958
FXUS63 KDMX 211140
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
540 AM CST TUE JAN 21 2025
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- DANGEROUSLY LOW WIND CHILLS INTO THIS MORNING WITH IMPROVING
CONDITIONS BY MIDDAY.
- CHANCES (30-50%) FOR FLURRIES/LIGHT SNOW EXPECTED LATE TONIGHT
INTO WEDNESDAY ACROSS MUCH OF CENTRAL IOWA. LIGHT
ACCUMULATIONS EXPECTED.
- TEMPERATURES REMAIN ON A ROLLER COASTER INTO THE WEEKEND BUT
CLOSER TO NORMAL THAN CURRENT READINGS. LITTLE THREAT OF
PRECIPITATION DURING THIS TIME.
DISCUSSION
ISSUED AT 427 AM CST TUE JAN 21 2025
IOWA IS IN THE GRIPS OF AN ARCTIC AIRMASS EARLY THIS MORNING WITH
NEARLY -33C AIR AT 850MB SLIDING ACROSS NORTHERN IOWA CURRENTLY. AIR
TEMPERATURES ARE GENERALLY FROM -10 TO -20 ACROSS THE AREA WITH WIND
CHILLS OF -25 TO -35. THE ONLY UPSIDE DURING THIS BITTER COLD
PERIOD IS THAT IT WOULD LIKELY HAVE BEEN SUBSTANTIALLY COLDER HAD AN
EXTENSIVE SNOW PACK BEEN IN PLACE ACROSS THE STATE. THAT BEING
SAID, THE BARE SOIL IS LIKELY TO ALLOW FROST TO PENETRATE RATHER
DEEP INTO THE GROUND. THE EXTREME COLD WARNING HAS BEEN EXPANDED TO
THE SOUTH TO INCLUDE THE ENTIRE FORECAST AREA EXPECT THE FAR
SOUTHERN TIER OF COUNTIES WHICH REMAIN ADVISORY THROUGH NOON. WITH
THE THERMAL TROF CURRENTLY ON TOP OF THE STATE AND EXPECTED TO MOVE
EAST, WARM ADVECTION INCREASES THROUGH THE DAY. THIS WILL LEAD TO
RISING TEMPERATURES THROUGH THE DAY UNDER SUNNY SKIES AND
STRENGTHENING SOUTHWEST SURFACE FLOW.
THE WARM ADVECTION PERSISTS INTO TONIGHT AHEAD OF THE NEXT SHORTWAVE
DROOPING SOUTHEAST INTO THE REGION ON THE BACKSIDE OF THE LONGWAVE
TROF ESTABLISHED ACROSS THE EASTERN UNITED STATES. THEREFORE, NON-
DIURNAL TEMPERATURES ARE ANTICIPATED OVERNIGHT WITH STEADY TO SLOWLY
RISING READINGS AND SOUTHWEST SURFACE FLOW PERSISTS ALONG WITH
THICKENING CLOUDS. STRONG ISENTROPIC LIFT IS EXPECTED BY THIS
EVENING INTO THE OVERNIGHT ASSOCIATED WITH THE WARM ADVECTION
DROPPING FROM MINNESOTA INTO IOWA. CONDENSATION PRESSURE DEFICITS
LOWER RAPIDLY INTO THE OVERNIGHT WITH THIS LIFT AND SOME FLURRIES TO
LIGHT SNOW CHANCES (30-50%) INCREASE ACROSS THE NORTH AFTER
MIDNIGHT. ON WEDNESDAY, STRONG MID LEVEL KINEMATIC FORCING ARRIVES
WITH THE SHORTWAVE AND THE LIFT IS EXPECTED TO SQUEEZE OUT FLURRIES
AND LIGHT SNOW ACROSS MUCH OF CENTRAL INTO SOUTHERN IOWA DURING THE
DAY WITH SOME LIGHT ACCUMULATIONS EXPECTED (70-80%) OF GENERALLY AN
INCH OR LESS.
THE FORCING SUBSIDES INTO WEDNESDAY EVENING WITH ANY LINGERING LIGHT
SNOW/FLURRIES ENDING ACROSS THE SOUTHEAST. OTHERWISE, RENEWED COLD
ADVECTION INCREASES INTO WEDNESDAY NIGHT AND THURSDAY BUT NOT NEARLY
TO THE EXTENT OF THE CURRENT COLD PUSH. THE UPPER FLOW REMAINS
BROADLY FROM THE NORTHWEST INTO THE WEEKEND AND EARLY NEXT WEEK WITH
ANOTHER ROUND OF WARMING FRIDAY INTO EARLY SATURDAY THEN ANOTHER
PUSH OF COLDER AIR FOR THE SECOND HALF OF THE WEEKEND. AT THIS
POINT, LITTLE PRECIPITATION IS EXPECTED GIVEN THE GENERAL LACK OF
MOISTURE.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 540 AM CST TUE JAN 21 2025
GENERALLY WIDESPREAD VFR CONDITIONS FOR MUCH OF THE PERIOD WITH
UNRESTRICTED VISIBILITIES. CEILINGS ARE INITIALLY UNRESTRICTED
WITH INCREASING CLOUDS LATER TONIGHT WITH LOWERING CEILINGS IN
ADVANCE OF AN APPROACHING SHORTWAVE. LOW CHANCES OF SNOW ARRIVE
IN NORTHERN IOWA LATE TONIGHT ALONG WITH THE INCREASING THREAT
OF MVFR CEILINGS. SURFACE WINDS STRENGTHEN FROM THE SOUTHWEST
TODAY REMAINING STRONG TONIGHT FROM THE SOUTH.
DMX WATCHES/WARNINGS/ADVISORIES
EXTREME COLD WARNING UNTIL NOON CST TODAY FOR IAZ004>007-
015>017-023>028-033>039-044>050-057>062-070>075-081>086.
COLD WEATHER ADVISORY UNTIL NOON CST TODAY FOR IAZ092>097.
DISCUSSION...COGIL
AVIATION...COGIL
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