034
FXUS63 KDMX 201125
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
525 AM CST MON JAN 20 2025
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- ARCTIC COLD SNAP CONTINUES. HIGH CONFIDENCE OF DANGEROUSLY
COLD WIND CHILLS OF -20F TO -35F TONIGHT INTO TUESDAY
MORNING.
- TEMPERATURES MODERATE MID-WEEK ALONG WITH CHANCES (20-30%) FOR
LIGHT SNOW WEDNESDAY AND AGAIN LATE THURSDAY. ACCUMULATIONS
WILL BE AN INCH OR LESS, BUT LOCALIZED MINOR TRAVEL IMPACTS
CANNOT BE RULED OUT.
DISCUSSION
ISSUED AT 243 AM CST MON JAN 20 2025
A DEEP, BROAD UPPER TROUGH NOW BLANKETS MUCH OF THE CONUS WITH A 498
DAM 500MB LOW CAMPING OUT BETWEEN THE GREAT LAKES AND HUDSON
BAY. AT THE SURFACE A 1040+MB SURFACE HIGH REMAINS ANCHORED OVER
THE NORTHERN PLAINS WITH A RIDGE AXIS STRETCHING SOUTH AND
EAST. NORTHERLY WINDS TO THE EAST OF THE DEEP SFC HIGH WILL
CONTINUE TO FUNNEL ARCTIC AIR INTO THE REGION TODAY AS TEMPS
STRUGGLE AGAIN AND BITTER CONDITIONS DOMINATE. TEMP ADVECTION
IS NEARLY NEUTRAL AT THE MOMENT, BUT COLD AIR ADVECTION TAKES
OVER AGAIN BY LATE MORNING INTO THE AFTERNOON AS ANOTHER
SHORTWAVE TROUGH ROUNDS THE PARENT UPPER LOW. LOW LEVEL CLOUD
COVER WILL INCREASE ALONG WITH THE POTENTIAL FOR MORE HCRS AND
SCATTERED FLURRIES AS THE TOP OF THE MIXED LAYER CROSSES THE
FROST POINT. THE COLD SNAP PEAKS TONIGHT AND WINDS RELAX A BIT
AS THE SFC HIGH DISLODGES EASTWARD. TEMPS RAPIDLY FALL AS CLOUD
COVER DISSIPATES AND CONDITIONS BECOME MORE FAVORABLE FOR
EFFICIENT RADIATIONAL COOLING. STATISTICAL GUIDANCE CONTINUES
TO BE MORE AGGRESSIVE THAN NBM OUTPUT AND ADVERTISES LOWS AS
COLD AS -20 OR COLDER OVER NORTHERN IOWA. STUCK WITH NBM FOR NOW
DUE TO UNCERTAINTIES WITH 5-10 MPH WIND BEING JUST ENOUGH TO
KEEP THE BOTTOM FROM COMPLETELY FALLING OUT ON TEMPS. THE
LIGHTER WINDS COMBINED WITH THE BITTER COLD TEMPS STILL PUSH
WIND CHILLS INTO DANGEROUS TERRITORY WITH -20F TO -35F WIND
CHILLS LIKELY.
WARM AIR ADVECTION RAMPS UP TUESDAY BENEATH BUILDING HEIGHTS ALOFT
AND WILL FINALLY BEGIN TO PULL US OUT OF THE COLD SNAP AS THE ARCTIC
AIRMASS IS SHUNTED EAST. TEMPS STEADILY RISE THROUGH SINGLE DIGITS
AND TEENS DURING THE DAY AND HOLD STEADY OR FURTHER WARM A BIT
MORE INTO TUESDAY NIGHT. HIGHS SHOULD THEN GENERALLY BE RIGHT
AROUND SEASONAL NORMS WEDNESDAY THROUGH THE REMAINDER OF THE
WEEK. MEAN NORTHWESTERLY FLOW ALOFT REMAINS ACTIVE AS A FEW
SHORTWAVES TRACK THROUGH THE REGION AND DELIVER OPPORTUNITIES
FOR LIGHT PRECIPITATION. THE FIRST WINDOW IS TUESDAY NIGHT INTO
WEDNESDAY AS THERMAL FORCING ACTIVATES A MID-LEVEL FGEN BAND
SLIDING NW TO SE THROUGH THE STATE. GEFS AND ECENS STILL SHOW
30-60% CHANCE FOR MEASURABLE PRECIP WITH THE HIGHEST CHANCES
NORTH, AND HAVE ALSO BEGUN TO SHOW LOW PROBS (10-20%) FOR UP TO
1" OF SNOW ACCUMULATION. HEDGING A BIT TOWARD THE DRIER SIDE OF
GUIDANCE GIVEN THAT MOISTURE WILL LIKELY BE A SCARCE COMMODITY
IN THE IMMEDIATE WAKE OF THE EXTREMELY DRY ARCTIC AIRMASS.
ANOTHER WAVE DROPS THROUGH LATE THURSDAY AND MAY BRING ANOTHER
ROUND OF LIGHT SNOW AND/OR FLURRIES, MAINLY WEST. MODELS START
TO DIVERGE MORE NOTABLY TOWARD THE WEEKEND AS THE UPPER FLOW
FLATTENS OUT. SPURIOUS LOW AMPLITUDE WAVES COULD DELIVER
ANOTHER OPPORTUNITY FOR LIGHT PRECIPITATION, BUT CONFIDENCE IN
TIMING AND LOCATION OF THESE DISTURBANCES IS NOT HIGH ENOUGH TO
DEVIATE AWAY FROM THE DRY NBM AT THIS POINT.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 524 AM CST MON JAN 20 2025
VFR CONDITIONS CURRENTLY PREVAIL ACROSS THE FORECAST AREA. ANOTHER
WAVE OF BROKEN TO OVERCAST LOW STRATUS CLOUDS WILL MOVE IN FROM THE
NORTH AFTER 15Z AND BLANKET THE AREA BEFORE BREAKING UP BY LATE
AFTERNOON OR EARLY EVENING. CIGS WILL GENERALLY BE RIGHT AROUND MVFR
THRESHOLDS WITH THE LOWEST CIGS AND HIGHEST CONFIDENCE OF MVFR
CONDITIONS AT KMCW AND KALO. CIGS ARE CURRENTLY FORECAST TO BE JUST
ABOVE 3K FT TO THE SOUTH AND WEST. SCATTERED FLURRIES ARE EXPECTED
TO DEVELOP WITHIN THE STRATUS CLOUD COVER AS WELL BUT SHOULD NOT
RESULT IN CATEGORICAL DEGRADATION. WINDS BECOME GUSTY OUT OF THE
NORTHWEST AGAIN TODAY BEFORE RELAXING AND BECOMING MORE WESTERLY
TONIGHT.
DMX WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR
IAZ004>007-015>017-023>028-033>039-044>050-057>059-070-071.
COLD WEATHER ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT CST
TONIGHT FOR IAZ004>007-015>017-023>028-033>039-044>050.
EXTREME COLD WARNING FROM MIDNIGHT TONIGHT TO 9 AM CST TUESDAY
FOR IAZ004>007-015>017-023>028-033>039-044>050.
COLD WEATHER ADVISORY FROM 6 PM THIS EVENING TO 9 AM CST
TUESDAY FOR IAZ057>062-070>075-081>086-092>097.
DISCUSSION...MARTIN
AVIATION...MARTIN
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