923
FXUS63 KMKX 202018
AFDMKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
318 PM CDT SUN APR 20 2025
KEY MESSAGES
- INCREASED RAIN CHANCES (+90%) FOR THIS AFTERNOON INTO MONDAY
MORNING WITH MULTIPLE WAVES OF SHOWERS AND FEW THUNDERSTORMS
THIS EVENING.
- THE HEAVIEST RAINFALL THROUGH TONIGHT(>60% CHANCE OF
EXCEEDING 0.5 INCH) WILL BE WEST OF I-39 CORRIDOR.
- WARM UP TUESDAY THROUGH THE END OF THE WEEK WITH WELL ABOVE
NORMAL HIGHS AND ADDITIONAL RAIN CHANCES FOR THE SECOND HALF
OF THE WEEK.
SHORT TERM
ISSUED 318 PM CDT SUN APR 20 2025
TONIGHT AND MONDAY:
RAINFALL CONTINUES ACROSS SOUTHERN WISCONSIN AS A LOW PRESSURE
SYSTEM STARTS TO ADVECT NORTH NORTHEAST OUT OF MO. A WING OF
850MB WARM AIR ADVECTION IS THE DRIVING FORCE FOR OUR SHOWERS
AND FEW RUMBLES OF THUNDER THIS AFTERNOON. WITH SOME DRIER AIR
AND WEAKER ASCENT BEHIND THE LEADING EDGE OF THE WAA HAS LED TO
SOME SCATTERED SHOWERS ACROSS SOUTHWESTERN AND SOUTH CENTRAL
WISCONSIN. SCATTERED SHOWERS/CONVECTION IS EXPECTED TO CONTINUE
THROUGH THE EVENING UNTIL THE LOW PRESSURE SYSTEM LIFTS INTO
WISCONSIN. DUE TO THE SCATTERED NATURE OF THE SHOWERS ITS
LIKELY FOR A FEW LULLS IN ACTIVITY, ESPECIALLY ACROSS
SOUTHEASTERN WISCONSIN. ONCE THE LOW BEHINDS TO LIFT THROUGH THE
REGION IT WILL BRING AN ADDITIONAL "ROUND" OF RAIN TO THE
STATE.
WITH THE LARGE SCALE ASCENT AND THE COLD FRONT DRAGGING ACROSS
THE REGION AS WELL THERE WILL BE A GREATER CHANCE FOR A FEW
RUMBLES OF THUNDER (ROUGHLY 60% CHANCE). THE GREATER THE WARM
AIR ADVECTION AT THE SURFACE PRIOR TO THE PASSAGE OF THE COLD
FRONT THIS EVENING THE BETTER THE CHANCES FOR THUNDER.
MEANWHILE AREAS ALONG AND WEST OF I-39 CONTINUE TO HAVE THE BEST
POTENTIAL FOR RAINFALL NEAR AN INCH. GUIDANCE AND ENSEMBLES
CONTINUE TO SHOW SUPPORT FOR LONGER DURATION AND MORE STEADY
RAINFALL FOR LOCATIONS WEST OF I-39. AREAS TO THE EAST ARE
EXPECTED TO CONTINUE TO SEE THE SHOWERY ACTIVITY WITH LOWER
RAINFALL RATES WHICH WILL RESULT IN 0.25 TO 0.5 INCHES OF RAIN
FOR AREAS TO THE EAST. OUTSIDE OF ANY THUNDERSTORMS RAINFALL
RATES ARE EXPECTED TO REMAIN LIGHT TO MODERATE WITH RATES AROUND
0.1 INCHES OR LESS. CAN'T RULE OUT SOME HEAVIER BUT BRIEF
RAINFALL WITH ANY THUNDERSTORMS ALONG THE COLD FRONT.
NOT ANTICIPATING ANY STRONGER OR SEVERE STORMS TODAY. HEATING AT
THE SURFACE IS VERY LIMITED TODAY UNDER THE RAIN AND CONTINUED
CLOUD COVER TO EVEN MAKE SOUTHERN WISCONSIN UNSTABLE. WHILE
THERE IS MID LEVEL WAA THERE IS LITTLE IN THE WAY OF LARGE SCALE
LIFT UNTIL THE LOW AND COLD FRONT MOVE THROUGH, BUT THE
ENVIRONMENT THEY ARE MOVING INTO IS FAIRLY STABLE. LAPSE RATES
ARE LOW AND MUCAPE IS TINY WITH VALUES AROUND 200 J/KG OR LESS.
ESSENTIALLY ENOUGH UPWARD INSTABILITY AND MOMENTUM IN THE MID
LEVELS TO GET SOME THUNDER, MAYBE SOME SMALL HAIL, BUT OTHERWISE
NOT MUCH TO WRITE HOME ABOUT.
A FEW WRAP AROUND SHOWERS WILL BE POSSIBLE EARLY MONDAY AS THIS
LOW PRESSURE SYSTEM DEPARTS THE STATE, OTHERWISE DRY CONDITIONS
ARE EXPECTED TO RETURN BY LATE MONDAY MORNING INTO MONDAY
AFTERNOON. SHOWERS WILL END FROM SOUTHWEST TO NORTHEAST. COOLER
TEMPERATURES SIMILAR TO TODAY ARE EXPECTED MONDAY. THOSE ALONG
THE LAKESHORE MAY FEEL THE GREATEST IMPACT HERE AS THERE WILL
NOT BE BREEZY WINDS COMING OFF THE COOL LAKE.
PATTERSON
LONG TERM
ISSUED 318 PM CDT SUN APR 20 2025
MONDAY NIGHT THROUGH SUNDAY:
THE SURFACE LOW THAT BROUGHT RAIN WILL CONTINUE TO MOVE
NORTHEAST INTO ONTARIO AND QUEBEC MONDAY NIGHT INTO TUESDAY. ON
ITS HEELS WILL BE A SURFACE HIGH PRESSURE AND AN UPPER LEVEL
RIDGE. THESE TWO FEATURES WILL MOVE THOUGH THE GREAT LAKES
QUICKLY WITH THE DRY WEATHER AND LIGHT WINDS ENDING BY TUESDAY
EVENING INTO WEDNESDAY. A SHORTWAVE TROUGH WILL SLIDE THROUGH
THE STATE LATE TUESDAY INTO WEDNESDAY BRINGING WITH IT A 40-60%
CHANCE FOR RAIN. THE SHORTWAVE WILL PROVIDE SOME UPPER LEVEL
LIFT WHILE WAA AND A LLJ IN THE MID TO LOW LEVELS INCREASE LIFT
AND MOISTURE. THERE REMAINS SOME UNCERTAINTY ON THE TRACK OF
THIS SHORTWAVE AND LOCATION OF THE LLJ. LITTLE SHIFTS COULD LEAD
TO SOME MORE MOISTURE OR MORE INSTABILITY LEADING TO A GREAT
POTENTIAL FOR THUNDERSTORMS AND MORE WIDESPREAD RAIN.
STRONG TO SEVERE STORMS ARE PRETTY CONDITIONAL HERE SIMILAR TO
SYSTEMS EARLIER IN THE WEAK. BEING A BIT ON THE PESSIMISTIC
SIDE, THE PRESENCE AND LOCATION OF THE LLJ WILL BE FAIRLY
CRUCIAL. NOT ONLY WILL THIS PROVIDE ASCENT AND MOISTURE, BUT IT
COULD FURTHER DESTABILIZE THE MID LEVELS. MODELS DO TRY TO
BRING IN CAPE AROUND 1000 J/KG, BUT WE MIGHT NOT BE ABLE TO
ACTUALIZE IF THERE IS A CAP. LOTS OF THINGS TO CONSIDER, BUT
BASED ON CURRENT MODELS IF ANYTHING DOES BECOME STRONGER ITS
LIKELY TO BE MORE A HAIL AND WIND CONCERN. WILL HAVE TO KEEP AN
EYE ON IT MOVING FORWARD.
ZONAL FLOW ALOFT IS EXPECTED WEDNESDAY THROUGH FRIDAY ACROSS THE
GREAT LAKES REGION. DURING THIS TIME WEAK HIGH PRESSURE WILL
KEEP THE STATE LARGELY DRY THROUGH THIS PERIOD. ANY SMALL
SHORTWAVE MOVING THROUGH THE LARGER FLOW COULD BRIEFLY ADD LOW
CHANCE POPS OF ROUGHLY 20%. THERE IS MUCH MORE UNCERTAINTY HERE
ON IF THESE SHORTWAVES WILL ACTUALLY BE THERE OR IF THERE TRACK
IS CORRECT. THUS MODELS ARE ALL OVER THE PLACE HERE. FRIDAY
NIGHT INTO SATURDAY LOOKS TO BE THE BEST POTENTIAL FOR OUR NEXT
CHANCE FOR RAIN AS THE ZONAL FLOW BEGINS TO BREAK DOWN.
PATTERSON
AVIATION
ISSUED 318 PM CDT SUN APR 20 2025
VFR CONDITIONS ARE EXPECTED TO CONTINUE ACROSS SOUTHERN
WISCONSIN THROUGH THIS AFTERNOON. RAIN IS MOVING IN FROM THE
SOUTHWEST THIS MORNING AND WILL OVERSPREAD THE ENTIRE AREA OVER
THE NEXT COUPLE HOURS. AS A LOW PRESSURE SYSTEM ADVANCES FROM
MO, LOWER MVFR TO IFR CEILINGS WILL MOVE FROM THE SOUTHWEST.
THESE LOWER CEILINGS ARE EXPECTED TO OVERSPREAD SOUTHERN
WISCONSIN THIS EVENING INTO TONIGHT. MORE SPECIFICALLY,AREAS
WEST OF I-39 (MSN AND JVL) WILL SEE MORE PERSISTENT RAINFALL
AND LOWER FLIGHT CONDITIONS WHILE AREAS FURTHER EAST ARE LIKELY
TO SEE MORE OFF AND ON TYPE OF SHOWERS THIS AFTERNOON AND
TONIGHT. CAN NOT RULE OUT A FEW THUNDERSTORMS THIS EVENING AND
TONIGHT.
BREEZY EASTERLY WINDS THIS MORNING ARE EXPECTED TO CONTINUE INTO
TONIGHT BEFORE BECOMING SOUTHERLY. SOUTHERLY WINDS OVERNIGHT
WILL BECOME WESTERLY BEHIND THE EXITING LOW PRESSURE SYSTEM
MONDAY. WESTERLY WINDS ARE EXPECTED THROUGH MONDAY NIGHT.
PATTERSON
MARINE
ISSUED 318 PM CDT SUN APR 20 2025
HIGH PRESSURE AROUND 30.5 INCHES CONTINUE TO PULL NORTHEAST
TOWARD THE NEW ENGLAND STATES. ON ITS HEELS IS A LOW PRESSURE
SYSTEM AROUND 29.6 INCHES IN MISSOURI THAT WILL ADVECT NORTHEAST
INTO WISCONSIN TONIGHT. THIS LOW PRESSURE SYSTEM WILL CONTINUE
NORTHEAST INTO ONTARIO THEN QUEBEC BY TUESDAY. EAST TO SOUTH
WINDS WILL BECOME GUSTY BETWEEN THIS INCOMING LOW AND EXITING
HIGH. GUSTS TO AROUND 30 KNOTS WILL BE POSSIBLE THROUGH TONIGHT
UNTIL WINDS BECOME SOUTHWEST TO WESTERLY. A SMALL CRAFT ADVISORY
IS IN EFFECT FOR THE NEARSHORE WATERS THIS EVENING AND TONIGHT.
WINDS WILL INCREASE AS THE LOW PRESSURE MOVES OVER THE LAKE
LEADING TO GALE FORCE GUSTS ACROSS THE SOUTHERN 2/3RDS OF THE
LAKE.
HIGH PRESSURE WILL BRIEFLY BUILD BACK INTO THE GREAT LAKES
REGION TUESDAY LEADING TO SOME LIGHTER NORTHWEST BECOMING LIGHT
AND VARIABLE. ADDITIONAL CHANCES FOR RAIN AND THUNDERSTORMS
MIDWEEK.
PATTERSON
MKX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
LM...SMALL CRAFT ADVISORY...LMZ643-LMZ644-LMZ645-LMZ646...7 PM
SUNDAY TO 7 AM MONDAY.
GALE WARNING...LMZ080-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-
LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-
LMZ872-LMZ874-LMZ876-LMZ878...7 AM MONDAY TO 7 PM MONDAY.
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