446
FXUS63 KDMX 152333
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
533 PM CST WED JAN 15 2025
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
KEY MESSAGES
- FEW FLURRIES/FREEZING SPRINKLES POSSIBLE NORTH AND EAST. NO
ACCUMULATIONS EXPECTED.
- MILDER TEMPERATURES TOMORROW AND FRIDAY
- FRIGID COLD TEMPERATURES MOVE INTO THE AREA SATURDAY THROUGH
MONDAY, WITH OVERNIGHT WIND CHILLS IN THE MINUS TEENS TO MINUS
TWENTIES.
DISCUSSION
ISSUED AT 156 PM CST WED JAN 15 2025
THIN STRATUS CONTINUES TO FESTER OVERHEAD TODAY, LEADING TO
BROKEN SUNSHINE OVER MUCH OF THE AREA EARLY THIS AFTERNOON. UP
ABOVE THE STRATUS, WE SEE PATCHES OF MID-LEVEL CLOUD COVER
SLOWLY DRIFTING OVERHEAD, INDICATIVE OF THE APPROACHING WAVE TO
OUR NORTH WHICH WILL BRING THE CHANCE FOR SOME VERY LIGHT
PRECIPITATION LATE THIS AFTERNOON AND EVENING. RADAR RETURNS ARE
ALREADY VISIBLE UPSTREAM OVER EASTERN SD AND CENTRAL MN, WITH
OFFICES TO OUR NORTHEAST REPORTING A MIX OF FLURRIES AND
FREEZING SPRINKLES BENEATH THEM, BUT WITH MINIMAL IMPACTS. THE
COVERAGE OF THESE RETURNS IS OUTPERFORMING GUIDANCE SOMEWHAT,
SUGGESTING WE MIGHT BE GETTING A BIT BETTER SATURATION THAN WHAT
THE MODELS HAD BEEN THINKING. FOR THIS REASON, HAVE EXPANDED
THE FLURRY/SPRINKLE MENTION A BIT FURTHER SOUTH AND WEST FOR
THIS AFTERNOON AND EVENING. STILL NOT EXPECTING MUCH FOR
IMPACTS OR ACCUMULATIONS ASIDE FROM ISOLATED SLICK SPOTS WITH
ANY FREEZING SPRINKLES THAT CAN REACH THE SURFACE.
BEHIND THIS TROUGH PASSAGE, WINDS SHIFT TO MORE WEST
NORTHWESTERLY AS SURFACE RIDGING BUILDS TO OUR WEST. THIS WILL
KEEP THE STATE IN A GENERAL WARM AIR ADVECTION REGIME, BOOSTING
TEMPERATURES ON THURSDAY INTO THE MID 30S. HOWEVER, QUICK ON THE
HEELS OF TONIGHT’S WAVE WILL BE ANOTHER AREA OF LOW PRESSURE
MOVING INTO THE AREA LATE THURSDAY INTO FRIDAY, FLIPPING FLOW TO
MORE SOUTHERLY AND BOOSTING THE WARM AIR ADVECTION EVEN MORE.
THIS WILL LEAD TO UNSEASONABLY WARM HIGHS ON FRIDAY BEFORE A
COLD FRONT SWEEPS DOWN INTO THE STATE LATER IN THE DAY. THAT
SAID, THE BOUNDARY IS CURRENTLY SLATED TO ARRIVE IN NORTHWESTERN
IOWA BY MID-DAY FRIDAY, WHICH MAY LIMIT HIGH TEMPERATURES SOME
FOR THOSE FURTHER NORTH AND WEST IN THE STATE. THE COLDER AIR
WILL LAG SOMEWHAT BEHIND THE ACTUAL WIND SHIFT, SO THE
TEMPERATURE DIFFERENCE WON’T BE TOO ABRUPT, BUT CLOUD COVER
ALONG THE BOUNDARY AND THE SWITCH FROM WARM SOUTHERLY FLOW TO
NEUTRAL/COLD NORTHWESTERLY FLOW WILL MITIGATE HEATING ONCE THIS
BOUNDARY IS THROUGH. THEREFORE, THE WARMEST TEMPERATURES WILL
LIKELY RESIDE FURTHER SOUTH IN THE STATE WHERE THE BOUNDARY
DOESN’T ARRIVE UNTIL AFTER SUNSET. THE NAM HAS ALSO BEGUN TO
PRODUCE A BIT OF PRECIPITATION ALONG THIS BOUNDARY AS IT PASSES
THROUGH ON FRIDAY, BUT SOUNDINGS INDICATE THIS IS PRIMARILY
DRIVEN BY A FEW HOURS OF ~1 KM DEEP SATURATION NEAR THE SURFACE
WITH A MODERATE AMOUNT OF LIFT ALONG THE BOUNDARY, WHICH WOULD
SUGGEST MORE OF A DRIZZLE/FREEZING DRIZZLE SIGNATURE. THE NAM
TENDS TO OVER-SATURATE THE LOW LEVELS, AND IS THE ONLY MODEL
SHOWING THIS AT THIS TIME, BUT CERTAINLY SOMETHING TO KEEP AN
EYE ON AS WE GET INTO THE HIGHER RESOLUTION WINDOW OVER THE NEXT
TWO DAYS.
BROAD UPPER LEVEL TROUGHING WILL SET UP AS WE GET INTO THE
WEEKEND, WITH MULTIPLE LOBES OF ENERGY PROPAGATING THROUGH IT.
AT THE SURFACE, THIS WELL RESULT IN A CONSTANT BARRAGE OF COLD
AIR WHICH WILL CAUSE TEMPERATURES TO PLUMMET THROUGH THE WEEKEND
AND INTO EARLY NEXT WEEK. TODAY’S GUIDANCE HAS COME IN COLDER
THAN PREVIOUS DAYS, BUT WITH THE COLDEST DAYS STILL BEING SUNDAY
INTO MONDAY. OVERNIGHT LOWS WILL DROP INTO THE TEENS TO SINGLE
DIGITS BELOW ZERO AND DAYTIME HIGHS ONLY REACH THE SINGLE DIGITS
ABOVE ZERO. WIND CHILLS WILL BE PARTICULARLY COLD MULTIPLE
NIGHTS IN A ROW, WITH -10S SOUTH TO -20S NORTH, AND EVEN A FEW
AREAS PUSHING -30 IN FAR NORTHERN IOWA. WHILE SUNDAY AND MONDAY
WILL BE THE COLDEST DAYS, SATURDAY WON’T BE COMFORTABLE EITHER,
AS COLD AIR ADVECTION WITH TIGHTENED PRESSURE GRADIENTS PRODUCE
WINDY CONDITIONS WITH THE COOLING TEMPERATURES. FORTUNATELY,
WHILE WINDS REMAIN LIGHT TO BREEZY, THEY WILL BE STEADILY
DIMINISHING INTO SUNDAY AND MONDAY WHILE THE TEMPERATURES GET
COLDER. AS WE GET INTO NEXT WEEK, RIDGING BEGINS TO BUILD AGAIN
TO THE WEST, WHICH SHOULD HELP TO END OUR COLD SPELL AND BRING
TEMPERATURES NEARER TO NORMAL AGAIN BY MID- WEEK.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 533 PM CST WED JAN 15 2025
SYSTEM PROGRESSES ACROSS THE STATE THIS EVENING WITH VFR
CEILINGS PASSING SOUTH THROUGH IOWA. A FEW FLURRIES OR SPRINKLES
MAY OCCUR BRIEFLY BUT SHOULD BE MINIMAL IN DURATION. ONCE THE
SYSTEM PASSES THIS EVENING VFR CONDITIONS ARE FORECAST WITH
UNRESTRICTED VISIBILITIES AND ANY CEILINGS REMAINING VFR.
SOUTHWEST SURFACE WINDS BECOME NORTHWEST BEHIND THE FRONT AS IT
PASSES THROUGH IOWA WITH THE WINDS REMAINING NORTHWEST INTO
THURSDAY.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...DODSON
AVIATION...COGIL
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