Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 160934
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
434 AM CDT TUE SEP 16 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 435 AM CDT TUE SEP 16 2014

THERE ARE PRIMARILY 3 MAIN ISSUES DURING THESE NEXT 24
HOURS...SOME OF WHICH MAY BE BIGGER DEALS THAN OTHERS.
THE FIRST INVOLVES WHETHER OR NOT A POTENTIALLY EXPANSIVE AREA OF
LOWER STRATUS CURRENTLY POSITIONED A FEW COUNTIES SOUTH-SOUTHWEST
OF THE CWA WILL SPREAD NORTHEAST OVER AT LEAST PARTS OF THE CWA
TODAY AND IF SO...HOW MUCH IMPACT TO HIGH TEMPS COULD OCCUR.
COMPARED TO 12-24 HOURS AGO...CONFIDENCE HAS WANED A BIT ON
WHETHER THESE CLOUDS REALLY WILL END UP AFFECTING MUCH OF THE AREA
AND FOR HOW LONG. ISSUE NUMBER 2 CONCERNS THUNDERSTORM CHANCES
TONIGHT...AS ALTHOUGH THE MAJORITY OF THE AREA CARRIES A PRETTY
GOOD CHANCE OF REMAINING STORM FREE...AT LEAST A SLIGHT CHANCE IS
REFLECTED FOR ROUGHLY THE SOUTHEAST 1/4 OF THE CWA POST-MIDNIGHT.
THIRDLY...ALTHOUGH MODELS/GUIDANCE ARE BY NO MEANS
UNANIMOUS...CONCERNS ARE INCREASING FOR AT LEAST SOME COVERAGE OF
POTENTIALLY IMPACTFUL FOG ISSUES LATE TONIGHT/EARLY WED MORNING
ESPECIALLY WITHIN THE WESTERN HALF OF THE CWA AS BREEZES AVERAGE
LIGHT AND SURFACE DEWPOINTS RISE 10+ DEGREES ABOVE CURRENTLY
OBSERVED VALUES...INDICATIVE OF INCREASING LOW LEVEL MOISTURE.

STARTING OFF WITH THE HERE AND NOW AS OF 08Z/3AM...A VERY QUIET
NIGHT CONTINUES ACROSS THE CWA UNDER NEARLY CLOUD-FREE SKIES. AT
THE SURFACE...A ROUGHLY 1025 MILLIBAR RIDGE AXIS IS CENTERED
SQUARELY OVER THE NEB/IA BORDER AREA...PROVIDING NEAR-CALM TO
LIGHT SOUTHEASTERLY BREEZES OF GENERALLY 6 MPH OR LESS. GIVEN THE
FAIRLY IDEAL RADIATIONAL COOLING CONDITIONS...TEMPS HAVE DROPPED
SOMEWHERE INTO THE 40S ACROSS MOST OF THE CWA AS EXPECTED...WITH
EVEN A FEW SITES VERY NEAR THE CWA SUCH AS COLUMBUS/BROKEN BOW AT
LEAST BRIEFLY INTO THE UPPER 30S. AUTOMATED AIRPORT SITES SUGGEST
THAT SOME VERY PATCHY...PRIMARILY LIGHT FOG LIKELY EXISTS OUT
THERE IN A FEW SPOTS...BUT BARRING NOTICEABLE CHANGES ITS
COVERAGE/IMPACT DOES NOT APPEAR WORTHY OF A FORMAL FORECAST
MENTION...WITH SOMEWHAT BETTER CHANCES OF A FEW DECENT VISIBILITY
REDUCTIONS POSSIBLY FOCUSING CLOSER TO THE NEB/IA BORDER. LOOKING
ALOFT TO THE MID-UPPER LEVELS...SHORT TERM MODEL DATA AND WATER
VAPOR IMAGERY INDICATES FAIRLY UNEVENTFUL AND BROAD NORTHWESTERLY
FLOW ALOFT OVER THE CENTRAL PLAINS...STEERED BETWEEN A LARGE SCALE
TROUGH OVER EASTERN CANADA AND A RIDGE EXTENDING NORTHWARD OVER
THE WESTERN CONUS. WAY OFF TO THE SOUTHWEST...TROPICAL STORM ODILE
SLOWLY CHURNS NORTHWEST UP THE BAJA PENINSULA.

LOOKING AHEAD AND STARTING WITH THE VERY SHORT TERM THROUGH
ROUGHLY SUNRISE...THE SURFACE RIDGE AXIS WILL CONTINUE A VERY SLOW
EASTWARD DEPARTURE...ALLOWING LIGHT SOUTH WINDS TO BECOME A BIT
BETTER ESTABLISHED ACROSS MUCH OF THE CWA. AS MENTIONED
ABOVE...THE BIGGEST SHORT TERM MYSTERY INVOLVES THE FATE OF THE
NORTHWEST KS STRATUS DECK...AS LAST FEW 11-3.9 MICRON SATELLITE
FRAMES SHOW ITS LEADING EDGES STARTING TO MAKE A PUSH TOWARD THE
SOUTHWESTERN FRINGES OF THE CWA...BUT UNLIKELY TO POTENTIALLY
INFILTRATE MUCH OF THE LOCAL AREA BEFORE SUNRISE. ALTHOUGH A FEW
PLACES MAY START STEADYING OUT A BIT ON THE TEMP-FALL...MOST OF
THE CWA IS ON TRACK TO REALIZE OVERNIGHT LOWS BETWEEN 41-46
DEGREES.

FOR THE DAYTIME HOURS 12Z-00Z/7AM-7PM...THE FORECAST REMAINS DRY
AS AM NOT EXPECTING THE VERY HIGH BASED WESTERN NEB SPRINKLES
CURRENTLY NOTED ON RADAR TO HAVE ANY IMPACT LOCALLY. THE MID-
UPPER LEVEL PICTURE REMAINS FAIRLY STEADY-STATE UNDER A BAND OF
MODESTLY STRONG NORTHWESTERLY FLOW...AS A RATHER SUBTLE LOW-
AMPLITUDE DISTURBANCE GRADUALLY APPROACHES THE LOCAL AREA FROM THE
NORTHWEST. AT THE SURFACE...THE COMBINATION OF A TIGHTENING
PRESSURE GRADIENT BETWEEN THE DEPARTING RIDGE AND MODEST HIGH
PLAINS PRESSURE FALLS TO THE WEST...ALONG WITH MIXING UP INTO A
WEAK-MODEST LOW LEVEL JET WILL PROMOTE INCREASING SOUTHERLY
BREEZES...ESPECIALLY DURING THE MID-MORNING TO MID-AFTERNOON
HOURS...WITH SUSTAINED SPEEDS GENERALLY 10-15 MPH AND GUSTS TO
AROUND 20 MPH ESPECIALLY WITHIN THE WESTERN 1/2 OF THE CWA. NOT TO
KEEP BEATING THE DRUM ON THIS ISSUE...BUT THE UNCERTAINTY IN THE
PRESENCE OR LACK THEREOF OF THE POTENTIAL INVADING STRATUS DECK
CERTAINLY RAISES SOME CONSIDERABLE QUESTIONS ON SKY COVER AND
RESULTANT TEMPS...WITH LIKELY AROUND A 5-DEGREE TEMP BUST
POTENTIAL ON THE LINE. BASED ON THE LATEST 06Z NAM 850 MILLIBAR
RELATIVE HUMIDITY PROGS...AT LEAST A LIMITED COVERAGE OF PARTLY-
MOSTLY CLOUDY SKIES SHOULD SLOWLY OVERTAKE THE CWA FROM SOUTHWEST-
NORTHEAST TODAY...WHILE THE LATEST HRRR LOW CLOUD COVER PRODUCT
SUGGESTS STRATUS COULD BE A MORE MINIMAL ISSUE AS ALTHOUGH IT
STILL BRINGS IT INTO MAINLY THE SOUTHWEST 1/2 TO 1/3 OF THE CWA IT
DIMINISHES IT AREA WITH TIME AND EVEN MIXES IT OUT ALMOST
COMPLETELY IN THE AFTERNOON. NOT SURPRISINGLY...THE OFFICIAL SKY
COVER FORECAST IS A HEDGE...SUGGESTING THAT THE DAY AS A WHOLE
STARTS OUT MOSTLY SUNNY IN MOST AREAS BUT THEN BECOMES AT LEAST
PARTLY CLOUDY WITH AT LEAST A BRIEF FEW HOURS OF MOSTLY CLOUDY
PASSING THROUGH. EVEN WITHOUT LOWER STRATUS...A FEW DECENT PATCHES
OF MID LEVEL CLOUDS COULD ALSO WORK OVERHEAD FROM THE NORTHWEST.
STAY TUNED FOR PLENTY OF SKY COVER FINE TUNING BY DAY SHIFT. HIGH
TEMP-WISE...FOLLOWED A BLEND OF VARIOUS MODELS/GUIDANCE TO YIELD
AROUND A 2-3 DEGREE RISE FROM PREV FORECAST...WHICH PUTS MOST OF
THE CWA IN THE 69-73 RANGE BUT WITH SLIGHTLY WARMER GENERALLY
74-77 IN FAR SOUTHWEST ZONES. BY THIS AFTERNOON SURFACE DEWPOINTS
SHOULD HAVE RISEN BACK UP SOMEWHERE IN THE 50S...HIGHEST
SOUTHWEST.

THIS EVENING-TONIGHT...THE MID-UPPER LEVEL STORY INVOLVES
CONTINUED FAIRLY STEADY-STATE NORTHWESTERLY FLOW ALOFT AS A VERY
LOW-AMPLITUDE/CHANNELED SHORTWAVE TROUGH SLIDES CLIPS THROUGH
MAINLY JUST TO THE NORTHEAST OF THE CWA ALONG A TRACK FROM THE
DAKOTAS THROUGH IA INTO NORTHERN MO. AS THIS WAVE PASSES BY...IT
WILL INDUCE A MODEST INCREASE IN THE LOW LEVEL JET AND ASSOCIATED
THETA-E ADVECTION/ISENTROPIC LIFT THAT WILL GRADUALLY VEER FROM
SOUTHWESTERLY TO MORE WESTERLY...ALTHOUGH THE MAIN NOSE OF THIS
FORCING LOOKS TO AIM EASTERN KS AND NOT SO MUCH LOCALLY. AS A
RESULT...THE MAJORITY OF BOTH DETERMINISTIC AND HIGHER RES-
SIMULATED REFLECTIVITY MODELS SUCH AS THE 4KM WRF-NMM FOCUS
OVERNIGHT CONVECTION AT LEAST A FEW COUNTIES EAST-SOUTHEAST OF THE
CWA. HOWEVER...GIVEN THAT THE PREVIOUS FORECAST ALREADY WAS
CARRYING A SLIGHT SHOWER/STORM CHANCE IN SOUTHEAST ZONES AND THAT
THE GFS IN PARTICULAR STILL TRIES TO INITIATE STORMS IN THIS
AREA...HAVE HELD ONTO THIS SLIGHT CHANCE MAINLY SOUTHEAST OF A
GENEVA-PLAINVILLE LINE POST-MIDNIGHT...BUT REMOVED ANY PRECIP
CHANCES EARLIER IN THE EVENING GIVEN THAT LIFT DOES NOT APPEAR
SUFFICIENT TO GENERATE CONVECTION BEFORE THEN. SHOULD ANY STORMS
BE REALIZED...CERTAINLY A FEW STRONG UPDRAFTS CAPABLE OF
PRODUCING AT LEAST NEAR-SEVERE HAIL CANNOT BE RULED OUT GIVEN THE
06Z NAM SUGGESTION OF UP TO AROUND 1500 J/KG MUCAPE IN THE
850-700MB LAYER AND AROUND 40KT OF DEEP LAYER SHEAR. AS A
RESULT...WILL CONTINUE TO MENTION NICKEL SIZE HAIL POTENTIAL IN
THE LOCAL HAZARDOUS WEATHER OUTLOOK IN SOUTHEAST AREAS...DESPITE
THE FACT THAT THE LATEST SPC DAY 1 OUTLOOK REMOVED THE 5 PERCENT
SEVERE PROBABILITY CONTOUR FROM THE CWA THAT HAD BEEN PRESENT ON
THE FORMER DAY 2 OUTLOOK. AGAIN THOUGH...NO MATTER WHAT THE
MAJORITY OF THE CWA SHOULD GET THROUGH THE NIGHT DRY. TURNING TO
THE SURFACE SITUATION...GENERALLY 5-8 MPH SOUTHEASTERLY BREEZES
THIS EVENING SHOULD BECOME EVEN LIGHTER AND MORE EASTERLY AFTER
MIDNIGHT. ASSUMING THAT OVERNIGHT SKIES AVERAGE NO WORSE THAN
PARTLY CLOUDY IN THE WAKE OF POTENTIAL EASTWARD-EXITING STRATUS
FROM THE DAYTIME HOURS...THE STAGE COULD BE SET FOR SOME
POTENTIALLY DECENT AT-LEAST-LIGHT FOG FORMATION...AND MAYBE SOME
MORE IMPACTFUL FOG ESPECIALLY WITHIN THE WESTERN 1/2 OF THE CWA
PER THE LATEST SREF VISIBILITY PROBABILITY PRODUCTS. EXPERIENCE
HAS SHOWN THAT FOG IS ALMOST NEVER A "SURE THING" UNTIL IT
ACTUALLY FORMS...BUT FELT IT WOULD BE PRUDENT TO INTRODUCE A
GENERIC PATCHY FOG WORDING TO ALL AREAS LATE TONIGHT...AND A
SOMEWHAT HARDER-HITTING AREAS OF FOG MENTION TO WESTERN COUNTIES.
ITS JUST TOO SOON TO SAY WHETHER OR NOT FOG COULD CAUSE IMPACTFUL
ISSUES FOR THE WED MORNING COMMUTE. AS FOR LOW TEMPS...MADE VERY
LITTLE CHANGE HERE...AS THE INCREASED LOW LEVEL MOISTURE SHOULD
HELP HOLD UP LOWS GENERALLY 5-10 DEGREES HIGHER THAN THIS
MORNING...AND AM CALLING FOR A RANGE FROM NEAR-50 FAR
NORTH...LOW-MID 50S CENTRAL AND NEAR 60 FAR SOUTH.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 435 AM CDT TUE SEP 16 2014

THE WARMEST DAY OF THE NEXT 7 DAYS WILL BE FRIDAY WITH HIGHS IN THE
MID 80S AHEAD OF A COLD FRONT. THE BEST CHANCE OF
SHOWERS/THUNDERSTORMS CURRENTLY APPEARS TO BE ASSOCIATED WITH THAT
COLD FRONTAL PASSAGE FRIDAY NIGHT INTO THE FIRST HALF OF SATURDAY.
THE COOLEST DAY OF THE WEEK WILL ACTUALLY BE TODAY WITH HIGHS OF 70
TO 75. SO OVERALL THIS WILL BE A RATHER NICE WEEK WITH HIGHS NEAR
NORMAL FOR THIS TIME OF YEAR...WHICH IS GENERALLY IN THE UPPER 70S.

WEDNESDAY/WEDNESDAY NIGHT...AN UPPER LEVEL RIDGE WILL BE CENTERED
OVER THE ROCKIES WITH NORTHWESTERLY FLOW ALOFT ACROSS THE CENTRAL
PLAINS. THERE WILL BE DECENT INSTABILITY AND WIND SHEAR ACROSS OUR
FORECAST AREA...BUT FORCING IS RATHER WEAK. THERE MAY BE A WEAK
UPPER WAVE RIDING DOWN THE EAST SIDE OF THE RIDGE OR PERHAPS
SLIGHTLY BETTER LIFT AFTER DARK WEDNESDAY NIGHT AS A WEAK LOW LEVEL
JET LIFTS OVER THE EAST SOUTHEAST SFC FLOW. HOWEVER...THE BETTER LOW
LEVEL JET SET UP APPEARS TO BE TO OUR SOUTHEAST OVER NORTHEAST
KANSAS. SO OVERALL...FORCING JUST SEEMS RATHER QUESTIONABLE AND WILL
ONLY CARRY LOWER END POPS BEGINNING WEDNESDAY NIGHT WITH THE REALITY
BEING MOST LOCATIONS WILL MORE LIKELY THAN NOT BE DRY.

THURSDAY...THE UPPER RIDGE OVER THE ROCKIES WILL SLIDE FURTHER EAST
INTO THE PLAINS AND PRECIPITATION CHANCES WILL DECREASE. A FEW
FORECAST MODELS ARE STILL HINTING AT LOW END CHANCES OF
PRECIPITATION ACROSS OUR FORECAST AREA...BUT AM NOT VERY OPTIMISTIC
THAT THERE WILL BE MUCH OUT THERE GIVEN THE RIDGE MOVING IN.
THEREFORE...DECREASED OUR POPS AND DOWNGRADED SHOWER AND
THUNDERSTORM CHANCES TO JUST ISOLATED SPRINKLES.

FRIDAY THROUGH SATURDAY...AS MENTIONED ABOVE...FRIDAY WILL BE THE
WARMEST DAY OF THE NEXT 7 DAYS AS GUSTY SOUTHERLY WINDS PUMP WARMER
AIR INTO THE REGION AHEAD OF AN APPROACHING COLD FRONT. AN
INTERESTING WRINKLE IN THIS FORECAST IS WHAT WILL HAPPEN WITH THE
REMNANTS OF HURRICANE ODILE...WHICH IS CURRENTLY LOCATED OVER THE
BAJA PENINSULA OF MEXICO. THE 00Z GFS AND 00Z ECMWF BOTH BRING
REMNANT MOISTURE FROM THIS DECAYING TROPICAL SYSTEM NORTH NORTHEAST
INTO THE CENTRAL PLAINS...WHERE IT WILL WORK INTO AN UPPER LEVEL
STORM SYSTEM THAT IS TRACKING EAST THROUGH THE CENTRAL PLAINS. THERE
ARE STILL PLENTY OF QUESTIONS WITH REGARD TO THE TIMING OF WHEN THE
TROPICAL MOISTURE PLUME WILL ARRIVE AND HOW THAT WILL INTERACT WITH
OUR MID LATITUDE UPPER TROUGH. THE MOST LIKELY TIME FOR
PRECIPITATION WILL BE FROM FRIDAY NIGHT THROUGH SATURDAY
MORNING...WITH THE SYSTEM EXITING TO OUR EAST BY SATURDAY AFTERNOON.
TEMPERATURES WILL BE SLIGHTLY COOLER SATURDAY BEHIND THE COOL
FRONT...BUT NOTHING MAJOR WITH HIGHS ONLY AROUND 5F COOLER.

SUNDAY THROUGH MONDAY...UPPER LEVEL RIDGING WILL RESUME ACROSS THE
WESTERN CONUS WITH DRY WEATHER LIKELY FOR OUR FORECAST AREA. HIGH
TEMPERATURES WILL BE NEAR NORMAL IN THE 70S.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z TUESDAY)
ISSUED AT 101 AM CDT TUE SEP 16 2014

ALTHOUGH CONFIDENCE IS REASONABLY HIGH IN BOTH VFR CEILING AND
VISIBILITY PREVAILING THROUGH THE PERIOD...ALONG WITH VERY LITTLE
IF ANY RISK OF PRECIPITATION...THERE IS SOME MAJOR UNCERTAINTY
REGARDING WHETHER OR NOT A POTENTIALLY EXPANSIVE CEILING RATHER
CLOSE TO THE VFR-MVFR HEIGHT BREAKPOINT COULD MOVE IN FOR SEVERAL
HOURS MAINLY DURING THE LATTER HALF OF THE PERIOD THIS
AFTERNOON/EVENING. PRESENTLY...A DECK OF CLOUDS AT THIS LEVEL ARE
LOCATED NEARLY 200 MILES SOUTHWEST OF THE TERMINALS...AND THE MAIN
QUESTION IS WHETHER THIS CLOUD DECK WILL CONTINUE TO GRADUALLY
EXPAND NORTHEAST WITH TIME. TAKING A BEST STAB AT TIMING...HAVE
DELAYED THE ONSET AND DEPARTURE OF POTENTIAL LOW-VFR CEILING A
FEW HOURS VERSUS PREVIOUS FORECAST...BUT AGAIN UNCERTAINTY IS
HIGH. VISIBILITY WISE...THERE APPEARS TO BE SOME VERY PATCHY
LIGHT FOG COMING AND GOING EARLY THIS MORNING...BUT BELIEVE ANY
SUB-VFR OBSERVATIONS SHOULD BE QUITE FLEETING AND THUS WILL
MAINTAIN PREVAILING VFR. AS FOR SURFACE WINDS...VERY LIGHT BREEZES
THIS MORNING WILL STEADILY INCREASE AFTER SUNRISE AS MIXING
DEEPENS...WITH MUCH OF THE DAY FEATURING A SOUTHERLY SUSTAINED
BREEZE OF 10-15KT WITH SLIGHTLY HIGHER GUSTS...BEFORE WINDS SUBSIDE
A BIT FROM A PREVAILING SOUTH-SOUTHEAST DIRECTION IN THE EVENING.

&&

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

$$

SHORT TERM...PFANNKUCH
LONG TERM...WESELY
AVIATION...PFANNKUCH


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