Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 121045
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
545 AM CDT FRI SEP 12 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 343 AM CDT FRI SEP 12 2014

THE PRIMARY FORECAST CONCERN CENTERS AROUND THE NEAR RECORD TO
RECORD LOW TEMPERATURES EXPECTED TONIGHT INTO EARLY SATURDAY
MORNING AND THE POTENTIAL IMPACTS DUE TO POSSIBLE FROST
DEVELOPMENT.

FROST THREAT TONIGHT...THE RECORD LOW TEMPERATURE FOR SATURDAY
MORNING SEPTEMBER 13TH IS 34 DEGREES IN BOTH HASTINGS AND GRAND
ISLAND. THE PERIOD OF RECORD IN BOTH CITIES IS OVER 100 YEARS. OUR
CURRENT FORECAST FOR OUR ENTIRE OUTLOOK AREA IS FOR LOWS OF 33 TO
36 DEGREES. THIS APPEARS TO BE A NEAR IDEAL SET UP FOR RADIATIONAL
COOLING WITH AN ABNORMALLY STRONG HIGH OF OVER 1030 MB SLIDING
ACROSS THE FORECAST AREA THIS EVENING. THE WIND WILL LIKELY BECOME
CALM BY THIS EVENING AND DO NOT EXPECT IT WILL START TO PICK UP
AGAIN UNTIL AFTER SUNRISE. IN ADDITION...SKIES WILL BE CLEAR
THROUGHOUT THE NIGHT...WHICH WILL FURTHER INCREASE OUR RADIATIONAL
COOLING. THE GROUND IS VERY MOIST FROM RECENT RAIN AND EXPECT
THERE WILL BE NO PROBLEM GETTING DEW AND FROST TO FORM DEPENDING
ON THE TEMPERATURE. AVERAGE MODEL GUIDANCE VALUES ARE IN THE 33 TO
36F RANGE...AND THAT IS FOR A 2M MEASURING HEIGHT TEMPERATURE. THE
TEMPERATURE RIGHT AT THE GROUND...GIVEN THE STRONG RADIATIONAL
COOLING AND TEMPERATURE INVERSION...COULD EASILY SLIP A FEW
DEGREES COOLER THAN THAT RESULTING IN AREAS OF FROST. EXPECT FROST
WILL BE MOST LIKELY AND MORE WIDESPREAD IN LOW LYING AREAS SUCH AS
IN VALLEYS AS WELL AS IN MORE RURAL AREAS. CONFIDENCE IN SEEING 2M
LOW TEMPERATURES OF 33 TO 36F IS HIGHEST ACROSS SOUTH CENTRAL
NEBRASKA AND ALONG AND NORTH OF HIGHWAY 36 IN KANSAS.
THEREFORE...A FROST ADVISORY HAS BEEN ISSUED FOR THESE AREAS. CAN
NOT COMPLETELY RULE OUT FROST IN OUR SOUTHERN MOST TIER OF
COUNTIES...BUT CONFIDENCE WAS NOT HIGH ENOUGH AT THIS TIME TO
WARRANT A FROST HEADLINE.

TODAY...WE MAY VERY WELL SEE ANOTHER RECORD LOW MAX TEMPERATURE
TODAY IN HASTINGS. THE RECORD LOW MAX TEMPERATURE IN HASTINGS FOR
TODAY IS 56 DEGREES SET BACK IN 1989 AND WE ARE CURRENTLY
FORECASTING A HIGH OF 53 DEGREES TODAY IN HASTINGS. THE RECORD
LOW MAX TEMPERATURE IN GRAND ISLAND IS 46 DEGREES AND IT IS
UNLIKELY TO BE BROKEN AS WE SHOULD RISE UP INTO THE LOWER 50S
TODAY IN GRAND ISLAND. YET IT IS CLEAR THAT WE WILL BE
SUBSTANTIALLY BELOW NORMAL GIVEN THE NORMAL HIGH FOR TODAY IS
80F...WHICH MEANS WE EXPECT TO BE OVER 25F COOLER THAN NORMAL
TODAY. THE CLOUDS ARE EXPECTED TO REMAIN THROUGHOUT MUCH OF THE
DAY NOT BREAKING UP UNTIL LATE AFTERNOON OR EARLY EVENING...WHICH
WILL SIGNIFICANTLY LIMIT DIURNAL HEATING.

AS FOR THE RAIN TODAY...MOST FORECAST MODELS QUICKLY BRING THE
PRECIPITATION TO AN END THIS MORNING FROM NORTHWEST TO SOUTHEAST.
AS OF 4 AM THE HEAVIEST RAIN HAS ALREADY PASSED SOUTHEAST OF THE
TRI CITIES AND EXPECT THE DECREASING TREND WILL CONTINUE WITH
LITTLE IF ANY ADDITIONAL RAINFALL AFTER 9 OR 10 AM.

TONIGHT...AS NOTED ABOVE...NEAR RECORD COOL TEMPERATURES WITH
FROST POSSIBLE. SEE ABOVE FOR MORE DETAILS.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 343 AM CDT FRI SEP 12 2014

FOR THOSE IN DESPAIR OVER THE RECORD CHILL CURRENTLY GRIPPING THE
PLAINS...OUR WARM SEASON ISN`T OVER YET...NOT BY A LONG SHOT. WE
HAVE SOME VERY VERY NICE WX IN STORE. KEEP IN MIND THAT HIGH TEMPS
ARE STILL AROUND 80F FOR MID SEPT.

AS A SIDE NOTE...THE HIGH OF 52F AT GRI YESTERDAY WAS 28F BELOW
NORMAL. THAT IS AN ASTOUNDING DEPARTURE FROM NORMAL. THE REGION HAS
NOT EXPERIENCED A SEPT 11TH THAT CHILLY IN RECORDED HISTORY AND
THAT IS AT LEAST 100 YEARS.

PATTERN: OVER THE PAST 30 DAYS THE MEAN FLOW FEATURED A RIDGE OVER
THE NE PACIFIC...A TROF OVER THE CNTRL USA AND A RIDGE IN THE E.
MULTI-DAY 500 MB ENSEMBLE MEANS FOR THE NEXT 10 DAYS FROM THE
EC/GFS/GEM/JMA (JAPAN MET AGENCY) ARE UNANIMOUS THAT THE LONGWAVES
WILL SHIFT TO A NE PACIFIC TROF/WRN USA RIDGE/ERN USA TROF. THIS
MEANS NW FLOW HERE AND PROBABLY DRIER/WARMER WX.

ALOFT: ONCE THE TROF CURRENTLY OVERHEAD EXITS LATE TODAY...CYCLONIC
NW FLOW WILL BE ESTABLISHED IN ITS WAKE. WATER VAPOR IMAGERY
REVEALED THE NEXT SHORTWAVE TROF WAS OVER BRITISH COLUMBIA. THIS
TROF WILL DROP SE AND PASS THRU THE DAKOTAS SAT...FOLLOWED BY
ANOTHER ON SUN. THEREAFTER QUITE NW FLOW. OVERALL THE LAST TWO
CYCLES OF DETERMINISTIC MODELS ARE IN EXCELLENT AGREEMENT THRU
00Z/THU. DURING THE DAY WED SUBSTANTIAL SPREAD DEVELOPS IN THE BASE
OF THE TROF OFF THE W COAST...AND ITS PROGRESSION INLAND. WHILE ALL
MODELS FCST THE RIDGE TO ADVANCE E TO THE ROCKIES...THE MAIN
QUESTION IS HOW PROGRESSIVE DOES IT BECOME? THE 18Z/00Z GFS SHOW ITS
TYPICAL BIAS OF BEING TOO PROGRESSIVE. SO UNCERTAINTY INCREASES NEXT
THU-FRI. THE 00Z EC DID COME INTO AGREEMENT WITH THE GFS VS ITS
PRIOR 2 CYCLES.

SURFACE: STRONG HIGH PRES WILL BE OVER THE CNTRL PLAINS SAT. AS IT
DEPARTS INTO THE MID MS VALLEY...THE NEXT COOL FRONT WILL ALREADY BE
DIVING THRU THE NRN PLAINS. FRONTAL PASSAGE WILL OCCUR SUN WITH NRN
PLAINS HIGH PRES QUICKLY SINKING INTO THE REGION MON. THIS HIGH
SHIFTS INTO THE ERN USA TUE-WED WITH RETURN FLOW DEVELOPING HERE.
WARM FRONTOGENESIS WILL OCCUR JUST N AND E OF THE FCST AREA WED-THU
AS THE WRN USA WARMS UP AND LOW PRES BEGINS MIGRATING THRU THE
ROCKIES.

HAZARDS: NOTHING SUBSTANTIAL...BUT SOME MINOR LOW-CONFIDENCE TSTM
CHANCES EXIST AT VARIOUS TIMES.

THE DAILY DETAILS...

SAT: A NEAR RECORD COLD START. SUNNY WITH STILL A SUBSTANTIAL CHILL
IN THE AIR AS TEMPS WILL STRUGGLE TO CLIMB TO 60-64F...AND S WINDS
GUSTING 20-25 MPH WILL NOT HELP. MODELS STILL SHOW A THERMAL TROF
OVER ERN KS/NEB SO USED TEMPS THAT WERE COOLER THAN MOS.

SAT NIGHT: A MODEST LOW-LVL JET WILL ADVECT AN ELEVATED MIXED LAYER
/EML/ OVER THE REGION.

SUN: COOL FRONTAL PASSAGE ROUGHLY 12PM-12AM FROM NW-SE. SIGNIFICANT
LOW-LVL WARM AIR ADVECTION AND MOISTURE RETURN WILL OCCUR UNDERNEATH
THE EML. WHILE THIS WILL RESULT IN SOME MODEST POTENTIAL INSTABILITY
...A CAP WILL BE IN PLACE. WITH THE BEST QG FORCING AND DEEPER LIFT
OCCURRING OVER THE DAKOTAS...IT IS DOUBTFUL MUCH MORE THAN AN
ISOLATED TSTM OR TWO OCCURS LATE AFTERNOON INTO SUN NIGHT. THE
"BEST" MULTI-MODEL QPF CLUSTERING AND 03Z SREF PROBABILITY FOR .10"
IN 12 HRS IS E OF THE FCST AREA.

WE WILL ADD ANOTHER 10F OR SO TO HIGH TEMPS VS SATURDAY.

MON: POSSIBLY A LEFTOVER SHWR/TSTM BEFORE NOON? OTHERWISE DECREASING
CLOUDS FROM THE N. WE LOSE A LITTLE GROUND ON TEMPS.

TUE: DRY AND PLEASANT BUT STILL 10F COOLER THAN NORMAL.

TUE NIGHT: THETA-E ADVECTION VIA THE LOW-LVL JET. LOTS OF
UNCERTAINTY ON THUNDER POTENTIAL. THE GFS LOOKS TOO ROBUST WITH ITS
LOW-LVL MOISTURE RETURN.

WED: SOME TEMP RECOVERY. LOOKING DRY BUT ONLY WITH AVERAGE
CONFIDENCE.

WED NIGHT: SAME PROBLEM AS TUE NIGHT. THE LOW-LVL JET WILL DEVELOP
...BUT THE GFS MOISTURE PLUME LOOKS TOO MOIST AND IT LIKELY OVERDONE
ON THE TSTM THREAT.

THU: BREEZY AND A LITTLE WARMER AND TEMPS BEGIN TO FLIRT WITH NORMAL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 540 AM CDT FRI SEP 12 2014

ANY MEASURABLE RAIN WILL QUICKLY COME TO AN END THIS
MORNING...LIKELY PRIOR TO 9 AM. ISOLATED SPRINKLES OR VERY LIGHT
RAIN MAY AT TIMES BE POSSIBLE AFTER 9 AM UNTIL ABOUT NOON WITH
DRY CONDITIONS EXPECTED BY THIS AFTERNOON. CEILINGS WILL BOUNCE
AROUND THIS MORNING FROM VFR TO IFR...WITH PREDOMINATELY VFR
CONDITIONS BY LATE MORNING IF NOT SOONER. THE WIND WILL QUICKLY GO
CALM THIS EVENING AND SKIES WILL CLEAR.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...FROST ADVISORY FROM 1 AM TO 8 AM CDT SATURDAY FOR NEZ039>041-
     046>049-060>064-072>077-082>087.

KS...FROST ADVISORY FROM 1 AM TO 8 AM CDT SATURDAY FOR KSZ005>007.

&&

$$

SHORT TERM...WESELY
LONG TERM...HALBLAUB
AVIATION...WESELY



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