557
FXUS63 KDMX 272342
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
542 PM CST WED NOV 27 2024
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
KEY MESSAGES
- CHANCES (20-30%) FOR LIGHT SNOW LATER THIS AFTERNOON AND
EVENING, MAINLY NORTH. ANY ACCUMULATIONS WILL BE LESS THAN AN
INCH.
- STRETCH OF BELOW NORMAL TEMPERATURES TO END THE WEEK AND
THROUGH THE WEEKEND.
- LIGHT SNOW MAY CLIP SOUTHWEST IOWA (60% CHANCE) FRIDAY NIGHT
INTO EARLY SATURDAY.
DISCUSSION
ISSUED AT 205 PM CST WED NOV 27 2024
ACTIVE NORTHWESTERLY SYNOPTIC FLOW WILL BE THE PRIMARY THEME THROUGH
THE CURRENT FORECAST PERIOD, DELIVERING A STRETCH OF BELOW NORMAL
TEMPERATURES AND A FEW WINDOWS FOR LIGHT WINTRY PRECIPITATION. AT
CURRENT ONE SUCH ZONE OF PRECIP IS SLIDING SOUTH OF THE STATE,
ASSOCIATED WITH A MID-LEVEL WAVE PASSING THROUGH KS/NE. OPTED TO
LEAVE IN SLIGHT CHANCE POPS FOR OUR FAR SOUTHERN TIER OF COUNTIES,
HOWEVER CONFIDENCE IS DIMINISHING THAT ANY PRECIP WILL BE REALIZED
ON THIS SIDE OF THE STATE BORDER DUE TO AN ABUNDANCE OF LOW LEVEL
DRY AIR. ANOTHER COMPACT PV CIRCULATION IS EVIDENT ON GOES WATER
VAPOR IMAGERY DROPPING OF THE DAKOTAS INTO MN. THIS PERTURBATION
IS LOSING STEAM AS IT DROPS SOUTHEAST, BUT MODELS SUSTAIN THE
ATTENDANT LIGHT SNOWFALL AS IT MOVES INTO NORTHERN IOWA LATER
THIS AFTERNOON AND EVENING. DESPITE A SATURATED DGZ, DRY LOW
LEVELS NEED TO BE OVERCOME AND LIKELY LIMITS THE SPATIAL EXTENT,
DURATION, AND INTENSITY OF THE SNOWFALL. WE STILL COULD SEE
LIGHT ACCUMS (<1") IN OUR FAR NORTHERN COUNTIES. GLOBAL ENSEMBLE
GUIDANCE IS MUTE FOR ANY PROBS OF ACCUMULATING PRECIP, BUT
HIRES GUIDANCE HAS SPIT OUT A FEW TENTHS. POTENTIAL FOR
ACCUMULATING SNOW DIMINISHES TO THE SOUTH, HOWEVER MODEL
SOUNDINGS SUGGEST PERHAPS SOME FLURRIES OR LIGHT SNOW AS FAR
SOUTH AS I-80 TONIGHT AS THE COLUMN BENEATH THE DGZ ATTEMPTS TO
SATURATE.
A PERIOD OF BELOW NORMAL TEMPS SETTLES IN FOR THE REST OF THE WEEK
AND WEEKEND AS A COLD 1030-40 MB HIGH IS ANCHORED ALONG THE
NORTHERN ROCKY MTN FRONT. HIGHS ONLY IN THE 20S WILL BE COMMON
ALONG WITH LOWS IN THE SINGLE DIGITS AND TEENS WITH THE COLDEST
DAYS EXPECTED SAT/SUN. LIGHT PRECIP CHANCES REMAIN IN THE
CARDS, STARTING OVER OUR NORTHERN COUNTIES LATE THURSDAY AS CAA
FORCES BL LAPSE RATES TO STEEPEN INTO THE DGZ. MODEL SOUNDINGS
ARE NOT AGGRESSIVELY SATURATED, BUT SOME SPURTS OF FLURRIES OR
LIGHT SNOW CANNOT BE RULED OUT. ANOTHER PASSING WAVE THROUGH THE
ACTIVE NORTHWESTERLY FLOW ALOFT WILL BRING LIGHT SNOWFALL
CHANCES TO REGION AGAIN FRIDAY NIGHT INTO EARLY SATURDAY.
DETERMINISTIC MODELS SHOW THE BULK OF THE UPPER DIVERGENCE AND
KINEMATIC SUPPORT PASSING SOUTH OF THE STATE, AND DRY AIR
IMPINGING FROM THE NORTH SHOULD ALSO ACT TO LIMIT THE NORTHERLY
EXTENT OF THE PRECIP. GEFS/ECENS BOTH ADVERTISE ~60% PROBABILITY
OF MEASURABLE PRECIP IN OUR FAR SOUTHWEST COUNTIES, SUGGESTING
SOME NORTHWARD VARIABILITY AMONGST ENSEMBLE MEMBERS.
PROBABILITIES QUICKLY DIMINISH WITH NORTH/EAST EXTENT, SO MUCH
OF THE AREA IS LIKELY TO REMAIN DRY. TEMPERATURES STEADILY
MODERATE NEXT WEEK AS THE SURFACE HIGH IS DISLODGED EAST AND
SOUTHERLY LOW-LEVEL FLOW IS RE-ESTABLISHED. NBM SUGGESTS HIGHS
IN THE 40S MAY RETURN FOR PARTS OF THE STATE TOWARD THE LATTER
HALF OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 540 PM CST WED NOV 27 2024
LOW STRATUS CONTINUES TO DRIFT SOUTH AND EAST THIS EVENING,
EVENTUALLY BRINGING MVFR CONDITIONS TO MOST SITES THROUGH THE
NIGHT AND INTO THE MORNING. FURTHER UPSTREAM, LIGHT WINTRY
PRECIPITATION HAS FALLEN OUT OF THE STRATUS IN NW IA, WHICH MAY
WORK IT'S WAY SOUTH AND EAST THROUGH THE NIGHT. AS OF RIGHT NOW,
ONLY HAVE CONFIDENCE FOR PRECIPITATION AT KMCW, BUT WILL BE
CLOSELY MONITORING TRENDS TO BE AS PROACTIVE AS POSSIBLE WITH
AMENDMENTS AT OTHER SITES.
EXPECTING SOME EROSION OF THE MVFR CLOUD DECK THROUGH THE DAY
TOMORROW, BUT STRATUS TENDS TO BE STUBBORN THIS TIME OF THE
YEAR, SO HAVE PROLONGED THE LENGTH OF MVFR CONDITIONS WITH THIS
TAF ISSUANCE, ESPECIALLY AT SITES FURTHER NORTH.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MARTIN
AVIATION...DODSON
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