164
FXUS63 KDMX 160848
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
248 AM CST THU JAN 16 2025
KEY MESSAGES
- WARMER TODAY AND INTO FRIDAY WITH HIGHS IN THE MID 30S TO MID 40S.
- SHARPLY COLDER THIS WEEKEND INTO EARLY NEXT WEEK. DANGEROUS
WIND CHILLS OF -20F OR COLDER AT TIMES SUNDAY INTO MONDAY,
ESPECIALLY OVER NORTHERN IOWA.
- FORECAST REMAINS DRY THROUGH THE NEXT 7 DAYS.
DISCUSSION
ISSUED AT 243 AM CST THU JAN 16 2025
TEMPERATURES ARE CONSIDERABLY WARMER THAN THIS TIME YESTERDAY AS
WARM AIR ADVECTION HAS EFFECTIVELY SCOURED OUT THE PREVIOUS COLD AIR
MASS. TEMPS OVERNIGHT ARE IN THE 20S AND 30S WITH THE WARMEST
READINGS ACTUALLY ON THE BACKSIDE OF A FRONTAL BOUNDARY NOSING INTO
THE WESTERN CWA. THE AIRMASS BEHIND THE FRONT IS HIGHLY MODIFIED
WITH WESTERLY DOWNSLOPE TRAJECTORIES AND ADIABATIC WARMING DOWN THE
HIGH PLAINS. THUS DESPITE WEST/NORTHWEST WINDS TEMPERATURES WILL
CONTINUE TO MARCH UPWARD TODAY WITH AFTERNOON HIGHS IN THE MID 30S
TO LOW 40S. A SWITCH TO SOUTHERLY WINDS WILL FURTHER BOOST
TEMPERATURES A BIT MORE FRIDAY WITH HIGHS IN THE LOW TO MID 40S.
FRIDAY HIGHS MAY BE ACHIEVED EARLY IN THE DAY AS SUBSTANTIAL
CHANGES ARE AFOOT WHICH WILL SEND TEMPERATURES INTO A NOSE DIVE
THROUGH THE WEEKEND INTO EARLY NEXT WEEK. A VIGOROUS SHORTWAVE
DIVING SOUTH OUT OF CANADA WILL WORK TO CARVE OUT A DEEPER
LONGWAVE TROUGH OVER THE EASTERN TWO-THIRDS OF THE CONUS AND
DISLODGE A ARCTIC AIR MASS ALL THE WAY TO THE GULF COAST. OUR
INITIAL COLD FRONTAL PASSAGE SLIDES THROUGH FRIDAY AFTERNOON,
ALTHOUGH THIS WILL NOT FEATURE MUCH OF A BAROCLINIC PUNCH AND
MOSTLY SERVE AS A WIND SWITCH TO THE NORTHWEST. A MUCH MORE
ROBUST PUSH OF COLD AIR ADVECTION ARRIVES FRIDAY EVENING INTO
FRIDAY NIGHT WHICH WILL FEATURE SHARPLY FALLING TEMPERATURES AND
GUSTY NORTHWEST WINDS. MODEL SOUNDINGS SHOW WINDS NEAR THE TOP
OF THE MIXED LAYER BETWEEN 30-40 KTS WITH THE STRONGEST VALUES
NORTH. THE CAA REGIME + PRESSURE RISES WILL BE FAVORABLE TO
TRANSPORT THIS HIGHER MOMENTUM AIR TO THE SURFACE AND PRODUCE
WIND GUSTS OF 30 TO 40 MPH. HRRR SHOWS SOME SHOWERY ELEMENTS
DROPPING SOUTH INTO THE STATE FRIDAY NIGHT AS THE CLOUD-BEARING
LAYER AND STEEP LOW LEVEL LAPSE RATES FALL THROUGH THE DGZ. NOT
CONFIDENT THAT MOISTURE AVAILABILITY WILL BE SUFFICIENT FOR ANY
PRECIP PRODUCTION, SO OPTING TO LEAVE THE FORECAST DRY FOR NOW.
THE COLD AIR ADVECTION CONTINUES THROUGH THE WEEKEND AS 850MB TEMPS
FALL TO -20C TO -30C OVER THE STATE. NBM CONTINUES TO TREND SLIGHTLY
COLDER AS IT CATCHES UP TO THE MEAN OF THE GUIDANCE ENVELOPE THROUGH
THIS PERIOD. HIGHS SATURDAY WILL ONLY BE IN THE TEENS FOLLOWED BY
THE SINGLE DIGITS FOR SUNDAY INTO MONDAY. SOME LOCATIONS IN FAR
NORTHERN IOWA MAY NOT EVEN MUSTER ABOVE ZERO. BRISK NORTHWEST WINDS
DROP WIND CHILL VALUES EVEN COLDER WITH ADVISORY-LEVEL WIND CHILLS
BELOW -20F LOOKING INCREASINGLY LIKELY SUNDAY INTO MONDAY,
ESPECIALLY OVER THE NORTHERN HALF OF THE CWA. THIS IS AN
IMPRESSIVELY COLD AIRMASS, AND FORTUNATELY THE REGION IS NOT
BLANKETED BY A WIDESPREAD SNOW PACK OR TEMPERATURES WOULD BE
CONSIDERABLY COLDER. ROUNDS OF STRATUS CLOUDS ARE LIKELY WITHIN THIS
ARCTIC REGIME, BUT FINDING TARGETS FOR POSSIBLE LIGHT SNOWFALL
ACTIVITY IS DIFFICULT GIVEN THE VERY DRY NATURE OF THE AIRMASS AND
TEMPERATURES FALLING BELOW THE DGZ THROUGH THE ENTIRE COLUMN.
THE COLD SNAP IS NOT PROLONGED AS A PROGRESSIVE PATTERN AND
SHORTWAVE RIDGING SCOURS OUT THE ARCTIC AIRMASS BY MID-WEEK. NBM
QUICKLY REBOUNDS TEMPERATURES CLOSER TO SEASONAL AVERAGES WITH
HIGHS IN THE LOW TO MID 30S. PRECIPITATION CHANCES REMAIN MUTED,
ALTHOUGH DETERMINISTIC MODELS SUGGEST A POSSIBLE WINDOW TOWARD
NEXT WEDNESDAY AND THURSDAY AS A SHORTWAVE TROUGH AXIS MOVES
THROUGH. ENSEMBLE MEMBERSHIP IS MAJORITY DRY AT THAT JUNCTURE,
BUT TRENDS WILL NEED TO BE WATCHED IN THE DAYS AHEAD.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1050 PM CST WED JAN 15 2025
GENERALLY VFR CONDITIONS FOR MUCH OF THE TAF PERIOD ACROSS
CENTRAL IOWA WITH MAINLY VFR CEILINGS. SOME MVFR CEILINGS MAY
GRAZE THE FAR NORTHEAST CORNER OF THE AREA ON THURSDAY.
VISIBILITIES REMAIN UNRESTRICTED WITH WEST TO NORTHWEST WINDS
INTO THURSDAY BEFORE BECOMING SOUTH ON THURSDAY EVENING.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MARTIN
AVIATION...COGIL
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