859
FXUS63 KDMX 301147
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
547 AM CST SAT NOV 30 2024
...UPDATED FOR THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- SLIGHT CHANCE FOR MEASURABLE LIGHT SNOW FAR SOUTH TODAY(>30%).
FLURRIES ARE EXPECTED INTO PARTS OF WEST CENTRAL AND CENTRAL
IOWA THIS AFTERNOON.
- ANOTHER ROUND OF LIGHT SNOW OR FLURRIES POSSIBLE LATE SUNDAY
AND SUNDAY NIGHT. MAY NEED TO DRAMATICALLY INCREASE LIGHT SNOW
CHANCES IF SATURATION POTENTIAL IMPROVES.
- MOSTLY COLD WEATHER THROUGH THE FORECAST OUTSIDE A BRIEF
REPRIEVE MID NEXT WEEK.
DISCUSSION
ISSUED AT 404 AM CST SAT NOV 30 2024
HIGH PRESSURE IS RIDGED FROM SASKATCHEWAN AND THROUGH THE DAKOTAS
AND INTO CENTRAL IOWA EARLY THIS MORNING. THIS SYSTEM IS WHAT IS
BRINGING THE VERY DRY DEW POINTS TO MUCH OF THE STATE. DEW POINTS AT
3 AM ARE MOSTLY IN THE SINGLE DIGITS TO EVEN A FEW BELOW ZERO VALUES
IN NORTHWEST IOWA. LOW PRESSURE THAT IS LIFTING INTO KANSAS IS
LIFTING SOME LIMITED MOISTURE AS FAR NORTHEAST AS THE SOUTHWEST
CORNER OF IOWA AS A WAVE OF THETA-E ADVECTION PASSES OVER THAT AREA.
IT IS IN THAT PORTION OF THE STATE WHERE THE HIGHEST TEMPERATURES
AND DEW POINTS RESIDE. SOME LIGHT SNOW MAY OCCUR NEAR THE
IOWA/MISSOURI BORDER THIS MORNING THOUGH LITTLE TO NO ACCUMULATION
IS EXPECTED. THE MAIN AREA OF LIGHT SNOW WILL BE SOUTH INTO
MISSOURI. ANOTHER AREA OF STRATUS IS UPSTREAM OVER THE WESTERN
DAKOTAS AND WILL BE STREAMING SOUTHEAST TODAY AND MOVE INTO
NORTHWEST THEN CENTRAL IOWA TODAY. FLURRIES TO VERY LIGHT SNOW IS
FALLING FROM THIS STRATUS CURRENTLY. SOUNDING PROFILES ACROSS AREA
SHOW SATURATION DOWN TO NEAR 2500 FT THEN VERY DRY AIR BELOW THAT
LAYER, AS MENTIONED ABOVE WITH THE DEW POINTS. THE STRATUS LAYER
WILL BE IN THE DENDRITIC GROWTH ZONE (DGZ) TEMPERATURES AND CLOUD
DEPTHS TO NEAR 11 KFT ALL WITHIN THE DGZ. EXPECT AMPLE DENDRITE
DEVELOPMENT FOR SOME OF THOSE SNOWFLAKES TO SURVIVE A MERE 2500 FT
FALL THROUGH THE DRY AIR BELOW. THEREFORE, HAVE EXPANDED THE LIGHT
SNOW CHANCES WEST AND MOVED FLURRIES EAST INTO CENTRAL IOWA.
SUNDAY DAYTIME WILL BE MOSTLY QUIET THOUGH SOME LIGHT SNOW CHANCES
WILL BEGIN TO MOVE INTO NORTHWEST IOWA DURING THE AFTERNOON AS THE
INITIAL KINEMATIC FORCING ARRIVES. A STRONGER SHORTWAVE AND THE MAIN
AREA OF KINEMATIC FORCING WILL BE ARRIVING INTO THE AREA SUNDAY
EVENING AND OVERNIGHT. THERE ARE SOME MOISTURE AVAILABILITY
DISCREPANCIES AMONGST GUIDANCE AS THIS SYSTEM ARRIVES BUT THE OVER
ALL TREND IS ANOTHER DEEPER SATURATING LAYER THROUGH THE DGZ WITH
BETTER SATURATION THAN TODAY. TO START, HAVE INCREASED FLURRY
MENTION AND IN SOME AREAS LIGHT SNOW. IF SATURATION POTENTIAL
CONTINUE TO TREND UPWARD, THIS MAY END UP BEING A HIGH POP/LOW QPF
TYPE EVENT AND THUS REQUIRE MUCH HIGH POPS.
THE STRONG UPPER NORTHERLY FLOW WILL RELAX FOR THE BEGINNING TO MID
PORTION OF NEXT WEEK AND WILL ALLOW TEMPERATURES TO MODERATE SOME BY
TUESDAY AND WEDNESDAY. HIGH TEMPERATURES WILL BE IN THE UPPER 20S TO
MID 30S TUESDAY AND YES THAT IS STILL SLIGHTLY BELOW NORMAL.
WEDNESDAY WILL HAVE HIGHS IN THE 30S AND 40S. ANOTHER WAVE OF COLD
AIR ARRIVES BY THURSDAY AND THAT WILL LEAD TO A BELOW NORMAL END TO
THE FORECAST PERIOD. THERE IS LITTLE TO NO PRECIPITATION IN THE
FORECAST AFTER SUNDAY NIGHT BUT THIS COLD WEATHER WILL LIKELY HAVE
SOME FLURRY POTENTIAL DURING THE COLDER PERIODS ASSOCIATED WITH
PASSING STRATUS.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 540 AM CST SAT NOV 30 2024
CIGS NEAR 4 KFT ARE CURRENTLY IN THE KDSM/KOTM AREAS WITH ONLY
CIRRUS PASSING OVER OTHER SITES. THERE IS A BROAD AREA OF MVFR
TO VFR STRATUS UPSTREAM ACROSS THE DAKOTAS. THAT STRATUS WILL
MOVE INTO CENTRAL IOWA TODAY. SOME OF THE MVFR CIGS WILL LIKELY
REACH PARTS OF THE FORECAST AREA WITH THE HIGHEST POTENTIAL
BEING AT KFOD/KDSM THOUGH AT THIS TIME, CONFIDENCE REMAINS LOW
ENOUGH TO KEEP VFR AT BOTH SITES. THE CIGS SHOULD LAST INTO
TONIGHT. THERE IS A LOW CHANCE (<15%) THAT IFR STRATUS MOVES
INTO FAR NORTHERN IOWA LATER TONIGHT. FLURRIES MAY ALSO OCCUR
THOUGH NO VISIBILITY RESTRICTIONS ARE EXPECTED. NORTHWEST WIND
OF 6-13 MPH WILL BE COMMON.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...DONAVON
AVIATION...DONAVON
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