Area Forecast Discussion
Issued by NWS North Platte, NE

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLBF 270114 CCA
AFDLBF

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE NORTH PLATTE NE
714 PM CST THU FEB 26 2015

.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 336 PM CST THU FEB 26 2015

HIGH PRESSURE WILL BUILD SOUTH TONIGHT FROM THE DAKOTAS INTO EASTERN
NEBRASKA TONIGHT. THIS WILL CAUSE WINDS TO SWITCH AROUND FROM NORTH
TO THE SOUTH AS THE HIGH BUILDS SOUTH. AS THIS OCCURS...WINDS WILL
BE LIGHT AND VARIABLE. THERE WILL BE CLOUD COVER OVER THE SOUTHWEST
PORTION OF THE FORECAST AREA OVERNIGHT WHERE THERE WILL BE SOME
MOISTURE RETURN CONTINUING IN THE SOUTHERLY FLOW FROM WESTERN TEXAS
INTO THE HIGH PLAINS. TEMPERATURES ACROSS THE FORECAST AREA TONIGHT
WILL BE WARMEST WHERE THE CLOUDS REMAIN IN PLACE...AND ALTHOUGH THE
COLDEST -20C 850MB AIR WILL HAVE MOVED EAST OF THE
AREA...TEMPERATURES AT THIS LEVEL WILL REMAIN AT -15C TO -18C SO
EVEN WITH THE CLOUD COVER...THESE AREAS WILL SEE LOWS IN THE LOW
SINGLE DIGITS. THE REMAINDER OF THE FORECAST AREA WILL OBSERVE
MOSTLY CLEAR SKIES AND LIGHT WINDS LEADING TO A STRONG RADIATIONAL
COOLING NIGHT AS THE BOUNDARY LAYER DECOUPLES. MOST OF THIS AREA
SHOULD SEE LOWS DROP BELOW ZERO. THE LIGHT WINDS WILL LIMIT WIND
CHILLS...THOUGH EVEN A FEW KTS OF WIND WILL DROP WIND CHILLS INTO
THE TEENS BELOW ZERO.

WITH THE MOISTURE RETURN INTO FAR SOUTHWEST NEBRASKA AND THE
SOUTHERN PANHANDLE TODAY HAVE SEEN A FEW FLURRIES IN SOME LOCATIONS.
THIS IS EXPECTED TO CONTINUE TONIGHT INTO FRIDAY MORNING SO HAVE
CONTINUED THE MENTION OF A SLIGHT CHANCE FOR LIGHT SNOW WEST OF A
LINE FROM OSHKOSH TO IMPERIAL. THINK THE LIKELIHOOD OF ANY
MEASURABLE SNOW WILL BE SMALL THOUGH.

THE SURFACE HIGH WILL BUILD EAST ON FRIDAY...BRINGING SOUTHERLY FLOW
ACROSS MUCH OF NEBRASKA...WITH INCREASING WINDS AS THE DAY
PROGRESSES DUE TO AN INCREASING PRESSURE GRADIENT AND DAYTIME
BOUNDARY LAYER MIXING. FORECAST SOUNDINGS INDICATE MIXING TO NEAR
800MB IN SOME LOCATIONS ALTHOUGH THAT SHOULD BE THE MAXIMUM MIXING
HEIGHT WITH MANY AREAS NOT MIXING QUITE TO THAT LEVEL. THERE WILL BE
WARM AIR ADVECTION ONGOING IN THOSE LEVELS WITH MANY PLACES SEEING
RISES IN TEMPERATURES OF 5 TO 8 DEGREES. SO DO EXPECT WARMER
TEMPERATURES THAN HAVE BEEN EXPERIENCED TODAY...GENERALLY IN THE 20S
SO REMAINING WELL BELOW NORMAL.

.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 336 PM CST THU FEB 26 2015

FRIDAY NIGHT THROUGH SUNDAY...THE MAIN SYNOPTIC PATTERN OVER THE
WEEKEND IS CHARACTERIZED BY AN UPPER LEVEL TROUGH DIGGING OVER THE
WESTERN U.S. WITH THE CENTER OF 500HPA LOW PRESSURE NEAR KLAX BY 00Z
MONDAY. THE AMPLIFICATION OF THE TROUGH RESULTS IN A SPLIT FLOW
REGIME OVER THE FORECAST AREA SATURDAY AND SUNDAY.

DID NOT ADJUST TEMPERATURES MUCH EXCEPT TRENDED A LITTLE BIT TOWARD
MAV GUIDANCE. KEPT FRIDAY NIGHT MIN TEMPS ABOVE GUIDANCE TO ACCOUNT
FOR INCREASING CLOUD COVER...MAINLY ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA.

ALTHOUGH THE GFS...NAM...AND EURO PLACE MID LEVEL FRONTOGENESIS AND
A 250HPA JET ACROSS THE AREA SATURDAY EVENING...PRECIPITATION
SIGNALS WERE QUITE MESSY. THE NAM KEEPS THE AREA MAINLY DRY WHEREAS
THE EURO AND GFS BRING BETTER MOISTURE INTO THE REGION...PRIMARILY
SOUTH OF HIGHWAY 2. OVERALL...TRENDED POPS DOWN A LITTLE THROUGH
SUNDAY DUE TO LACK OF CONFIDENCE IN MEASURABLE PRECIPITATION. AT
KLBF...NAM SOUNDINGS SHOW A DRY LAYER FROM THE SURFACE TO AROUND
800HPA EXCEPT BRIEFLY SATURDAY NIGHT. ANY HYDROMETEORS FORMED IN THE
MOIST MID LAYER WILL LIKELY EVAPORATE BEFORE REACHING THE SURFACE.
ON THE CONTRARY...GFS BRINGS THE MOIST LAYER CLOSER TO THE SURFACE
EARLY SATURDAY AND KEEPS THE COLUMN SATURATED FOR A LONGER PERIOD
INTO SUNDAY MORNING. CANNOT IGNORE THE STRONG ISENTROPIC UPGLIDE
SIGNAL IN THE GFS...MOST EVIDENT AT 295K...AND MAINTAINED CHANCE
POPS GENERALLY ALONG AND SOUTH OF INTERSTATE 80. REMOVED POPS EXCEPT
FOR THE SOUTHERN TIER OF COUNTIES BY SUNDAY 12Z AS THE GFS DRIES THE
COLUMN CONSIDERABLY.

SUNDAY NIGHT THROUGH THURSDAY...THE TROUGH SLOWLY MOVES EAST THROUGH
THE WEEK...WITH THE AXIS DRAPED ACROSS THE FORECAST AREA 00Z
THURSDAY. ONE 250HPA JET STREAK FORMS SUNDAY EVENING AND STRETCHES
ROUGHLY FROM BROKEN BOW TO DETROIT...PLACING WESTERN NEBRASKA IN THE
RIGHT ENTRANCE REGION. THE GFS IS A LITTLE MORE AGGRESSIVE WITH THIS
WAVE...QUICKLY SATURATING THE COLUMN MONDAY MORNING. PRECIPITATION
TYPE WILL BE A BIT TRICKY MONDAY AS WARMER AIR WORKS INTO THE
REGION. THE GFS BRINGS ABOVE FREEZING 850HPA TEMPS NORTH TO THE
SOUTH DAKOTA BORDER BY 00Z TUESDAY. THE EURO IS DELAYED ABOUT 12
HOURS AND KEEPS 850HPA TEMPS ABOUT 5C COOLER MONDAY AFTERNOON AND
EVENING. MAX SURFACE TEMPS BUMPED UP A LITTLE MONDAY WITH MID 30S
SOUTH AND UPPER 30S NORTH. KEPT PTYPE AS SNOW FOR NOW...BUT A PERIOD
OF FZRA AND EVENTUALLY RAIN IS POSSIBLE. THE SECOND 250HPA JET
STREAK ARRIVES MONDAY NIGHT...BUT THE BEST ENERGY APPEARS TO STAY
JUST EAST OF THE FORECAST AREA. IF PTYPE REMAINS ALL SNOW...NOT TOO
CONCERNED FOR ACCUMULATION. THERE IS A CONSIDERABLE AMOUNT OF
LIFT...BUT THE OVERALL TEMPERATURE PROFILE IS TOO WARM AND THE DGZ
DOES NOT STAY SATURATED FOR LONG. TUESDAY...BOTH MODELS BRING A
QUICK COOLDOWN AT 850HPA AND DRIER AIR INTO THE REGION AND AM MORE
CONFIDENT WITH LIGHT SNOW BEING THE MAIN PTYPE. THE NEXT SURGE OF
MOISTURE ARRIVES WEDNESDAY WITH THE PASSAGE OF THE MAIN TROUGH AXIS
AND COLD FRONT. THIS TIME AROUND...MUCH COLDER AIR IS PRESENT AND
THE SNOW GROWTH ZONE IS CLOSER TO THE SURFACE...PLACING THE BEST
MOISTURE AND LIFT ABOVE IT. AGAIN...EXPECTING ANY SNOW TO BE RATHER
LIGHT WITH RELATIVELY LOW RATIOS. NORTHWEST FLOW RESUMES
THURSDAY...BRINGING A LULL IN THE SNOW BUT CONTINUING BELOW NORMAL
TEMPERATURES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 519 PM CST THU FEB 26 2015

VFR IS GENERALLY EXPECTED EAST OF HIGHWAY 61 OVERNIGHT AND
FRIDAY. THE MODEL CONSENSUS SUGGESTS THE BANK OF MVFR CIGS AROUND
KONL WILL TO DISSIPATE THIS EVENING. SOME MODELS SUCH AS THE RAP
AND NAM APPEAR TO MAINTAIN THESE CIGS OVERNIGHT THROUGH 15Z FRIDAY
AND THEN MIX THEM OUT.

A BANK OF MVFR CIGS ACROSS ERN COLO IS PROGGED BY THE MODELS TO
LIFT SLOWLY NORTH TONIGHT AND FRIDAY...GENERALLY ALONG AND WEST OF
HIGHWAY 61.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...BROOKS
LONG TERM...DS
AVIATION...CDC








USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.