Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121959
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
259 PM CDT SAT APR 12 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 258 PM CDT SAT APR 12 2014

VERY CHILLY WITH PERIODS OF RAIN THE NEXT COUPLE DAYS...AND MAYBE
SOME SNOW BY MONDAY.

THE UPR FLOW ACRS NOAM IS AMPLIFYING...WITH TROF DEEPENING OVER
THE MIDWEST/PLAINS STATES. THE DEVELOPING HIGH AMPLITUDE PATTERN
WL PERSIST FOR A FEW DAYS...THEN THE FLOW WILL START TO FLATTEN
AND BECOME MORE SPLIT AGAIN.

THIS IS A COOL WET WEATHER PATTERN FOR THE AREA. IMPULSES RIDING
NE OUT OF THE CENTRAL U.S. UPR TROF WL BRING SEVERAL ROUNDS OF
PCPN TO THE FCST AREA THE NEXT COUPLE DAYS...THE FINAL OF WHICH
COULD END AS SNOW. THE HEAVIEST PCPN IS EXPECTED ACRS THE SE
PORTION OF THE FCST AREA...WHICH WL BE CLOSER TO THE MOISTURE
FLOWING IN FM THE S. ANOTHER ROUND OF PCPN IS POSSIBLE LATER IN
THE WEEK...SO AMNTS ARE LIKELY TO END UP ABV NORMAL FOR THE
PERIOD. THE ABUNDANT CLDS...PCPN...AND LCN OF THE FCST AREA N OF
THE MAIN FRONTAL BOUNDARY WL KEEP TEMPS ON THE COOL SIDE...AND
WELL BLO NORMAL.
&&

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 258 PM CDT SAT APR 12 2014

WET AND COOL DAY TODAY AS FIRST WAVE IS SLOWLY MOVING OUT OF
EASTERN WISCONSIN AS SUPPORT SHIFTS SOUTH AND EAST OF AREA. EAST WIND
AND CLOUDS HAVE KEPT TEMPS IN THE LOW 40S...THOUGH SEEING SOME
RECOVERY AFTER RAIN PULLS OUT OVER CENTRAL WI. LOWERED MAX TEMPS
FOR TODAY SIGNIFICANTLY EARLIER IN SHIFT...LEAVING ROOM FOR SOME
RECOVERY LATE THIS AFTERNOON.

QUESTION IN FORECAST IS TIMING OF NEXT WAVE OF PCPN. NAM AND EC
HAVE TRENDED TOWARDS LATE SUN AFTERNOON AS UPPER WAVE BEGINS TO
LIFT NORTH OUT OF SOUTHERN PLAINS AND SEE INCREASING SUPPORT FROM
COUPLED JET LIKE FEATURE.

STRONG TEMPERATURE CONTRAST OVER WARM FRONT OVER SOUTHERN WI WITH
MID 70S OVER SOUTHERN WI...TO AROUND 40 TO THE NORTH. GIVEN
AVAILABLE INSTABILITY THINK MESO MODEL HRRR`S THOUGHTS OF COMPLEX
MOVING ALONG FRONT THIS EVENING/TONIGHT...CLIPPING SOUTHERN CWA GOOD. HAVE
KEPT LIKELY POPS THOUGH MUCH OF TONIGHT OVER FAR SOUTH.

MOST OF INSTABILITY SHOVED SOUTH ON SUN...THUS HAVE KEPT THUNDER
OUT OF CWA. HAVE BROUGHT TEMPS UP A BIT ON SUN GIVEN DRIER LOOK.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 258 PM CDT SAT APR 12 2014

ANOTHER ROUND OF SIG PCPN WL BE SURGING NEWD IN THE BAROCLINIC
ZONE SUN NGT. THE HEAVIEST PCPN WL BE IN THE SE PART OF THE AREA.
THE MAIN QUESTION IS NOW QUICKLY THE COLD AIR WILL ARRIVE...AND
ALLOW THE PCPN TO CHG TO SNOW. THE CHANGEOVER WL DEPEND ON THE
EXACT THERMAL PROFILE...WHICH IS NEVER EASY TO GAUGE IN ADVANCE.
FCST CONFIDENCE IS RATHER LOW...BUT BEST GUESS IS THAT WE/LL SEE A
COUPLE INCHES OF SLUSHY SNOW ON THE GROUND FM ATW/GRB NEWD THROUGH
MNM/SUE BY MID-MORNING MONDAY.

THE MAIN AREA OF PCPN SHOULD SHIFT E OF THE AREA AT SOME POINT
MONDAY...THOUGH EXACT TIMING IS UNCERTAIN. SEVERAL OF THE MODELS
SUGGEST ANOTHER WAVE RIDING NEWD OUT OF THE PLAINS WL CAUSE THE
PCPN TO BUILD BACK WWD MON NGT/TUE. THIS DOESN/T LOOK QUITE RIGHT
GIVEN THE OPEN NATURE OF THE UPR TROF AND THE LCN OF THE FCST AREA
CLOSE TO THE LARGE SCALE TROF AXIS. SO UNLESS THERE IS SOME SIGN
OF THE TROF CLOSING OFF AT LEAST TEMPORARILY...THINK SIG PCPN WL
STAY TO OUR E ONCE IT SHIFTS OUT OF THE AREA MONDAY. THERE COULD
BE SOME FLURRIES HOWEVER...AND EVEN LAKE-EFFECT SHSN OVER N-C WI.

TEMPS ALOFT APPEAR COLD ENOUGH FOR FZN PCPN AT THE ONSET OF THE
NEXT PCPN EVENT LATER IN THE WEEK. BUT SUSPECT WE/LL SEE SOME
WARMING OF TEMPS ALOFT WITH LATER MODEL RUNS...AND BOUNDARY LAYER
TEMPS COULD BE A CONCERN FOR PCPN TYPE DURING THE DAY. SO TRENDED
TOWARD MORE OF A MIX N AND LIQUID S. OTHERWISE...NO SIG CHANGES
TO THE CONSENSUS BASED INITIALIZATION GRIDS FOR THE XTD PART OF
THE FCST.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1235 PM CDT SAT APR 12 2014

COMPLEX OF SHOWERS AND FEW THUNDERSTORMS CONTINUE TO MOVE EAST
THROUGH CENTRAL AND EAST CENTRAL WI. THIS AREA TO BE EAST OF AREA
MID AFTERNOON WITH MORE SCATTERED SHOWERS FOLLOWING. TO THE NORTH
BAND OF LIGHT RAIN HAS MOVED TO THE NORTH OF AREA...THOUGH AREA OF
MVFR CIGS EXPANDING EAST AND SOUTH THROUGH AREA. MODELS TENDING TO
INDICATE SECOND COMPLEX TO DEVELOP OVER EASTERN IOWA BY LATE
AFTERNOON...CLIPPING SOUTHERN TAF SITES AS IT MOVES EAST ALONG THE
WARM FRONT OVER SOUTHERN WI. CIGS TO CONTINUE TO DETERIORATE OVER
AREA WITH IFR CIGS EXPECTED OVERNIGHT. WIND EXPECTED TO KEEP VSBYS
FROM GOING BELOW MVFR LEVELS.
&&

.HYDROLOGY...
ISSUED AT 258 PM CDT SAT APR 12 2014

CURRENT FCST QPF FOR THE PERIOD THROUGH SUNDAY NIGHT RANGES
FROM LESS THAN ONE HALF INCH ACROSS NORTH CENTRAL WISCONSIN TO 1 TO 2
INCHES SOUTH OF LINE FROM MARINETTE TO SHAWANO TO WISCONSIN
RAPIDS...WITH THE HIGHER 2 INCH AMOUNTS OVER WAUSHARA TO CALUMET
TO MANITOWOC COUNTIES. THIS REGION OF OF HIGHER FORECAST RAIN
AMOUNTS ALSO OVER AN AREA WHICH LOSS THE SNOW COVER FOR A WHILE
NOW AND RIVERS HAVE DROPPED...WHICH IS SIMILAR TO SOUTHERN
WISCONSIN WHERE EVEN HIGHER RAINFALL IS ANTICIPATED. THE RAIN WILL
FALL IN A 36-42 HOUR PERIOD WITH SOME BREAKS EXPECTED. SOME
CONCERNS FOR SOME WATER PROBLEMS ESPECIALLY IN THE SOUTH WHERE
SOME TRAINING OF STORMS CURRENTLY OCCURRING...LATER SCANS SHOWING
SOME DRIFT TO SOUTH THOUGH WITH HIGHER RETURNS. URBAN SMALL
STREAM ADVISORIES MAY BE NEEDED OVER FAR SOUTH.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....TE
LONG TERM......SKOWRONSKI
AVIATION.......TE
HYDROLOGY......TE






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