545
FXUS63 KDMX 071155
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
548 AM CST FRI NOV 7 2025
..UPDATED FOR THE 07/12Z AVIATION DISCUSSION
KEY MESSAGES
- BREEZY FRIDAY WITH A FEW SPRINKLES POSSIBLE NORTH.
- RAIN/SNOW MIX ACROSS THE STATE SATURDAY. HIGHEST RAIN AND SNOW
AMOUNTS NEAR EACH OTHER ACROSS THE MID-SECTION OF IOWA.
ADDITIONAL RAIN/SNOW POSSIBLE AFTER SUNSET SATURDAY.
- HIGHS IN THE 30S SUNDAY AND MONDAY.
UPDATE
ISSUED AT 433 AM CST FRI NOV 7 2025
OUR FIRST ROUND OF FORCING FOR THE WEEKEND WAS LOCATED OVER NORTH
DAKOTA THIS MORNING AND IT WAS PRODUCING A RAIN/SNOW MIX OVERNIGHT.
IT WILL BE STARVED OF MOISTURE BY THE TIME IT REACHES IOWA THIS
AFTERNOON, BUT WILL HAVE A WELL-MIXED BOUNDARY LAYER TO PRODUCE SOME
SPRINKLES/SHOWERS IN NORTHERN IOWA. CURRENTLY EXPECTING COVERAGE TO
BE SPARSE AND RAIN AMOUNTS WILL LIKELY BE LIGHT ENOUGH TO REMAIN
UNMEASURABLE. CHANCES ARE CAPPED AT 15% FOR THESE REASONS AND MAY BE
ADJUSTED THROUGH THE DAY DEPENDING ON OBSERVATIONS UPSTREAM. THIS
WAVE ALSO BRINGS A BLANKET OF STRATUS CLOUDS WITH IT, COMPLICATING A
TRICKY, BUT CRUCIAL, TEMPERATURE FORECAST FOR THE NEXT 36 HOURS.
A SYNOPTIC WAVE CURRENTLY ENTERING NORTH AMERICA IN THE PNW WILL
RIDE AN UPPER-LEVEL JET IN THE NORTHWEST FLOW, MAKING ITS ARRIVAL
KNOWN EARLY SATURDAY MORNING. THE FEATURE WILL PIVOT AROUND THE
TROUGH OF THE HUDSON LOW, EXTENDING ITS EFFECTS FOR IOWA FOR MUCH OF
SATURDAY. THE MORNING HOURS WILL FEATURE PRECIPITATION, LIKELY A
MIXTURE OF RAIN AND SNOW, ACROSS NORTHERN IOWA. GIVEN THE STRATUS
THAT WILL INSULATE TEMPERATURES TONIGHT, CONFIDENCE IS ON MORE RAIN
AROUND SUNRISE. THE 00Z HREF SUPPORTS THIS THINKING AS ITS
PROBABILITIES FOR LOWS BELOW 33 DEGREES DON'T BECOME LIKELY UNTIL
YOU TRAVERSE INTO MINNESOTA. WHATEVER VALUE NORTHERN IOWA SITS AT
SATURDAY MORNING, NORTHWEST FLOW AND STRATUS WILL KEEP HIGHS WITHIN
A FEW DEGREES. AS FOR SOUTHERN IOWA, WAA AHEAD OF THE SYSTEM WILL
ALLOW HIGHS TO EXCEED 40 DEGREES, THE CUTOFF FOR THOSE TEMPERATURES
SITTING SOMEWHERE NEAR THE INTERSTATE 80 CORRIDOR (THIS ALSO SERVES
AS THE TRANSITION ZONE FOR P-TYPES OF RAIN/SNOW IN THE AFTERNOON). A
N-S CROSS SECTION OF THE STATE SHOWS A FRONT NEAR THE SURFACE IN THE
WARMER SECTOR, BUT THEN ANGLING INTO THE MIDLEVELS (AND DGZ) IN THE
NEARBY COLD SECTOR. LAPSE RATES IN AND ABOVE THE DGZ ARE AT OR
GREATER THAN 7 C/KM. LOW STATIC STABILITY CAN BE FOUND FOR MUCH OF
THAT SAME LAYER. CONVECTIVE INSTABILITY, INDICATED BY FOLDING
THETA-E SURFACES, IS MOSTLY FOUND IN AND NEAR THE DGZ AND
COLLOCATED WITH THE FRONT. ADD -20 MICROBARS OF LIFT TO THE MIX,
AND YOU HAVE A NARROW REGION OF SNOW PRODUCTION CAPABLE OF
OVERCOMING THE WARM GROUND, HENCE WHY MODELS LIKE THE GFS AND
NAM HAVE A NARROW BAND OF 2"+. IN SUMMARY: THE SOUTHERN HALF OF
THE STATE WILL BE PRIMARILY RAIN. THE TRANSITION ZONE NEAR I-80
WILL CONTAIN THE HIGHEST AMOUNTS OF BOTH RAIN AND SNOW, THE
HIGHEST SNOWFALL AMOUNTS APPEAR TO RESIDE SOMEWHERE ALONG OR
BETWEEN THE HIGHWAY 20 AND HIGHWAY 30 CORRIDORS. NORTH OF THERE,
THE RAIN/SNOW MIX WILL TRANSITION TO ALL SNOW BY THE AFTERNOON,
PRODUCING SNOWFALL AMOUNTS UP TO AN INCH.
WE WON'T BE OUT OF THE WOODS FOR PRECIPITATION ONCE THIS SYSTEM
MOVES OFF SATURDAY EVENING. ANOTHER FEATURE TAKES ITS PLACE
ALONG THE NORTHWEST FLOW. THE CAA WILL STEEPEN LOW-LEVEL LAPSE
RATES AND DELAY DECOUPLING AFTER SUNSET FOR THE STATE, ENOUGH SO
THAT CAPE VALUES UP TO AROUND 100 J/KG CAN BE FOUND AROUND THE
MO RIVER VALLEY. IN RESPONSE, ALL OF THE 00Z CAMS HAVE
PRECIPITATION CONTINUING INTO SATURDAY NIGHT, THE HRRR BEING THE
MOST ROBUST OUT OF THE GUIDANCE. IT DEVELOPS A RAIN/SNOW MIX
BAND ALONG THE WEAK PRESSURE TROUGH. JUST HOW DYNAMIC IS THE
BAROCLINIC BOUNDARY? MOST GUIDANCE DELAYS THE MIDLEVEL CAA UNTIL
AFTER THE WAVE PASSES, MAKING THE SATURATED CONVECTIVE COVERAGE
IN SOUNDINGS MORE SHALLOW. THAT BEING SAID, SHOULD LAPSE RATES
STEEPEN HIGHER INTO THE PROFILE, CONVECTIVE SNOW PRODUCTION
ENTERS THE PICTURE WHICH WOULD BRING SIGNIFICANT REDUCTIONS TO
VISIBILITY DUE TO SNOWFALL. THE GROUND WILL THEN FREEZE SHORTLY
AFTER THIS PRECIPITATION THANKS TO TEMPERATURES FALLING INTO THE
20S, MEANING THAT SLICK SPOTS COULD DEVELOP ON ROADS. SUNDAY
HIGHS WILL LIKELY BE UNDER 35 DEGREES, DELAYING A CHANCE AT A
THAW.
DISCUSSION
ISSUED AT 129 PM CST THU NOV 6 2025
SYNOPTIC 500 MB ANALYSIS REVEALS A LARGE GYRE SPINNING OVER HUDSON
BAY, WITH A SERIES OF TROUGHS MOVING INTO AND ACROSS THE
NORTHWESTERN U.S. IN AN OTHERWISE ROUGHLY ZONAL FLOW PATTERN. THE
FIRST BROAD TROUGH IS CROSSING THE NORTHERN U.S. ROCKIES AND HIGH
PLAINS THIS AFTERNOON, AND IS COMPRISED OF TWO EMBEDDED SHORTWAVES.
THE LEADING WAVE IS APPROACHING IOWA AT THIS TIME FROM SOUTH
DAKOTA/NEBRASKA, SPREADING MID/HIGH LEVEL CLOUDS TOWARD OUR FORECAST
AREA, WHILE THE SECOND IS LAGGING OVER MONTANA AND SOUTHWESTERN
CANADA AND WILL REACH IOWA ON FRIDAY MORNING. AS THE INITIAL
SHORTWAVE MOVES OVERHEAD THIS EVENING AND TONIGHT, PRECEDING LOW-
LEVEL WARM AIR/MOISTURE ADVECTION AND BROAD FORCING FOR ASCENT WILL
EVENTUALLY ALLOW SOME SHOWERS TO FORM, HOWEVER BY THE TIME THAT
OCCURS IT WILL MOSTLY BE EAST OF OUR AREA OVER EASTERN IOWA AND
ILLINOIS/WISCONSIN TONIGHT. THAT BEING SAID, THERE IS A WINDOW FOR
THE FIRST LIGHT SHOWERS TO DEVELOP IN OUR EASTERN/SOUTHEASTERN
COUNTIES THIS EVENING BEFORE QUICKLY MOVING OUT, AND THUS HAVE
MAINTAINED LOW (MOSTLY 20-40%) POPS IN THAT AREA THIS EVENING UNTIL
MIDNIGHT. ALSO INTRODUCED MENTION OF ISOLATED THUNDERSTORMS AS SHORT-
TERM GUIDANCE HAS TRENDED TOWARD SOME WEAK INSTABILITY IN OUR
SOUTHEAST FOR A FEW HOURS AROUND/AFTER SUNSET. AS THE SECOND 500 MB
SHORTWAVE THEN MOVES OVER ON FRIDAY, EFFECTIVELY BRINGING UP THE
REAR OF THE BROADER TROUGH WITHIN WHICH IT IS EMBEDDED, IT WILL
PROVIDE ANOTHER SHOT OF FORCING THAT SOME MODEL SOLUTIONS ARE
DEEMING SUFFICIENT TO GENERATE A FEW LIGHT SHOWERS IN OUR
NORTHEASTERN COUNTIES AROUND FRIDAY AFTERNOON. FORECAST SOUNDINGS
INDICATE THERE WILL BE MORE SUBSTANTIAL LOW-LEVEL DRY AIR TO
OVERCOME AT THAT TIME HOWEVER, SO HAVE LEFT THE FORECAST DRY FOR
NOW. ANY RAIN THAT MAY OCCUR WOULD BE VERY SPOTTY AND LIGHT AND
OF NO IMPACT.
BY SATURDAY MORNING A SHARPER AND MORE ENERGETIC 500 MB TROUGH AND
VORTICITY MAXIMUM, WHOSE PROGENITOR IS CURRENTLY SITTING OFF
THE COAST OF BRITISH COLUMBIA, WILL MOVE SOUTHEASTWARD OVER THE
WESTERN DAKOTAS AND SUBSEQUENTLY CROSS IOWA AND MISSOURI
SATURDAY INTO SATURDAY NIGHT. MEANWHILE, AS THE HUDSON BAY GYRE
CONTINUES TO SIT AND SPIN, PERHAPS DRIFTING DOWN INTO FAR
NORTHERN ONTARIO, A PRONOUNCED TROUGH WILL SWING AROUND IT AND
APPROACH THE CANADA/U.S. BORDER AROUND INTERNATIONAL FALLS BY
MIDDAY SATURDAY. THIS FEATURE WILL EVENTUALLY REACH IOWA ON
SATURDAY NIGHT, HOT ON THE HEELS OF THE PRECEDING TROUGH MOVING
IN FROM THE WEST EARLIER IN THE DAY. THE NET RESULT OF THIS
SCENARIO WILL BE PRECIPITATION SPREADING ACROSS IOWA ON
SATURDAY, ASSOCIATED WITH THE FIRST TROUGH, FOLLOWED BY MUCH
COLDER TEMPERATURES AND PERHAPS A SECOND BOUT OF LIGHTER
PRECIPITATION SURGING INTO THE REGION SATURDAY EVENING/NIGHT IN
ASSOCIATION WITH THE SECOND/NORTHERN TROUGH.
THE PRECIPITATION ON SATURDAY IS PROBLEMATIC AND POTENTIALLY
IMPACTFUL DUE TO THE COLDER TEMPERATURES WORKING INTO THE AREA. AS
THE MID/UPPER TROUGH MOVES OVERHEAD, AN ASSOCIATED SURFACE LOW WILL
MOVE RIGHT ALONG OR JUST SOUTH OF THE IOWA/MISSOURI BORDER. AROUND
THE NORTHERN HEMISPHERE OF THIS LOW A DEFORMATION ZONE WILL PIVOT
OVER OUR FORECAST AREA, WITH RIBBONS OF FRONTOGENETICAL FORCING
MOVING OVERHEAD AND ENHANCING THE BROAD LIFT ACCOMPANYING THE
TROUGH. THIS WILL PROVIDE MORE THAN ENOUGH SUPPORT FOR SATURATION OF
THE COLUMN AND WIDESPREAD PRECIPITATION, SPREADING FROM WEST TO EAST
DURING THE DAY, BEFORE THE FORCING CUTS OFF AFTER THE LOW PASSES BY
AROUND LATE AFTERNOON OR SO. FORECAST SOUNDINGS UNANIMOUSLY DEPICT A
DEEP SATURATED LAYER WELL BELOW FREEZING, WITH LIFT CONCENTRATED
WITHIN THAT LAYER AND SUPPORTING GENERATION OF SNOW DURING THE DAY.
IN FACT, MOST DETERMINISTIC MODEL SOLUTIONS PAINT A TRANSIENT
BULLSEYE OF FORCING WITHIN THE DENDRITIC GROWTH ZONE, INDICATING THE
POTENTIAL FOR A FEW HOURS OF HIGH-RATE SNOWFALL PRODUCTION ALOFT.
THE BUGABOO IS WET-BULB TEMPERATURES WITHIN THE SURFACE LAYER, AND
WHETHER THEY REMAIN WARM ENOUGH AND DEEP ENOUGH TO MELT THE FALLING
SNOW AND RESULT IN MORE RAIN THAN SNOW AT THE SURFACE. MOST
SOLUTIONS DEPICT THE NEAR-SURFACE WARM LAYER AS VERY SHALLOW, WITH
SURFACE WET-BULB TEMPERATURES COOLING DURING THE AFTERNOON AS THE
HEAVIEST PRECIPITATION FALLS WHICH IS CONSISTENT WITH THE
TRADITIONAL "DYNAMIC COOLING" SCENARIO. HOWEVER, WITH THIS PERIOD OF
HEAVIER PRECIPITATION POTENTIAL/DYNAMIC COOLING REACHING CENTRAL
IOWA AROUND MIDDAY IT WILL BE FIGHTING DIABATIC HEATING AND THE
ADMITTEDLY WEAK SOLAR INSOLATION MAXIMUM, SO THE P-TYPE
FORECAST IS VERY UNCERTAIN IN THAT AREA. CONFIDENCE IN SNOWFALL
IS HIGHER ACROSS OUR NORTHERN COUNTIES WHERE WET-BULB
TEMPERATURES WILL INITIALLY BE LOWER AND MORE DIFFICULT TO WARM
ABOVE FREEZING, WHICH IS ALSO CONSISTENT WITH CLIMATOLOGY. HAVE
CONTINUED THE TREND OF COOLING TEMPERATURES DURING THE DAY
SATURDAY BELOW NBM GUIDANCE, WITH A BLEND TOWARD THE NBM 25TH,
NAM, AND CONSALL, AND ALSO BUMPED DEWPOINTS DOWN A COUPLE OF
DEGREES DURING THE HEAVIEST PRECIPITATION WINDOW TO LOWER WET-
BULB TEMPERATURES FARTHER. WHILE THE OFFICIAL FORECAST DOES NOT
INDICATE MEASURABLE SNOWFALL ACCUMULATIONS EXCEPT IN OUR
NORTHERN COUNTIES, THERE IS CERTAINLY THE POTENTIAL FOR MORE
WIDESPREAD IMPACTS IF COOLER/SNOWIER SOLUTIONS PREVAIL, AND THIS
POSSIBILITY WILL BE CLOSELY MONITORED LEADING UP TO THE STORM.
ALL GUIDANCE SHUTS OFF THE FORCING SHARPLY AROUND OR SHORTLY AFTER
21Z ON SATURDAY AS THE LOW BEGINS TO MOVE AWAY, RESULTING IN
PRECIPITATION ENDING OR BECOMING VERY LIGHT BY THE END OF THE DAY.
HOWEVER, AS THE SECOND TROUGH DISCUSSED ABOVE SURGES DOWN FROM THE
NORTH SATURDAY EVENING, IT WILL BRING A QUICK SHOT OF SECONDARY
FORCING WHICH ADMITTEDLY WILL BE WEAKER AND WITH LESS MOISTURE TO
WORK WITH. EVEN SO, THIS MAY STILL BE SUFFICIENT TO GENERATE SOME
FLURRIES OR LIGHT SNOW INTO EARLY SATURDAY NIGHT, AND IN FACT THE
NAM (WHICH IS BY FAR THE MOST BULLISH ON THIS) INDICATES SOME
POSSIBILITY OF IMPACTFUL SNOW SHOWERS MOVING THROUGH WITH THE
SECONDARY TROUGH. FOR NOW, HAVE ADDED SLIGHT CHANCE (20%) POPS TO
ACCOUNT FOR THIS POTENTIAL. BARRING THE STRONGER NAM SOLUTION ANY
SUCH LIGHT SNOW WOULD LIKELY HAVE LITTLE IMPACT, BUT IF IT ABLE TO
SIGNIFICANTLY REDUCE VISIBILITY OR ACCUMULATE ON ROADS THEN THERE
MAY BE ADDITIONAL TRAVEL IMPACTS AFTER DARK SATURDAY EVENING/NIGHT.
AFTER THE TWO TROUGHS MOVE THROUGH IOWA SATURDAY-SATURDAY NIGHT,
MUCH COLDER AIR WILL SURGE ACROSS THE REGION IN NORTHWESTERLY FLOW
FROM SATURDAY NIGHT THROUGH SUNDAY. LATE SATURDAY NIGHT INTO SUNDAY
MORNING, THE RAPIDLY FALLING TEMPERATURES AND GUSTY NORTH NORTHWEST
WINDS MAY PROMOTE FREEZING OF PREVIOUSLY FALLEN SNOW/RAIN ON SOME
SURFACES AND THERE IS A POSSIBILITY OF ICY ROADS AS A RESULT, WHICH
MAY OCCUR EVEN WELL AFTER THE PRECIPITATION HAS ENDED AS
TEMPERATURES FALL INTO THE LOW TO MID-20S EARLY SUNDAY MORNING.
HIGHS SUNDAY ARE NOW ONLY IN THE LOW TO MID-30S ACROSS THE AREA, SO
ANY ICE OR SNOW THAT HAS FORMED/FALLEN MAY NOT MELT MUCH EVEN DURING
THE DAY, DEPENDING ON THE DEGREE OF CLEARING THAT CAN OCCUR. IT WILL
REMAIN COLD MONDAY AS A SURFACE HIGH PRESSURE RIDGE MOVES OVER THE
REGION, WHICH MAY RESULT IN EVEN COLDER LOWS MONDAY MORNING IN THE
TEENS ACROSS MUCH OF THE AREA, FOLLOWED BY HIGHS MONDAY AFTERNOON
AROUND 35-40 DEGREES. FROM TUESDAY THROUGH THE REST OF NEXT WEEK
IOWA WILL RESIDE BENEATH BENIGN WEST NORTHWESTERLY STEERING FLOW,
WHICH SHOULD SUPPORT QUIETER WEATHER AND A STEADY MODIFICATION OF
TEMPERATURES, WITH A RETURN OF MORE SEASONAL READINGS BY
MIDWEEK.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 548 AM CST FRI NOV 7 2025
VFR CONDITIONS ARE EXPECTED AT ALL LOCATIONS DURING THE DAYTIME
HOURS TODAY. MVFR CONDITIONS ARE EXPECTED AT KMCW BEGINNING EARLY
THIS EVENING. MAINLY HIGH CLOUDS EXPECTED DURING THE DAY TODAY, BUT
THEN LOWERING LATER THIS AFTERNOON INTO THIS EVENING AHEAD OF
ANOTHER SYSTEM ARRIVING. WINDS OUT OF THE W WILL TURN MORE NW
THROUGH THE DAY, BECOMING BREEZY WITH GUSTS TO 20-25 KT THROUGH THE
AFTERNOON, BEFORE GRADUALLY DECREASING AND BECOMING N TO NE LATE IN
THE PERIOD. INTRODUCED PROB30 AT KFOD LATE IN THE PERIOD TO
ADVERTISE THE RAMP-UP OF PRECIP CHANCES SATURDAY MORNING. KMCW IS
CLOSE BEHIND BUT OPTED TO NOT INTRODUCE PROB30 THERE AT THIS TIME.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...JIMENEZ
DISCUSSION...LEE
AVIATION...ZOGG
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