189
FXUS63 KGRB 240337
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1037 PM CDT SAT MAR 23 2019
UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE
SHORT TERM
TONIGHT AND SUNDAY
ISSUED AT 249 PM CDT SAT MAR 23 2019
THE MAIN FORECAST FOCUS TO BE ON TEMPERATURES TONIGHT AND EXTENT
OF PRECIPITATION ON SUNDAY AS TWO WEATHER SYSTEM MERGE OVER THE
GREAT LAKES.
THE 19Z MSAS SURFACE ANALYSIS SHOWED AN AREA OF HIGH PRESSURE OVER
NORTHERN INDIANA WHICH ENGULFED THE ENTIRE GREAT LAKES REGION WITH
CLEAR SKIES AND MODEST WEST-SOUTHWEST WINDS. A WEAK AREA OF LOW
PRESSURE WAS SITUATED OVER THE CENTRAL PLAINS WITH MID/HIGH-LEVEL
CLOUDS PULLING NORTH ACROSS THE MIDWEST. FARTHER NORTH, A COLD
FRONT WAS SITUATED OVER CENTRAL ONTARIO/SOUTHERN MANITOBA. LITTLE
IN THE WAY OF CLOUDS WERE EVIDENT IN THE VICINITY OF THE FRONT.
GENERALLY QUIET WEATHER CONDITIONS ARE EXPECTED ACROSS THE REGION
TONIGHT AS THESE TWO SYSTEMS BEAR DOWN ON THE GREAT LAKES. THE
WEAK SURFACE LOW (AND ITS ASSOCIATED MID-LEVEL SHORTWAVE TROUGH)
OVER THE CENTRAL PLAINS WILL BRING LIGHT RAIN TOWARD SOUTHWEST WI
BY DAYBREAK. THE WEST-EAST ORIENTATED COLD FRONT IS FORECAST TO
DROP SOUTH INTO NORTHERN WI BY DAYBREAK. MODELS SUGGEST THAT ANY
PRECIPITATION WOULD BE POST-FRONTAL, THUS NO PRECIPITATION
EXPECTED IN THE NORTH TONIGHT. DO ANTICIPATE AN INCREASE IN MID/
HIGH CLOUDS OVERNIGHT, HOWEVER THE AIR MASS IS STILL VERY DRY OVER
NORTHEAST WI, THUS TEMPERATURES SHOULD QUICKLY FALL THIS EVENING
EVEN BEFORE THE CLOUDS ARRIVE. LOOK FOR MIN TEMPERATURES IN THE
LOWER TO MIDDLE 20S NORTH, UPPER 20S TO LOWER 30S SOUTH.
THE SOUTHERN SYSTEM IS PROGGED TO TRACK EAST ACROSS THE MIDWEST/
MID-MS VALLEY PM SUNDAY WITH THE NORTHERN PERIPHERY OF LIGHT RAIN
ONLY REACHING THE SOUTHERN THIRD OF WI. MEANWHILE, THE COLD FRONT
WILL CONTINUE PUSHING SOUTH AND MOVE THROUGH CENTRAL/EAST-CENTRAL
WI AROUND MID-MORNING. CANNOT RULE OUT A SMALL CHANCE OF
PRECIPITATION ACROSS NORTHERN WI FROM MID-MORNING TO MID-
AFTERNOON, BUT ANY PRECIPITATION WOULD BE VERY LIGHT SINCE ANY
GULF MOISTURE WOULD BE INTERCEPTED BY THE SOUTHERN SYSTEM.
PRECIPITATION TYPE TO BE THE BIGGEST FORECAST ISSUE AS STRONG CAA
BEHIND THE COLD FRONT WOULD FAVOR SNOW RATHER THAN RAIN. PROBLEM
IS THAT THERE IS A LACK OF ICE CRYSTALS ALOFT, WHICH WOULD FAVOR
FREEZING DRIZZLE. HAVE GONE WITH A DRIZZLE/FREEZING DRIZZLE MIX
FOR NOW DEPENDING ON TEMPERATURES. GUSTY NORTHEAST WINDS IN THE
WAKE OF THE COLD FRONT WILL LIKELY LEAD TO A MINIMAL RISE IN
TEMPERATURES, ESPECIALLY ACROSS THE NORTH. LOOK FOR READINGS TO
ONLY REACH THE MIDDLE TO UPPER 30S FAR NORTH-CENTRAL WI, BUT LOWER
50S OVER PARTS OF CENTRAL WI.
LONG TERM
SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 249 PM CDT SAT MAR 23 2019
NORTHWEST UPPER FLOW SHOULD KEEP DRY WEATHER ACROSS THE REGION
THROUGH AT LEAST WEDNESDAY. THIS WILL ALLOW FOR SLOW MELTING OF
SNOW WITH MILD DAYS AND BELOW FREEZING NIGHTS.
JET ENERGY OUT AHEAD OF WESTERN UNITED STATES UPPER TROUGH WILL
BRING THE CHANCE OF SHOWERS WEDNESDAY NIGHT THROUGH THURSDAY.
MODEL DIFFERENCES INCREASE AFTER THAT WITH DIFFERING IDEAS OF
PHASING OF NORTHERN AND SOUTHERN STREAM SHORTWAVES. THIS RESULTS
IN SIGNIFICANT DIFFERENCES IN THE TIMING AND AMOUNT OF PRECIPITATION,
AS WELL AS PRECIPITATION TYPE.
IT IS NOT OUT OF THE QUESTION THAT THERE WILL BE SIGNIFICANT SNOW
SOMEWHERE IN THE FORECAST AREA BY THE END OF THE WEEK, AS WELL AS
POSSIBLE FLOOD PROBLEMS WITH RIVERS ALREADY AT BANKFULL IN MANY AREAS.
AVIATION
FOR 06Z TAF ISSUANCE
ISSUED AT 1032 PM CDT SAT MAR 23 2019
VFR CONDITIONS ARE EXPECTED OVERNIGHT, WITH JUST AN INCREASE IN
HIGH CLOUDS OVERNIGHT. LOW PRESSURE OVER THE CENTRAL PLAINS WILL
TRACK SOUTH OF THE REGION LATER TONIGHT INTO SUNDAY, WITH THE
LEADING EDGE OF LIGHT RAIN ONLY REACHING SOUTHERN WI. A CANADIAN
COLD FRONT WILL SWEEP SOUTH THROUGH THE REGION LATE TONIGHT AND
SUNDAY MORNING, CAUSING A WIND SHIFT TO THE NORTHEAST, AND
BRINGING BLUSTERY CONDITIONS TO THE FOX VALLEY AND LAKESHORE AREAS
BY AFTERNOON. MVFR CEILINGS ARE EXPECTED TO DEVELOP A FEW HOURS
AFTER THE FRONTAL PASSAGE. SPOTTY VERY LIGHT DRIZZLE OR FREEZING
DRIZZLE IS POSSIBLE OVER NORTH CENTRAL AND FAR NORTHEAST WI FROM
MID-MORNING THROUGH EARLY AFTERNOON, BUT THE CHANCE IS TOO LOW TO
MENTION AT THE RHI TAF SITE AT THIS TIME. CLEARING WILL PROGRESS
SOUTH ACROSS THE REGION DURING THE LATE AFTERNOON AND EVENING.
HYDROLOGY
ISSUED AT 249 PM CDT SAT MAR 23 2019
FAVORABLE CONDITIONS FOR A SLOW SNOWMELT ACROSS THE NORTH WILL
CONTINUE INTO EARLY NEXT WEEK. A SYSTEM IS EXPECTED TO AFFECT THE
AREA DURING THE LATTER PART OF NEXT WEEK, HOWEVER THE MEDIUM
RANGE MODELS CONTINUE TO EXHIBIT CONSIDERABLE DAY TO DAY CHANGES
IN THE FORECAST TRACK AND INTENSITY OF THE SYSTEM. THEREFORE,
CONFIDENCE REMAINS LOW ON WHERE THE AXIS OF POTENTIALLY HEAVY RAIN
OR SNOW WOULD FALL. PEOPLE LIVING NEAR RIVERS, STREAMS AND CREEKS
SHOULD CONTINUE TO WATCH FOR UPDATES ON THIS SYSTEM IN THE COMING
DAYS.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM.....KALLAS
LONG TERM......RDM
AVIATION.......KIECKBUSCH
HYDROLOGY......KALLAS
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