Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 062023
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
323 PM CDT WED MAY 6 2015

.SYNOPSIS...
ISSUED AT 323 PM CDT WED MAY 6 2015

AN ACTIVE UPPER LEVEL PATTERN CONTINUES ACROSS THE
WESTERN HALF OF THE CONUS TDY WITH A CLOSED LOW OVER NERN COLORADO.
A SECONDARY SHORTWAVE WAS NOTED SOUTH OF THE LOS ANGELES
BASIN...WITH A SECOND CLOSED LOW NOTED OVER SRN WASHINGTON STATE.
ACROSS THE EASTERN CONUS...A NEGATIVE TILTED RIDGE EXTENDED NORTH OF
HIGH PRESSURE LOCATED OVER WESTERN NORTH CAROLINA INTO SERN
MANITOBA. AT THE SURFACE...LOW PRESSURE WAS PRESENT SOUTHWEST OF
KIMBALL NEBRASKA WITH A SURFACE TROUGH EXTENDING NORTH AND SOUTH OF
THE LOW ACROSS EASTERN COLORADO AND EASTERN WYOMING. EAST OF THE
TROUGH...SOUTHERLY AND SOUTHEASTERLY WINDS CONTINUED TO PUSH LOW
LEVEL MOISTURE INTO THE REGION TDY. TEMPERATURES WERE GENERALLY IN
THE LOWER TO MID 60S WITH DEW POINTS IN THE UPPER 50S TO AROUND
60.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 323 PM CDT WED MAY 6 2015

LOW PRESSURE SYSTEM CONTINUES TO IMPACT THE PLAINS IN THE SHORT
TERM. WATER VAPOR SHOWING A SMALL DRY SLOT WORKING INTO THE
AREA...HOWEVER MODELS ARE FILLING THIS IN SOME OVERNIGHT. NOT MUCH
HAS CHANGED IN THINKING AS LOW PRESSURE SYSTEM CONTINUES TO LIFT
ACROSS THE AREA. ISOLATED TO SCATTERED ACTIVITY WILL BE THE MAIN
FOCUS OVERNIGHT. PWATS NEAR THE MAX FOR EARLY MAY...JUST OVER 1
INCH. ANY SHOWERS WILL HAVE THE POTENTIAL FOR HEAVY RAIN...ALTHOUGH
MOVEMENT IS SWIFT AND THE HEAVY RAIN SHOULD BE BRIEF. THERE JUST
WILL BE SEVERAL BRIEF SHOWER TO PASS OVERHEAD...ESPECIALLY ALONG AND
EAST OF HIGHWAY 83. TO THE WEST OF 83 MORE WRAP AROUND/DEFORMATION
ZONE WILL RESULT IN MORE STEADY LIGHTER RAINFALL. MODELS VARY ON HOW
FAR EAST THE WRAP AROUND PRECIP MAKES IT ON THURSDAY IT LIFTS NORTH.
THUS MORE UNCERTAINTY FOR POPS TOMORROW AND HAVE GENERALLY LOWER
POPS. AS THE SFC LOW LIFTS INTO THE DAKOTAS...A COLD FRONT WILL PUSH
INTO NW NEB. THIS WILL HOLD TEMPS IN THE MID AND UPPER 50S FOR
TOMORROW. AHEAD OF THE FRONT...60S TO AROUND 70.

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 323 PM CDT WED MAY 6 2015

THURSDAY NIGHT THROUGH
SATURDAY...IN THE MID RANGE PERIODS...PRECIPITATION CHANCES ARE THE
MAIN FORECAST CHALLENGE. HIGH PRESSURE WILL PUSH SOUTH INTO THE
DAKOTAS LATE THURSDAY. THIS WILL FORCE A COLD FRONT INTO SOUTHERN
NEBRASKA EARLY IN THE EVENING HOURS. MOISTURE WILL POOL JUST AHEAD
OF THIS FEATURE...AND COMBINED WITH SURFACE HEATING AND THE
FRONT...SHOULD LEAD TO THUNDERSTORM DEVELOPMENT THURSDAY NIGHT...ACROSS THE
SRN CWA. HAVE LEFT SOME LOW POPS IN THE FORECAST IN THE SOUTH...AND
TRIMMED THEM OUT OF MOST OF THE CENTRAL AND NORTHERN SANDHILLS AS
THE FRONT WILL BE FURTHER SOUTH THAN PREVIOUSLY FCST. ON
FRIDAY...UPPER LEVEL LOW PRESSURE WILL TRACK FROM SRN CALIFORNIA
INTO SRN NEVADA. SURFACE LOW PRESSURE WILL DEVELOP OVER SERN
COLORADO...THEN DEEPEN AND LIFT NORTH INTO NERN COLORADO SATURDAY.
AS THE LOW DEEPENS...EASTERLY WINDS WILL BEGIN TO INCREASE ACROSS
WESTERN AND NORTH CENTRAL NEBRASKA FRIDAY...LEADING TO INCREASED
MOISTURE IN THE FORECAST AREA FRIDAY AFTERNOON. THE MODELS BEGIN TO
DIVERGE WITH THE DEGREE OF MOISTURE RETURN AS EARLY AS FRIDAY
AFTERNOON WITH THE GFS BEING MORE AGGRESSIVE VS THE NAM SOLN. THIS
SEEMS TO BE A BY PRODUCT OF FRONTAL POSN FRIDAY AFTERNOON. HIGH
PRESSURE IS MUCH WEAKER ACROSS THE DAKOTAS WITH THE GFS VS THE NAM
SOLN...AND THIS STRONGER HIGH PRESSURE IN THE NAM RESULTS IN A MORE
SRN POSN OF THE FRONTAL BOUNDARY FRIDAY...AND THUS DRIER CONDS IN
THE FORECAST AREA FRIDAY. ATTM...THINKING IS THAT THE FRONT IS TOO
FAR SOUTH WITH THE NAM SOLN GIVEN THE PERSISTENT SSW FLOW IN THE
MID LEVELS AND HAVE TRENDED THE FCST MORE TOWARD THE WETTER GFS
SOLN. WITH RESPECT TO PRECIPITATION TIMING FRIDAY...IT SHOULD HOLD OFF
UNTIL THE AFTERNOON HRS UNTIL SFC HEATING CAN DESTABILIZE THE
BOUNDARY LAYER. FOR FRIDAY NIGHT...PRECIPITATION CHANCES WILL SPREAD
NORTH AND EAST AS AN UPPER LEVEL DISTURBANCE TRACKS FROM SWRN
NEBRASKA INTO CENTRAL NEBRASKA BY 12Z SAT. POPS WILL INCREASE DURING
THE PERIOD WITH THE GREATEST INCREASE IN THE SOUTH AND SOUTHWEST
INVOF THE SLOWLY NORTHWARD LIFTING WARM FRONT. ON SATURDAY...SURFACE
LOW PRESSURE WILL DEEPEN FURTHER ACROSS NERN COLORADO IN RESPONSE TO
THE UPPER LEVEL LOW TRACKING INTO CENTRAL COLORADO. LIGHT RAIN
SHOWERS WILL BEGIN TO INCREASE IN COVERAGE LATE SATURDAY AFTERNOON
AND BECOME PREVALENT BY SATURDAY EVENING. WITH ABUNDANT CLOUDS IN
PLACE...HIGHS WILL STRUGGLE TO GET OUT OF THE
50S.

LONG RANGE...SATURDAY NIGHT THROUGH WEDNESDAY...THE MAIN FORECAST
CHALLENGE CONTINUES TO BE PRECIPITATION CHANCES AND PRECIPITATION
TYPES FOR THE LATER HALF OF THE WEEKEND AND EARLY NEXT WEEK. A
POWERFUL UPPER LEVEL LOW WILL LIFT NORTHEAST FROM COLORADO INTO THE
HIGH PLAINS SAT NIGHT INTO MONDAY. STRONG SURFACE LOW PRESSURE WILL
ACCOMPANY THE UPPER LEVEL LOW...SO STRONG SURFACE WINDS WILL RESULT
WITH THIS SYSTEM. HIGH CONFIDENCE EXISTS IN THE PRECIPITATION CHANCE
FORECAST THIS WEEKEND AS A BROAD SWATH OF PCPN WILL DEVELOP AHEAD OF
THE H5 LOW...THEN ON THE NORTHERN AND WESTERN PERIPHERY OF THE
SYSTEM...THANKS TO DEEP EASTERLY WINDS...PLENTY OF MOISTURE AND
ABUNDANT LIFT IN THE MID LEVELS. LITTLE WAS CHANGED IN THE INHERITED
POP FCST AS IT HAS A DECENT HANDLE ON THE EVOLVING SITUATION. PTYPES
HOWEVER CONTINUE TO BE PROBLEMATIC WITH THIS SYSTEM AS THERE IS SOME
DISAGREEMENT BETWEEN THE MID RANGE SOLNS ON THE TRACK OF THE H5 LOW
AND LOCATION OF SNOWFALL ON THE WESTERN PERIPHERY OF THIS FEATURE.
LOOKING AT THE MID RANGE SOLNS...THE ECMWF IS COLDEST AND FURTHEST
EAST WITH THE PROGRESSION OF THE H5 LOW...TAKING THIS FROM ROUGHLY
BURLINGTON COLORADO AT 12Z SUNDAY...TO WEST OF YANKTON SD BY 12Z
MONDAY. DURING THE SAME TIME PERIOD THE GFS FROM 12Z THIS
MORNING...TRACKS THIS FEATURE FROM THE WESTERN SANDHILLS TO YANKTON
SD BY 12Z MONDAY. THE GFS ENSEMBLE MEAN FROM LAST NIGHT TRACKS THE
LOW FROM STERLING COLORADO INTO CENTRAL SOUTH DAKOTA. WITH MODEL
DIFFERENCES AND THE ECMWF PULLING IN COLDER AIR ON THE BACK SIDE OF
THE SYSTEM...SNOWFALL COULD REACH OUR PANHANDLE COUNTIES LATE
SATURDAY NIGHT INTO SUNDAY. LOW TEMPERATURES IN THE CRINIT GRIDS FOR
SAT NIGHT AND SUN NIGHT HAVE TRENDED LOWER THIS AFTERNOON WITH LOWS
APPG THE FREEZING MARK IN THE EASTERN PANHANDLE. DECIDED TO WORD THE
FCST SAT NIGHT AND SUNDAY NIGHT WITH RAIN OR SNOW WORDING SINCE
THERE IS SOME DOUBT AS TO WHERE THE CHANGEOVER TO SNOW WILL OCCUR.
WEST OF OUR AREA...IT IS LOOKING REAL DICEY ACROSS THE WESTERN
PANHANDLE AND EASTERN WYOMING WHERE THE CHANGEOVER WILL BE MUCH
EARLIER.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 323 PM CDT WED MAY 6 2015

SLOW MOVING LOWER PRESSURE SYSTEM WILL CONTINUE TO ROTATE ACROSS THE
AREA OVER THE NEXT 24 HOURS. THIS EVENING SOME ISOLATE THUNDER MAY
IMPACT THE TAF TERMINALS...HOWEVER EXPECT ACTIVITY TO LIFT QUICKLY
TO THE NORTH. MORE LIKELY WILL BE SCATTERED RAIN SHOWERS. CIGS HAVE
BEEN BOUNCING AROUND FROM VFR TO MVFR AS SCATTERED SHOWERS MOVE
ACROSS THE AREA. A DRY SLOT IS GETTING WRAPPED INTO THE SYSTEM AND
THIS SHOULD KEEP CIGS IN THE VFR CATEGORY FOR SEVERAL HOURS. HOWEVER
LATE TONIGHT THE DRY SLOT SHIFTS EAST WITH WRAP AROUND MOISTURE TO
BRING CIGS BACK TO MVFR CONDITIONS.

&&

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

$$

SYNOPSIS...CLB
SHORT TERM...MASEK
LONG TERM...CLB
AVIATION...MASEK





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