577
FXUS64 KLZK 211952
AFDLZK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LITTLE ROCK AR
152 PM CST SAT DEC 21 2024
..NEW SHORT TERM, LONG TERM
SHORT TERM
(THIS EVENING THROUGH MONDAY)
ISSUED AT 1236 PM CST SAT DEC 21 2024
EARLY AFTERNOON WATER VAPOR SATELLITE IMAGERY SHOWED A COMPACT
SHORTWAVE TROUGH OVER SOUTHEAST ARKANSAS, MOVING SOUTHEAST. A
LARGE UPPER TROUGH WAS IN PLACE OVER THE NORTHEASTERN CONUS WITH
BROAD RIDGING OVER THE CONUS ROCKIES LEAVING ARKANSAS AND THE
CENTRAL UNITED STATES IN GENERAL UNDER NORTHWEST FLOW ALOFT.
VISIBLE SATELLITE IMAGERY SHOWED CLEAR SKIES OVER MOST OF ARKANSAS
WHILE SURFACE OBSERVATIONS SHOWED TEMPERATURES IN THE MID 30S
ACROSS NORTHERN ARKANSAS TO THE MID 40S IN THE SOUTH. DEW POINT
VALUES ACROSS THE STATE WERE PRETTY MUCH IN THE MID 20S STATEWIDE.
WINDS HAD VEERED AROUND TO THE SOUTHEAST FOR ALL BUT FAR EASTERN
ARKANSAS WHERE WINDS REMAINED EAST-NORTHEASTERLY AS OF 1 PM CST.
THE SHORTWAVE TROUGH OVER ARKANSAS WAS ALREADY SPREADING LARGE
SCALE FORCING FOR SUBSIDENCE OVER THE STATE, AND ALTHOUGH
SUBSIDENCE WILL WEAKEN AS THE SHORTWAVE DEPARTS, WEAK FORCING FOR
SUBSIDENCE WILL REMAIN IN CONTROL OF THE WEATHER OVER THE NATURAL
STATE FOR AT LEAST THE NEXT 24 HOURS. DESPITE THE LARGE TROUGH
OVER THE NORTHEASTERN CONUS AND RIDGE OVER THE ROCKIES, THE
PATTERN ALOFT IS EXPECTED TO BE PROGRESSIVE OVER THE NEXT SEVERAL
DAYS WHICH WILL USHER IN A FAIRLY ACTIVE WEATHER PATTERN FOR
ARKANSAS IN THE WEEK AHEAD. WE'LL START TO FEEL THIS TRANSITION
TAKE PLACE ON MONDAY AS A STRONG SHORTWAVE TROUGH WELL OFF TO THE
NORTH AND A MUCH WEAKER SHORTWAVE TROUGH PASS TO THE SOUTH OF
ARKANSAS. WHILE NEITHER FEATURE IS CLOSE ENOUGH TO DIRECTLY IMPACT
THE STATE, THESE FEATURES WILL HELP TO ESTABLISH A WARM AND HUMID
AIR ADVECTION PATTERN OVER THE REGION OUT AHEAD OF A LARGER AND
STRONGER UPPER LEVEL TROUGH THAT IS ON TRACK TO MOVE OVER THE
STATE ON CHRISTMAS EVE.
IN THE SHORT TERM FORECAST WHAT THIS MEANS FOR US HERE IN ARKANSAS
IS THAT WE'LL SEE SOME INCREASING CLOUDS ON SUNDAY, BUT WARMER
TEMPERATURES AS SOUTHERLY WINDS RETURN TO THE ENTIRE STATE.
BECAUSE OF THE COLD START TO THE DAY SUNDAY MORNING, TEMPERATURES
WON'T BE SIGNIFICANTLY WARMER THAN TODAY, BUT SHOULD TOP OUT IN
THE UPPER 40S TO LOWER 50S FOR MOST LOCATIONS, OR ABOUT 5 DEGREES
WARMER THAN TODAY'S HIGH TEMPERATURES. CLOUD COVER LOOKS TO
INCREASE IN COVERAGE SUNDAY NIGHT INTO MONDAY MORNING AS SOUTHERLY
WINDS TAP INTO SOME GULF MOISTURE, AND THIS WILL KEEP SUNDAY
NIGHT/MONDAY MORNING'S TEMPERATURES ABOUT 5-10 DEGREES WARMER
ALLOWING TEMPERATURES TO CLIMB INTO THE MID 50S ACROSS THE STATE
BY MONDAY AFTERNOON. WITH PERSISTENT SOUTHERLY WINDS TAPPING INTO
GULF MOISTURE, WE WILL SEE AT LEAST SOME SMALL RAIN CHANCES ON
MONDAY, WITH THE MOST LIKELY RAIN CHANCES EXPECTED TO OCCUR OVER
NORTHWEST ARKANSAS WHERE WARM AND HUMID AIR ADVECTION IS EXPECTED
TO BE STRONGEST ACROSS THE STATE. RAIN CHANCES WILL CONTINUE TO
INCREASE AS WE HEAD INTO CHRISTMAS EVE AS A STRONG TROUGH
APPROACHES THE STATE FROM THE NORTHERN CONUS ROCKIES.
CAVANAUGH
LONG TERM
(MONDAY NIGHT THROUGH NEXT SATURDAY)
ISSUED AT 1236 PM CST SAT DEC 21 2024
A WARM AND HUMID AIR ADVECTION REGIME WILL REMAIN IN PLACE ACROSS
ALL OF ARKANSAS MONDAY NIGHT AS A STRONG UPPER LEVEL TROUGH MOVES
SOUTHEAST OUT OF THE NORTHERN ROCKIES AND OVER THE SOUTHERN
PLAINS. MODELS HAVE THIS TROUGH DIGGING ALMOST DUE SOUTH OVER THE
PLAINS ON CHRISTMAS EVE WITH JUST A SLIGHT EASTERN PUSH BY THE
AFTERNOON HOURS OF THE DAY ON TUESDAY. THIS WILL CAUSE STRONG
DIFFERENTIAL POSITIVE VORTICITY ADVECTION (PVA) TO COUPLE WITH
THE ONGOING LOW-LEVEL WARM AIR ADVECTION REGIME TO BRING NEARLY
100 PERCENT RAIN CHANCES ACROSS ARKANSAS FROM CHRISTMAS EVE DAY
THROUGH THE OVERNIGHT HOURS INTO CHRISTMAS MORNING. AS THIS TROUGH
EXITS OFF TO THE EAST ON CHRISTMAS DAY, WE MAY CATCH A BREAK FROM
WIDESPREAD RAIN SHOWERS AND ISOLATED THUNDERSTORMS DURING THE
AFTERNOON HOURS OF THE DAY AS LIFT AND RAIN DIMINISH FROM WEST TO
EAST ACROSS ARKANSAS THROUGHOUT THE DAY.
AS THIS IS HAPPENING ACROSS ARKANSAS, THE WESTERN HALF OF THE
CONUS IS EXPECTED TO SEE A FAIRLY SIGNIFICANT PATTERN BREAKDOWN AS
MODELS INDICATE A POWERFUL UPPER LEVEL LOW PRESSURE SYSTEM WILL
BASICALLY JUST PLOW THE ROCKY MOUNTAIN RIDGE OUT OF THE WAY AND
MOVE DIRECTLY FROM THE PACIFIC OCEAN OVER THE SOUTHWESTERN CONUS
AND APPROACH THE SOUTHERN PLAINS BY CHRISTMAS DAY AFTERNOON. THIS
IS IMPORTANT BECAUSE THIS FOLLOW UP UPPER LEVEL LOW PRESSURE
SYSTEM WILL PREVENT AN AIRMASS EXCHANGE IN THE FORM OF A STRONG
FRONTAL PASSAGE FROM THE CHRISTMAS EVE NORTHERN ROCKIES STORM
SYSTEM. SO DESPITE RAIN CHANCES COMING TO AN END ON CHRISTMAS DAY
BEHIND THE DEPARTING UPPER TROUGH, THE UNSEASONABLY WARM AND HUMID
AIRMASS ISN'T GOING ANYWHERE, KEEPING TEMPERATURES ON CHRISTMAS
EVE UP INTO THE 50S AND 60S, WITH HARDLY ANY CHANGE IN
TEMPERATURES THROUGH THE NIGHT OF CHRISTMAS DAY.
AFTER CHRISTMAS DAY, LONGER RANGE MODEL GUIDANCE STARTS TO DIVERGE
ON THE DETAILS OF WHAT THE ACTIVE WEATHER PATTERN WILL LOOK LIKE
TO CLOSE OUT THE HOLIDAY WEEK. HERE'S WHAT MODELS SEEM TO AGREE ON
FIRST:
ON THURSDAY, THE BIG UPPER LOW THAT PLOWS DIRECTLY EAST FROM THE
PACIFIC OCEAN TOWARDS THE SOUTHERN PLAINS REMAINS ON AN EASTERLY
TRACK AND ONCE AGAIN SPREADS LARGE SCALE FORCING FOR ASCENT IN THE
FORM OF COUPLED LOW-LEVEL WARM AIR ADVECTION AND UPPER LEVEL PVA
OVER ARKANSAS, BRINGING ANOTHER NEAR CERTAIN ROUND OF SHOWERS AND
THUNDERSTORMS ACROSS THE STATE. MOST MODEL GUIDANCE AGREES THAT
THIS UPPER LOW WILL BECOME NEGATIVELY TILTED (WHICH ESSENTIALLY
MEANS THAT COLD AIR ALOFT WILL MOVE OVER WARM AIR NEAR THE
SURFACE), BUT THERE ARE SOME FAIRLY SIGNIFICANT DIFFERENCES
REGARDING THE DETAILS OF WHEN AND WHERE THIS OCCURS. REGARDLESS,
WITH A WARM AND HUMID AIRMASS IN PLACE AND COLD AIR MORE LIKELY
THAN NOT TO MOVE OVER WARM HUMID AIR NEAR THE SURFACE, THERE IS
AT LEAST A CONDITIONAL CHANCE FOR SEVERE THUNDERSTORMS OVER
PORTIONS OF ARKANSAS THURSDAY AFTERNOON AND EVENING. BECAUSE OF
THE UNCERTAINTY REGARDING THE DETAILS OF THE EVOLUTION OF THIS
LARGE UPPER LOW, THE STORM PREDICTION CENTER HAS NOT YET OUTLOOKED
THE AREA FOR SEVERE STORMS IN THEIR DAY 4-8 PRODUCT. CERTAINLY
SOMETHING TO KEEP AN EYE ON AS WE GET INTO EARLY NEXT WEEK.
AFTER THE PASSAGE OF THURSDAY'S STORM SYSTEM, MODELS INTRODUCE
QUITE A BIT OF UNCERTAINTY REGARDING THE AMPLITUDE AND PLACEMENT
OF KEY SYNOPTIC FEATURES THAT WILL GUIDE THE FUNDAMENTALS OF THE
FORECAST FOR FRIDAY AND BEYOND. AS A RESULT, I WON'T GET INTO THE
WEEDS ON THE 6-8 DAY FORECAST BECAUSE MODEL GUIDANCE IS UNLIKELY
TO CONVERGE ON A CONSENSUS SOLUTION FOR AT LEAST A FEW DAYS. THERE
IS A PRETTY GOOD CHANCE FOR AT LEAST ONE MORE ROUND OF SHOWERS AND
THUNDERSTORMS ON FRIDAY OR SATURDAY, AND TEMPERATURES ARE MORE
LIKELY THAN NOT TO REMAIN ABOVE NORMAL AS IT DOESN'T LOOK LIKE ANY
SIGNIFICANT AIRMASS EXCHANGE TAKES PLACE THROUGH THE END OF THE
FORECAST PERIOD. WITH THIS ADDITIONAL POSSIBLE ROUND OF SHOWERS
AND THUNDERSTORMS, WE WILL HAVE TO PAY CLOSE ATTENTION TO ANY
THREAT OF FLOODING AS DORMANT VEGETATION SIMPLY WON'T SOAK UP
MULTIPLE ROUNDS OF PRECIPITATION LIKE IT WOULD IN THE WARM SEASON.
CAVANAUGH
PRELIMINARY POINT TEMPS/POPS
BATESVILLE AR 25 47 34 52 / 0 0 0 10
CAMDEN AR 26 54 34 61 / 0 0 0 0
HARRISON AR 26 49 35 52 / 0 0 0 20
HOT SPRINGS AR 26 50 34 53 / 0 0 0 10
LITTLE ROCK AR 28 50 35 56 / 0 0 0 10
MONTICELLO AR 28 53 35 61 / 0 0 0 0
MOUNT IDA AR 26 52 35 54 / 0 0 0 10
MOUNTAIN HOME AR 25 47 34 51 / 0 0 0 20
NEWPORT AR 26 46 33 51 / 0 0 0 10
PINE BLUFF AR 27 51 34 59 / 0 0 0 0
RUSSELLVILLE AR 26 50 34 53 / 0 0 0 10
SEARCY AR 25 48 32 53 / 0 0 0 0
STUTTGART AR 28 49 35 56 / 0 0 0 0
LZK WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...CAVANAUGH
LONG TERM....CAVANAUGH
AVIATION...67
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