Area Forecast Discussion
Issued by NWS North Platte, NE

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FXUS63 KLBF 161807
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
107 PM CDT WED APR 16 2014

.SYNOPSIS...
ISSUED AT 349 AM CDT WED APR 16 2014

ANALYSIS OF THE 07Z MSL DATA SHOWED LOW PRESSURE CENTERED NEAR
THE NEBRASKA-SOUTH DAKOTA BORDER NORTH OF VALENTINE. THAT SYSTEM
HAD ORIGINATED IN SOUTHWEST CANADA OVER SOUTHERN ALBERTA. WATER
VAPOR IMAGERY SHOWED A CLOSED VORTICITY CENTER ASSOCIATED WITH THE
SURFACE LOW. FROM THE SURFACE LOW...A COLD FRONT EXTENDED INTO
NORTHEAST COLORADO TO SOUTHEAST UTAH. ANOTHER SURFACE FRONT WAS
INDICATED WITH A WAVE IN SOUTHWEST NORTH DAKOTA AND THE FRONT
EXTENDING TO SOUTHEAST BRITISH COLUMBIA. MUCH COLDER AIR WAS NORTH
OF THAT SECOND FRONT.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 349 AM CDT WED APR 16 2014

AS THE ALBERTA STORM SYSTEM MAKES ITS WAY TO THE EAST-NORTHEAST...
THE FRONT WILL PUSH ON THROUGH NEBRASKA. A LOOK AT THE 295K AND 300K
THETA SURFACES SHOWS FRONTOGENESIS AND SYSTEM RELATIVE LIFT (LOCAL
PRESSURE DERIVATIVE EXCEEDING 10UB/S). WITH THE MOST FAVORABLE
MOISTURE AND DEGREE OF SATURATION IN THE NORTH...THAT IS THE AREA
WITH THE HIGHEST CHANCES OF SHOWERS. AS THE FRONT PUSHES ON THROUGH
THIS MORNING...THE SYSTEM RELATIVE LIFT AND FRONTOGENESIS ALSO
SHIFTS TO SOUTH CENTRAL NEBRASKA WHERE THE MOISTURE AND LEVEL OF
SATURATION IS NOT REAL FAVORABLE. ELEVATED FRONTOGENESIS CAN BE
DISCERNED IN NORTH CENTRAL NEBRASKA AS THE SECOND FRONT COMES INTO
NORTHERN NEBRASKA. THAT SHOULD LOSE ITS IMPETUS LATE MORNING TO
EARLY AFTERNOON WHEN THE THE TERMS BEGIN TO BALANCE.

IN THE COLD AIR ADVECTION IN THE WAKE OF THE FRONT...IT WILL BE
PRETTY WINDY WITH 20-30MPH SUSTAINED WIND GUSTING TO 35 LATE MORNING
TO EARLY AFTERNOON. THEN THE PRESSURE GRADIENT WEAKENS AND WIND
BEGINS DECREASING. AT THIS TIME...IT DOES NOT APPEAR THAT THE
RADIATION INVERSION WILL SET UP BEFORE LATE EVENING. BREEZY
CONDITIONS ARE LIKELY TO CONTINUE UNTIL THAT TIME.

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 349 AM CDT WED APR 16 2014

REMNANT COLD AIR WILL BE IN PLACE OVER NEBRASKA TO START THIS
PERIOD AS THE UPPER LEVEL TROUGH CURRENTLY MOVING INTO THE REGION WILL
BE ORIENTED NORTH TO SOUTH THROUGH THE PLAINS THURSDAY
MORNING. SKIES WILL CLEAR OUT FROM WEST TO EAST EARLY IN THE DAY
AS THE TROUGH MOVES EAST BRINGING SUBSIDENT AIR INTO THE REGION.
HOWEVER...WITH GOOD SUN THE SURFACE SHOULD WARM EFFICIENTLY AND
WITH THE COLD AIR ALOFT LOW LEVEL LAPSE RATES WILL BE QUITE STEEP.
THE MODELS ARE SHOWING A SMALL POOL OF MOISTURE MOVING INTO
NEBRASKA THROUGH THE DAY BETWEEN 800MB AND 650MB AND WITH THE
LAPSE RATES EXPECTED...COULD SEE SCATTERED SHOWERS DEVELOP LATE IN
THE MORNING AND IN THE AFTERNOON. DON/T EXPECT WIDESPREAD COVERAGE
WITH ANY OF THIS ACTIVITY...OR NOT COVERAGE OF MEASURABLE
PRECIPITATION TO BE HIGH SO JUST HAVE SLIGHT TO LOW CHANCE
PERCENTAGES IN THE FORECAST THROUGH THE DAY. WARM AIR ADVECTION
WILL BE ONGOING THROUGH THE DAY AS THE UPPER LEVEL TROUGH MOVES
EAST SO ANY PRECIPITATION EARLY IN THE MORNING WILL LIKELY BEGIN
AS SNOW...BUT AS TEMPERATURES THROUGHOUT THE COLUMN WARM...IT WILL
CHANGE OVER TO RAIN. HOW WARM TEMPERATURES GET ON THURSDAY WILL
DEPEND ON HOW FAST THE TROUGH MOVES EAST. ALSO TO CONSIDER...SOME
OF THE MODELS KEEP THE EASTERLY LOW LEVEL FLOW OVER THE NORTH AND
EASTERN PARTS OF THE FORECAST AREA THROUGH THE DAY WHICH COULD
HIGHLY INHIBIT TEMPERATURES FROM WARMING MUCH. FOR THIS FORECAST
PACKAGE KEPT HIGHS SIMILAR TO THE PRIOR FORECAST WITH HIGHS
RANGING FROM THE MID 40S TO AROUND 60 DEGREES.

AN ADDITIONAL WEAK SHORTWAVE WILL MOVE OUT OF ALBERTA THURSDAY
EVENING AND WILL QUICKLY MOVE INTO THE UPPER MISSISSIPPI RIVER
VALLEY. THE MAJORITY OF THE PRECIPITATION WILL STAY NORTH AND EAST
OF THE LOCAL AREA...HOWEVER THE SOUTHWEST EDGE MAY JUST CLIP THE
NORTHEAST PART OF THE FORECAST AREA SO DID ADD IN A SLIGHT CHANCE
FOR PRECIPITATION LATE THURSDAY NIGHT. SOUNDING PROFILES INDICATE
DEW POINTS WILL BE INCREASING THROUGH THE PERIOD SO IF
PRECIPITATION DOES OCCUR AND BEGINS AS SNOW...IT SHOULD SWITCH
OVER TO RAIN BY 12Z.

FRIDAY IS LOOKING DRY AS THE UPPER LEVEL RIDGE BUILDS IN...WARMING
THE AIR AND KEEPING IT DRY. THEN ON SATURDAY CHANCES FOR
PRECIPITATION WILL RETURN BY THE AFTERNOON. THERE WILL BE TWO
SYSTEMS CROSSING THE COUNTRY...THE FIRST BEING A LARGE UPPER LEVEL
TROUGH OVER THE FOUR CORNERS...WITH THE SECOND BEING AN TROUGH
MOVING ACROSS SOUTHERN CANADA. THERE ARE DIFFERENCES IN MODEL
SOLUTIONS ON WHERE THE SPECIFICS IN THE SURFACE FEATURES AND UPPER
LEVEL FEATURES WILL BE...BUT THEY ALL ARE INDICATING LOW PRESSURE
AT THE SURFACE LINKING UP. WITH INCREASED MOISTURE THROUGH THE DAY
FRIDAY...DO EXPECT PRECIPITATION TO DEVELOP SOMETIME ON SATURDAY.
CURRENTLY THE BEST CHANCES LOOK TO BE EAST OF A LINE FROM IMPERIAL
TO VALENTINE...BUT JUST A SLIGHT SHIFT IN THE FEATURES OF THIS
SYSTEM WILL BRING A DIFFERENT OUTCOME. SO WILL WATCH CLOSELY.
INSTABILITY WILL BUILD AHEAD OF THE SYSTEM...BUT SOUNDINGS SHOW IT
BEING QUITE LIMITED SO JUST WENT WITH ISOLATED THUNDER MENTION.
CHANCES FOR RAIN WILL CONTINUE IN THE SOUTHEAST PORTIONS OF THE
FORECAST AREA INTO SUNDAY AS THE FRONTAL SYSTEM IS SLOW TO MOVE
OUT OF THE AREA.

WARM AND DRY IS THEN EXPECTED FOR THE FIRST PART OF THE WORK
WEEK...WHERE FOCUS THEN MOVES TO THE MIDDLE OF NEXT WEEK. THE LONG
RANGE MODELS ARE COMING TOGETHER NICELY...BRINGING INCREASED
CONFIDENCE ON A DEEP UPPER LEVEL TROUGH TO MOVE ONTO THE WEST
COAST ON TUESDAY. THIS WILL BE WATCHED CLOSELY THROUGH THE NEXT
WEEK AS THIS SOLUTION COULD LEAD TO THE FIRST SEVERE EVENT OF
THE SEASON FOR THE LOCAL AREA AT MID WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 106 PM CDT WED APR 16 2014

COMPLEX WEATHER THIS AFTERNOON IN THE WAKE OF A DEPARTING COLD
FRONT. NW WINDS GUSTING TO 25 TO 35 KTS INTO THE EVENING HOURS.
SOME ISOLD/SCT RAIN SHOWERS DRIFTING SE ACROSS WEST
CENTRAL/CENTRAL NEB THIS AFTERNOON...ALTHOUGH BEGINNING TO SEE
DRY AIR INFLUENCE AND RADAR RETURNS DIMINISHING. THIS TREND
SHOULD CONTINUE WITH LITTLE OF THIS AREA OF PRECIP LINGERING INTO
THE EVENING HOURS. ALSO GOING TO SEE SOME MVFR LOCALLY IFR
CIGS...MAINLY ACROSS NRN/CENTRAL NEB...INCLUDING KVTN...INTO THE
EVENING BEFORE LIFTING TO VFR. CONFIDENCE IN WIDESPREAD VFR
OVERNIGHT IS DIMINISHING AS THE LATEST NAM MODEL DOES HOLD THE
LOWER MVFR CIGS THROUGH THE NIGHT...AND WILL BE MONITORED CLOSELY.
AT THIS TIME EXPECT AS A SECONDARY DISTURBANCE MOVES INTO THE
REGION OVERNIGHT...MIXING WILL BREAK UP THE LOWER CLOUDS. CANNOT
RULE OUT SOME LIGHT PRECIP WITH THE SECOND WAVE...HOWEVER IS
ANTICIPATED TO REMAIN ACROSS THE PANHANDLE...WELL WEST OF THE TAF
SITES.

&&

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

&&

$$

SYNOPSIS...SPRINGER
SHORT TERM...SPRINGER
LONG TERM...BROOKS
AVIATION...MASEK





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