Area Forecast Discussion
Issued by NWS Hastings, NE

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FXUS63 KGID 021009
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
509 AM CDT THU OCT 2 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 510 AM CDT THU OCT 2 2014

IN ESSENCE...THESE NEXT 24 HOURS MARK THE BEGINNING STAGES OF THE
TRANSITION TO AT LEAST SEVERAL DAYS OF A MORE FALL-LIKE WEATHER
PATTERN AND LESS-SO A LATE SUMMER ONE. HIGHLIGHTS DURING THESE
NEXT 24 HOURS INCLUDE THE ENDING OF THE OVERNIGHT STRONG-SEVERE
STORM RISK BUT A CONTINUATION OF FAIRLY WIDESPREAD SHOWER ACTIVITY
THROUGH THIS MORNING...A MAINLY DRY AFTERNOON AND EVENING FOR MOST
OF THE CWA...AND THEN A POTENTIALLY INCREASING CHANCE FOR PASSING
GENERALLY LIGHT RAIN SHOWERS LATE TONIGHT ALONG WITH SOME GUSTY
NORTHWEST WINDS.

STARTING OFF WITH THE HERE AND NOW AS OF 0930Z/430AM...IT WAS A
FAIRLY ACTIVE EVENING/OVERNIGHT ACROSS PARTS OF THE CWA IN TERMS
OF STRONG TO MARGINALLY SEVERE STORMS...BUT WITH THE EXCEPTION OF
ONE SEVERE STORM THAT TRACKED JUST NORTH OF THE STATE LINE FROM
WEBSTER TO THAYER COUNTIES...THE MAJORITY OF SEVERE WEATHER
ACTUALLY OCCURRED EARLIER IN THE NIGHT BEFORE THE ROUGHLY MIDNIGHT
ISSUANCE OF SEVERE THUNDERSTORM WATCH 514...WHICH AT ONE TIME
INCLUDED ALL BUT THE NORTHERN-MOST 3 COUNTIES IN THE CWA. AT ANY
RATE...THIS WATCH HAS BEEN STEADILY WHITTLED-DOWN THROUGH THE
NIGHT...AND THE REMAINING 10 COUNTIES WILL LIKELY BE CANCELLED
SHORTLY AFTER THE ISSUANCE OF THIS PRODUCT AROUND 5 AM...AS ANY
REMAINING THUNDERSTORM THREAT BEYOND THIS POINT WILL LIKELY
CONSIST OF NO MORE THAN SMALL SUB-SEVERE HAIL. RAIN WISE...VARIOUS
BUT LIMITED PORTIONS OF THE CWA RECEIVED AT LEAST 1-2 INCHES
OVERNIGHT (INCLUDING THE CITY OF HASTINGS)...BUT THIS WAS MORE THE
EXCEPTION THAN THE RULE ACROSS THE CWA AS A WHOLE.LOOKING AT THE
BIG PICTURE ALOFT PER WATER VAPOR IMAGERY AND SHORT TERM MODEL
DATA...A VIGOROUS SHORTWAVE TROUGH CENTERED ALONG AN AXIS FROM
THE WESTERN DAKOTAS SOUTHWARD TO A VORT MAX CENTERED OVER CO/NM IS
IN THE PROCESS OF SHIFTING EAST- SOUTHEAST INTO THE CENTRAL
PLAINS. MEANWHILE UPSTREAM A SECONDARY/REINFORCING SHORTWAVE
TROUGH AND ASSOCIATED UPPER JET STREAK IS IN THE PROCESS OF
ORGANIZING AS IT DIVES SOUTHEAST THROUGH SOUTHWEST/SOUTH CENTRAL
CANADA. AT THE SURFACE...THE FIRST IN A SERIES OF COLD FRONTS
(PARTLY CONVECTIVELY-DRIVEN) HAS PASSED THROUGH THE CWA...TURNING
BREEZES OUT OF THE NORTH-NORTHWEST AT GENERALLY 10-20 MPH WITH
SOME HIGHER GUSTS. AS COOLER/MORE STABLE AIR HAS GRADUALLY
FILTERED IN BEHIND THIS BOUNDARY...EVEN ELEVATED INSTABILITY
BETWEEN THE 850-700 MILLIBAR LAYER HAS ALSO MADE A STEADY DECREASE
FROM NORTHWEST-TO- SOUTHEAST...WITH LATEST SPC MESO-ANALYSIS
INDICATING THAT GENERALLY NO MORE THAN 500 J/KG MUCAPE REMAINS
EVEN IN THE SOUTHEASTERN CWA...WITH ESSENTIALLY ZERO CONVECTIVE
INSTABILITY IN NORTHWEST ZONES. LOW TEMPS THIS MORNING ARE ON
TRACK TO RANGE FROM LOW 50S NORTHWEST TO UPPER 50S SOUTHEAST.

LOOKING AHEAD IN THE FORECAST AND STARTING WITH EARLY THIS MORNING
THROUGH AROUND 7AM/12Z...WILL MAINTAIN PRETTY HIGH POPS ACROSS THE
CWA AS THE NEXT ROUND OF FAIRLY WIDESPREAD SHOWER ACTIVITY TRACKS
ACROSS/INTO THE AREA FROM THE WEST-SOUTHWEST. HOWEVER...WITH
INSTABILITY ON THE WANE NOT EXPECTING ANY ADDITIONAL STRONG/SEVERE
STORMS ALTHOUGH CERTAINLY SOME SMALL HAIL CANNOT BE RULED OUT
ESPECIALLY IN KS ZONES.

TURNING TO THE DAYLIGHT HOURS...AND STARTING WITH THE BIG PICTURE
ALOFT...THE AFOREMENTIONED LARGE-SCALE SHORTWAVE TROUGH WILL
STEADILY SHIFT EASTWARD ACROSS THE CENTRAL PLAINS OVER THE COURSE
OF THE DAY...WITH ITS AXIS GENERALLY BECOMING ALIGNED FROM EASTERN
NEB TO SOUTHERN OK BY DAYS END. AS THIS TROUGH AXIS PUSHES
THROUGH...EVEN MEAGER CONVECTIVE INSTABILITY WILL GRADUALLY PUSH
EAST-SOUTHEAST OUT OF THE CWA...BUT LARGE-SCALE FORCING WILL
PERSIST IN THE FORM OF MID LEVEL FRONTOGENESIS INCLUDED AT/NEAR
THE 700MB LEVEL WELL THROUGH THE MORNING HOURS...AND EVEN INTO THE
AFTERNOON HOURS IN EASTERN ZONES BEFORE CLEARING THE CWA. AS A
RESULT...AND FOLLOWING CLOSELY TO SIMULATED REFLECTIVITY AS
PRESENTED IN THE 00Z 4KM WRF-NMM AND 00Z 4KM NSSL WRF...FAIRLY
WIDESPREAD SHOWER ACTIVITY WITH EMBEDDED/ISOLATED THUNDER WILL
CONTINUE THIS MORNING...WITH THE MAIN RISK FOR ADDITIONAL THUNDER
CONFINED TO ROUGHLY THE SOUTHEAST 1/2 OF THE CWA INCLUDING KS
ZONES. BY EARLY THIS AFTERNOON...ANY LINGERING RAIN SHOWERS SHOULD
LARGELY BE CONFINED TO ABOUT THE EASTERN 1/4 OF THE CWA...WITH ALL
AREAS EXPECTED TO BE DRY BY MID-AFTERNOON AT THE LATEST WITH
INCREASING SUNSHINE IN THE WAKE OF A MOSTLY CLOUDY MORNING. MADE
LITTLE CHANGE TO PREVIOUS FORECAST HIGH TEMPS...AIMING MOST OF THE
CWA INTO THE 63-67 RANGE. ALTHOUGH IT WON/T BE AS BREEZY/WINDY AS
TOMORROW SHOULD BE...SUSTAINED NORTHWEST WINDS OF GENERALLY 12-20
MPH WILL PREVAIL MOST OF TODAY WITH HIGHER GUSTS.

FOR THIS EVENING/TONIGHT...THE BASIC STORY IS THAT A DRY/TRANQUIL
EVENING WILL TURN A BIT MORE ACTIVE LATE IN THE NIGHT WITH A
RETURN OF SHOWER CHANCES ALONG WITH INCREASING NORTH-NORTHWEST
WINDS. IN THE BIG PICTURE ALOFT...THE FIRST SHORTWAVE TROUGH WILL
CONTINUE TO DEPART THE AREA...PUTTING THE CWA GENERALLY IN BETWEEN
WAVES DURING THE EVENING. HOWEVER AFTER MIDNIGHT...THE
AFOREMENTIONED TRAILING WAVE/VORT MAX CURRENTLY OVER CANADA WILL
QUICKLY SLIDE SOUTH-SOUTHEAST ALONG AN AXIS FROM THE DAKOTAS TO
NORTHERN KS...ACCOMPANIED BY A STOUT NORTHWESTERLY UPPER LEVEL JET
STREAK. AS THIS OCCURS...THE MOSTLY CLEAR SKIES AND LIGHT WESTERLY
BREEZES ANTICIPATED THIS EVENING WILL GIVE WAY TO INCREASING
CLOUDS AND SCATTERED RAIN SHOWERS WORKING FROM NORTHWEST-SOUTHEAST
ACROSS THE CWA LATER IN THE NIGHT. ALTHOUGH RAIN AMOUNTS SHOULD BE
FAIRLY LIGHT AND AVERAGE AROUND ONE-TENTH OF AN INCH OR LESS IN
MOST AREAS...THE CHANCE OF MEASURABLE RAIN SEEMS TO BE INCREASING
WITH TIME...AND THE CURRENT 20-30 PERCENT POPS MAY VERY WELL NEED
RAISED BY NEXT FEW SHIFTS. MEANWHILE AT THE SURFACE...AN EVEN
STRONGER COLD FRONT WILL RACE INTO/ACROSS THE CWA LATER
TONIGHT...USHERING IN SUSTAINED NORTH-NORTHWEST WINDS OF AT LEAST
15-20 MPH WITH HIGHER GUSTS...AND VERY POSSIBLY A FAIRLY BRIEF
PERIOD OF NEAR-ADVISORY 25-30 MPH SUSTAINED WINDS AND GUSTS TO
AROUND 40 MPH ASSOCIATED WITH THE INITIAL PRESSURE- RISE SURGE. AM
NOT FORESEEING THE NEED FOR A FORMAL WIND ADVISORY TONIGHT GIVEN
THIS EXPECTED BRIEF DURATION...BUT NEXT SHIFTS MAY WANT TO TAKE A
CLOSER LOOK. SPEAKING OF THE STRENGTH OF THIS COLD
FRONT...FORECAST SOUNDING THERMAL PROFILES EVEN SUGGEST THAT A FEW
WET SNOWFLAKES COULD EVEN TRY MIXING IN WITH THE BACK EDGE OF
DEPARTING SHOWERS VERY LATE TONIGHT MAINLY IN NORTHERN ZONES...BUT
FEEL THE LOWEST LEVELS SHOULD REMAIN JUST WARM ENOUGH TO KEEP THE
VAST MAJORITY OF THIS LIGHT PRECIP AS RAIN...AND WILL FOREGO ANY
SNOW MENTION IN THE OFFICIAL FORECAST. ACTUAL LOW TEMPS TONIGHT
WERE CHANGED VERY LITTLE...RANGING FROM UPPER 30S NORTHWEST TO MID
40S SOUTHEAST.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 510 AM CDT THU OCT 2 2014

THE BIGGEST CHALLENGE WILL BE DETERMINING CHANCES OF RAIN EARLY
FRIDAY MORNING AND FROST/FREEZE FRIDAY NIGHT/SATURDAY MORNING.

THE LAST PERTURBATION OF ENERGY SHOULD JUST BE EXITING TO THE EAST
OF THE CWA ON FRIDAY...AND MAY JUST CLIP OUR FAR SOUTHEAST FOR
PRECIPITATION CHANCES EARLY FRIDAY MORNING. MOST NUMERICAL MODELS
ARE IN DECENT AGREEMENT WITH THIS.

A REINFORCING SHOT OF COLD AIR COMING IN ON THE HEALS OF A DEPARTING
LONGWAVE TROUGH AXIS. THIS SHOULD BE A STRONG PUNCH WITH 850 MB
TEMPERATURES NOT MUCH ABOVE ZERO. DESPITE THE CLEARING SKY...COLD
AIR ADVECTION WILL BE STRONG. I FAVOR CONSRAW FOR HIGHS
FRIDAY...WHICH TENDS TO DO BETTER WHEN WE ARE EXPECTING MUCH BELOW
NORMAL TEMPERATURES FOR HIGHS...AS IS THE CASE FOR FRIDAY...BEHIND
THE COLD FRONT. THIS LED ME TO LOWER HIGHS EVEN MORE FOR
FRIDAY...WITH LOWER TO MID 50S EXPECTED. OPERATIONAL MODELS...AND
EVEN MODEL ENSEMBLES HAVE NOT YET CAUGHT UP TO HOW COLD IT LOOKS
LIKE IT WILL BE...BUT THE ECMWF MODEL ENSEMBLES DO APPEAR TO BE
SUPERIOR TO THE GFS ENSEMBLES IN THIS REGARD. FOR SUSTAINED
WIND...IT STILL APPEARS THAT WE WILL FALL JUST BELOW WIND ADVISORY
CRITERIA...BUT I ACTUALLY RAISED GUSTS TO NEAR 40 MPH IN OUR NORTH
WITH THE EXPECTED SURFACE PRESSURE GRADIENT...STEEP LOW-LEVEL LAPSE
RATES AND MIXING. CONSRAW IS FAVORED FOR GUSTS HERE...RATHER THAN
THE STANDARD GUST TOOL.

FOR FRIDAY NIGHT/SATURDAY MORNING...I KEPT TEMPERATURES SIMILAR TO
THE PREVIOUS FORECAST AND FROST/FREEZE APPEARS TO BE A CONCERN.
CONSRAW INDICATES THAT WE MAY HAVE ENOUGH WIND SPEED FROM TIME TO
TIME TO TAMP DOWN SOME OF THE POTENTIAL FROST IN CENTRAL AND
SOUTHERN PARTS OF THE CWA. AREAS TOWARD LEXINGTON/ORD MAY BE COLD
ENOUGH TO FREEZE.

AS A RIDGE GRADUALLY BUILDS AND PUSHES EAST IN THE WESTERN UNITED
STATES...WE WILL GRADUALLY WARM INTO EARLY NEXT WEEK. I RETAINED THE
DRY FORECAST FOR THE LONG TERM...HOWEVER...WE WILL HAVE A FAIRLY
STRONG UPPER LEVEL JET PUNCHING DOWN FROM THE NORTH ON THE EASTERN
EDGE OF THE LONGWAVE TROUGH...WHICH MAY THROW A WRENCH INTO OUR DRY
FORECAST. FOR NOW...WE APPEAR DRY ENOUGH TO ONLY INCREASE SKY
COVER A BIT FOR THIS PERIOD.

&&

.AVIATION...(FOR THE 06Z KGRI/KEAR TAFS THROUGH 06Z THURSDAY)
ISSUED AT 1216 AM CDT THU OCT 2 2014

A LINE OF STRONG TO MARGINALLY SEVERE THUNDERSTORMS IS EXPECTED TO
TRACK EAST ACROSS THE TERMINALS OVER THE NEXT FEW HOURS. BASED ON
RADAR TRENDS...EXPECT THESE STORMS TO EVENTUALLY REACH GRAND
ISLAND AROUND 02/09Z. EXPECT TEMPORARY MVFR OR EVEN BRIEF IFR
CONDITIONS TO DEVELOP NEAR THE LINE...WITH LIGHT RAIN SHOWERS
FILLING IN ALONG WITH MVFR STRATUS BEHIND THIS LINE THROUGH THE
MORNING HOURS. IN ADDITION...WINDS WILL BECOME GUSTY...WITH A
MARKED SHIFT...BECOMING NORTHWESTERLY AT BOTH TERMINALS ON THE
BACKSIDE OF THIS ACTIVITY LATER THIS MORNING. WHILE SOME SHOWERS
MAY LINGER ACROSS THE AREA DURING THE DAYTIME HOURS
THURSDAY...EXPECT THE TERMINALS TO REMAIN LARGELY DRY AFT ABOUT
02/14Z...WITH CEILINGS LIFTING AND CLOUDS THINNING BY LATE
AFTERNOON.

&&

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

$$

SHORT TERM...PFANNKUCH
LONG TERM...HEINLEIN
AVIATION...ROSSI


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