419
FXUS63 KMKX 181014
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
414 AM CST WED DEC 18 2024
KEY MESSAGES
- ACCUMULATING SNOW REMAINS LIKELY THURSDAY MORNING THROUGH
THURSDAY EVENING ACROSS THE ENTIRETY OF SOUTHERN WISCONSIN.
INCREASING POTENTIAL FOR 2+ OF SNOW OVER THE MAJORITY OF
SOUTHERN WI. THURSDAY AM AND ESPECIALLY PM COMMUTES COULD BE
IMPACTED.
- PERIODS OF LAKE-ENHANCED SNOW CONTINUE THURSDAY NIGHT THROUGH
THE FIRST HALF OF FRIDAY ACROSS EASTERN WISCONSIN,
PARTICULARLY EAST-CENTRAL WISCONSIN. INCREASING POTENTIAL FOR
6+ INCHES STORM-TOTAL SNOW IN FOND DU LAC AND SHEBOYGAN
COUNTIES, HENCE A WINTER STORM WATCH HAS BEEN ISSUED FOR THESE
COUNTIES. FRIDAY AM COMMUTE IMPACTS MAY OCCUR NEAR LAKE MI.
- THE NEXT ROUND OF ARCTIC AIR SETTLES INTO SOUTHERN WISCONSIN
THIS WEEKEND, WITH TEMPERATURES MODERATING INTO EARLY NEXT
WEEK.
SHORT TERM
ISSUED 410 AM CST WED DEC 18 2024
TODAY AND TONIGHT:
700MB FGEN AND ASSOCIATED LIGHT SNOW HAVE NEARLY EXITED THE
SOUTHEASTERN CWA BY NOW. SOME SLICK SPOTS POSSIBLE FOR THE AM
COMMUTE TODAY, BUT NO FURTHER ACCUMULATING SNOW EXPECTED TODAY
(FLURRIES CAN'T BE COMPLETELY RULED OUT WITH LINGERING LOW
STRATUS THIS MORNING, BUT ARE NOT LIKELY). NORTHWEST WINDS TODAY
WILL USHER IN A COOLER AIRMASS, WITH OVERNIGHT LOWS IN THE
TEENS TO AROUND 20. NEXT CHANCE FOR SNOW ARRIVES THURSDAY
MORNING.
SHEPPARD
LONG TERM
ISSUED 410 AM CST WED DEC 18 2024
THURSDAY THROUGH TUESDAY:
THE TRACK FOR THURSDAY'S CLIPPER SYSTEM REMAINS WIDELY DISPUTED
BETWEEN MODELS (EVEN AT SUCH A SHORT RANGE). THAT SAID, A
PATTERN IS BEGINNING TO EMERGE... COARSER-RESOLUTION LONGER-
RANGED MODELS (ECMWF, GFS, CANADIAN) HAVE CONVERGED ON A TRACK
THAT TAKES THE CENTER OF THE LOW PRESSURE THROUGH NORTHERN
ILLINOIS, WHILE HIGHER RESOLUTION CAMS (RAP / HRRR) PREFER A
NORTHERN WISCONSIN / MICHIGAN-UP TRACK. IT IS TOO EARLY TO SAY
WHICH OF THESE WILL PAN OUT, BUT THE CONVERGENCE OF ECMWF, GFS,
AND CANADIAN MODEL GUIDANCE ON THE ILLINOIS TRACK HAS LEAD TO AN
INCREASE IN SNOW PROBS ACROSS OUR CWA COMPARED TO THE PRIOR
FORECAST ITERATION.
SNOW IS UNLIKELY TO BEGIN UNTIL ROUGHLY 5 AM THURSDAY OR LATER
(REGARDLESS OF TRACK), BUT ALL AREAS ARE LIKELY TO RECEIVE THE
FIRST DOSE OF SNOWFALL BEFORE LATE THURSDAY MORNING (AM COMMUTE
IMPACTS MAY OCCUR). THE NORTHERN WI SYSTEM TRACK WOULD PREFER A
MID-DAY LULL IN SNOWFALL FOLLOWED BY MODERATE TO HEAVY SNOW
SHOWERS ALONG THE COLD FRONT IN THE LATE AFTERNOON / EVENING,
WHILE THE ILLINOIS TRACK WOULD ALLOW FOR A MORE PERSISTENT
SNOWFALL THROUGHOUT THURSDAY. EITHER WAY, THURSDAY PM COMMUTE
IMPACTS ARE LIKELY. AS THE LOW DEPARTS TO THE EAST, LAKE-
ENHANCEMENT IS LIKELY TO ALLOW FOR CONTINUED SNOW SHOWERS FOR
THE EASTERN CWA INTO THURSDAY NIGHT AND FRIDAY MORNING. JUDGING
BY THE MODELED WIND FIELD (ILLINOIS SYSTEM TRACK), THE BEST
COMBINATION OF SHORELINE CONVERGENCE AND LAKE ENHANCEMENT WOULD
BE OVER EAST-CENTRAL WI, HENCE A WINTER STORM WATCH HAS BEEN
ISSUED FOR FOND DU LAC AND SHEBOYGAN COUNTIES, DUE TO INCREASING
POTENTIAL OF 6+ INCHES OF STORM- TOTAL SNOWFALL. THE REMAINDER
OF THE CWA HAS WIDESPREAD POTENTIAL FOR 2-4 INCHES OF SNOW,
PERHAPS A BIT LOWER POTENTIAL FAR SOUTHWESTERN WI. NO FURTHER
HEADLINES HAVE BEEN ISSUED AT THIS TIME, BUT A WINTER WEATHER
ADVISORY COULD EASILY BE ISSUED FOR THE MAJORITY OF THE CWA
ON THE NEXT FORECAST ITERATION (IF CONFIDENCE IN THE IL TRACK
INCREASES).
MOSTLY DRY WEATHER EXPECTED FRIDAY AFTERNOON AND ONWARD (ASIDE
FROM SLIGHT CHANCES OF LIGHT LAKE EFFECT SNOW SHOWERS IN LAKE
MICHIGAN COUNTIES). SIMILAR STORY FOR THE REMAINDER OF THE
WEEKEND AS THE ARCTIC HIGH PRESSURE PASSES BY. COOL WEATHER THIS
WEEKEND, BUT WITH RELATIVELY LIGHT WINDS.
SHEPPARD
AVIATION
ISSUED 410 AM CST WED DEC 18 2024
THE OVERNIGHT SNOW EVENT HAS ENDED. LOW STRATUS LEAVES THE
POTENTIAL FOR A FLURRY OR TWO LATER THIS MORNING, BUT NOTHING
MORE. CURRENTLY OBSERVING SCATTERED MVFR-ALTITUDE CLOUDS, WITH
OVERCAST 40,000-60,000 FEET VFR CEILINGS ACROSS THE REGION. AS
SEEN UPSTREAM (IN CENTRAL WI AND SOUTHERN MN), CEILINGS ARE
LIKELY TO BOUNCE BETWEEN MVFR AND LOW-END VFR THROUGHOUT TODAY,
WITH DRY WEATHER AND MODEST NORTHWEST WINDS.
LIGHT AND VARIABLE WINDS TONIGHT, WITH CONTINUED DRY WEATHER
UNTIL 5 AM LOCAL TIME THURSDAY. CONFIDENCE ON THE TRACK OF AN
APPROACHING ALBERTA CLIPPER SYSTEM LEAVES MUCH OF THE EXTENDED FORECAST
IN QUESTION, BUT HERE ARE THE PRIMARY EXPECTATIONS... LIGHT TO
MODERATE SNOW OVERTAKES THE REGION FROM WEST TO EAST THURSDAY
MORNING, WITH ARRIVAL TIMES FROM 5 AM TO 10 AM. WINDS GENERALLY
SOUTHEAST THURSDAY MORNING. A LULL IN THE SNOW POSSIBLE IN THE
AFTERNOON (BUT LIKELY CONTINUED SNOW). SNOW TAPERS OFF IN THE
WEST LATE THURSDAY EVENING, WITH CONTINUED SNOW EAST (NEAR LAKE
MICHIGAN) OVERNIGHT INTO FRIDAY MORNING. INCREASING POTENTIAL
OF 6+ INCHES AT KSBM AND KFLD. WIDESPREAD POTENTIAL FOR 2-4
INCHES ELSEWHERE (SUBJECT TO CHANGE BASED ON SYSTEM TRACK).
SHEPPARD
MARINE
ISSUED 410 AM CST WED DEC 18 2024
BRISK NORTHWEST WINDS WILL BECOME ESTABLISHED ACROSS THE OPEN
WATERS TODAY AS 30.5 INCH HIGH PRESSURE MIGRATES FROM THE
NORTHERN GREAT PLAINS INTO THE MISSISSIPPI RIVER VALLEY. WINDS
WILL TAPER TONIGHT INTO EARLY THURSDAY MORNING AS THE
AFOREMENTIONED AREA OF HIGH PRESSURE MOVES ACROSS LAKE MICHIGAN.
WINDS WILL SHIFT PREDOMINANTLY OUT OF THE SOUTH DURING THE DAY
TIME HOURS ON THURSDAY AS 29.9 INCH LOW PRESSURE APPROACHES LAKE
MICHIGAN FROM THE UPPER MISSISSIPPI VALLEY. THE APPROACH OF THE
SURFACE LOW WILL BE ACCOMPANIED BY PERIODS OF SNOW AND RAIN
SHOWERS. THE LOW WILL MOVE OVER AND EAST OF THE OPEN WATERS
THURSDAY EVENING INTO FRIDAY MORNING, RESULTING IN GUSTY NORTH
WINDS ACROSS THE LAKE FRIDAY AFTERNOON.
SHEPPARD
MKX WATCHES/WARNINGS/ADVISORIES
WI...WINTER STORM WATCH...WIZ051-WIZ052...6 AM THURSDAY TO NOON
FRIDAY.
LM...NONE.
VISIT US AT WEATHER.GOV/MILWAUKEE
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSMILWAUKEE
WWW.TWITTER.COM/NWSMILWAUKEE
WWW.YOUTUBE.COM/NWSMILWAUKEE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page