513
FXUS63 KGRB 190024
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
624 PM CST FRI JAN 18 2019
UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE
SHORT TERM
TONIGHT AND SATURDAY
ISSUED AT 252 PM CST FRI JAN 18 2019
MAIN CONCERN IN THE SHORT-TERM WILL BE THE CHANCES OF LIGHT SNOW
THIS EVENING INTO SATURDAY MORNING, ACROSS MAINLY THE SOUTHERN TIER
OR TWO TIERS OF COUNTIES. THIS WOULD BE FROM KEWAUNEE COUNTY WEST TO
AROUND SOUTHERN MARATHON COUNTY AND POINTS SOUTH. OTHERWISE, THE
HEAVIER SNOW POTENTIAL WILL LIKELY REMAIN CLOSE TO THE LAKE MICHIGAN
SHORELINE AND MOST NOTABLE FOR MANITOWOC COUNTY AND POSSIBLY
SOUTHERN KEWAUNEE COUNTY, WHERE LAKE EFFECT/ENHANCEMENT WILL DEVELOP
AND LINGER INTO SATURDAY AFTERNOON. IN FACT, HAVE ISSUED A WINTER
WEATHER ADVISORY FOR MANITOWOC COUNTY FROM THIS EVENING THROUGH
EARLY SATURDAY AFTERNOON.
WIDESPREAD CLOUD COVER WAS OBSERVED ON VISIBLE SATELLITE IMAGERY
THIS AFTERNOON ACROSS MUCH OF THE MIDWEST. ADDITIONALLY, WATER VAPOR
IMAGERY SHOWS TWO KEY FEATURES. ONE IS THE STRONGER UPPER-LEVEL WAVE
ACROSS THE CENTRAL PLAINS WITH A SECONDARY/WEAK SHORTWAVE SLIDING
ACROSS SOUTHERN MN. RADAR TRENDS CONTINUE TO SHOW A FAIRLY WIDE
SWATH OF LIGHT TO MODERATE SNOW STRETCHING ACROSS EASTERN SD INTO
THE SOUTH HALF OF MN AND SLOWLY WORKING INTO WEST-CENTRAL AND
SOUTHWEST WI THIS AFTERNOON. THE HEAVIER SNOW BAND HAS BEEN NOTED
OVER NORTHERN IA INTO FAR SOUTHERN MN, WHERE VISIBILITIES HAVE
GENERALLY BEEN LESS THAN A MILE. FARTHER NORTH, VISIBILITIES HAVE
GENERALLY BEEN IN THE 2 TO 5 MILE RANGE.
TONIGHT: THE AFOREMENTIONED STRONG UPPER LOW OVER THE CENTRAL PLAIN,
ALONG WITH THE ASSOCIATED SURFACE LOW, WILL SHIFT EASTWARD INTO THE
MID-MISSISSIPPI VALLEY BY SATURDAY MORNING. AT THE SAME TIME, THE
NORTHERN PIECE OF ENERGY IS EXPECTED TO SLIDE EASTWARD AND CROSS THE
CWA. AS THESE FEATURES SLIDE THROUGH AND SOUTH OF THE AREA, THE
AFOREMENTIONED LIGHT SNOW IS EXPECTED TO SHIFT EASTWARD THIS
EVENING. THE BEST CHANCE OF SEEING ACCUMULATING SNOW WILL LIKELY BE
ALONG THE SOUTHERN COUPLE TIERS OF COUNTIES, GENERALLY SOUTH OF A
LINE FROM SOUTHERN MARATHON COUNTY TO ROUGHLY SOUTHERN BROWN COUNTY.
THOSE LOCATIONS COULD SEE AN INCH OR TWO BY MIDNIGHT OR SHORTLY
THEREAFTER. THE SHARP CUTOFF TO ACCUMULATING SNOW STILL SEEMS TO BE
AN ISSUE, AS THE NORTH HALF OF THE AREA SEES DRY NORTHEAST FLOW
FILTERING INTO THOSE LOCATIONS. THERE WILL LIKELY BE SOME FLURRIES
OR LIGHT SNOW, BUT ACCUMULATIONS FARTHER NORTH ARE EXPECTED TO
REMAIN LIGHT. AS THE SYSTEMS SHIFT FARTHER EAST OVERNIGHT, WINDS
WILL SHIFT TO THE NORTH/NORTHEAST ALLOWING LAKE EFFECT/ENHANCED SNOW
TO DEVELOP ALONG LAKE MICHIGAN. 850MB TEMPERATURES WILL BE COLD
ENOUGH AS THEY DROP DOWN TO AROUND THE -16C TO -18C RANGE. LAKE
TEMPS ARE ANALYZED AROUND 5C, WHICH GIVES DELTA T VALUES IN THE 21C
TO 23C RANGE. INVERSION HEIGHTS (LAKE INDUCED) ARE EXPECTED TO PUSH
UP AROUND 5KFT, WITH A FAIRLY DEEP LAYER IN THE DGZ. THIS SHOULD
ALLOW FOR AT LEAST MODERATE LAKE EFFECT SNOW OVERNIGHT. CURRENT
THINKING IS THAT SOUTHERN MANITOWOC COUNTY WOULD HAVE THE BEST
CHANCE OF SEEING SNOWFALL RANGING FROM 1 TO 4 INCHES BY 12Z
SATURDAY. THIS WILL BE LARGELY DUE TO THE MORE FAVORABLE WIND
DIRECTION/FETCH ALONG WITH ENHANCED LOW-LEVEL CONVERGENCE.
SATURDAY: NORTHEASTERLY FLOW WILL CONTINUE THROUGH MUCH OF THE DAY
AS THE AFOREMENTIONED SYSTEMS CONTINUE TO SLIDE OFF TO THE EAST.
THIS FLOW WILL KEEP LAKE EFFECT SNOW IN THE FORECAST THROUGHOUT THE
DAY ALONG WITH INCREASED CLOUD COVER. AGAIN, THIS WILL LIKELY REMAIN
ALONG OR CLOSE TO THE LAKE MICHIGAN SHORELINE IN MANITOWOC COUNTY
AND POSSIBLY PORTIONS OF KEWAUNEE COUNTY, WHERE AN ADDITIONAL INCH
OR SO OF SNOW MAY FALL. THIS WOULD BRING SNOWFALL TOTALS UP TO THE
2 TO 5 INCH RANGE FOR MANITOWOC COUNTY. OTHERWISE, THE REST OF
THE AREA WILL LIKELY SEE IMPROVING CONDITIONS ALONG WITH SOME
AFTERNOON SUNSHINE. TEMPERATURES WILL REMAIN CHILLY, WITH NORTH-
CENTRAL LOCATIONS LIKELY REMAINING IN THE UPPER SINGLE DIGITS,
WHILE THE REST OF THE AREA REMAINS IN THE TEENS ABOVE ZERO.
LONG TERM
SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 252 PM CST FRI JAN 18 2019
UPPER TROUGH AT 500MB WILL APPROACH THE WESTERN UNITED STATES ON
SUNDAY, THEN TRACK ACROSS THE CENTRAL UNITED STATES TUESDAY INTO
WEDNESDAY. WESTERN RIDGE WILL THEN BUILD LATER NEXT WEEK INTO THE
WEEKEND OF THE JAN 26-27, WITH CORRESPONDING DOWNSTREAM TROUGH
ACROSS THE EASTERN HALF OF THE UNITED STATES WILL LEAD TO BELOW
NORMAL TEMPERATURES FOR MUCH OF THE PERIOD.
FOR SATURDAY NIGHT, CONTINUED A SMALL CHANCE OF SNOW SHOWERS
ACROSS PORTIONS OF FAR EASTERN KEWAUNEE AND MANITOWOC AS LOW
LEVEL WINDS ARE STILL FLOWING OFF THE LAKE. HIGH PRESSURE BUILDS
INTO THE REGION LATE SATURDAY NIGHT AND ACROSS THE REGION ON
SUNDAY. THINGS GET MORE INTERESTING SUNDAY NIGHT AND MONDAY WITH
RETURN SOUTH/SOUTHEAST FLOW OFF THE LAKE. LAKE TO 850MB
TEMPERATURE DIFFERENCES OF 15C TO 20C NOTED SUNDAY NIGHT INTO
MONDAY MORNING SHOULD BRING LAKE EFFECT SNOW SHOWERS OFF LAKE
MICHIGAN. WITH INCREASING SOUTHERLY FLOW MONDAY, THERE COULD BE
SOME DECENT LAKE EFFECT SNOW SHOWERS MOVING NORTHWARD INTO
NORTHERN DOOR COUNTY. WILL NEED TO WATCH THIS SCENARIO OVER THE
NEXT DAY OR TWO. WOULD NOT BE SURPRISE ME IF NORTHERN DOOR COUNTY
RECEIVES AT LEAST SEVERAL INCHES OF SNOW.
SYSTEM WILL APPROACH FROM THE WEST MONDAY AFTERNOON. SNOW IS
EXPECTED TO BREAK OUT ACROSS THE REGION MONDAY NIGHT WITH SNOW
CONTINUING INTO TUESDAY AFTERNOON/EVENING. SEVERAL INCHES OF SNOW
ARE POSSIBLE WITH THIS SYSTEM, CREATING HAZARDOUS CONDITIONS FOR
MOTORISTS. THE SNOW SHOULD END SOMETIME TUESDAY NIGHT. DRY
CONDITIONS ARE EXPECTED ON WEDNESDAY, EXCEPT ACROSS THE FAR NORTH
WHERE THERE IS A CHANCE OF LAKE EFFECT SNOW SHOWERS. LOW
CONFIDENCE IN THE CHANCES OF SNOW SHOWERS ON THURSDAY AND FRIDAY.
BELOW NORMAL TEMPERATURES THROUGH THE PERIOD, EXCEPT TUESDAY WHERE
TEMPERATURES WILL BE CLOSE TO NORMAL AND WILL THE WARMEST DAY
DURING THE PERIOD.
AVIATION
FOR 00Z TAF ISSUANCE
ISSUED AT 624 PM CST FRI JAN 18 2019
A WINTER STORM MOVING ACROSS THE OHIO VALLEY WILL
PRODUCE CLOUDS ACROSS THE AREA TONIGHT AND SATURDAY, WITH SOME
LIGHT SNOW OR FLURRIES SOUTH OF A GREEN BAY TO WAUSAU LINE, AND
LAKE EFFECT SNOW NEAR LAKE MICHIGAN. MVFR OR IFR CONDITIONS ARE
POSSIBLE LATER TONIGHT AND PART OF SATURDAY AT MTW BUT IT SHOULD
REMAIN VFR ELSEWHERE.
GRB WATCHES/WARNINGS/ADVISORIES
WINTER WEATHER ADVISORY UNTIL NOON CST SATURDAY FOR WIZ050.
SHORT TERM.....COOLEY
LONG TERM......ECKBERG
AVIATION.......RDM
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