Area Forecast Discussion
Issued by NWS North Platte, NE

Home | Current Version | Previous Version | Text Only | 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
000
FXUS63 KLBF 181818
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
118 PM CDT FRI APR 18 2014

.SYNOPSIS...
ISSUED AT 356 AM CDT FRI APR 18 2014

ANALYSIS OF THE 07Z MSL DATA SHOWED A WEAK WARM/STATIONARY FRONT
FROM A LOW IN SOUTHWEST MONTANA...ACROSS NORTHEAST WYOMING AND
EXTREME SOUTHWEST SOUTH DAKOTA...THROUGH NORTHERN NEBRASKA. THERE
WAS A MINOR DEWPOINT DISCONTINUITY ACROSS THE FRONT WITH 30-35F IN
NEBRASKA AND 25-30F IN SOUTHERN SOUTH DAKOTA.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 356 AM CDT FRI APR 18 2014

WARM ADVECTION OVER WESTERN NEBRASKA WILL BRING SOME TEMPERATURES
INTO THE AREA THAT ARE MUCH WARMER THAN THEY WERE YESTERDAY WITH
LOW TO MID 70S WELL WITHIN REACH. THE TIGHTENING OF THE PRESSURE
GRADIENT LEADING A SURFACE TROUGH WILL BRING SOME PRETTY WINDY
CONDITIONS WITH SOUTH WIND 20 TO 30 MPH.

LATE TONIGHT...AS THE COLD FRONT MAKES ITS WAY INTO NORTHERN
NEBRASKA... SOME DECENT SYSTEM-RELATIVE ISENTROPIC LIFT DEVELOPS.
THIS CAN BE SEEN QUITE WELL ON THE 300K SURFACE AS THE LOWER
PRESSURES COME INTO THE NORTH AT A RATE OF 40MB PER 3 HOUR
INCREMENT. IT ALSO SHOWS UP WITH LOCAL PRESSURE DERIVATIVE OF ABOUT
3.5UB/S. ALSO...A CROSS SECTION IN NORTH CENTRAL NEBRASKA GIVES
EVIDENCE OF FRONTOGENETIC FORCING IN THE 295-305K LAYER. IN THE
CROSS SECTION...THETA-E SHOWS SOME INSTABILITY AS WELL.  HOWEVER...
THE AIR IT ENCOUNTERS IS FAIRLY DRY AND THE SHOWERS WILL BE
ISOLATED.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 356 AM CDT FRI APR 18 2014

LOOKING AT SATURDAY...MODELS ARE IN GOOD AGREEMENT WITH THE UPPER
LEVEL SYSTEM...WITH A WEAK SHORTWAVE TROUGH OVER NORTH DAKOTA AND
INTO THE SOUTHERN PARTS OF SASKATCHEWAN AND MANITOBA. ALSO...AN UPPER
LEVEL TROUGH WILL BE OVER THE FOUR CORNERS. THE SURFACE LOW
ASSOCIATED WITH THE NORTHERN SYSTEM WILL LINK UP WITH LOW PRESSURE
JUST AHEAD OF THE SOUTHERN SYSTEM. THIS WILL DRAPE A COLD FRONT
SOMEWHERE ACROSS THE FORECAST AREA THROUGH THE DAY. THE FRONT WILL
BE THE FOCUS OF SHOWER AND THUNDERSTORM DEVELOPMENT THROUGH THE
DAY AND SATURDAY NIGHT...BUT DIFFERENCES IN PLACEMENT OF THE FRONT
BY THE MODELS INDICATE THERE IS SIGNIFICANT UNCERTAINTY FOR WHERE
THE HIGHER PRECIPITATION CHANCES ARE NEEDED. THE FRONT IS
GENERALLY THROUGH THE AREA BY LATE AFTERNOON SO THE MAJORITY OF
PRECIPITATION WILL BE SOUTH AND EAST OF THE FORECAST AREA DURING
THE AFTERNOON. THE LOW LEVEL JET KICKS IN SATURDAY EVENING...WHICH
BRINGS SOME LIFT OVER THE FRONT AND INTO THE SOUTHEAST PARTS OF
THE FORECAST AREA. SO START TO INCREASE CHANCES FOR RAIN DURING
THE EVENING AND OVERNIGHT HOURS. THE LOW LEVEL JET DOES START TO
VEER TO THE EAST PRIOR TO MIDNIGHT...BUT THE FRONT REMAINS NEARLY
STATIONARY SO COULD CONTINUE TO GET SOME LIGHTER ACTIVITY OVER THE
FORECAST AREA THROUGH THE DAY SUNDAY AS ENERGY CONTINUES TO EJECT
OUT OF THE MAIN UPPER LOW WHICH WILL BE SLOWLY HEADED EAST. THAT
BEING SAID...IT IS ENTIRELY POSSIBLE FOR THE FRONT TO SETUP JUST
FAR ENOUGH TO THE SOUTHEAST TO KEEP ANY CHANCES FOR PRECIPITATION
OUT OF THE LOCAL AREA. ALTHOUGH CAPE IS FAIRLY LOW...THERE IS
ENOUGH INSTABILITY TO CONTINUE THE MENTION OF THUNDER...ALTHOUGH
DID BACK OFF SOME AREAS TO ISOLATED MENTION STARTING AT 06Z
SUNDAY. AT THIS TIME...WIND PROFILES ARE NOT SHOWING ENOUGH SHEAR
TO INDICATE A SUBSTANTIAL SEVERE THREAT.

THE RIDGE BUILDS IN FOR THE FIRST PART OF THE WORK WEEK...LEADING
TO ABOVE NORMAL TEMPERATURES FOR MANY AREAS AS HIGHS WILL REACH
THE 70S AND POSSIBLY LOW 80S IN SOME LOCATIONS.

FOCUS THEN TURNS TO THE SYSTEM AT MID WEEK. THERE ARE CERTAINLY
DIFFERENCES BETWEEN THE LONG RANGE MODELS AS THE
ECMWF/GFS/GEM/GFSENSEMBLE ALL HAVE DIFFERENT SCENARIOS FOR THE
UPPER LEVEL LOW TO MOVE ACROSS THE CONUS. WHAT IS AGREED UP0N IS
THAT THE PRIMARY LOW WILL TRACK ACROSS THE NORTHERN PLAINS
ALTHOUGH TIMING DIFFERENCES ARE SIGNIFICANT. THIS WILL NOT ONLY
IMPACT PRECIPITATION CHANCES...BUT ALSO TEMPERATURES. THERE IS
GOOD LIFT AHEAD OF THE SYSTEM...WITH SHOWERS AND THUNDERSTORMS
LOOKING TO DEVELOP ON THE WARM FRONT WEDNESDAY AFTERNOON THEN
FURTHER TO THE WEST WEDNESDAY NIGHT AS THE COLD FRONT MOVES
THROUGH. THE ECMWF SHOWS THIS OCCURRING OVER NEBRASKA...WHILE THE
GFS IS FURTHER EAST...WITH THIS SAME OUTCOME OVER MINNESOTA AND
IOWA. IF THE FRONT REMAINS CLOSE TO THE AREA FOR THURSDAY...COULD
GET ANOTHER ROUND OF STORMS THURSDAY AFTERNOON. CURRENT
INDICATIONS ARE THAT THERE WILL BE SUFFICIENT SHEAR TO NEED TO
WATCH FOR THE THREAT FOR SEVERE STORMS WHEREVER THEY MAY FORM
WEDNESDAY AND THURSDAY...BUT WITH THE AMOUNT OF UNCERTAINTY DON/T
HAVE THE CONFIDENCE AT THIS TIME TO START MENTIONING THAT
POTENTIAL IN OUTLOOKS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 117 PM CDT FRI APR 18 2014

SCATTERED TO BROKEN HIGH CIRRUS CLOUDS AT 30000FT ARE EXPECTED
THROUGH THE AFTERNOON AND INTO EARLY THIS EVENING. SOME MID LEVEL
CLOUDS NEAR 12000FT TO 15000FT WILL DEVELOP LATE TONIGHT. A
SOUTHERLY LOW LEVEL JET NEAR 50 KTS WILL SLOWLY BRING GULF MOISTURE
NORTHWARD INTO THE AREA TONIGHT...BUT NOT ENOUGH TO SUPPORT A LOW
CLOUD STRATUS LAYER. WINDS WILL BE AN ISSUE THIS AFTERNOON INTO THIS
EVENING...WITH SUSTAINED SOUTHERLY WINDS OF 20 TO 25 KTS AND GUSTS
TO 35 KTS. WINDS WILL SLOWLY DIMINISH OVERNIGHT TONIGHT...AND BECOME
NORTHEAST SATURDAY MORNING IN RESPONSE TO DEVELOPING SURFACE LOW
PRESSURE ACROSS NORTHEAST/EASTERN COLORADO.

&&

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

$$

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




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