Area Forecast Discussion
Issued by NWS Hastings, NE

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000
FXUS63 KGID 191731
AFDGID

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1131 AM CST FRI DEC 19 2014

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 415 AM CST FRI DEC 19 2014

MAP ANALYSIS INDICATES UPPER TROPOSPHERIC TROUGHING EXTENDING FROM
THE NORTHERN PLAINS INTO THE SOUTHERN ROCKIES...AS WELL AS RIDGING
OVER THE WESTERN CONUS AND QUASI-ZONAL FLOW OVER THE EASTERN CONUS.
ENHANCED UPPER TROPOSPHERIC JET ENERGY EXTENDS FROM THE SOUTHERN
PLAINS...EAST/NORTHEAST INTO THE SOUTHEASTERN CONUS AND MID-
ATLANTIC. UPPER TROPOSPHERIC FLOW OVER OUR AREA REMAINS FAIRLY WEAK
HOWEVER...MAXING OUT AT AROUND 35KTS NEAR 29000FT AGL PER 00Z
SOUNDING DATA FROM KLBF AND KOAX. AT THE SURFACE AN AREA OF HIGH
BAROMETRIC PRESSURE EXISTS ACROSS THE GREAT LAKES REGION...AND A
TROUGH IS NOTED STRENGTHENING ALONG THE FRONT RANGE OF THE ROCKIES.
RESULTANT BOUNDARY-LAYER FLOW ACROSS OUR AREA REMAINS FROM THE
SOUTH/SOUTHEAST.

GUIDANCE FROM THE NAM...OPERATIONAL GFS AND EC ALL SUGGEST THE UPPER
TROPOSPHERIC TROUGH...CURRENTLY TO OUR WEST...WILL ADVANCE EAST
TODAY...LIKELY CLEARING OUR AREA BY 00Z THIS EVENING. THIS SHOULD
THEN ALLOW NORTHWESTERLY UPPER TROPOSPHERIC FLOW TO OVERTAKE OUR
AREA HEADING INTO TONIGHT. AT THE SURFACE...SOUTH/SOUTHEASTERLY FLOW
IS EXPECTED TO PERSIST ACROSS THE AREA TODAY...WITH THIS FLOW
BECOMING MORE SOUTH/SOUTHWESTERLY TONIGHT.

GUIDANCE CONTINUES TO SUGGEST DPVA AND UPPER TROPOSPHERIC THERMAL
ADVECTION IN ASSOCIATION WITH THE PASSING TROUGH AXIS WILL REMAIN
VERY WEAK TODAY AND AS A RESULT...DRY CONDITIONS ARE FORECAST BOTH
TODAY AND TONIGHT. THAT SAID...PERSISTENT ISENTROPIC UPGLIDE AND
SATURATION...PRIMARILY ALONG THE 280K SURFACE...WILL LIKELY CONTINUE
PROMOTING A HEALTHY LAYER OF STRATUS ACROSS THE REGION TODAY.
GUIDANCE FROM THE NAM DOES SUGGEST THIS LAYER OF STRATUS WILL MAKE A
PUSH EAST TODAY AND TONIGHT AND AS A RESULT...THERE IS A POSSIBILITY
WESTERN PORTIONS OF OUR CWA COULD ACTUALLY SEE SOME CLEARING.

IN ADDITION TO THE STRATUS...FOG WILL ALSO REMAIN POSSIBLE ACROSS
MUCH OF THE AREA FOR A TIME THIS MORNING. SO FAR THIS
MORNING...VISIBILITY RESTRICTION HAS NOT BEEN TOO BAD...GENERALLY
FALLING INTO THE 4-6SM RANGE. THE ONLY EXCEPTION IS ALONG THE
WESTERN PERIPHERY OF THE STRATUS SHIELD WHERE A THIN CORRIDOR OF
VISIBILITY RESTRICTION IN THE 1/4 - 1/2SM RANGE HAS DEVELOPED.
ALTHOUGH SUNSHINE WILL BE LIMITED FOR MANY LOCATIONS
TODAY...INCREASED DIABATIC HEATING POST-SUNRISE SHOULD STILL ALLOW
FOR ENOUGH BOUNDARY-LAYER MIXING TO DIMINISH THE FOG. GIVEN ALL
THIS...WENT AHEAD WITH FOG IN THE FORECAST FOR MUCH OF THE AREA
THROUGH 15Z. ANOTHER ROUND OF FOG THEN SEEMS LIKELY TONIGHT BUT
AGAIN...VISIBILITY RESTRICTION IS ONLY EXPECTED TO FALL INTO THE 4-
6SM RANGE...WITH PERHAPS A THING CORRIDOR OF 1/4 - 1/2SM VISIBILITY
RESTRICTION ALONG THE BACK SIDE OF THE STRATUS SHIELD AS IT MOVE
EAST ACROSS THE AREA.

ASSUMING WEST/SOUTHWESTERN PORTIONS OF THE CWA CAN BREAK INTO SOME
SUNSHINE TODAY...AFTERNOON HIGHS SHOULD EASILY CLIMB THROUGH THE 30S
AND INTO THE LOW TO MID 40S SOUTHWEST OF A LINE FROM KLXN TO KK61.
LOCATIONS FARTHER NORTHEAST HOWEVER...WHERE CLOUD COVER SHOULD
REMAIN MUCH MORE DENSE THROUGHOUT THE DAY...AFTERNOON HIGHS
GENERALLY IN THE MID 30S ARE CURRENTLY FORECAST. LITTLE CHANGE IN
THE BOUNDARY-LAYER AIR MASS SHOULD THEN PROMOTE SIMILAR TEMPERATURE
READINGS TONIGHT WHEN COMPARED TO EARLY THIS MORNING...WITH LOWS IN
THE TEENS AND LOWER 20S CURRENTLY FORECAST.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 415 AM CST FRI DEC 19 2014

ALTHOUGH ON THE SURFACE THIS 6-DAY TIME FRAME DOES NOT APPEAR TO
FEATURE A "LOT OF ACTIVE WEATHER"...AS IS OFTEN THE CASE THERE
ARE LIKELY MORE FORECAST CHALLENGES THAN MIGHT MEET THE EYE AT
FIRST GLANCE AS THE GENERAL MID-UPPER LEVEL PATTERN REMAINS
FAIRLY ACTIVE. JUST TO NAME A FEW QUESTIONS/CHALLENGES IN
GENERALLY CHRONOLOGICAL ORDER:

1) CONFIDENCE IN SKY COVER AND ITS POTENTIALLY SIGNIFICANT IMPACT
ON TEMPERATURES IN DEFINITELY BELOW AVERAGE ESPECIALLY RIGHT AWAY
DURING THE SATURDAY-SUNDAY TIME FRAME...AS THIS FORECAST HEAVILY
ASSUMES THAT THE AREA SHAKES AT LEAST PARTIALLY FREE OF THIS
SEEMINGLY-ENDLESS PARADE OF OVERCAST DAYS.

2) WILL FOG BECOME AN ISSUE ON EARLY SATURDAY MORNING (AT LEAST A
PATCHY FOG MENTION REMAINS IN THE FORECAST HERE) BUT ALSO
POSSIBLY ON SATURDAY NIGHT/SUNDAY MORNING AND SUNDAY NIGHT/MONDAY
MORNING AS WELL (NOT CURRENTLY IN THE FORECAST)? WHILE TYPICAL FOG
MODELING TOOLS SUCH AS FROM THE SREF/NAM VISIBILITY PRODUCTS
SUGGESTS FOG COULD VERY WELL OCCUR...THIS FORECASTER WONDERS HOW
MUCH OF THIS IS "REAL" AND HOW MUCH IS POTENTIALLY FALSE BASED ON
AN OVER-ZEALOUS MODEL DEPICTION OF LOW-LEVEL RELATIVE HUMIDITY DUE
TO SNOW COVER INFLUENCES. NOT TO MENTION...NIGHT-TIME LOW LEVEL
FLOW/SURFACE BREEZES ARE EXPECTED TO AVERAGE WEST-SOUTHWESTERLY ON
THESE NIGHTS...WHICH IS OFTEN NOT A VERY FAVORABLE DEVELOPMENT FOR
MORE THAN LIGHT FOG ISSUES AROUND HERE.

3) ARE PRECIP CHANCES ON SUNDAY NIGHT HIGH ENOUGH (CURRENTLY ONLY
20-30 PERCENT)...AND IF PRECIP DOES OCCUR...WILL IT TAKE THE FORM
OF RAIN AS CURRENTLY FORECASTED/EXPECTED...OR POSSIBLY TRY TO FALL
AS AT LEAST BRIEF FREEZING RAIN/SNOW AS SOME MODEL TEMP FIELDS
WOULD SUGGEST?

4) COULD MONDAY AND/OR TUESDAY END UP BEING AT
LEAST 10 MPH WINDIER OUT OF THE NORTHWEST THAN CURRENTLY FORECAST?
THIS ONE IS PROBABLY A DECENT BET...AS THE CURRENT DEFAULT MULTI-
MODEL BLEND MAX SUSTAINED SPEEDS OF GENERALLY 20-25 MPH ARE LIKELY
UNDERDONE.

5) COULD CURRENTLY "DRY" FORECAST PERIODS SUCH AS TUESDAY/TUESDAY
NIGHT END UP NEEDING AT LEAST LOW-END POPS FOR "NUISANCE"
PRECIPITATION?

6) LAST BUT NOT LEAST...HOW ABOUT CHRISTMAS DAY WEATHER? ALTHOUGH
THE LATEST OFFICIAL FORECAST ADVERTISES A 20-30 PERCENT CHANCE OF
SNOW AND/OR A RAIN-SNOW MIX (MAINLY COURTESY OF THE DEFAULT
MULTI- MODEL BLEND THAT CENTRAL REGION NWS OFFICES USE TO
INITIALIZE THE DAY 4-7 PERIOD)...THE LATEST 00Z DETERMINISTIC
ECMWF CLEARLY HOLDS OFF ANY PRECIP CHANCES UNTIL CHRISTMAS NIGHT
INTO FRIDAY...AND EVEN THEN THERE ARE STILL TONS OF QUESTIONS
REGARDING WHETHER THIS IS JUST A LIGHT/MINOR PRECIP POTENTIAL OR
POSSIBLY A MORE IMPACTFUL ONE.

OF COURSE THESE PRECEDING 6 POINTS OF UNCERTAINTY ARE JUST A
SAMPLING OF THE VARIOUS ISSUES THAT NEED SORTED OUT DURING THIS
NEXT WEEK...BUT AT LEAST WE CAN SAY WITH REASONABLE CONFIDENCE
THAT NO "MAJOR" WEATHER SYSTEMS SHOULD IMPACT THE REGION THROUGH
CHRISTMAS DAY...AND TEMPERATURES SHOULD AVERAGE NEAR-TO-SLIGHTLY-
ABOVE NORMAL FOR LATE DECEMBER WITH HIGHS ON MOST DAYS GENERALLY
AIMED SOMEWHERE BETWEEN THE MID-30S AND MID-40S WITH ONLY LIMITED
EXCEPTIONS. IN FACT...THERE ARE CURRENTLY NO WEATHER ELEMENTS
PRESENTLY-ELIGIBLE FOR INCLUSION IN THE HAZARDOUS WEATHER OUTLOOK
PRODUCT (HWOGID).

GETTING INTO MORE METEOROLOGICAL DETAIL IN MAINLY 24-HOUR
BLOCKS...

SATURDAY DAYTIME-SATURDAY NIGHT...CONFIDENCE IS FAIRLY HIGH THAT
THE GOING DRY FORECAST WILL REMAIN INTACT...BUT WITH VARIOUS
MODELS SUCH AS THE NAM/GFS/ECMWF AGREEING THAT AT LEAST ONE
WEAK/LOW AMPLITUDE SHORTWAVE TROUGH WILL PASS THROUGH THE AREA
MAINLY SAT NIGHT...CANNOT RULE OUT SOME SPOTTY LIGHT PRECIP AT
LEAST PASSING BY NEAR THE AREA. ACTUALLY THE VERY FIRST ISSUE
RIGHT AWAY SATURDAY MORNING INVOLVES WHETHER OR NOT FOG
DEVELOPMENT AMOUNTS TO MUCH ACROSS THE AREA. AT THIS POINT...ITS
JUST A TOUGH CALL GIVEN UNCERTAINTY IN LARGER SCALE STRATUS FIELD
TRENDS...BUT IN COLLABORATION WITH THE SHORT TERM FORECASTER OPTED
TO MAINTAIN A PATCHY FOG POTENTIAL MAINLY WITHIN THE EASTERN 1/2
OF THE CWA WELL INTO THE MORNING HOURS. DOWN AT THE LOW LEVELS AND
SURFACE SATURDAY...WEAK-BUT-EVIDENT WARM AIR ADVECTION WILL BE
UNDERWAY AS BREEZES AVERAGE AROUND 10 MPH OR LESS FROM A
SOUTHWEST-TO- WESTERLY DIRECTION. OF COURSE...THIS SHOULD IN
THEORY RESULT IN A NICE BOOST IN DAYTIME HIGHS VERSUS THESE
PRECEDING SEVERAL DAYS...BUT EVEN AT THIS CLOSE TIME RANGE THERE
IS SOME UNCERTAINTY REGARDING SKY COVER GIVEN JUST HOW STUBBORN
STRATUS HAS HELD LATELY. HOWEVER...WITH THE MORE PREVALENT
WESTERLY COMPONENT TO THE LOW LEVEL FLOW...THE PRIMARY BATCH OF
STRATUS CURRENTLY ENTRENCHED OVER THE AREA SHOULD BE
SHOVING/DEPARTING EASTWARD...AND THUS FOR NOW WILL ASSUME AT LEAST
PARTLY CLOUDY SKIES ARE ATTAINED ACROSS THE CWA. THUS FOR
RESULTANT HIGH TEMPS...MADE LITTLE CHANGE TO PREVIOUS FORECAST
HERE (AND DISREGARDING THE NAM AND ITS USELESS/OVERDONE SNOW-COVER
SCHEME IN WESTERN ZONES)...AIMING MOST OF THE CWA INTO THE LOW 40S
AND FAR SOUTHWEST COUNTIES SUCH AS PHILLIPS/ROOKS RIGHT AROUND 50.
ON SATURDAY NIGHT...NUDGED DOWN LOWS VERY SLIGHTLY...CALLING FOR
LOW-MID 20S MOST AREAS. AS OUTLINED IN "POINT NUMBER 2"
ABOVE...CANNOT COMPLETELY RULE OUT SOME FOG AGAIN SATURDAY NIGHT
INTO SUNDAY MORNING...BUT GIVEN THE LACK OF CONFIDENCE FEEL THAT
THE "ONE NIGHT AT A TIME" APPROACH IS PROBABLY BEST.

SUNDAY DAYTIME-SUNDAY NIGHT...KEPT THE DAYTIME PERIOD VOID OF
PRECIP MENTION BUT IT COULD BE A CLOSE CALL...AS IF ANYTHING...AT
LEAST LIGHT/BRIEF MEASURABLE PRECIP CHANCES SEEM TO BE TRENDING UP
A BIT FOR SUNDAY NIGHT. THE RESPONSIBLE FEATURE HERE WILL BE A
NORTHWEST-FLOW TROUGH THAT DIVES SOUTHEAST INTO THE CENTRAL PLAINS
FROM WESTERN PORTIONS OF THE UNITED STATES-CANADA BORDER AND
STRENGTHENS AS IT DOES SO AS UPPER JET ENERGY PUNCHES IN BEHIND
IT. DOWN LOW...THE RESULT WILL BE A SURFACE LOW STRENGTHENING
GENERALLY ALONG A MONTANA-IOWA TRACK...AND DRAGGING AT LEAST A
WEAK COLD FRONT THROUGH THE LOCAL AREA SUNDAY NIGHT INTO MONDAY
MORNING. WITH FAIRLY STEADY WESTERLY-NORTHWESTERLY BREEZES AND
INCREASING CLOUDS SUNDAY NIGHT...FELT THAT SOME NUMERICAL GUIDANCE
WAS TOO COLD ON LOWS...AND AS A RESULT KEPT THE ENTIRE CWA FROM
DROPPING NO LOWER THAN THE 32-26 RANGE. THANKFULLY...THIS SHOULD
MITIGATE ANY LIGHT FREEZING RAIN POTENTIAL...AND WITH WARM TEMPS
ALOFT THIS SHOULD PROMOTE AT LEAST A BRIEF POTENTIAL FOR PLAIN
LIQUID RAIN SHOWERS...UNLESS OF COURSE LATER MODEL RUNS TREND IN
COLDER AIR FASTER. STILL PLENTY OF TIME TO FINE-TUNE THIS...AS
POPS ARE STILL NO HIGHER THAN 20-30 PERCENT AND HIGHEST IN EAST.
TEMP-WISE...SUNDAY COULD VERY WELL END UP BEING THE MILDEST OF THE
NEXT 7...AND AGAIN MADE LITTLE CHANGE TO PREVIOUS HERE WITH MAINLY
MID-UPPER 40S AND MAYBE SOME 50S SOUTHWEST.

MONDAY DAYTIME-MONDAY NIGHT...THE AFOREMENTIONED TROUGH CONTINUES
ORGANIZING/DEEPENING OVER THE CENTRAL CONUS...WITH A PARENT
SURFACE LOW GENERALLY EXPECTED TO TRACK NEAR THE IA/MN BORDER. AS
MENTIONED IN "POINT 4" ABOVE...THIS WILL LIKELY PLACE THE CWA IN A
RATHER BREEZY NORTHWEST WIND REGIME. THE LOCAL AREA WILL ALSO
REMAIN PRONE TO AT LEAST LIGHT PERIODS OF RAIN AND/OR SNOW...AND
LOW POPS CONTINUE THROUGH THESE 24 HOURS MAINLY WITHIN THE
NORTHEAST 1/2 OF THE CWA.

TUESDAY DAYTIME-TUESDAY NIGHT...THE MAIN DEEP TROUGH AXIS STARTS
MOVING OFF FARTHER EAST-SOUTHEAST ALONG AN AXIS FROM THE GREAT
LAKES-GULF COAST...BUT WITH REINFORCING SHORTWAVE ENERGY DROPPING
DOWN THROUGH THE LOCAL AREA ON THE BACKSIDE OF THIS
TROUGH...WOULD NOT BE SURPRISED TO SEE AT LEAST ONE PESKY AREA OF
FAIRLY LIGHT PRECIP TO BRUSH THROUGH THE CWA DURING THIS TIME PER
THE LATEST ECMWF SOLUTION. FOR NOW THOUGH...A DRY FORECAST
CONTINUES HERE BUT IT COULD BE RATHER WINDY FOR SURE.

WEDNESDAY DAYTIME-WED NIGHT...FOR BEING SEVERAL DAYS
OUT...CONFIDENCE IN THE CURRENTLY-DRY FORECAST IS ACTUALLY FAIRLY
DECENT HERE AS BOTH THE ECMWF/GFS MODEL SOLUTIONS ADVERTISE A
PERIOD OF LARGER-SCALE SHORTWAVE RIDGING MOVING OVERHEAD BETWEEN
THE DEPARTING EARLY-WEEK TROUGH AND THE NEXT UPSTREAM WAVE
INVADING THE WESTERN CONUS.

CHRISTMAS DAY...AS COVERED IN "POINT 6" ABOVE...DON/T GET TOO
CAUGHT UP IN THE 20-30 PERCENT SNOW AND OR SNOW/RAIN CHANCES YET.
ALTHOUGH THE AFOREMENTIONED WESTERN CONUS TROUGH WILL LIKELY BE
APPROACHING THE CENTRAL PLAINS...THE LATEST MODEL RUNS HAVE
PREDICTABLY SLOWED THINGS DOWN A BIT...MEANING THAT MOST IF NOT
ALL OF THE AREA COULD VERY WELL GET THROUGH AT LEAST SUNSET
PRECIP-FREE. STAY TUNED FOR SOME POSSIBLE/LIKELY CHANGES AND/OR
DELAYS TO PRECIP TIMING HERE. TEMP-WISE...HIGHS ARE VERY
PRELIMINARILY AIMED SOMEWHERE IN THE 30S ACROSS THE ENTIRE
CWA...WHICH IS OF COURSE RIGHT ON PAR WITH SEASONAL AVERAGES.

&&

.AVIATION...(FOR THE 18Z KGRI/KEAR TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1120 AM CST FRI DEC 19 2014

FOG HAS BEEN PERSISTENT IN THE KEAR TERMINAL AREA...BUT THERE HAS
BEEN SOME LIGHT FOG IN THE KGRI TERMINAL AREA. EXPECT THERE WILL
BE AN IMPROVEMENT IN VISIBILITY THIS AFTERNOON. THE LOW CLOUDS
CONTINUE TO PROVE A CHALLENGE. THE WESTERN EDGE OF THE CLOUDS IS
TO THE WEST OF KEAR AND EXPECT THAT THERE COULD BE SOME BREAKS IN
THE LOW CLOUDS IN THE KEAR TERMINAL AREA...BUT DO NOT EXPECT IT TO
GET INTO KGRI. ONCE THE LOWER CLOUDS MOVE OUT THERE WILL LIKELY BE
SOME FOG REFORMING DURING THE OVERNIGHT HOURS.

&&

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

$$

SHORT TERM...BRYANT
LONG TERM...PFANNKUCH
AVIATION...JCB


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