864
FXUS63 KLBF 211807
AFDLBF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTH PLATTE NE
1207 PM CST THU NOV 21 2024
KEY MESSAGES
- DRY CONDITIONS WITH MODERATING TEMPERATURES (BACK INTO THE
50S) ARE EXPECTED TO ROUND OUT THE WORKWEEK AND INTO EARLY
THIS WEEKEND.
- THE FIRST OF A SERIES OF COOLER AIRMASSES ARRIVES FOR SUNDAY
AND MONDAY, WITH MUCH COOLER HIGHS AND A THREAT FOR LIGHT SNOW
ACROSS PORTIONS OF WESTERN NEBRASKA.
- ADDITIONAL COLD AIR INTRUSIONS (WITH WINTRY PRECIPITATION ALSO
POSSIBLE) INTO THE CENTRAL US LOOK INCREASINGLY LIKELY LATE
WEEK AND BEYOND, POTENTIALLY IMPACTING THANKSGIVING HOLIDAY
TRAVEL.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED AT 400 AM CST THU NOV 21 2024
CURRENTLY, NORTHWEST WINDS REMAIN BREEZY EAST OF HIGHWAY 183, WHERE
THE SURFACE PRESSURE GRADIENT REMAINS CONSTRICTED. THESE AREAS ARE
IN CLOSER PROXIMITY TO A DEPARTING SURFACE LOW, CURRENTLY CENTERED
OVER THE UPPER PENINSULA OF MICHIGAN. ALOFT, STRONG NORTHWEST FLOW
PREVAILS ON THE WESTERN PERIPHERY OF AN UPPER LOW CENTERED OVER
WESTERN MICHIGAN. UPSTREAM, AN UPPER RIDGE AXIS WAS POSITIONED
ACROSS THE INTERMOUNTAIN WEST.
FOR TODAY AND TONIGHT, HEIGHTS BUILD ALOFT AS THE UPPER LOW
CONTINUES TO PULL AWAY INTO THE OHIO RIVER VALLEY. ADDITIONALLY,
SHORTWAVE RIDGING BEGINS TO TRANSLATE EASTWARD INTO THE NORTHERN
PLAINS BY THIS AFTERNOON. AS SURFACE HIGH PRESSURE SPILLS INTO THE
UPPER MIDWEST, WINDS TRANSITION SOUTHERLY ACROSS WESTERN NEBRASKA.
COMBINED WITH THE INCREASING SUBSIDENCE ALOFT KEEPING SKIES CLEAR
TODAY, THE INCREASING WARM ADVECTION SHOULD BOOST HIGHS INTO THE LOW
TO MIDDLE 50S ACROSS SOUTHWEST NEBRASKA. LIGHT NORTHWEST WINDS
PERSIST INTO THIS AFTERNOON ACROSS NORTH CENTRAL NEBRASKA IN CLOSER
PROXIMITY TO THE SURFACE HIGH PRESSURE CENTER, AND KEEPS HIGHS IN
THE UPPER 30S TO LOW 40S. VERY DRY AIR REMAINS IN PLACE ACROSS THE
AREA TODAY, AND AGAIN WILL LEAD TO HUMIDITY VALUES DROPPING INTO THE
LOW 20 PERCENT RANGE ACROSS MUCH OF THE SANDHILLS AND WESTERN
NEBRASKA. HOWEVER, WINDS LOOK TO REMAIN LARGELY BELOW 15 MILES PER
HOUR AND TEMPER THE FIRE WEATHER THREAT. WEAK SOUTHERLY FLOW
PERSISTS OVERNIGHT, WITH LOWS SLIGHTLY WARMER THAN THIS MORNING, IN
THE LOW TO MIDDLE 20S.
BROAD UPPER RIDGING REMAINS ESTABLISHED ACROSS MUCH OF THE
CENTRAL CONUS INTO FRIDAY, WITH HIGH CLOUDS EXPECTED TO INCREASE
THROUGH THE DAY TOMORROW. EVEN WITH THE INCREASED CIRRUS, WEST-
SOUTHWEST FLOW AT THE SURFACE WILL ALLOW FOR HIGHS TO CLIMB BACK
INTO THE 50S FOR MUCH OF THE AREA, WITH PORTIONS OF SOUTHWEST
NEBRASKA MAKING A RUN FOR 60 DEGREES.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED AT 400 AM CST THU NOV 21 2024
THE LONG TERM BEGINS ON THE MORE BENIGN SIDE, WITH THE UPPER
RIDGE REMAINING THE PREDOMINANT FEATURE OF NOTE LOCALLY. THAT
SAID, SOME UNCERTAINTY EXITS FOR THE DAY SATURDAY DUE TO THE
POSITIONING OF A SURFACE WARM FRONT. UNCERTAINTY IS LARGELY TIED
TO THE STRENGTH OF A DEEPENING SURFACE LOW OVER WYOMING.
GUIDANCE SOLUTIONS WITH A DEEPER SURFACE LOW SHOW A MORE
AGGRESSIVE NORTHWARD PUSH OF THE SURFACE WARM FRONT INTO
SOUTHERN SOUTH DAKOTA, ALLOWING FOR WARMER TEMPERATURES ACROSS
MUCH OF WESTERN AND NORTH CENTRAL NEBRASKA. IN FACT, LATEST NBM
GUIDANCE SHOWS IMPRESSIVE 25-75TH PERCENTILE MAX TEMPERATURE
SPREADS OF 10-14F ACROSS MUCH OF THE SANDHILLS AND NORTHERN
NEBRASKA. THE CURRENT FORECAST SITS NEARER TO THE GUIDANCE MEAN,
BUT WILL LIKELY NEED TO BE TWEAKED AS CONFIDENCE IN FRONTAL
PLACEMENT BECOMES MORE CLEAR.
BY SATURDAY NIGHT, AN UPPER LOW WILL EJECT INTO THE NORTHERN PLAINS,
WITH THE AFOREMENTIONED DEEPENING SURFACE LOW EJECTING EASTWARD
ACROSS WESTERN NEBRASKA. THIS DRAGS A COLD FRONT THROUGH THE
AREA SUNDAY MORNING, WITH STRONG SURFACE HIGH PRESSURE QUICKLY
SPILLING INTO THE NORTHERN PLAINS IN ITS WAKE. AS THIS COLDER
AIRMASS PUSHES SOUTHWARD, SOME GUIDANCE DOES SHOW THE POTENTIAL
FOR SOME LIGHT SNOW ACROSS PORTIONS OF WESTERN NEBRASKA. THAT
SAID, THIS IS NOT WIDELY SUPPORTED, AND ENSEMBLE PROBABILITIES
REMAIN VERY LOW (0-20%) FOR AREAS EVEN SEEING AS MUCH AS 1" OF
SNOWFALL. AT THIS TIME, ANY WINTRY PRECIPITATION IMPACTS LOOK
LOW, THOUGH THIS WILL LEAD TO MUCH COLDER TEMPERATURES SUNDAY
AND MONDAY.
TEMPERATURES MODERATE SLIGHTLY ON TUESDAY, BEFORE THE NEXT ROUND OF
COLD AIR ARRIVES FOR WEDNESDAY AS ANOTHER COLD FRONT PUSHES THROUGH
THE AREA. THIS MARKS THE BEGINNING OF A POTENTIALLY LONGER STRETCH
OF MUCH COLDER TEMPERATURES FOR THE THANKSGIVING HOLIDAY AND BEYOND.
ADDING TO THIS, A GROWING PERCENTAGE OF ENSEMBLE MEMBERS SHOW AT
LEAST SOME PRECIPITATION CENTERED NEAR AND JUST AFTER THANKSGIVING,
AND WITH THE COLD AIR IN PLACE COULD MATERIALIZE INTO A THREAT FOR
ACCUMULATING SNOWFALL. WITH BUSY HOLIDAY TRAVEL, THIS WILL NEED TO
BE MONITORED CLOSELY GOING FORWARD. UNFORTUNATELY FOR MUCH OF
THE CENTRAL US, ANOMALOUS UPPER RIDGING LOOKS TO REMAIN
ESTABLISHED ACROSS ALASKA AS WE HEAD INTO THE POST-HOLIDAY
WEEKEND. THE STRENGTH OF THIS RIDGING WILL BE VITAL IN
DETERMINING SUBSEQUENT COLD SHOTS. IN FACT, THE GUIDANCE THAT
SHOWS MORE ROBUST RIDING ANCHORED OVER THE NORTHERN
PACIFIC/ALASKA DEVELOP CROSS POLAR FLOW, ENABLING THE COLDEST
AIRMASS OF THE SEASON TO FILTER SOUTHWARD INTO MUCH OF THE
CENTRAL CONUS BY LATE WEEKEND/EARLY NEXT WEEK. THE EXACT
MAGNITUDE OF COLD AIR REMAINS UNCERTAIN, THOUGH CONFIDENCE IS
BEGINNING TO GROW IN A PERIOD OF SUB-FREEZING (POTENTIALLY WELL
BELOW FREEZING) HIGHS AS WE HEAD TOWARDS THE BACK HALF OF THE
HOLIDAY WEEKEND AND INTO THE FIRST PART OF DECEMBER.
AVIATION /18Z TAFS THROUGH 18Z FRIDAY/
ISSUED AT 1206 PM CST THU NOV 21 2024
SKIES WILL BE CLEAR ACROSS THE AREA OVER THE NEXT 24 HOURS.
WINDS WILL BE LIGHT AT UNDER 10 KTS TODAY THROUGH FRIDAY
MORNING.
LBF WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...BROWN
LONG TERM...BROWN
AVIATION...BUTTLER
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