Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 211137
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
537 AM CST SUN DEC 21 2014

.UPDATE...
ISSUED AT 537 AM CST SUN DEC 21 2014

LATEST SATELLITE TRENDS AND SURFACE OBSERVATIONS SUGGEST THE BAND
OF STRATUS...WHICH WAS IMPACTING NORTHEASTERN PORTIONS OF THE
CWA...HAS MOVED NORTHEAST AND DISSIPATED. AS A RESULT...THE
CEILING IS RAPIDLY RISING ACROSS OUR NORTHEAST AND VISIBILITY IS
ALSO IMPROVING DRAMATICALLY. IN FACT...AS OF 1130Z...THE LOWEST
VISIBILITY ACROSS THE CWA IS KAUH AT 3SM. GIVEN THESE
TRENDS...WENT AHEAD AND CANCELLED THE DENSE FOG ADVISORY WHICH WAS
IN EFFECT ACROSS OUR NORTHEAST.

ALSO CONTINUING TO MONITOR THE STRATUS MOVING IN FROM
WEST/SOUTHWESTERN KANSAS. THIS STRATUS IS NOW MOVING INTO OUR
SOUTHEASTERN CWA...WITH A CEILING OF 500FT AGL CURRENTLY BEING
REPORTED AT KK61. CURRENT THINKING IS THIS STRATUS SHOULD REMAIN
OVER ROUGHLY THE SOUTHEASTERN ONE-THIRD OF THE CWA. SOME
RESTRICTION IN VISIBILITY...DUE TO FOG UNDERNEATH THE
STRATUS...WILL ALSO BE POSSIBLE ACROSS OUR SOUTHEAST BUT CURRENT
OBSERVATIONS SUGGEST THIS RESTRICTION IS NO LOWER THAN 4SM. WILL
GO AHEAD WITH PATCHY FOG IN THE FORECAST ACROSS OUR SOUTHEAST FOR
THIS MORNING.

REMAINDER OF THE FORECAST REMAINS IN GOOD SHAPE WITH ONLY A FEW
TWEAKS MADE TO HOURLY TEMPERATURE AND DEW POINT GRIDS TO REFLECT
CURRENT OBSERVATIONS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 412 AM CST SUN DEC 21 2014

MAP ANALYSIS INDICATES AN UPPER TROPOSPHERIC TROUGH AXIS
EXTENDING FROM SOUTH-CENTRAL CANADA INTO THE SOUTHERN
PLAINS...WITH QUASI- ZONAL UPPER TROPOSPHERIC FLOW OVER THE
EASTERN CONUS AND NORTHWESTERLY FLOW OVER THE WESTERN CONUS. AT
THE SURFACE...AN AREA OF HIGH BAROMETRIC PRESSURE PERSISTS NEAR
THE GREAT LAKES REGION...WHILE TROUGHING ALSO CONTINUES ALONG THE
FRONT RANGE OF THE ROCKIES. BOUNDARY-LAYER FLOW ACROSS OUR AREA
REMAINS FROM THE SOUTH FOR THE MOST PART AS A RESULT.
FINALLY...SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE A
STRATUS SHIELD PERSISTING GENERALLY EAST OF HIGHWAY 281 AND NORTH
OF I-80...WITH VISIBILITY RESTRICTION OF 1/4SM TO 1SM IN FOG
UNDERNEATH THIS STRATUS. IT IS ALSO WORTH MENTIONING THAT ANOTHER
BAND OF STRATUS IS NOTED OVER SOUTHWESTERN KANSAS AND QUICKLY
ADVANCING NORTHEAST.

SATELLITE TRENDS THROUGH THE PAST COUPLE HOURS INDICATE THE BAND
OF STRATUS OVER OUR NORTHEAST IS BEGINNING TO MOVE
NORTHEAST...WITH CLEARING SKIES AND VISIBILITY IMPROVING ALONG AND
SOUTHWEST OF A LINE FROM KODX...TO KHSI AND KJYR. A LOW CEILING
AND DENSE FOG IS STILL BEING REPORTED AT SOME LOCATIONS FARTHER
NORTHEAST HOWEVER. GIVEN ALL THIS...WHEN AHEAD AND TRIMMED THE
DENSE FOG ADVISORY ALONG THE SOUTHWESTERN PERIPHERY...BUT KEPT
LOCATIONS FARTHER NORTHEAST IN THE HEADLINE THROUGH 17Z. IT IS
POSSIBLE THIS HEADLINE WILL NEED ADJUSTED FURTHER SHOULD THE
STRATUS AND FOG CONTINUE MOVING NORTHEAST...BUT WILL HOLD OFF AND
MONITOR FOR THE TIME-BEING TO ENSURE THE STRATUS DOES NOT SLOW AS
IT DID YESTERDAY MORNING.

WILL ALSO NEED TO CONTINUE MONITORING THE STRATUS APPROACHING
FROM THE SOUTHWEST. DID GO AHEAD AND INCREASE CLOUD COVER ACROSS
OUR SOUTH/SOUTHEAST FOR THIS MORNING IN ANTICIPATION OF THIS
STRATUS. THERE IS ALSO A POSSIBILITY OF ADDITIONAL FOG MOVING IN
ALONG WITH THIS STRATUS...HOWEVER CURRENT OBSERVATIONS TO OUR
SOUTHWEST DO NOT CURRENTLY INDICATE WIDESPREAD DENSE FOG AND AS A
RESULT...WILL HOLD OF FROM INTRODUCING FOG TO OUR SOUTH/SOUTHEAST
UNTIL SUCH OBSERVATIONS MATERIALIZE.

GUIDANCE FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST THE
UPPER TROPOSPHERIC TROUGH AXIS...CURRENTLY OVER THE CENTRAL
CONUS...WILL LINGER OVER THE CENTRAL CONUS THROUGH THE NEXT 24
HOURS AS AN UPPER TROPOSPHERIC SHORT WAVE APPROACHES THE CENTRAL
PLAINS FROM THE NORTHWEST. AT THE SURFACE...AN AREA OF LOW
BAROMETRIC PRESSURE IS EXPECTED TO DEVELOP OVER THE NORTHERN HIGH
PLAINS BY 06Z MONDAY...WITH THIS LOW THEN EXPECTED TO MOVE INTO
EASTERN SOUTH DAKOTA BY 12Z MONDAY. AS A RESULT...BOUNDARY-LAYER
FLOW ACROSS OUR AREA SHOULD REMAIN FROM THE SOUTH THROUGH MUCH OF
THE SHORT-TERM FORECAST PERIOD...WITH THE EXCEPTION BEING 06-12Z
MONDAY AS A BAROCLINIC ZONE CLEARS THE AREA THUS ALLOWING FOR A
WEST/NORTHWESTERLY WIND BY SUNRISE MONDAY.

AN OVERALL LACK IN OMEGA SHOULD PROMOTE DRY CONDITIONS ACROSS OUR
AREA THROUGH TODAY. THAT WILL CHANGE THIS EVENING INTO TONIGHT AS
DPVA AND UPPER TROPOSPHERIC THERMAL ADVECTION INCREASES AHEAD OF
THE APPROACHING UPPER TROPOSPHERIC SHORT WAVE. AT THIS TIME IT
APPEARS THE ENTIRE CWA COULD OBSERVE MEASURABLE PRECIPITATION
TONIGHT...BUT THE HIGHEST PROBABILITY RESIDES ACROSS OUR
NORTH/NORTHEAST IN CLOSEST PROXIMITY TO THE GREATEST OMEGA.

FORECAST PROXIMITY SOUNDINGS FROM ACROSS THE CWA...PER THE NAM
AND OPERATIONAL GFS...SUGGEST A STRONG WARM LAYER ALOFT WILL
PROMOTE LIQUID PRECIPITATION ACROSS OUR CWA THROUGH THE OVERNIGHT
HOURS TONIGHT. IT IS IMPORTANT TO NOTE THAT SOME SETS OF GUIDANCE
SUGGEST LOCATIONS ACROSS OUR NORTH/NORTHEAST COULD OBSERVE SURFACE
TEMPERATURE READINGS AT OR BELOW FREEZING TOWARDS DAYBREAK MONDAY.
THAT SAID...IT CURRENTLY APPEARS AS THOUGH PRECIPITATION SHOULD BE
COMING TO AN END ACROSS OUR NORTH/NORTHEAST BY 09Z MONDAY...THUS
PREVENTING FREEZING RAIN FROM BEING REALIZED. OBVIOUSLY THIS WILL
NEED TO BE CLOSELY MONITORED TO ENSURE PRECIPTIATION DOES NOT
LINGER LONGER THAN EXPECTED TONIGHT...AND TO ENSURE THE SUB-
FREEZING SURFACE TEMPERATURE READINGS DO NOT INFILTRATE THE REGION
ANY FASTER THAN CURRENTLY FORECAST.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 412 AM CST SUN DEC 21 2014

PRIMARY FORECAST CONCERN CONTINUES TO LIE WITH PRECIPITATION
CHANCES RIGHT OFF THE BAT...THEN AGAIN CLOSER TO CHRISTMAS.

THE FIRST 36 HOURS OR SO OF THE LONG TERM PERIOD /MONDAY THROUGH
TUESDAY/ CONTINUE TO LOOK TO BE A MORE ACTIVE TIME FRAME...WITH
UPPER LEVEL LOW PRESSURE DRIVING THE AREAS WEATHER. SOME
UNCERTAINTIES REMAIN WITH THE FORECAST...SO OVERALL CONFIDENCE IS
ON THE LOWER SIDE...WITH MODELS SHOWING SOME DIFFERENCE AT THE
START OF THE PERIOD WITH THE LOCATION OF THE MAIN UPPER LEVEL LOW
MONDAY MORNING...RANGING FROM THE ERN SD/NEB BORDER LIKE THE GFS
TO CLOSER TO THE CENTRAL SD/ND BORDER LIKE THE ECMWF /NAM AND SREF
ARE IN BETWEEN/. EXPECTING THAT PRECIP THAT SHIFTED EAST THROUGH
THE AREA WITH THAT LEAD DISTURBANCE TO HAVE MOVED EAST OF THE
CWA...WITH INCREASING PRECIP CHANCES DURING THE DAYTIME HOURS
MONDAY BEING DRIVEN BY THE UPPER LEVEL LOW ITSELF. QUESTION IS HOW
FAST WILL THE MOISTURE WRAPPING AROUND THE BACK OF THE SYSTEM WORK
ITS WAY INTO NRN PORTIONS OF THE CWA...WITH SOLUTIONS LIKE THE GFS
BRINGING THINGS IN QUICKER PARTLY DUE TO ITS MORE SRN PLACEMENT TO
START THE DAY...VS THE ECMWF WHICH HAS A SLOWER ONSET AS IT
EVENTUALLY SHIFTS INTO THAT ERN SD/NEB BORDER AREA AS WELL BY THE
END OF THE DAY. LOOKING TO THE MONDAY OVERNIGHT HOURS...MODELS NOT
SHOWING A WHOLE HECK OF A LOT OF PROGRESS WITH THIS SYSTEM...WHICH
IS SHOWN TO LINGER AROUND THE MISSOURI RIVER BETWEEN
NEB/IA...BEFORE FINALLY STARTING TO MAKE MORE OF AN EASTWARD PUSH
DURING THE DAY ON TUESDAY.

WHAT PRECIP DOES START TO WORK ITS WAY INTO THE NORTH DURING THE
DAY ON MONDAY /ECMWF SUGGESTS ITS POST 00Z BEFORE ANYTHING WORKS
IN/ MAY START OUT AS A RA/SN MIX...BUT COLDER AIR USHERED IN BY A
FRONTAL BOUNDARY PASSING THROUGH THE REGION SHOULD BRING A
TRANSITION TO ALL SNOW BY LATE AFTERNOON FOR AT LEAST THE
NORTH...CENTRAL PORTIONS OF THE CWA MAY STICK WITH THE MIX A
LITTLE LONGER. SHOULD SEE ALL SNOW DURING THE OVERNIGHT HOURS AND
WHAT LINGERS ACROSS MAINLY THE EAST INTO TUESDAY. WHILE NOT
EXPECTING SIGNIFICANT ACCUMULATIONS...SOME LOCATIONS MAINLY
ALONG/NORTH OF I-80 COULD SEE A HALF INCH...CLOSER TO AN INCH IN
AREAS AROUND VALLEY/GREELEY COUNTIES. BY ITSELF...NOT SUCH A
WORRY...BUT MODELS CONTINUE TO SHOW THE POTENTIAL FOR GUSTY
NORTHWEST WINDS DEVELOPING MONDAY NIGHT AND INTO TUESDAY...WHEN
THE BETTER CHANCES FOR SNOW EXIST. THERE IS DECENT AGREEMENT AMONG
MODELS SHOWING A STRONGER CORRIDOR OF WINDS OFF THE SFC NEAR
50KTS...SOME OF WHICH COULD WORK ITS WAY DOWN TO THE SFC. ANY
FALLING SNOW COMBINED WITH SUSTAINED SPEEDS AROUND 25 MPH WITH
HIGHER GUSTS POSSIBLE...COULD RESULT IN SOME TRAVEL ISSUES. WILL
MENTION IN THE HWO...AND WILL HAVE TO KEEP A CLOSE EYE ON HOW
MODELS TREND TO SEE HOW MUCH OF AN ISSUE THIS MAY BECOME.

AS FAR AS TEMPERATURES GO MON/TUE...EXPECTING THAT HIGHS OF UPPER
30S TO UPPER 40S ON MON WILL BE MET EARLIER ON IN THE DAY...WITH
STEADY/FALLING TEMPS AS THE COLD FRONT MOVES THROUGH. TUES LOOKS
TO TOP OUT IN THE 30S.

LOOKING TO TUESDAY NIGHT THROUGH CHRISTMAS EVE NIGHT...STILL
GOING WITH A DRY FORECAST ACROSS THE CWA. SEE SHARP NORTHWESTERLY
FLOW EARLY ON BECOME MORE DEAMPLIFIED WITH TIME AS THIS LATEST
TROUGH AXIS CONTINUES MOVING EAST AND SHORTWAVE RIDGING MOVES IN
FROM THE WEST AHEAD OF THE NEXT DISTURBANCE...WHICH BY CHRISTMAS
DAY MORNING HAS MOVED INTO THE NRN ROCKIES. WINDS BECOME MORE
WESTERLY WITH TIME...AND DIMINISH IN SPEED. OVERNIGHT LOWS ARE IN
THE 20S...WITH HIGHS ON CHRISTMAS EVE DAY EXPECTED TO BE NOT TOO
FAR FROM AVERAGE FOR THIS TIME OF YEAR...WITH MID 30S FORECAST IN
THE NORTHEAST TO MID 40S SW.

FOR CHRISTMAS DAY...WHILE STILL LOOKING AT DRY CONDITIONS FOR
MUCH OF THE DAY...CONFIDENCE IS NOT HIGH AS WE GET INTO THE
AFTERNOON HOURS...AND CONTINUING INTO THE OVERNIGHT HOURS. THE
NEXT UPPER LEVEL SHORTWAVE DISTURBANCE OVER THE NRN ROCKIES NEAR
SUNRISE WILL WORK ITS WAY EAST...EMERGING ONTO THE PLAINS
POTENTIALLY BY LATE AFTERNOON. DEPENDS ON THE MODEL. THE GFS IS
NOT AS STRONG/DOESNT DIG AS FAR SOUTH AS THE ECMWF...LOSING A BIT
OF ITS PUNCH WITH TIME AND RESULTING IN FAIRLY LIGHT SNOW ACROSS
MAINLY THE NEB PORTION OF THE CWA. THE ECMWF PUSHES A NICE BAND OF
SNOW ACROSS THE REGION AS THE TROUGH AXIS SWINGS
THROUGH...BRINGING THE POTENTIAL FOR AT LEAST A FEW INCHES OF SNOW
TO PORTIONS OF THE CWA. THERE HAS BEEN SOME INCONSISTENCY WITH THE
MODELS...SO ITS HARD AT THIS POINT TO FULLY TRUST ONE OVER THE
OTHER. DID BUMP UP POPS A BIT...INTO THE 30-40 PERCENT RANGE FOR
MAINLY CHRISTMAS NIGHT. PLENTY OF DETAILS TO WORK OUT IN THE
COMING DAYS.

CURRENTLY HAVE THE DRY FORECAST RETURNING FOR FRIDAY AND
SATURDAY...WITH THE AREA SITTING IN DRIER NORTHWESTERLY UPPER
LEVEL FLOW IN THE WAKE OF THIS LAST SYSTEM. HIGHS ON CHRISTMAS DAY
ARE CURRENTLY FORECAST TO REACH THE MID 30S/MID 40S...BUT HOW
MODELS TREND WITH THE PRECIP CHANCES COULD RESULT IN NOTABLE
ADJUSTMENTS TO THAT. FRI/SAT HIGHS ARE FORECAST TO GENERALLY TOP
OUT IN THE 30S.

&&

.AVIATION...(FOR THE 12Z KGRI/KEAR TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 537 AM CST SUN DEC 21 2014

VFR CONDITIONS ARE NOW EXPECTED AT BOTH TAF SITES THROUGH
TODAY...WITH IFR CONDITIONS POSSIBLE AGAIN TONIGHT.

THE BAND OF STRATUS WHICH WAS IMPACTING KGRI THROUGH THE
OVERNIGHT HOURS...HAS MOVED OFF TO THE NORTHEAST THUS ALLOWING FOR
VFR CONDITIONS AT KGRI. ALTHOUGH HIGH-LEVEL CLOUDS WILL REMAIN
POSSIBLE ACROSS THE REGION TODAY...GUIDANCE NOW SUGGESTS VFR
CONDITIONS WILL PERSIST AT BOTH TAF SITES THROUGH THE DAY. IT IS
WORTH MENTIONING THAT THERE IS ANOTHER BAND OF STRATUS ADVANCING
NORTHEAST FROM WEST/SOUTHWESTERN KANSAS INTO SOUTHEASTERN
NEBRASKA...BUT AT THIS TIME IT IS BELIEVED THIS STRATUS WILL
REMAIN SOUTH/SOUTHEAST OF KEAR AND KGRI AND IF THIS HOLDS
TRUE...THE NEXT OPPORTUNITY FOR SUB-VFR CONDITIONS WILL PRESENT
ITSELF TONIGHT STARTING AROUND 03Z AS A CEILING NEAR OR BELOW
1000FT AGL MOVES IN. LIGHT RAIN WILL ALSO ACCOMPANY THIS CLOUD
COVER AND AT THIS TIME...THE PROBABILITY OF MEASURABLE
PRECIPITATION IS HIGH ENOUGH TO GO PREVAILING -RA AT
KGRI...HOWEVER CONFIDENCE IS NOT QUITE HIGH ENOUGH TO DO THE SAME
AT KEAR. GIVEN ALL THIS...WENT AHEAD WITH A CEILING AT 900FT AGL
FOR BOTH TAF SITES 03-09Z...WITH PREVAILING LIGHT RAIN AT KGRI
ALSO DURING THE 03-09Z TIME FRAME. MAY ALSO SEE SOME VISIBILITY
RESTRICTION IN BR AND/OR PRECIPITATION 03-09Z...BUT AT THIS TIME
CONFIDENCE IS NOT HIGH ENOUGH TO GO ANY LOWER THAN 6SM. WENT AHEAD
AND PRESENTED VFR CONDITIONS AT BOTH TAF SITES 09Z ONWARD AS
GUIDANCE SUGGESTS THE LOW CLOUDS AND PRECIPITATION SHOULD BE
MOVING EAST/SOUTHEAST OF THE AREA BY THEN. THE SURFACE WIND WILL
START THE TAF PERIOD FROM THE SOUTH...BUT BECOME
WEST/NORTHWESTERLY BY THE END OF THE TAF PERIOD AS A BAROCLINIC
ZONE CLEARS THE AREA.

&&

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

$$

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



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