772
FXUS63 KDMX 162351
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
551 PM CST THU JAN 16 2025
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
KEY MESSAGES
- CONTINUED WARM INTO FRIDAY, BUT TURNING WINDY AND COLDER
FRIDAY NIGHT
- MOST SIGNIFICANT ARCTIC AIR OF THE SEASON COMING WITH
PROLONGED BITTER COLD THIS WEEKEND THROUGH TUESDAY
- <=30% CHANCE OF MEASURABLE LIGHT RAIN OR LIGHT SNOW FRIDAY
AFTERNOON AND EVENING, OTHERWISE MAINLY DRY THROUGH THE PERIOD
(THU 23RD).
DISCUSSION
ISSUED AT 342 PM CST THU JAN 16 2025
MILD, ZONAL FLOW WAS IN PLACE ACROSS THE MIDWEST BUT THAT WILL
TURN TO A COLD, EXPANSIVE CENTRAL CONUS MEAN TROUGH WITH H5
HEIGHTS DOWN TO 516 DAM OR LESS BY LATE THE WEEKEND. THE
INTRODUCTORY MECHANISM WILL BE AN ELONGATED PV ANOMALY ACROSS
THE SOUTHWESTERN CANADIAN PROVINCES THIS AFTERNOON WITH AN
ASSOCIATED SURFACE LOW JUST AHEAD. BY MIDDAY TOMORROW THE
SURFACE LOW SHOULD BE OVER SOUTHERN ONTARIO WITH ITS ATTENDANT
SURFACE TROUGH AND WIND SHIFT PASSING THROUGH IOWA. TEMPS TODAY
WERE TOWARD THE EXTREME HIGH END OF THE GUIDANCE ENVELOP AND
EXPECT SIMILAR CONDITIONS FRIDAY WITH HIGHS WELL INTO THE 40S.
THE TRUE COLD FRONT WILL ARRIVE ACROSS NORTHERN IOWA BY SUNSET
HOWEVER USHERING IN MUCH COLDER TEMPERATURES AND GUSTY NORTHWEST
WINDS. THE COLD ADVECTION AND STEEP LOW LEVEL LAPSE RATES MAY
TRIGGER SOME WEAK CONVECTION WITH EITHER LIGHT SNOW OR RAIN
SHOWERS DEPENDING ON TEMPS, WHICH MAY LINGER INTO THE EVENING
SOUTH IN THE FORM OF FLURRIES OR LIGHT SNOW SHOWERS. WINDS MAY
GUST TO 35 MPH OR MORE NORTH FRIDAY NIGHT.
THE MAIN WEATHER STORY OF THE PERIOD, A PROLONGED PERIOD OF
ARCTIC AIR, WILL BECOMING ENTRENCHED ACROSS IOWA AND THE MIDWEST
THIS WEEKEND THROUGH TUESDAY, DRIVEN BY ANOMALOUSLY HIGH
NORTHERN ROCKIES/CANADIAN SURFACE HIGH PRESSURE AND AN EXTENDED
PERIOD OF REINFORCING NORTHWEST FLOW AT LOW LEVELS. WIDESPREAD
BELOW ZERO LOWS ARE EXPECTED FOR THREE NIGHTS (SAT NIGHT-MON
NIGHT) WITH HIGHS NO BETTER THAN THE SINGLE DIGITS ABOVE ZERO
SUN AND MON. COLD WEATHER ADVISORIES (REPLACEMENT OF WIND CHILL
ADVISORIES) WILL LIKELY BE NEEDED AT LEAST OFF AND ON THROUGH
THIS PERIOD.
THE PATTERN SHOULD BEGIN TO MODIFY HEADING INTO TUESDAY WHEN THE
LAST SHORT WAVE ENTERS THE BASE OF THE LONG WAVE TROUGH FOLLOWED
BY RISING HEIGHTS INTO MIDWEEK. CONFIDENCE IN HOW THIS EVOLVES
IS NOT GREAT WITH CLUSTER ANALYSIS SHOWING A FAIRLY EVEN
DISTRIBUTION AMONG MEMBERS, HOWEVER MOST SOLUTIONS SUGGEST A
MILDER TREND BACK TOWARD NORMAL TEMPS. WITH NO GREAT FEEL ON
SHORT WAVE TRACK OR STRENGTH, THE FORECAST REMAINS DRY FOR THE
MOMENT. HOWEVER ONE WINDOW TO WATCH IS WED NIGHT INTO THU. 12Z
EPS AND GEFS PROBABILITIES FOR MEASURABLE PRECIPITATION ARE
AROUND 40% NORTH, SO THIS WOULD BE A WINDOW TO MONITOR IF THOSE
TRENDS PERSIST THROUGH FUTURE MODEL CYCLES.
AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 551 PM CST THU JAN 16 2025
RIDGE AXIS IS CURRENTLY PASSING OVER THE STATE WITH WEST
NORTHWEST SURFACE WINDS BECOMING SOUTHWEST. THESE WINDS BECOME
SOUTHERLY OVERNIGHT WITH NON-CONVECTIVE LOW LEVEL WIND SHEAR
DEVELOPING EARLY FRIDAY MORNING AS A LOW LEVEL JET INTENSIFIES
AHEAD OF NEXT SYSTEM. OTHERWISE, VFR CONDITIONS ARE FORECAST
OVERNIGHT INTO FRIDAY MORNING WITH ONLY HIGH CIRRUS OVERHEAD. ON
FRIDAY, THE LOW LEVEL NON-CONVECTIVE WIND SHEAR IS EXPECTED TO
ABATE AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT SLIDES
QUICKLY SOUTH THROUGH THE STATE ON FRIDAY WITH WINDS BECOMING
NORTHWEST BY THE END OF THE PERIOD AND STRENGTHENING. CEILINGS
WILL ALSO DROP QUICKLY BEHIND THE FRONT ON FRIDAY AFTERNOON.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...SMALL
AVIATION...COGIL
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