821
FXUS63 KGRB 232002
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
202 PM CST SUN FEB 23 2020
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE
SHORT TERM
TONIGHT AND MONDAY
ISSUED AT 201 PM CST SUN FEB 23 2020
EARLY THIS AFTERNOON, A SURFACE COLD FRONT CONTINUED TO TRACK
ACROSS THE STATE. THE FRONT WASN'T AMOUNTING TO MUCH OTHER THAN
WINDS VEERING MORE WESTERLY AND CREATING SOME GUSTS TO 20 TO 30
KNOTS. THE COMBINATION OF SUNNY SKIES AND WAA BROUGHT TEMPERATURES
WELL INTO THE 40S, WITH READINGS AT 2 PM RANGING FROM THE MIDDLE
40S TO LOW 50S.
CHALLENGE IN THE SHORT TERM IS CLOUD AND TEMPERATURE TRENDS. SOME
OF THE SHORT-TERM GUIDANCE MAY BE OVERDOING THE LOW LEVEL
MOISTURE, THEREFORE USED A BLEND OF THE GFS, EC, CANADIAN AND ADJ
GUIDANCE WHICH SEEMED TO HAVE A BETTER HANDLE ON THE CURRENT
SITUATION. SOME HIGH CLOUDS MAY MAKE IT INTO THE AREA TONIGHT, BUT
CONFIDENCE IS LOW. CONFIDENCE IS ALSO LOW ON THE POTENTIAL FOR ANY
LOW CLOUDS TO DEVELOP ACROSS THE NORTH. STRATUS DEVELOPMENT LAST
NIGHT WAS RELATIVELY SHORT-LIVED, BUT THERE COULD BE ENOUGH
BOUNDARY LAYER MOISTURE/WINDS TO GENERATE SOME LOW CLOUDS
TONIGHT. WENT WITH A PARTLY CLOUDY SOLUTION ACROSS CENTRAL AND
NORTH- CENTRAL WI. LOWS TONIGHT WILL BE IN THE UPPER TEENS TO
MIDDLE 20S.
FOR MONDAY, WINDS WILL VEER NORTHEAST WHICH SHOULD ALLOW FOR
COOLER AIR TO FILTER INTO THE AREA, ALONG WITH INCREASING CLOUDS
DURING THE AFTERNOON. HIGHS WILL BE IN THE MID TO UPPER 30S.
LONG TERM
MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 201 PM CST SUN FEB 23 2020
MAIN CONCERN IN THE EXTENDED FORECAST WILL BE THE POTENTIAL FOR A
WINTER STORM SYSTEM TO IMPACT PORTIONS OF THE AREA BY MID-WEEK.
THERE HAS BEEN A CONTINUED SOUTHEASTWARD TREND WITH THIS SYSTEM.
MONDAY NIGHT INTO TUESDAY: LOW PRESSURE ACROSS THE MID-MISSISSIPPI
VALLEY IS EXPECTED TO LIFT EAST-NORTHEASTWARD TOWARD THE OHIO RIVER
VALLEY THROUGH THIS TIME PERIOD. ALOFT, AN INTENSIFYING VORT
MAX/CLOSED 500MB LOW IS EXPECTED TO SLIDE ACROSS THE CENTRAL PLAINS
INTO THE MID-MISSISSIPPI VALLEY. THE BETTER UPPER-LEVEL JET ENERGY
(LEFT-EXIT REGION) IS EXPECTED TO REMAIN WELL SOUTHEAST OF THE AREA
THROUGH THIS TIME PERIOD. THE BETTER SYSTEM DYNAMICS REMAINING
SOUTHEAST OF THE AREA ALONG WITH FAIRLY DRY AIR ON THE NORTHERN
FRINGES OF THE SURFACE AND 850MB LOW, WILL KEEP CONDITIONS MAINLY
DRY ACROSS NORTHEAST WISCONSIN THROUGH THIS TIME PERIOD. LOWS ARE
EXPECTED TO BE IN THE 20S WITH HIGHS EXPECTED TO BE IN THE 30S
ACROSS MUCH OF THE AREA.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT: MODELS ARE STILL STRUGGLING
TO SETTLE ON EXACTLY HOW FAR NORTH OR SOUTH THE HEAVIEST BAND OF
SNOW WILL SET UP ACROSS THE AREA. THIS SYSTEM IS JUST BEGINNING TO
BE SAMPLED BETTER AS IT IS PUSHING INTO THE NORTHWEST CONUS TODAY,
WHICH SHOULD BEGIN TO INCREASE CONFIDENCE IN THE SYSTEM OVER THE
NEXT 24 HOURS. THERE HAS BEEN A CONTINUED TREND TO SHIFT THE HEAVIER
SNOW BAND TO THE SOUTHEAST. THIS IS LARGELY A RESULT OF THE BOTH THE
SURFACE LOW AND 850MB LOW SHIFTING A BIT FARTHER SOUTHEAST. EVEN THE
GFS (OUTLIER) HAS TRENDED THAT DIRECTION. THE ONE THING THAT MODELS
ARE IN GOOD AGREEMENT ABOUT IS THAT THE PRECIPITATION SHOULD BE
MAINLY IN THE FORM OF SNOW WHERE ANY PRECIPITATION FALLS. THE GFS IS
STILL THE FARTHEST NORTHWEST (BRINGING THE HEAVIEST SNOW TO EAST-
CENTRAL/FAR NORTHEAST WI), WHILE THE 12Z CANADIAN/EC IS FARTHEST
SOUTHEAST, BRINGING LITTLE TO NO SNOW FOR MOST OF NORTHEAST WI. THE
NAM IS MORE IN THE MIDDLE OF THE PACK BRINGING A HEAVIER BAND OF
SNOW TO LOCATIONS SOUTHEAST OF A LINE FROM ROUGHLY DOOR COUNTY TO
GREEN BAY TO APPLETON. THE HEAVIEST SNOW WOULD LIKELY OCCUR NEAR
MANITOWOC IN ANY OF THE AFOREMENTIONED SCENARIOS. SOME LAKE
ENHANCEMENT MAY ALSO OCCUR, BUT TEMPERATURES SEEM MARGINAL FOR THAT
AT THIS POINT AND WILL BE LARGELY RELIANT UPON SURFACE TO 850MB WIND
DIRECTION. MODEL PLUMES GENERALLY PAINT OUT MEAN VALUES AROUND 1 TO
2 INCHES FROM THE DOOR PENINSULA SOUTHWEST TO GREEN BAY AND
APPLETON, WITH A QUICK CUTOFF TO THE NORTHWEST OF THAT LINE. CLOSER
TO THE SHORELINE, NEAR MANITOWOC, MODEL PLUMES ARE CLOSER TO MEAN
VALUES OF 3 TO 6 INCHES. THE MODEL SPREAD IS VERY SIGNIFICANT, SO
THOSE ARE VERY PRELIMINARY NUMBERS WITH FAIRLY LOW CONFIDENCE.
AGAIN, THE CONFIDENCE IN THE RANGE OF VALUES IS LOW ENOUGH AT THIS
POINT TO KEEP FROM ISSUING ANY TYPE OF WINTER HEADLINES, BUT THEY
MAY BE NEEDED OVER THE NEXT COUPLE OF DAYS.
REST OF THE EXTENDED: SOME WRAP-AROUND MOISTURE MAY LINGER ACROSS
THE AREA THROUGH THE DAY THURSDAY AS ADDITIONAL SHORTWAVE ENERGY
PASSES THROUGH THE AREA. THIS MAY LEAD TO SOME LIGHT SNOW SHOWERS OR
FLURRIES ACROSS THE AREA ALONG WITH SOME LIGHT LAKE EFFECT SNOW
ACROSS NORTH-CENTRAL PORTIONS OF THE AREA. OTHERWISE, FAIRLY QUIET
WEATHER IS EXPECTED INTO NEXT WEEKEND AS HIGH PRESSURE AND RISING
500MB HEIGHTS BEGIN TO BUILD INTO MUCH OF WI. THIS WOULD LEND
SUPPORT FOR A WARMING TREND TOWARD NEXT WEEKEND INTO EARLY IN THE
NEXT WEEK.
AVIATION
FOR 18Z TAF ISSUANCE
ISSUED AT 1119 AM CST SUN FEB 23 2020
PRIMARILY VFR FLIGHT CONDITIONS THROUGH 18Z MONDAY WITH PERIODS
OF LLWS. CLEAR SKIES WERE NOTED ACROSS THE AREA LATE SUNDAY
MORNING, WHICH IS EXPECTED TO CONTINUE UNTIL AT LEAST EARLY THIS
EVENING. MODELS ARE STRUGGLING TO HANDLE THE POTENTIAL FOR CLOUD
DEVELOPMENT TONIGHT. OPTED TO BRING IN SCATTERED HIGH CLOUDS
ACROSS ALL TAF SITES, AND SOME LOWER STRATUS AT KRHI AFTER
MIDNIGHT. WOULD NOT BE SURPRISED IF THERE WERE A COUPLE HOURS OF
LOWER CLOUDS AT THE KAUW AND KCWA SITES LATE TONIGHT, BUT
CONFIDENCE IS LOW. MEANWHILE, MODERATE SW WIND GUSTS AND LLWS
AROUND 1000 TO 1500 FEET WILL PERSIST THROUGH THE EVENING.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM.....KLJ
LONG TERM......COOLEY
AVIATION.......KLJ
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