Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 201812
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1212 PM CST SAT DEC 20 2014

.UPDATE...
ISSUED AT 1209 PM CST SAT DEC 20 2014

HAVE ONCE AGAIN EXTENDED THE TIME FOR THE DENSE FOG ADVISORY. THE
WESTERN EDGE OF THE FOG MAY IMPROVE A LITTLE THIS AFTERNOON BUT
HAVE SOME CONCERN WHETHER THE FOG WILL LIFT. IF IT DOES NOT LIFT
IN THE NEXT FEW HOURS IT HAS THE POTENTIAL TO LINGER THROUGH THE
NIGHT.

UPDATE ISSUED AT 950 AM CST SAT DEC 20 2014

THE DENSE FOG IS PERSISTING A LITTLE LONGER FOR SOME AREAS. HAVE
EXTENDED THE TIME UNTIL NOON FOR MUCH OF THE ADVISORY AREA AND
HAVE ADDED IN COUNTIES FURTHER TO THE EAST WHERE THE FOG HAS
EXPANDED INTO. THE WESTERN EDGE IS TRYING TO MOVE TO THE EAST.
WILL HAVE TO WATCH TO SEE HOW IT PROGRESSES IN THE NEXT COUPLE
HOURS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CST SAT DEC 20 2014

MAP ANALYSIS INDICATES A WEAKENING UPPER TROPOSPHERIC TROUGH AXIS
MOVING INTO THE MID-MISSISSIPPI VALLEY AND A RIDGE AXIS OVER THE
CENTRAL TO NORTHERN ROCKIES. UPPER TROPOSPHERIC FLOW OVER OUR AREA
REMAINS FROM THE NORTHWEST AS A RESULT...BUT IS FAIRLY WEAK AT
AROUND 40KTS NEAR 30000FT AGL. AT THE SURFACE AN AREA OF HIGH
BAROMETRIC PRESSURE IS NOTED ACROSS THE GREAT LAKES REGION...WITH
A TROUGH ALONG THE FRONT RANGE OF THE ROCKIES. BOUNDARY-LAYER FLOW
ACROSS OUR AREA REMAINS FROM THE SOUTH TO SOUTHWEST AS A RESULT.
SATELLITE DATA AND SURFACE OBSERVATIONS ALSO INDICATE A BAND OF
STRATUS EXTENDING FROM NORTHEASTERN KANSAS INTO EASTERN NEBRASKA.
FOG IS ALSO NOTED UNDERNEATH THIS STRATUS SHIELD. VISIBILITY
RESTRICTION IN THIS FOG IS GENERALLY IN THE 3-6SM RANGE THROUGH
MOST LOCATIONS...WITH THE ONLY EXCEPTION BEING ALONG THE WESTERN
PERIPHERY OF THE STRATUS SHIELD WHERE VISIBILITY RESTRICTION OF
1/4SM TO 1SM IS BEING OBSERVED. THE WESTERN PERIPHERY OF THE
STRATUS CURRENTLY EXTENDS FROM NEAR KODX TO NEAR KK61 AND AS A
RESULT...LOCATIONS GENERALLY WEST OF HIGHWAY 281 ARE OBSERVING
CLEAR SKIES AND LITTLE IF ANY VISIBILITY RESTRICTION...WHILE
LOCATIONS FARTHER EAST ARE OBSERVING VISIBILITY RESTRICTION OF
1/4-1SM WITH A CEILING OF 100-500FT AGL.

GUIDANCE FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST THE
NORTHWESTERLY UPPER TROPOSPHERIC FLOW OVER OUR AREA WILL BECOME
QUASI-ZONAL THROUGH THE NEXT 24 HOURS AS AN UPPER TROUGH AXIS
BEGINS TO DEVELOP OVER THE CENTRAL PLAINS BY 12Z SUNDAY. MEANWHILE
AT THE SURFACE...THE TROUGH ALONG THE FRONT RANGE IS EXPECTED TO
STRENGTHEN SOMEWHAT THUS ALLOWING FOR CONTINUED SOUTH TO
SOUTHWESTERLY BOUNDARY-LAYER FLOW. GIVEN ALL THIS...AN OVERALL
LACK IN OMEGA SHOULD PREVENT MEASURABLE PRECIPITATION FROM BEING
REALIZED ACROSS OUR AREA THROUGH THE NEXT 24 HOURS...AND SUCH HAS
BEEN PRESENTED IN THE FORECAST.

AS FOR THE STRATUS AND FOG CURRENTLY IMPACTING PORTIONS OF THE
AREA...SATELLITE TRENDS THROUGH THE PAST SEVERAL HOURS INDICATE
THE CLOUD DECK...AS WELL AS THE FOG...IS MOVING EAST AT 5-10KTS.
ASSUMING THIS TREND PERSISTS...THE STRATUS AND FOG SHOULD CLEAR
OUR AREA TO THE EAST BY 15Z OR 16Z. UNTIL THAT POINT HOWEVER...A
THIN CORRIDOR OF DENSE FOG WILL CERTAINLY REMAIN POSSIBLE ALONG
THE WESTERN PERIPHERY OF THE CLOUD DECK...PRIMARILY ALONG OUR
EXTREME EASTERN CWA AND AS A RESULT...OPTED TO CONTINUE THE DENSE
FOG ADVISORY FOR LOCATIONS GENERALLY EAST OF HIGHWAY 281 UNTIL
16Z.

LOOKING AHEAD TO TONIGHT...THE NAM SUGGESTS ANOTHER ROUND OF
STRATUS COULD BE REALIZED OVER OUR EAST/SOUTHEASTERN CWA AS
ISENTROPIC UPGLIDE AND SATURATION...PRIMARILY ALONG THE 280-300K
SURFACES...COMMENCES. THE OPERATIONAL GFS IS NOT NEARLY AS ROBUST
WITH THE CLOUD COVER...BUT GIVEN THE TRENDS OF THE PAST FEW DAYS
OPTED TO PLAY IT SAFE AND INCREASE CLOUD COVER ACROSS THE
CWA...WITH THE MOST DENSE CLOUD COVER RESIDING ACROSS OUR
EAST/SOUTHEASTERN CWA. THERE ARE ALSO SOME INDICATIONS...AGAIN
PRIMARILY FROM THE NAM...OF FOG DEVELOPMENT ACROSS OUR
EAST/SOUTHEASTERN CWA AND AS A RESULT...WENT AHEAD WITH FOG IN THE
FORECAST LATE TONIGHT INTO SUNDAY MORNING ACROSS OUR
EAST/SOUTHEAST.

ADDITIONAL SUNSHINE...WHEN COMPARED TO THE PAST SEVERAL
DAYS...SHOULD RESULT IN A SIGNIFICANT INCREASE IN DIABATIC HEATING
AND WARMER TEMPERATURE READINGS TODAY WHEN COMPARED TO THE PAST
FEW DAYS...WITH HIGHS IN THE 40S TO LOW 50S FORECAST FOR THE MUCH
OF THE CWA TODAY. THE ONLY EXCEPTION IS ACROSS OUR EAST/NORTHEAST
WHERE CLOUD COVER MAY LINGER A BIT LONGER THUS HELPING KEEP
AFTERNOON TEMPERATURE READINGS IN THE UPPER 30S. LITTLE CHANGE IN
THE BOUNDARY-LAYER AIR MASS AND AN ANTICIPATED INCREASE IN CLOUD
COVER SHOULD THEN PROVIDE SIMILAR TEMPERATURE READINGS TONIGHT
WHEN COMPARED TO EARLY THIS MORNING...WITH LOWS GENERALLY IN THE
20S CURRENTLY FORECAST.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 356 AM CST SAT DEC 20 2014

PRIMARY FORECAST CONCERN REVOLVES AROUND PRECIPITATION CHANCES.

THE START OF THE LONG TERM PERIOD SUNDAY MORNING HAS MODELS IN
PRETTY GOOD AGREEMENT WITH THE OVERALL STORY...SHOWING THE AREA
UNDER GENERALLY ZONAL FLOW...INFLUENCED BY A WEAK TROUGH AXIS
EXTENDING SOUTH FROM THE PARENT LOW OVER THE ND/CAN BORDER.
EXPECTING TO SEE S/SWRLY WINDS IN PLACE...DRIVEN BY A TROUGH AXIS
IN PLACE THROUGH THE HIGH PLAINS. KEPT THE DAYTIME HOURS ON SUNDAY
DRY...ONE DISTURBANCE IS MOVING OUT BUT ANOTHER IS QUICK ON ITS
HEELS. SOME UNCERTAINTY EXISTS AS WE GET INTO THE LATTER PORTIONS
OF THE DAY...AS SOME MODELS SHOW THE POTENTIAL FOR SOME LIGHT
PRECIP/LIGHT DZ BUILDING NORTH AND POSSIBLY CLIPPING THE SERN
CORNER OF THE CWA AHEAD OF THIS NEXT DISTURBANCE. THINK THAT
BETTER PRECIP CHANCES WILL HOLD OFF UNTIL AFTER 00Z. FORECAST HIGH
TEMPERATURES FOR SUNDAY REMAIN GENERALLY IN THE 40S.

SUNDAY NIGHT THROUGH TUESDAY IS A MESSY TIME FRAME WITH PERIODIC
PRECIP CHANCES. MODELS SHOWING ANOTHER UPPER LEVEL SHORTWAVE
DISTURBANCE SLIDING SOUTHEAST OUT OF WCENTRAL CANADA INTO THE
DAKOTAS...EVENTUALLY DEVELOPING INTO A CLOSED LOW PRESSURE SYSTEM
BY MONDAY MORNING. THERE IS GOOD AGREEMENT WITH MODELS SHOWING NOT
A LOT OF EASTWARD MOVEMENT WITH THIS SYSTEM DURING THE DAYTIME
HOURS...WITH THE GENERAL LOCATION OVER ERN OR SRN PORTIONS OF MN.
MONDAY NIGHT INTO TUESDAY...A SHORTWAVE DISTURBANCE ROTATING
AROUND THIS LOW PUSHES THROUGH THE REGION...WHILE THE LOW IS STILL
HANGING AROUND THE MN REGION. THIS MORE ACTIVE PORTION OF THE
PATTERN LOOKS TO PRESENT THE CWA WITH SOME PRECIP CHANCES...THOUGH
MODELS ARE FAIRLY SCATTERED WITH THE GENERALLY LIGHT QPF...AND
DISAGREE SOME WITH THE TIMING AND LOCATION. THUS COULDNT GO TOO
HIGH WITH POPS...KEPT THINGS IN THE 20-30 PERCENT RANGE UNTIL
BETTER AGREEMENT CAN BE REACHED BETWEEN MODELS. EVEN THOUGH WE ARE
GETTING INTO THE LATTER PARTS OF THE MONTH...MODELS CONTINUE TO
SHOW THE AIRMASS SUNDAY NIGHT INTO MONDAY BEING WARM ENOUGH TO
SUPPORT MAINLY RAIN FOR PRECIP TYPE...THOUGH A RA/SN MIX IN NRN
LOCATIONS NOT OUT OF THE QUESTION. A COLD FRONT WILL START WORKING
ITS WAY THROUGH THE AREA DURING THE DAY ON MONDAY...WITH THE
COLDER AIR WORKING ITS WAY IN MORE INTO MONDAY NIGHT/TUESDAY...SO
THE LATER PORTIONS OF THE EVENT LOOK TO SEE A SWITCH OVER TO
SNOW...BUT THINGS SHOULD BE WINDING DOWN...SO NOTABLE
ACCUMULATIONS ARE NOT EXPECTED. BEHIND THIS FRONTAL PASSAGE ON
MONDAY...AND CONTINUING INTO TUESDAY...GUSTY NORTHWEST WINDS ARE
EXPECTED. WHILE SPEEDS IN THE 15 TO 25 MPH RANGE ARE EXPECTED
MONDAY...A TIGHTENING PRESSURE GRADIENT ALONG WITH STRONGER WINDS
ALOFT BUILDING IS EXPECTED TO RESULT IN WINDS IN THE 20 TO
POSSIBLY 30 MPH RANGE. HIGHS IN THE 40S EXPECTED ONCE AGAIN MONDAY
/THOUGH MAY BE REACHED EARLIER IN THE DAY/...WITH 30S FORECAST FOR
TUESDAY.

LOOKING AHEAD TO THE CHRISTMAS EVE /WED/ AND CHRISTMAS DAY
/THURS/ TIME FRAME...EXPECTING DRY CONDITIONS FOR WED...WITH
MODELS IN PRETTY GOOD AGREEMENT SHOWING THE MAIN UPPER LEVEL
TROUGH AXIS FINALLY HAVING SHIFTED FAR ENOUGH EAST TO MOVE PRECIP
ON. NORTHWESTERLY UPPER LEVEL FLOW IS EXPECTED TO BE IN PLACE
DURING THE DAYTIME HOURS...BECOMING MORE ZONAL WITH TIME WED NIGHT
AS ANOTHER UPPER LEVEL DISTURBANCE STARTING TO WORK ITS WAY
THROUGH THE ROCKIES. W/NW WINDS ARE FORECAST WITH SPEEDS ARND 15
MPH...WITH HIGHS IN THE MID 30S TO MID 40S.

MORE UNCERTAINTY/LOWER CONFIDENCE IS IN PLACE AS WE GET INTO
CHRISTMAS DAY/NIGHT AND FRIDAY...AS MODELS VARY ON THE EVOLUTION
OF THE NEXT UPPER LEVEL SYSTEM. THE GFS/ECMWF BOTH KEEP MOST OF/IF
NOT ALL OF THE DAYTIME HOURS DRY...WITH THE EC TRYING TO PUSH SOME
PRECIP INTO NWRN PORTIONS OF THE CWA BY THE END OF THE DAY. THE EC
IS SHOWING A STRONGER SYSTEM...DIGGING FURTHER SOUTH INTO THE
ROCKIES...BEFORE PUSHING OUT ONTO THE PLAINS THURS NIGHT/FRIDAY
AND BRINGING ACCUMULATING SNOW TO THE CWA. THE GFS SHOWS MORE OF A
NW FLOW CLIPPER TYPE SYSTEM...WITH THE BRUNT OF THE LIFT/QPF
SLIDING ACROSS SD/NRN NEB...BARELY CLIPPING THE NRN FRINGE OF THE
CWA BEFORE QUICKLY SLIDING EAST OF THE CWA EARLY FRIDAY MORNING.
AT THIS POINT CANT REALLY BUY FULL INTO EITHER SOLUTION...AND HAVE
LOW CHANCE POPS CWA-WIDE. ALONG WITH POPS...TEMPS MAY NEED
ADJUSTMENT DEPENDING ON HOW MODELS TREND...AS THE ECMWF IS ALSO A
MUCH COLDER SOLUTION.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1127 AM CST SAT DEC 20 2014

FOG CONTINUES TO BE PERSISTENT IN THE KGRI TERMINAL AREA.
SATELLITE HAS NOT SHOWN ANY EASTWARD MOVEMENT OF THE CLOUDS AND
VISIBILITY HAS CONTINUED TO BE AT 1/4 MILE OR LESS. WILL KEEP WITH
PERSISTENCE FOR A COUPLE MORE HOURS THEN BELIEVE THAT THE
VISIBILITY WILL IMPROVE...BUT NOT ESCAPE THE LOW CLOUDS AND FOG.
IF IT DOES NOT MOVE OUT THIS AFTERNOON EXPECT THAT IT WILL RETURN
AS THE SUN GOES DOWN TONIGHT. KEAR TERMINAL HAS A LITTLE LIGHT FOG
THAT SHOULD IMPROVE THIS AFTERNOON AS WELL. THE HIGH CLOUDS MOVING
IN SHOULD KEEP THE FOG AND LOW CLOUDS OUT OF THE AREA.


&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...DENSE FOG ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR NEZ040-041-
     047>049-062>064-076-077-086-087.

KS...NONE.
&&

$$

UPDATE...JCB
SHORT TERM...BRYANT
LONG TERM...ADP
AVIATION...JCB



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