000
FXUS63 KGRB 241801
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
101 PM CDT FRI MAY 24 2013

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 343 AM CDT FRI MAY 24 2013

AMPLIFIED UPR PATTERN IN PLACE ACRS NOAM...WITH UPR TROFS OVER
THE PAC NW AND ERN NOAM...WITH A SHARP RIDGE IN BETWEEN. THE ERN
TROF WL LINGER THROUGH THE HOLIDAY WEEKEND...THEN PULL OFF TO THE
NE. STG JET WL WORK EWD ACRS THE PAC THE NEXT FEW
DAYS...EVENTUALLY ADDING CONSIDERABLE ENERGY TO THE WRN TROF. THAT
WL CAUSE IT TO EXPAND EWD INTO THE PLAINS DURING THE LATTER HALF
OF THE FCST PERIOD...WITH THE DOWNSTREAM MID-CONTINENT RIDGE
BROADENING AND EXPANDING EWD BEHIND THE DEPARTING ERN TROF. THE
CHANGES WL EVENTUALLY RESULT IN A LONGER WAVELENGTH PATTERN WITH
UPR TROF CENTERED OVER THE ROCKIES...AND BROAD RIDGING OVER MOST
OF THE ERN CONUS.

NWLY UPR FLOW HAS USHERED A CHILLY AIR MASS INTO THE AREA...SO
TEMPS WL START OUT BLO NORMAL. BUT A WARMING TREND IS EXPECTED
DURING THE PERIOD AS UPR HEIGHTS RISE...WITH READINGS REACHING ABV
NORMAL LEVELS BY THE MIDDLE OF NEXT WK. HUMIDITIES WL PROBABLY
ALSO BE ON THE INCREASE. THERE IS LITTLE CHC FOR SIG PCPN THE NEXT
FEW DAYS...BUT PROSPECTS FOR SUCH WL BE MUCH HIGHER DURING THE
MIDDLE TO LATTER PART OF NEXT WK WHEN THE WARM HUMID AIR ARRIVES
IN THE AREA AND A FRONTAL BOUNDARY LIKELY SETS UP ACRS THE RGN.
&&

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 343 AM CDT FRI MAY 24 2013

QUIET WX EXPECTED. LOW-LEVEL ANTICYCLONE WL LINGER ACRS THE GREAT
LAKES RGN THROUGH SAT. PLENTY OF SUNSHINE EXPECTED TDA. GUID TEMPS
STILL SEEMED A LITTLE COOL...SO STUCK CLOSE TO PREV FCST.

MID-LVL SHRTWV WL FORCE ITS WAY THROUGH THE CENTRAL NOAM RIDGE
POSN TNGT...THEN TURN SE AND HEAD INTO THE BASE OF THE ERN NOAM
TROF SAT. UPR SPEED MAX SLIDING DOWN THE ERN SIDE OF THE UPR RIDGE
WL BE PULLING THROUGH THE LOWER GREAT LAKES RGN AT THE SAME TIME.
THE COMBINATION OF FORCING FM THE SHRTWV...DIV IN THE RRQ OF THE
UPR JET...AND SOME ISENT LIFT ON THE BACK SIDE OF THE LOW-LEVEL
ANTICYCLONE WL LEAD TO THE FORMATION OF A BAND OF PCPN TO OUR W
EARLY TNGT. THAT PCPN WL PUSH E TOWARD THE FCST AREA LATE TNGT...
BUT WL ENCOUNTER VERY DRY AIR AS IT DOES SO. QUESTION IS HOW FAR E
PCPN CAN GET BEFORE IT WIPES OUT. THE MODELS HAVE STRUGGLED WITH
THIS FOR SEVERAL DAYS...BUT NOW SEEM TO BE IN COMIMG INTO BETTER
AGREEMENT. FOLLOWED THE LATEST ECMWF AND NAM...BOTH OF WHICH
SUGGEST SOME LGT PCPN WL BRUSH THE W LATE TNGT AND VERY EARLY SAT
MORNING BEFORE DISSIPATING. SINCE WE/LL PROBABLY HAVE PCPN FALLING
OUT OF A MID-DECK AND INTO DRY AIR AT LOW-LEVELS...OPTED TO GO
WITH JUST SPRINKLES. THE ARRIVAL OF THE CLDS WL MITIGATE THE
FROST/FREEZE POTENTIAL FOR THE N...BUT THE FAR NE COULD STILL FALL
OFF ENOUGH EARLIER IN THE NGT TO ALLOW SOME PATCHY FROST.

ONCE THE SHRTWV SHIFTS OFF TO THE SE LATER SAT...DRY AIR FM THE E
WL STRENGTHEN ITS GRIP ON THE AREA. THAT SHOULD LEAD TO SOME DECR
IN CLDS DURING THE DAY.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 343 AM CDT FRI MAY 24 2013

ANOTHER COOL NIGHT IS IN STORE FOR MUCH OF THE AREA SATURDAY
NIGHT. AREAS OF FROST ARE POSSIBLE AGAIN ACROSS PORTIONS OF NORTH-
CENTRAL AND FAR NORTHEAST WISCONSIN. AS BEEN THE CASE THE LAST
SEVERAL NIGHTS...THE MODELS CONTINUE TO SHOW DIFFERENCES IN HOW
FAR EAST CONVECTION FROM THE PLAINS MAKES INTO WISCONSIN FROM
SATURDAY NIGHT THROUGH MEMORIAL DAY. HAVE TRENDED TOWARD THE MORE
CONSISTENT ECMWF MODEL FOR THIS TIME PERIOD...THUS KEPT IT DRY FOR
SATURDAY NIGHT THROUGH SUNDAY NIGHT. AGAIN FOLLOWED THE ECMWF ON
MONDAY WHICH INDICATED MOST OF THE PRECIPITATION WOULD DRY UP BY
THE TIME IT REACHED MARSHFIELD AND WISCONSIN RAPIDS. DO HAVE A
SMALL CHANCE OF SHOWERS ACROSS THE FAR SOUTHWEST ON MEMORIAL DAY
JUST IN CASE A FEW SPRINKLES OR LIGHT SHOWERS SNEAK INTO CENTRAL
WISCONSIN.

A CHANGE IN THE WEATHER PATTERN IS EXPECTED NEXT WEEK AS 500MB
RIDGE BUILDS ACROSS THE EASTERN UNITED BY THE END OF THE WEEK. IF
THE ECMWF IS CORRECT...WE WILL BE ON THE NORTHERN PERIPHERY OF THE
500MB RIDGE WHICH IS COMMONLY KNOWN AS THE RING OF FIRE. COULD BE
AN UNSETTLED PERIOD FROM TUESDAY THROUGH THURSDAY DEPENDING ON HOW
QUICK WARM FRONT LEFT NORTHWARD ON TUESDAY/TUESDAY NIGHT AND THEN
WHERE SURFACE BOUNDARY/OUTFLOW BOUNDARIES FROM CONVECTION SET UP.
WITH THE AMOUNT OF HEAT AND HUMIDITY TO THE SOUTH OF THE WARM
FRONT AND ON THE CONVECTIVE PARAMETERS...SOME OF THE STORMS COULD
BECOME STRONG OR SEVERE AND WOULD ALSO PRODUCE LOCALLY HEAVY RAIN.
WHEN THIS WOULD OCCUR IT STILL VERY HIGHLY UNCERTAIN. ALSO MAX
TEMPERATURES ALSO PROBLEMATIC DEPENDING ON TIMING OF THESE
CONVECTIVE COMPLEX...THUS HIGHS WEDNESDAY/THURSDAY COULD BE
SEVERAL DEGREES WARMER IF THERE IS MORE SUNSHINE THAN WHAT IS
CURRENTLY EXPECTED.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 100 PM CDT FRI MAY 24 2013

MID AND HIGH CLOUDS TO INCREASE THIS AFTERNOON AND
EVENING WHEN A MID-LEVEL WARM FRONT LIFTS INTO THE NORTHERN
MISSISSIPPI VALLEY.  CLOUDS WILL THICKEN AND LOWER TONIGHT...AND A
FEW SPRINKLES WILL BE POSSIBLE AFTER MIDNIGHT.  CLOUD BASES TO
REMAIN HIGH...SO VFR CONDITIONS TO REMAIN THROUGH THE TAF PERIOD.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......ECKBERG
AVIATION.......MPC