256
FXUS63 KLBF 181748
AFDLBF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1148 AM CST MON NOV 18 2024
KEY MESSAGES
- A STORM SYSTEM MOVES THROUGH THE AREA TODAY AND TONIGHT, WITH
RAIN ANTICIPATED EAST OF HIGHWAY 83. PRECIPITATION AMOUNTS OF
GREATER THAN 0.50" ARE EXPECTED EAST OF HIGHWAY 183.
- AS THE SYSTEM DEPARTS, STRONG WINDS PERSIST TUESDAY AND
WEDNESDAY, ALONG WITH MUCH COOLER TEMPERATURES (HIGHS IN THE
UPPER 30S TO 40S).
- DRY CONDITIONS ARE THEN EXPECTED LATE WEEK INTO THE WEEKEND,
WITH HIGH TEMPERATURES REMAINING IN THE 40S TO LOW 50S.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 412 AM CST MON NOV 18 2024
CURRENTLY, AN UPPER LEVEL LOW WAS CENTERED OVER SOUTHERN NEW MEXICO,
WITH BROAD SOUTH-SOUTHWESTERLY FLOW NOTED ACROSS THE PLAINS AHEAD OF
THIS LOW. AT THE SURFACE, LIGHT SOUTH WINDS WERE OBSERVED, WITH A
DEEP SURFACE LOW APPROACHING THE RED RIVER OF TX/OK.
FOR TODAY, EXPECT THE AFOREMENTIONED UPPER LOW TO QUICKLY EJECT
NORTHEASTWARD THROUGH THIS AFTERNOON, REACHING SOUTHEASTERN
NEBRASKA BY THIS EVENING. AS THIS OCCURS, THE LOW WILL QUICKLY
TAKE ON A NEGATIVE TILT, BEFORE QUICKLY OCCLUDING OVER NORTHWEST
IOWA EARLY TUESDAY MORNING. THE ASSOCIATED SURFACE LOW WILL
TAKE A SIMILAR TREK, MOVING INTO EXTREME SOUTHEAST NEBRASKA THIS
EVENING, WHILE DEEPENING TO SUB-990MB. IT IS THE PROGRESSION OF
THESE FEATURES THAT WILL DRIVE TODAY'S FORECAST, AS THE
DEFORMATION AXIS PRECIPITATION SHIELD MOVES NORTHWARD INTO
CENTRAL/EASTERN NEBRASKA ON THE WESTERN PERIPHERY OF THE SURFACE
LOW. GUIDANCE CONTINUES TO COME INTO BETTER AGREEMENT WITH
RESPECT TO THE PRECISE TRACK OF RAIN THIS AFTERNOON, WITH THE
HIGHEST CONFIDENCE FOR AREAS NEAR AND EAST OF HWY 183. A MUCH
ADVERTISED SHARP WESTERN CUTOFF TO PRECIPITATION SHOULD OCCUR
NEAR AND WEST OF THE HWY 83 CORRIDOR, AS THE SURFACE LOW REMAINS
JUST A LITTLE TOO FAR SOUTHEAST FOR MORE FAVORABLE
ACCUMULATIONS ACROSS WESTERN NEBRASKA. THIS SYSTEM IS HIGHLY
ANOMALOUS, WITH PWAT VALUES EXCEEDING THE 99TH PERCENTILE (AND
APPROACHING/EXCEEDING CLIMO MAXIMUMS FOR MID-NOVEMBER) ACROSS
PORTIONS OF CENTRAL INTO EASTERN NEBRASKA. THIS SHOULD LEAD TO
EFFICIENT RAINFALL ACCUMULATION THIS AFTERNOON, AND AMOUNTS OF
0.50-1.0" ARE EXPECTED FOR AREAS EAST OF HWY 183. THE
AFOREMENTIONED SHARP GRADIENT WILL LEAD TO QUICKLY DECREASING
TOTALS WITH WESTWARD EXTENT, WITH LITTLE TO NO ACCUMULATIONS
NEAR AND WEST OF HWY 83.
PRECIPITATION QUICKLY TRANSLATES ACROSS CENTRAL AND NORTH CENTRAL
NEBRASKA THIS AFTERNOON, ENDING FROM NORTH TO SOUTH LATE THIS
EVENING AS THE SURFACE LOW BEGINS TO DEPART AND OCCLUSION BEGINS
TONIGHT. AS A SURFACE COLD FRONT PUSHES THROUGH THE AREA FROM WEST
TO EAST TONIGHT, WINDS QUICKLY STRENGTHEN FROM THE NORTHWEST IN ITS
WAKE. THIS IS LARGELY DRIVEN BY STRENGTHENING COLD ADVECTION
(PROMOTING AMPLE MECHANICAL MIXING) AND A NEARLY UNIDIRECTIONAL WIND
PROFILE IN THE LOWEST FEW KILOMETERS. NORTHWEST WINDS STRENGTHEN
OVERNIGHT, WITH GUSTS OF 30 TO 40 MILES PER HOUR EXPECTED THROUGH
THE AFTERNOON AND EVENING HOURS TUESDAY. THE PERSISTENTLY STRONG
WINDS THROUGH THE DAY ARE AIDED BY CONTINUED COLD ADVECTION, ALONG
WITH SOME DIURNAL MIXING AS SOME CLEARING MAY OCCUR TUESDAY MORNING
AS THE UPPER LOW BEGINS TO EXIT THE AREA. THE STRONG COLD ADVECTION
WILL ALSO LEAD TO MUCH COOLER CONDITIONS TUESDAY, WITH HIGHS
STRUGGLING TO REACH THE UPPER 30S TO 40S ACROSS THE AREA.
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
ISSUED AT 431 AM CST MON NOV 18 2024
A COMPLEX SYNOPTIC EVOLUTION THEN AWAITS US FOR TUESDAY NIGHT INTO
WEDNESDAY, THAT TRANSLATES AGAIN TO A PERIOD OF STRONG WINDS ACROSS
PORTIONS OF WESTERN AND NORTH CENTRAL NEBRASKA. ALOFT, THE PRIMARY
FEATURES OF NOTE WILL BE THE AFOREMENTIONED OCCLUDING LOW OVER
THE UPPER MIDWEST, A RAPIDLY DEEPENING UPPER LOW OFF THE COAST
OF THE PACIFIC NORTHWEST, AND ANOTHER WEAKER SHORTWAVE
TRAVERSING THE ROCKIES. THE INTERACTION OF THE POWERFUL UPSTREAM
PACIFIC NORTHWEST TROUGH AND THE DOWNSTREAM SHORTWAVE/OCCLUDING
LOW WILL LEAD TO A RAPIDLY CONSTRICTING PV GRADIENT ALOFT, AND
THIS PROMOTES JETOGENESIS OVER THE CENTRAL/NORTHERN PLAINS EARLY
WEDNESDAY MORNING AS THE AFOREMENTIONED ROCKIES SHORTWAVE
BEGINS TO CLOSE OFF AS IT EJECTS INTO THE NORTHERN PLAINS. AS
THIS POWERFUL JET CORE (H3 WINDS ~145-155KTS) TRANSLATES ACROSS
THE AREA WEDNESDAY MORNING, GUIDANCE SHOWS A TEXTBOOK TROPOPAUSE
FOLD IN ASSOCIATION WITH THE TIGHTENING THERMAL GRADIENT ALOFT.
AS A CONSEQUENCE, VERY HIGH MOMENTUM FLOW ALOFT IS COMPRESSED
DOWNWARDS, AND WILL PROMOTE ANOTHER PERIOD OF STRONG WINDS ON
WEDNESDAY. COLD ADVECTION DOES WEAKEN TUESDAY NIGHT INTO
WEDNESDAY MORNING, AND THIS LOOKS TO KEEP WINDS SOMEWHAT WEAKER
(20-30 MPH) OVERNIGHT. THE STRONGEST WINDS LOOK TO OCCUR AS
DIURNAL MIXING OCCURS WEDNESDAY AFTERNOON. THE HIGHEST GUSTS ARE
EXPECTED ACROSS NORTH CENTRAL NEBRASKA, WHERE TIMING OF THE
BEST DYNAMICS AND MIXING OVERLAP. THIS IS WHERE GUSTS IN EXCESS
OF 50MPH ARE EXPECTED DURING THE AFTERNOON HOURS, AND AT LEAST
SOME THREAT EXISTS FOR LOCALIZED GUSTS APPROACHING 60MPH. TRENDS
WILL CONTINUE TO BE MONITORED FOR ANY NEED FOR HIGH WINDS
HEADLINES GOING FORWARD.
A SECONDARY THREAT WEDNESDAY LOOKS TO BE ELEVATED TO LOCALLY NEAR-
CRITICAL FIRE CONDITIONS ACROSS MUCH OF WESTERN AND NORTH CENTRAL
NEBRASKA. THE PV ANOMALY MOVING OVERHEAD NOT ONLY LEADS TO VERY
STRONG WINDS, BUT ALSO QUICKLY FALLING HUMIDITY VALUES AS VERY DRY
AIR ALOFT IS MIXED DOWNWARDS WEDNESDAY AFTERNOON. THIS SENDS
DEWPOINTS INTO THE LOW TEENS TO SINGLE DIGITS, AND IN COMBINATION
WITH EVEN THE COOLER TEMPERATURES IN THE 40S WILL LEAD TO HUMIDITY
VALUES FALLING AS LOW AS 20 PERCENT ACROSS PORTIONS OF THE SANDHILLS
AND SOUTHWEST NEBRASKA. THE COMBINATION OF THE DRY CONDITIONS AND
STRONG WINDS WILL INCREASE FIRE CONCERNS WEDNESDAY AFTERNOON.
QUIETER AND DRY CONDITIONS THEN AWAIT US AS WE HEAD INTO LATE WEEK
AND THE WEEKEND, AS AN UPPER RIDGE AXIS ESTABLISHES OVER THE PLAINS.
THIS WILL LEAD TO SLOWLY MODERATING TEMPERATURES BACK INTO THE 40S
TO LOW 50S BEFORE THE NEXT SYSTEM OF NOTE APPROACHES THE AREA LATE
WEEKEND.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1145 AM CST MON NOV 18 2024
THERE WILL BE A TIGHT WEST TO EAST GRADIENT IN CONDITIONS ACROSS
CENTRAL AND WESTERN NEBRASKA THROUGH THE FIRST PART OF THE VALID
PERIOD. LOW PRESSURE MOVING UP FORM THE SOUTH WILL PUSH RAIN AND
SUB-VFR CONDITIONS UP THROUGH EASTERN NEBRASKA PRIMARILY EAST
OF HWY 83 WITH DRY VFR CONDITIONS TO THE WEST. TAF SITES WILL BE
ON THE DIVIDING LINE BUT ANTICIPATE VFR WILL HOLD, THOUGH WILL
USE VCSH AT KLBF WHERE PRECIPITATION WILL BE CLOSE TO THE
AIRFIELD.
AS THE LOW PULLS OFF TO THE NORTH TONIGHT EXPECT STRONG GUSTY
WINDS WILL SURGE IN FROM THE WEST WITH GUSTS GENERALLY AROUND
35KT AT KLBF AND AROUND 40KT AT KVTN. GUSTS WILL DIMINISH A BIT
AROUND DAYBREAK BUT WILL RAMP UP AGAIN TOWARD THE END OF THE
VALID PERIOD AS DIURNAL HEATING MIXES THE BOUNDARY LAYER. ALSO
EXPECT A SUB-VFR CIG AT KVTN AS THE WINDS ARRIVE WITH
PROBABILISTIC GUIDANCE SHOWING A BETTER THAN EVEN CHANCE FOR A
PERIOD OF CIGS AT OR BELOW 3KFT BEFORE DAYBREAK.
LBF WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...BROWN
LONG TERM...BROWN
AVIATION...MBS
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