Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KGRB 211756
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1156 AM CST FRI NOV 21 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 358 AM CST FRI NOV 21 2014

CLEAR SKIES AND LIGHT WINDS ALLOWED TEMPERATURES TO FALL
BELOW ZERO OVER ALL BUT THE LAKESHORE AND FOX VALLEY EARLY TODAY. SURFACE
HIGH OVER NORTHERN OHIO VALLEY MOVES QUICKLY OFF TO THE SOUTHEAST WHILE
A SURFACE LOW MOVES FROM LAKE WINNIPEG TO JAMES BAY. THE PRESSURE GRADIENT
BETWEEN THEM WILL PRODUCE INCREASING SOUTH WINDS TODAY AND SLIGHTLY
WARMER TEMPERATURES THAN THE LAST FEW DAYS. SHOULD BE A MOSTLY
SUNNY DAY WITH MIDDLE AND HIGH CLOUDS ARRIVING TOWARDS EVENING.
HIGHS WILL BE ABOUT 15 DEGREES BELOW NORMAL.

BIG QUESTION TONIGHT AND SATURDAY IS WHETHER LOW LEVEL MOISTURE
INCREASES ENOUGH TO PRODUCE FREEZING DRIZZLE. DEW POINTS HAVE RISEN
INTO THE 50S AND 60S IN TEXAS AND OKLAHOMA AND LOW CLOUDS ARE SEEN
MOVING NORTHWARD ON SATELLITE. FORECAST SOUNDING SUGGEST THAT THE
LOW LEVEL MOISTURE WILL ARRIVE DURING THE LATE EVENING OR AFTER
MIDNIGHT AS A 40 TO 50 KNOT LOW LEVEL JET MATERIALIZES. SURFACE
TEMPERATURES SHOULD BE BELOW FREEZING SO WILL HAVE A CHANCE OF
FREEZING DRIZZLE FOR THE ENTIRE AREA. LOW TEMPERATURES WILL LIKELY
OCCUR DURING THE EVENING WITH RISING TEMPERATURES OVERNIGHT. CHANCE
OF FREEZING DRIZZLE SATURDAY THOUGH THE MOISTURE MAY MIX OUT DURING
THE AFTERNOON. HIGH TEMPERATURES SHOULD BE ABOVE FREEZING FOR THE
FIRST TIME IN MORE THAN A WEEK.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 358 AM CST FRI NOV 21 2014

THE LATEST GFS ENSEMBLE MEAN INDICATES THAT ANOTHER VERY COLD
STRETCH OF WEATHER WILL BE PRESENT FOR THE MIDDLE TO THE END OF NEXT
WEEK BEFORE THE UPPER FLOW FLATTENS AGAIN FOR THE FIRST WEEK OF
DECEMBER. A LOT CAN CHANGE BEFORE NOW AND THEN...BUT IN THE
MEANTIME...THE MAIN FORECAST CONCERN IS THE DEEP CYCLONE DUE TO MOVE
ACROSS THE REGION LATE IN THE WEEKEND INTO EARLY NEXT WEEK.  THE
MEDIUM RANGE MODELS HAVE TRENDED SLIGHTLY EAST AND SLOWER WITH THE
TRACK/TIMING OF THE SURFACE LOW.  WILL CONTINUE A BLEND OF THE
ECMWF/GFS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...AS LOW PRESSURE BEGINS TO
ORGANIZE OVER THE SOUTHERN PLAINS SATURDAY NIGHT...BACKING WINDS WILL
SUPPORT ANOTHER SURGE OF LOW LEVEL MOISTURE.  AS THIS
OCCURS...RELATIVELY SHALLOW MOISTURE TRAPPED BENEATH A LOW INVERSION
WILL DEEPEN FOR AN IMPROVING CHANCE OF DRIZZLE LATE SATURDAY NIGHT.
SURFACE TEMPS WILL BE AROUND FREEZING ACROSS NORTH-CENTRAL
WISCONSIN...SO WILL LEAVE A CHANCE OF FREEZING DRIZZLE IN THE
FORECAST.  MOISTURE WILL CONTINUE TO DEEPEN AS LOW PRESSURE MOVES
NORTH INTO THE CENTRAL MISSISSIPPI VALLEY ON SUNDAY.  INCREASING
FORCING VIA UPPER DIVERGENCE AND MID-LEVEL FGEN WILL SUPPORT AN AREA
OF RAIN LIFTING NORTH OVER CENTRAL AND EASTERN WISCONSIN SUNDAY
AFTERNOON.  THIS RAIN WILL CONTINUE TO IMPACT THESE REGION SUNDAY
NIGHT...THOUGH SOME CHANGE OVER TO A MIX OR SNOW IS POSSIBLE IN THE
ROUTE 39/51 CORRIDOR LATE.  WILL RAISE MIN TEMPS A DEGREE OR TWO
SATURDAY NIGHT.  LITTLE CHANGE TO TEMPS OTHERWISE.

REST OF THE FORECAST...THE DEEPENING CYCLONE WILL CONTINUE TO TRACK
NORTHEAST ACROSS NORTHERN MICHIGAN AND INTO ONTARIO ON MONDAY.
COLDER AIR WILL SLOWLY WRAP IN BEHIND THE LOW...BUT MOST OF THE
PRECIP LOOKS TO BE CONFINED TO THE COMMA HEAD OVER WESTERN AND
NORTHERN WISCONSIN. SMALL ACCUMULATIONS OF SNOW WILL BE POSSIBLE
THERE.  BETTER CHANCES OF SNOW EVERYWHERE WILL OCCUR MONDAY NIGHT
WHEN A TRAILING SHORTWAVE MOVES OVER THE REGION. DECENT
ACCUMULATIONS WILL BE POSSIBLE WITHIN THE SNOW BELT FROM LAKE
EFFECT.  THE SNOW WILL BE DIMINISHING ON TUESDAY WHEN WEAK HIGH
PRESSURE ARRIVES.  THEN LIGHT SNOW WILL BE POSSIBLE AGAIN DURING THE
WEDNESDAY-THURSDAY PERIOD FROM WEAK CLIPPER SYSTEM.  BACK INTO THE
DEEP FREEZE BY THE END OF THE WEEK.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1155 AM CST FRI NOV 21 2014

VFR CONDITIONS EXPECTED INTO THE EVENING HOURS AS AN AREA OF HI
PRES MOVES FARTHER AWAY FROM WI. AN INCREASING SW LOW-LEVEL JET
(UP TO 50 KTS) WL QUICKLY TRANSPORT WARMER/MORE MOIST AIR INTO WI
TNGT. EXPECT TO SEE A MVFR STRATUS DECK OVERSPREAD NE WI AFTER 03Z
WITH FREEZING RAIN/DRIZZLE ARRIVING SHORTLY THEREAFTER. CIGS ARE
EXPECTED TO DROP TO IFR CONDITIONS LATE TNGT INTO SAT MORNING WITH
THE FREEZING RAIN/DRIZZLE GRADUALLY CHANGING TO LIGHT RAIN OR
DRIZZLE AS WARMER AIR CONTS TO GET PUMPED INTO THE REGION. THESE
STRONG SW WINDS HAVE ALSO PROMPTED THE NEED TO MENTION LLWS IN ALL
TAF SITES FOR TNGT.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....RDM
LONG TERM......MPC
AVIATION.......AK





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.