018
FXUS63 KDMX 171128
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
528 AM CST FRI JAN 17 2025
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES TODAY WITH HIGHS IN THE 40S.
- TURNING SHARPLY COLDER AS AN ARCTIC AIRMASS BLANKETS THE
REGION TONIGHT THROUGH EARLY NEXT WEEK. THE COLD SNAP PEAKS
SUNDAY INTO MONDAY WITH A HIGH PROBABILITY OF DANGEROUS WIND
CHILLS AT TIMES, ESPECIALLY OVER NORTHERN IOWA.
- FEW LIGHT RAIN/SNOW SHOWERS AND/OR FLURRIES POSSIBLE (20%
CHANCE) LATER THIS AFTERNOON INTO THIS EVENING. NO
ACCUMULATION OR TRAVEL IMPACTS EXPECTED. FORECAST IS DRY THIS
WEEKEND INTO AT LEAST THE FIRST HALF OF NEXT WEEK.
DISCUSSION
ISSUED AT 238 AM CST FRI JAN 17 2025
LOOKING AT ANOTHER MILD DAY ON THE HEELS OF YESTERDAY WHICH OUTRAN
TEMPERATURE GUIDANCE. SOUTH WINDS AND WARM AIR ADVECTION GIVE
TEMPS ANOTHER BOOST AND OPTED TO PUSH HIGHS TOWARD THE 90TH
PERCENTILE OF NBM GUIDANCE. THIS HAS EVERYONE SQUARELY IN THE
40S, POSSIBLY EVEN NEAR 50 SOUTH. ENJOY THE MILD CONDITIONS AS
THE WELL ADVERTISED COLD SNAP IS QUICKLY APPROACHING. WATER
VAPOR IMAGERY SHOWS AN ELONGATED PV ANOMALY ALONG THE CANADIAN
BORDER AND AN ATTENDANT DEEP SURFACE REFLECTION IN SOUTHERN
MANITOBA. INITIAL COLD FRONT SWEEPS THROUGH THIS AFTERNOON, BUT
THE PRIMARY BAROCLINIC PUSH LAGS BEHIND AND DOES NOT SURGE
THROUGH UNTIL THIS EVENING INTO THE OVERNIGHT. THIS IS
ACCOMPANIED BY BLUSTERY NORTHWEST WINDS GUSTING 30 TO 35 MPH OR
HIGHER. NOT EXPECTING WINDS TO REACH ADVISORY CRITERIA AS MODEL
SOUNDINGS HAVE FLOW AT THE TOP OF THE MIXED LAYER AROUND 35 TO
NEAR 40 KTS AND ISALLOBARIC TENDENCIES ARE MODEST. HIRES MODELS
FEATURE A WEAK SIGNAL FOR ISOLATED SHOWERY ACTIVITY AS NEAR
SURFACE LAPSE RATES STEEPEN BENEATH A NARROW CLOUD-BEARING
LAYER. MOISTURE DEPTH IS SHALLOW AND BACKGROUND SYNOPTIC SUPPORT
MARGINAL WHICH MAY LIMIT ANY ACTIVITY FROM MATERIALIZING IN OUR
AREA. MAINTAINED LOW CHANCES (<= 20%) FOR LIGHT RAIN AND/OR
SNOW SHOWERS AND SOME FLURRIES. MEASURABLE PRECIP IS UNLIKELY.
LITTLE CHANGE TO THE FORECAST THROUGH THE WEEKEND INTO EARLY
NEXT WEEK AS SUCCESSIVE REINFORCING SHOTS OF COLD AIR FURTHER
DEPRESS TEMPERATURES. STILL LOOKING AT THE COLD SNAP PEAKING
SAT NIGHT THROUGH MON NIGHT AS HIGHS ONLY STRUGGLE INTO THE
SINGLE DIGITS, POTENTIALLY NOT EVEN CLIMBING ABOVE ZERO NORTH.
DANGEROUSLY COLD WIND CHILLS OF -15 TO -30 AT TIMES WITH THE
COLDEST VALUES ALSO ACROSS THE NORTH. COLD WEATHER HEADLINES
LOOK NEAR CERTAIN AT THIS POINT AND WILL BE EVALUATED IN THE
NEAR FUTURE.
TEMPERATURES MODERATE BACK CLOSER TO SEASONAL NORMS AS SHORTWAVE
RIDGING BUILDS OVER THE REGION TOWARD THE MIDDLE OF NEXT WEEK.
A PRECIP WINDOW MAY MATERIALIZE THROUGH THIS PERIOD AS A SERIES
OF SHORTWAVE TROUGHS MOVE THROUGH THE REGION AND SOUTHERLY LOW
LEVEL FLOW ADVECTS APPRECIABLE MOISTURE NORTHWARD. DETERMINISTIC
OUTPUT AT THAT TIME RANGE IS NOT IN THE BEST AGREEMENT ON
PATTERN EVOLUTION AND MOISTURE AVAILABILITY. GEFS/ECENS MEANS
SUGGEST A 20- 30% OF MEASURABLE PRECIP, BUT NBM OUTPUT REMAINS
MUTED. FORECAST REMAINS DRY FOR NOW BUT PRECIP CHANCES MAY NEED
TO BE INTRODUCED BASED ON WHAT DIRECTION MODEL TRENDS FAVOR IN
THE DAYS AHEAD.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 527 AM CST FRI JAN 17 2025
CHANGING CONDITIONS WILL OCCUR THROUGH THE CURRENT TAF PERIOD. THIS
MORNING STARTS OUT WITH SOUTH TO SOUTHWEST WINDS. A PASSING FRONTAL
BOUNDARY TURNS WINDS TO NORTHWESTERLY THIS AFTERNOON AND CONDITIONS
BECOME QUITE GUSTY AS WE GO THROUGH THE EVENING INTO THE OVERNIGHT
WITH WIND GUSTS IN EXCESS OF 30 KNOTS LIKELY AT TIMES. IN ADDITION,
CIGS DROP AS A STRATUS DECK MOVES IN BEHIND THE FRONT. HAVE INCLUDED
MENTION OF MVFR CIGS AT KMCW AND KALO WHERE PROBABILITIES (50-60%)
ARE HIGHEST. FURTHER SOUTH AND WEST, CONFIDENCE IS HINDERED DUE TO
MODEL GUIDANCE BREAKING UP THE CLOUD COVERAGE AND MAY ONLY PRODUCE
SCT COVERAGE. IT'S POSSIBLE THAN BKN OR OVC MAY BE OBSERVED AT TIMES
AND COULD BE COVERED WITH A TEMPO GROUP, BUT DUE TO LOW CONFIDENCE
THIS IS NOT INCLUDED IN THE TAF FOR CENTRAL AND SOUTHERN IOWA
TERMINALS AT THIS TIME. POTENTIAL FOR WINTRY PRECIP IS LOW (<=20%)
AND SHOULD ANY ACTIVITY MATERIALIZE IT WILL BE MINIMAL IN IMPACT AND
NOT RESULT IN FURTHER CATEGORICAL REDUCTIONS.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MARTIN
AVIATION...MARTIN
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