204
FXUS63 KABR 231124
AFDABR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
524 AM CST MON DEC 23 2024
KEY MESSAGES
- AREA OF LIGHT WINTRY MIX OF PRECIPITATION MOVES ACROSS NORTHEAST
SOUTH DAKOTA THIS MORNING. LITTLE TO NO ACCUMULATION IS EXPECTED.
PRECIPITATION IS EXPECTED TO BE OUT OF THE AREA AROUND DAYBREAK THIS
MORNING.
- THERE IS AROUND A 30% CHANCE OF LIGHT RAIN FORECAST FRIDAY INTO
EARLY SATURDAY OVER MAINLY EASTERN SD AND WESTERN MN.
- TEMPERATURES WILL RUN AROUND 5 TO 20 DEGREES ABOVE NORMAL THROUGH
NEXT MONDAY.
UPDATE
ISSUED AT 524 AM CST MON DEC 23 2024
AVIATION DISCUSSION HAS BEEN UPDATED BELOW IN ACCORDANCE WITH THE
12Z TAF ISSUANCE.
SHORT TERM /TODAY THROUGH TUESDAY AFTERNOON/
ISSUED AT 241 AM CST MON DEC 23 2024
AS OF THE TIME OF THIS WRITING (~2 AM), PRECIPITATION IS MOVING
INTO THE AREA FROM NORTH DAKOTA. FREEZING RAIN AND SNOW ARE THE
EXPECTED PRECIPITATION TYPES OUT OF THIS SYSTEM PER MODEL
SOUNDINGS. HOWEVER, ATTEMPTING TO DISTINGUISH BETWEEN THE TWO IS
TRICKY BECAUSE THERE IS NOT GREAT AGREEMENT ON WHAT THE MOISTURE
ALOFT IS DOING. LIMITED OBSERVATIONS ARE AVAILABLE AT THIS TIME,
AND WHILE WEBCAMS SHOW PRECIPITATION, IT IS TRICKY TO ATTEMPT TO
DETERMINE PRECIP TYPE WHEN THEY SHOW NO ACCUMULATION ON THE ROADS.
RADAR RETURNS UP TO 10K FEET AGL SUGGEST SOME LEVEL OF MOISTURE
ALOFT, WHICH ACCORDING TO MODEL SOUNDINGS IS ON THE LOWER EDGE OF
THE DGZ AND THEREFORE LIKELY TO BE PRODUCING ICE CRYSTALS.
SOUNDINGS ALSO SUGGEST THAT THERE IS STILL A WARM LAYER NEAR THE
SURFACE, WHICH IS SUPPORTED BY THE CC AND PRODUCT SHOWING SOME
MELTING BELOW ~4K FEET AGL. THIS WOULD SUGGEST THAT FREEZING RAIN
IS THE MOST LIKELY SURFACE PRECIPITATION TYPE, BUT IN REALITY
THERE IS PROBABLY SOME SNOW MIXED IN THERE TOO. COOLER AIR AT THAT
LEVEL IS EXPECTED TO MOVE IN OVER THE NEXT FEW HOURS, SO WHEN
THAT HAPPENS EXPECT A CHANGEOVER TO SNOW AS THE DOMINANT
PRECIPITATION TYPE. THE SYSTEM IS EXPECTED TO WEAKEN AS IT
PROGRESSES OVER NORTHEASTERN SOUTH DAKOTA TONIGHT AND BE CLEAR OF
THE FORECAST AREA AROUND DAYBREAK.
CLOUDY CONDITIONS TODAY DUE TO A LOW STRATUS DECK LINGERING OVER THE
AREA. THERE ARE CHANCES FOR SOME PATCHY FOG TO FORM THIS MORNING
ALONG THE WESTERN EDGE OF THE STRATUS DECK, WHICH LIKELY SETS UP
OVER CENTRAL SOUTH DAKOTA. THESE CLOUDS WILL KEEP HIGHS OVER
NORTHEASTERN SD/WESTERN MN TO THE 20S TODAY, WHILE THE MID 30S TO
LOW 40S ARE EXPECTED OVER CENTRAL SOUTH DAKOTA. PERSISTENT CLOUDS
WILL KEEP OVERNIGHT LOWS IN THE TEENS TO LOW 20S ACROSS THE FORECAST
AREA.
MONDAY NIGHT INTO TUESDAY MORNING, A COUPLE CAMS HAVE PICKED UP
POTENTIAL FOR SOME LIGHT PRECIPITATION ALONG A FRONTAL BOUNDARY OVER
THE WESTERN PART OF THE FORECAST AREA. HAVE OPTED TO KEEP ONLY
SLIGHT CHANCE POPS IN THE FORECAST FOR NOW AND WILL MONITOR TRENDS
IN THE CAMS MOVING FORWARD TO DETERMINE HOW THOSE CHANCES WILL
EVOLVE.
LONG TERM /TUESDAY EVENING THROUGH SUNDAY/
ISSUED AT 241 AM CST MON DEC 23 2024
OUR OSCILLATING WAVES AT 500MB CONTINUE AT 00Z WEDNESDAY, WITH A
TROUGH OVER MN/IA AND EASTERN SD AND A RIDGE SET UP OVER EASTERN MT
THROUGH THE WESTERN DAKOTAS DOWN THROUGH NM, AND YET ANOTHER TROUGH
ONSHORE FROM WA DOWN THROUGH CA. LOW LEVEL MOISTURE WILL REMAIN
TRICKY, WITH THE NAM GUIDANCE CONTINUING THE MOISTURE NEAR AND BELOW
900MB. THE OTHER SOLUTIONS ARE NOT AS ABUNDANT WITH THIS MOISTURE.
STILL, EVEN THE ENS VISIBILITY METEOGRAMS HAVE SHOWN OFF AND ON
VISIBILITY RESTRICTIONS DUE TO THE LOW LEVEL MOISTURE/FOG/OR ONGOING
PRECIPITATION. THIS LOWER VISIBILITY IS NOW MORE FOCUSED ON THURSDAY
AND FRIDAY THROUGH THE WEEKEND. THAT WOULD MAKE SENSE WITH THE RAIN
FRIDAY ADDING TO THE LOW LEVEL MOISTURE THROUGH THE WEEKEND. WINDS
SATURDAY NIGHT INTO SUNDAY, WITH 20-25KTS JUST ABOVE THE SURFACE,
MAY HELP TO KEEP THE ATMOSPHERE A BIT MIXED, AND LIMIT FOG SLIGHTLY.
FOG WILL NOT BE ADDED TO THE FORECAST THIS FAR OUT AT THIS TIME, BUT
WE'LL CONTINUE TO MONITOR FOR THE POTENTIAL. ANOTHER ITEM OF NOT
WITH THE WINDS WILL BE THE POTENTIAL FOR THE LOW LEVEL DRIFTING OF
SNOW OVER THE LEOLA HILLS OF MCPHERSON COUNTY SUNDAY. WHILE IT'S
CURRENTLY IN THE FORECAST, IT MAY NOT HAPPEN DUE TO WHAT AND HOW
MUCH PRECIPITATION IS OCCURRING OVER THAT AREA THIS MORNING. EVEN A
LIGHT FREEZING DRIZZLE OR FREEZING RAIN WILL COAT THE SNOW AND ACT
TO LIMIT THE MOVEMENT OF THE SNOW.
MOVING BACK TO THE MENTION OF RAIN ON FRIDAY, THE TROUGH OVER THE
WEST COAST TO START US OUT AT 00Z WEDNESDAY WILL DEVELOP A LOW NEAR
THE 4-CORNERS AREA OF THE INTERIOR SOUTHWEST DURING THE DAY
WEDNESDAY WILL SHIFT OVER THE CENTRAL PLAINS THURSDAY AS AN OPEN
WAVE. AS IT OPENS UP IT IS REINFORCED BY AN ADDITIONAL WAVE MOVING
IN FROM OUR WEST. THIS IS NOW ALLOWING PRECIPITATION TO MOVE MUCH
FARTHER NORTH. WHILE 850MB TEMPERATURES STAY ABOVE 0C, SURFACE
TEMPERATURES WHICH ARE CURRENTLY FORECAST TO BE A COUPLE OF DEGREES
ABOVE FREEZING, DO HAVE THE POTENTIAL TO BE CLOSER TO OR SLIGHTLY
BELOW FREEZING. THE ENS PRECIPITATION TYPE METEOGRAMS SHOW THIS
WELL, WITH A LOW CHANCE (5%) OF PRECIPITATION ON THE 12Z RUN.
HOWEVER IF PRECIPITATION DOES FALL IT WOULD BE FREEZING RAIN. RAIN,
WITH LESS THAN HALF OF THE SOLUTIONS AS WET SNOW, IS BEING INDICATED
AT WATERTOWN. WE'LL SEE HOW THESE SUBTLE DIFFERENCES CHANGE AS WE
GET CLOSER TO FRIDAY. A 20-40% CHANCE OF PRECIPITATION LOOKS
REASONABLE AT THIS TIME. JUST NOTE THAT PRECIPITATION TYPES MAY
CHANGE SLIGHTLY.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 524 AM CST MON DEC 23 2024
TERMINALS KABR,KATY,KPIR,KMBG
LIGHT WINTRY MIX OF PRECIPITATION CONTINUES TO FALL OVER
NORTHEASTERN SOUTH DAKOTA AND WESTERN MINNESOTA THIS MORNING. CLOUD
DECK HAS BEEN CONSISTENTLY MVFR THROUGH THE NIGHT AND THAT TREND IS
EXPECTED TO CONTINUE. SOME VISIBILITY REDUCTIONS DOWN TO 4SM AT
TIMES HAVE ALSO BEEN OBSERVED. EVEN AS PRECIPITATION MOVES OUT, LOW
CLOUDS ARE EXPECTED TO HANG AROUND THROUGH THE DAY TODAY, LIKELY
STILL PRODUCING MVFR CEILINGS.
THIS MORNING OVER NORTH CENTRAL SOUTH DAKOTA SOME PATCHY FOG LOOKS
TO BE IN PLACE BASED ON SATELLITE IMAGERY AND UPSTREAM OBSERVATIONS.
ONLY MINOR VISIBILITY REDUCTIONS WITH THAT THIS MORNING, AGAIN DOWN
TO 4SM. THE BIGGER FOG CONCERN WILL COME TOMORROW MORNING, WHERE
VISIBILITIES AND CEILINGS COULD POTENTIALLY REACH IFR OR LIFR AT THE
LOWEST. MODEL GUIDANCE CURRENTLY SUGGESTS LOW VISIBILITIES WILL BE
IN PLACE ACROSS MOST OF NORTHEAST AND CENTRAL SOUTH DAKOTA WELL
AFTER SUNRISE TUESDAY, ALTHOUGH THAT MAY BE UNREALISTIC DUE TO WINDS
INCREASING MARGINALLY (BUT POTENTIALLY ENOUGH TO DISPELL THE FOG)
DURING THAT TIME.
ABR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
UPDATE...BC
SHORT TERM...BC
LONG TERM...KF
AVIATION...BC
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