FXUS63 KLBF 112020
AFDLBF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
320 PM CDT SUN MAY 11 2008

.DISCUSSION...
AS PROMISED...WINDS HAVE TURNED TO THE SOUTH BUT TEMPERATURES ARE
STRUGGLING TO RISE INTO THE 60S AS COOL AIR IS RECYCLING NORTHWARD.
THE NAM12 SHOWS SLY WINDS INCREASING TONIGHT WITH THE FORMATION OF
A LOW LEVEL JET. ALL MODELS INDICATE DEEP LOW PRESSURE WILL FORM
MONDAY AFTN ACROSS NERN COLO. THE NAM LOWERS THE SFC LOW TO 986 MB...
VERY DEEP FOR MAY BUT NOT OUT OF THE REALM OF POSSIBILITY.
SIMILARLY SLY H85 WINDS MONDAY EVENING INCREASE TO 55KTS AT 03Z AND
65KT AT 06Z IN THE VICINITY OF THE TRIPLE PT OVER SWRN NEB PROVIDING
EXCELLENT CONVERGENCE. SEVERE WEATHER PARAMETERS ARE ALL POINTING
TOWARD THE DEVELOPMENT OF AN ISOLATED SUPERCELL OR TWO ACROSS SWRN
NEB BETWEEN 21Z AND 00Z WITH STORM MOTION TO THE EAST AND NORTHEAST.
THE NAM12 ALSO FORMS AN ELEVATED MCS AND LIFTS IT NEWD UP AND OVER
THE SFC COLD FRONT WHICH WILL BE DROPPING SOUTH DURING THE AFTN.
PRECIPITABLE WATER INCREASES TO WELL OVER AN INCH BEHIND THE COLD
FRONT SUPPORTING THE NAM12 FCST FOR MCS DEVELOPMENT. WITH DEEP
MOISTURE ALOFT...STRONG LIFT AND VERY COLD AIR ALOFT THE SPC HAS
OUTLOOK MUCH OF WESTERN AND NORTH CENTRAL NEBRASKA OF A 5 PERCENT
CHANCE OF SEVERE THUNDERSTORMS. LARGE HAIL SEEMS LIKELY NORTH OF THE
COLD FRONT MONDAY EVENING.

THE OFFICIAL FCST USES A 50-50 BLEND OF THE DRIER GFS AND WETTER
NAM12 FOR POPS...QPF AND CLOUDS TONIGHT THROUGH WEDNESDAY. THE STORM
SYSTEM MOVING IN LATE MONDAY AFTN IS EXPECTED TO PRODUCE ISOLATED
TO SCATTERED THUNDERSTORMS THROUGH MONDAY NIGHT WITH SCATTERED
SHOWERS CONTINUING TUESDAY. THE NAM12 MAX TEMPERATURES WERE
HEAVILY FAVORED MONDAY WHILE A BLEND OF GUIDANCE AND NAM12 WAS USED
FOR TUESDAY. THUS HIGHS MONDAY ARE EXPECTED TO VARY FROM LOWER 60S
NORTHWEST TO LOWER 80S SOUTHWEST AND 70S EAST AND NORTHEAST. HIGHS
TUESDAY ARE HELD TO 50S WITH COOL...MOIST AND CLOUDY CONDITIONS
PREVAILING THROUGHOUT THE DAY. WINDS BEHIND THE COLD FRONT MONDAY
EVENING WILL BE FLIRTING WITH WIND ADVISORY CONDITIONS BUT THE
BLENDED GUIDANCE SUGGESTED 20 TO 30 MPH. THE DIURNAL TIMING OF
THE GUST MODEL MINIMIZED GUSTINESS ACROSS NEBRASKA. BREEZY TO WINDY
CONDITIONS CONTINUE TUESDAY ALONG AND EAST OF HIGHWAY 83.

BY TUESDAY EVENING SKIES SHOULD BE CLEARING OUT AND MIN TEMPERATURES
WEDNESDAY MORNING COULD BE CLOSE TO FREEZING. BLENDED GUIDANCE
CONTINUES TO TREND DOWN AND NOW INDICATES A LIGHT FREEZE COULD OCCUR
ACROSS NORTHWEST NEBRASKA. LATER FCSTS MAY NEED TO ISSUE A FREEZE
WATCH FOR THIS PORTION OF THE FORECAST AREA OR MORE AS WARRANTED.

WEDNESDAY...ANOTHER WEATHER SYSTEM WILL BE APPROACHING THE FCST AREA
LATE IN THE DAY...PERHAPS EARLY ENOUGH FOR ISOLATED SHOWERS TO
DEVELOP IN THE MORNING NORTHWEST WITH ACTIVITY SPREADING SOUTH AND
EAST THROUGHOUT THE DAY. ITS A NORTHWEST FLOW EVENT WITH VERY LITTLE
MOISTURE OR LOW LEVEL CONVERGENCE. THUS THE ATM WILL BE MOISTENING
UP FROM THE TOP DOWN. THE BLENDED GUIDANCE OF THE MEX...DGEX AND
NAM12 INDICATE LOWER 60S FOR HIGHS. THIS IS VERY CLOSE TO THE MAX
TEMPS INDICATED IN THE GFSBUFFER SOUNDINGS. H5 TEMPERATURES REMAIN
AT -20C IN THE WAKE OF THE COLD FRONT WHICH MOVED THROUGH LATE MONDAY
AND TUESDAY SO 60S WEDNESDAY SEEM REASONABLE.

ISOLATED TO SCATTERED SHOWERS ARE EXPECTED TO CONTINUE WEDNESDAY
NIGHT AND THURSDAY AS VERY COLD AIR CONTINUES ALOFT. HIGHS THURSDAY
WILL REMAIN IN THE LOWER 60S UNDER GENERALLY CLOUDY SKIES. CLOUDS...
MOISTURE AND A SERIES OF WEAK DISTURBANCES THROUGH FRIDAY ARE
EXPECTED TO PREVENT ADDITIONAL FREEZING WEATHER AT NIGHT.

H5 TEMPERATURES FRIDAY FINALLY RISE ABOVE -20C AND A WARMING TREND
DEVELOPS IN RESPONSE TO DEEP LOW PRESSURE IN THE EASTERN U.S. AND
RISING HEIGHTS WEST. THIS WARMING TREND SHOULD CONTINUE THROUGH THE
WEEKEND WITH DRY WEATHER AND PARTLY CLOUDY SKIES. HIGHS FRIDAY
ARE FCST TO RISE INTO THE UPPER 60S WITH LOWER 70S SATURDAY AND
SUNDAY. THESE FCST HIGHS TEMPERATURES ARE A BLEND OF THE DGEX AND MEX
GUIDANCE AND ARE VERY CLOSE TO THE GFSBUFFER SOUNDINGS.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED THROUGH 18Z MONDAY. THIS EVENING THE H85
SOUTHERLY JET WILL STRENGTHEN FROM 40 TO 50 KNOTS CREATING LOW LEVEL
WIND SHEAR FROM 03Z TO 15Z MONDAY AT TERMINALS KLBF AND KVTN. SOUTH
SURFACE WINDS OF 5 TO 15 KNOTS CAN BE EXPECTED DURING THE PERIOD
WITH WIND SHEAR INCREASING BETWEEN 1000-2000 FEET AFTER 03Z.
&&

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

&&

$$

CDC/TLK