNOON BETWEEN THE SURFACE
TEMP/DEWPOINT. AGAIN...ALTHOUGH THE POTENTIAL FOR SEVERE STORMS
EXISTS...AM KEEPING POPS LOW DUE TO LOW CONFIDENCE IN COVERAGE
AMOUNTING TO MUCH. ANY RISK FOR SEVERE STORMS SHOULD MAINLY FOCUS
WITHIN COUNTIES ALONG AND ESPECIALLY WEST OF HIGHWAY 281 AND
MAINLY BEFORE 10-11PM...WITH ANY SEVERE RISK STEADILY WANING
THEREAFTER. ALTHOUGH PREVIOUS FORECAST INDICATED NO MENTION OF
SHOWERS/STORMS POST-06Z/1AM...HAVE NOW EXTENDED A SLIGHT CHANCE
MENTION OF SHOWERS/STORMS THROUGH 09Z/4AM IN MOST AREAS...AND EVEN
ADDED A MENTION OF A SLIGHT CHANCE OF SPRINKLES THROUGH THE
REMAINDER OF THE LATE NIGHT IN EASTERN COUNTIES. IN OTHER
WORDS...WOULD NOT BE SURPRISED AT ALL TO SEE AT LEAST A FEW ROGUE
SHOWERS/WEAK STORMS LINGERING WELL INTO THE NIGHT. FOR NOW...HAVE
SOMEWHAT RELUCTANTLY KEPT ANY FORMAL MENTION OF THUNDERSTORMS OUT
OF SEVERAL FAR EASTERN COUNTIES TONIGHT...BUT EVEN THIS MAY NOT BE
A SURE THING PER THE LATEST 18Z NAM. IN OTHER DEPARTMENTS
TONIGHT...NOT COUNTING ANY POSSIBLE CONVECTIVE EFFECTS...BREEZES
SHOULD GENERALLY AVERAGE 10-15 MPH FROM THE SOUTH...AND MADE VERY
LITTLE CHANGE TO LOW TEMPS...AIMING MOST OF THE CWA BETWEEN 54-59
DEGREES.

SUNDAY DAYTIME (12Z-00Z/7AM-7PM): IT STILL APPEARS THAT SUNDAY
AFTERNOON CARRIES A BIT GREATER CHANCE THAN TODAY OF FEATURING A
LATE AFTERNOON (PRE-7PM) RISK OF STRONG-SEVERE STORMS...PRIMARILY
WITHIN THE NORTHWESTERN 1/3 OR SO OF THE CWA ALONG AN INVADING
COLD FRONT (PLEASE SEE LONG TERM SECTION BELOW FOR MORE INSIGHT
INTO THE EVENING HOURS). LIKE TODAY`S SETUP...THE OFFICIAL SPC DAY
2 OUTLOOK CARRIES ONLY A MARGINAL RISK...BUT IF MIXED LAYER CAPE
IS ULTIMATELY ABLE TO CLIMB INTO AT LEAST THE 1500-2000 J/KG
RANGE...WOULD NOT BE SURPRISED TO SEE UPCOMING DAY 1 OUTLOOKS
UPGRADE TO A SLIGHT RISK FOR PARTS OF THE LOCAL AREA. NOTE...THE
LATEST NAM SUGGESTS HIGHER CAPE THAN THIS BUT THIS MODEL ALSO
APPEARS A BIT OVERDONE ON LOW LEVEL MOISTURE/DEWPOINTS. AT ANY
RATE...EXPECT THE MAJORITY OF THE DAY (MORNING-EARLY AFTERNOON) TO
REMAIN DRY AND STORM-FREE...AND THE CURRENT FORECAST MAINTAINS A
PRECIP-FREE MENTION DURING THIS TIME. THAT BEING SAID...THERE ARE
ALSO HINTS THAT MUCH LIKE THIS MORNING...THERE COULD BE AT LEAST
SOME LIGHT SHOWERS/SPRINKLES LINGERING PAST SUNRISE IN EASTERN
COUNTIES...AND THE NIGHT SHIFT MAY HAVE TO CONSIDER ADDING THIS
POTENTIAL DEPENDING ON HOW THINGS TONIGHT UNFOLD. AT ANY
RATE...LOW LEVEL FORCING PICKS UP ESPECIALLY IN THE NORTHWESTERN
CWA DURING THE AFTERNOON AS A HALFWAY DECENT COLD FRONT IS DRIVEN
SOUTHWARD ACROSS NEB BY THE PASSAGE OF A SHORTWAVE TROUGH
TRAVERSING SOUTHERN CANADA. THE NUMBER 1 QUESTION FOR THE
AFTERNOON IS JUST WHEN STRONG-SEVERE STORMS COULD INITIATE ALONG
THE BOUNDARY...WITH SOME MODELS SUGGESTING AS EARLY AS THE 2-3 PM
TIME FRAME...AND OTHERS CLOSER TO 6-7PM. IN REALITY...THE TRUTH
WILL PROBABLY BE SOMEWHERE IN BETWEEN...AND AM GOING WITH MODEST
40 POPS IN NORTHWESTERN COUNTIES AFTER 3PM...ONLY SLIGHT CHANCE
20S IN THE TRI-CITIES AREA...AND ACTUALLY NO MENTION OF AFTERNOON
SHOWERS/STORMS WHATSOEVER GENERALLY SOUTH OF A PHILLIPSBURG-GENEVA
LINE (SHOULD HOLD OFF HERE UNTIL AFTER 7 PM WITH THE FRONT STILL
OFF TO THE NORTH). ALTHOUGH INSTABILITY SHOULD BE HIGHER THAN
TODAY...DEEP LAYER SHEAR MAY ACTUALLY BE A BIT WEAKER...ONLY
AVERAGING 25-30KT AT BEST. THIS SHOULD RESULT IN AN INITIALLY
NARROW LINE OF MULTICELL STORMS...WHICH GRADUALLY EXPAND IN
COVERAGE SOUTHEASTWARD AS THE EVENING WEARS ON. AGAIN...SEVERE
PARAMETERS DON/T POINT TO A "MAJOR EVENT" AND ALSO DO NOT SUGGEST
MUCH OF A TORNADO THREAT GIVEN THE COLD-FRONTAL FORCING...BUT AT
LEAST A FEW STORMS WITH HAIL POTENTIAL TO AROUND GOLF BALL
SIZE/WINDS 60-70 MPH CERTAINLY APPEAR POSSIBLE. ALL OF THIS BEING
SAID...WANT TO REITERATE THAN THE MAIN RISK FOR ANY SEVERE STORMS
DURING THE PRE-7PM TIME FRAME SHOULD MAINLY BE NORTHWEST OF A LINE
FROM ROUGHLY ELWOOD-GRAND ISLAND-GENOA. BRIEFLY TURNING TO OTHER
ELEMENTS...BREEZES SUNDAY ACROSS MOST OF THE CWA SHOULD AVERAGE
10-15 MPH FROM THE SOUTH WITH SOME HIGHER GUSTS...ALTHOUGH
WESTERN/NORTHERN COUNTIES WILL BE MORE PRONE TO A LIGHT/VARIABLE
REGIME BEFORE THE FRONT ARRIVES VERY LATE IN THE DAY AND TURNS
WIND NORTHERLY. TEMP-WISE...ASSUMING SKIES AVERAGE NO WORSE THAN
PARTLY CLOUDY...EXPECT READINGS TO CLIMB A FEW DEGREES WARMER
THAN TODAY...AND HAVE MOST OF THE CWA AIMED INTO THE 84-88 RANGE.

.LONG TERM...(SUNDAY EVENING THROUGH SATURDAY)
ISSUED AT 340 PM CDT SAT MAY 2 2015

OVERALL THE UPCOMING WEEK IS SHAPING UP TO BE WET WITH MULTIPLE
CHANCES FOR THUNDERSTORMS.

SUNDAY NIGHT...THE PATTERN ALOFT WILL TRANSITION SOUTHWESTERLY AS AN
UPPER TROUGH EDGES INTO SOUTHERN CALIFORNIA. A COLD FRONTAL BOUNDARY
WILL SAG SOUTH FM THE DAKOTAS SUNDAY AFTN AND IS PROGGED TO EXTEND
FM SW TO NE NEB BY 00Z MONDAY. CONVERGENCE ALONG THE BOUNDARY IS
EXPECTED TO FOCUS CONVECTION AND TSTMS MAY BE ONGOING AT THE START
OF THE PERIOD WITH THE FRONT EXPECTED TO BECOME MORE ACTIVE DURING
THE EVENING HOURS. MODELS VARY WITH THE DEGREE OF INSTABILITY WITH
AN AVERAGE OF 1500 TO 2000 J/KG PROGGED BY MODELS...WITH SHEAR
AROUND 30KTS AND STORMS WHICH DEVELOP WILL BE CAPABLE OF PRODUCING
LARGE HAIL AND DAMAGING WINDS AS THE PRIMARY HAZARDS.

CONVECTION IS EXPECTED TO PERSIST SUNDAY NIGHT AIDED BY A
STRENGTHENING LLVL JET AND ALSO AS STORMS WHICH DEVELOP ALONG THE
HIGH PLAINS IN UPSLOPE FLOW...AND ALONG SFC TROUGH/DRY LINE WORK
EASTWARD DURING THE OVERNIGHT HOURS. MONDAY IS LOOKING CLOUDY...
COOL AND WET...WITH CONVECTION POTENTIALLY CONTINUING THROUGH THE
DAY FM OVERNIGHT ACTIVITY AND REDEVELOPMENT OF STORMS IS ANTICIPATED
DURING THE AFTN/EVENING ALONG THE SFC BOUNDARY ORIENTED FM SW KANSAS
INTO SE NEB/NE KS. STRONG TO SEVERE STORMS AGAIN WILL BE POSSIBLE IN
THE VCNTY OF THE BOUNDARY PRIMARILY LATE MONDAY AFTN THRU MONDAY
EVENING. IN A SIMILAR SETUP TO SUNDAY NIGHT...TSTMS SHLD CONTINUE
THRU THE OVERNIGHT HOURS AIDED BY A STRENGTHENING LLVL JET AND AS A
LEAD SHORTWAVE TROUGH LIFTS OUT OF THE SW CONUS SYSTEM.

ALTHOUGH DIFFICULT TO PINPOINT TIMING...TUESDAY COULD SEE A LULL IN
TSTM ACTIVITY DURING THE DAY AS THE BOUNDARY LIFTS NORTH AND THE SFC
LOW/TROUGH REORGANIZES ALONG THE HIGH PLAINS AHEAD OF THE UPPER WAVE
LIFTING THRU THE CENTRAL ROCKIES. INITIAL FOCUS FOR STORMS TUESDAY
EVENING SHOULD BE ALONG THE HIGH PLAINS WITH THE ACTIVITY SPREADING
NORTH AND EASTWARD IN WAA AHEAD OF THE SYSTEM AND AS THE WAVE ITSELF
LIFTS OUT ACROSS THE PLAINS WEDNESDAY/WEDNESDAY NIGHT. OF NOTE IS
THAT PRECIPITABLE WATER VALUES WILL BE ON THE RISE MONDAY NIGHT AND
REMAIN FAIRLY HIGH...AROUND OR JUST OVER ONE INCH THROUGH THE MIDDLE
OF THE WEEK AND THESE VALUES ARE ON THE ORDER OF ONE TO TWO STANDARD
DEVIATIONS ABOVE NORMAL FOR THIS TIME OF YEAR. GOOD RAINFALL AMOUNTS
ARE LIKELY IN TSTMS AND SEVERAL ROUNDS OF CONVECTION/RAIN WILL
LIKELY LEAD TO HEALTHY RAINFALL TOTALS WHEN ALL IS SAID AND DONE.

PCPN AGAIN LOOKS TO WIND DOWN FOR A TIME THURSDAY BEHIND THE
WEAKENING UPPER WAVE LIFTING INTO THE UPPER MIDWEST...WHILE TO THE
WEST YET ANOTHER UPPER LOW CLOSES OFF/DEEPENS ALONG THE WESTERN
CONUS. THIS WILL MAINTAIN A SOUTHWEST FLOW ACROSS OUR REGION AHEAD
OF THE UPPER LOW THRU THE REMAINDER OF THE WORKWEEK AND INTO THE
WEEKEND. WITH A FRONTAL BOUNDARY MEANDERING ACROSS OUR REGION JUST
CANNOT RULE OUT TSTM CHANCES AT ANY GIVEN TIME THEREFORE THE
POTENTIAL REMAINS FOR ACTIVE/WET SPRING CONDITIONS.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1254 PM CDT SAT MAY 2 2015

CONFIDENCE REMAINS REASONABLY HIGH IN VFR CEILING/VISIBILITY
THROUGHOUT THE PERIOD...WITH THE MAIN QUESTION MARK CONSISTING OF
WHETHER OR NOT EITHER SITE COULD POSSIBLY SEE A BRIEF PASSING
SHOWER/THUNDERSTORM PRIMARILY DURING THE 02Z-07Z TIME FRAME
TONIGHT. IN ADDITION...HAVE INTRODUCED A MENTION OF LOW LEVEL WIND
SHEAR (LLWS) FOR SEVERAL HOURS TONIGHT AT KGRI GIVEN THAT THERE
COULD EASILY BE AT LEAST A 30KT BULK SHEAR DIFFERENCE BETWEEN THE
SURFACE AND ROUGHLY 1200 FT AGL ...BUT HELD OFF AT KEAR WHERE THE
LOW LEVEL JET DOES NOT APPEAR TO BE QUITE AS STRONG. GETTING BACK
TO CHANCES FOR SHOWERS/STORMS TONIGHT...OPTED TO COVER THIS SLIM
POSSIBILITY WITH A GENERIC VICINITY THUNDERSTORM (VCTS)
MENTION...WHICH CAN OBVIOUSLY BE REMOVED OR "UPGRADED" TO A TEMPO
GROUP AS TRENDS BECOME CLEARER WITH TIME. SHOULD ANY STORMS HAPPEN
TO DIRECTLY AFFECT THE TERMINALS...A BRIEF PERIOD OF GUSTY WINDS
AND SMALL HAIL COULD OCCUR. OTHERWISE...ASSUMING NO THUNDERSTORM
INFLUENCES...PREVAILING BREEZES THROUGH THE PERIOD SHOULD REMAIN
OUT OF THE SOUTH AT AROUND 12KT OR LESS...WITH SOME SLIGHTLY
HIGHER GUSTS POSSIBLE AT TIMES MAINLY THIS AFTERNOON/EVENING.

&&

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

$$

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


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