000
FXUS63 KGRB 220935
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
435 AM CDT WED MAY 22 2013

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SYNOPSIS...
ISSUED AT 425 AM CDT WED MAY 22 2013

UPR LOW DIGGING DOWN THE WEST COAST WL KICK THE UPR TROF NOW OVER
THE PLAINS EWD TOWARD NEW ENGLAND...RESULTING IN A HIGHLY
AMPLIFIED BUT FAIRLY STABLE UPR PATTERN ACRS THE CONUS FOR MUCH OF
THE PERIOD. BY LATE IN THE PERIOD...THE WRN TROF WL START TO
EXPAND EWD AS STG PAC JET HEADS INTO CA.

TEMPS WL START OUT BLO NORMAL...THEN MODERATE DURING THE SECOND
HALF OF THE FCST PERIOD...LIKELY TO ABV NORMAL LEVELS BY THE
MIDDLE TO END OF NEXT WK. THE MAIN PCPN EVENT WL OCCUR EARLY AS
PLAINS UPR TROF CROSSES THE RGN. THAT SYSTEM WL BE A GOOD PCPN
PRODUCER...ESP FOR THE SE PART OF THE FCST AREA.
&&

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 425 AM CDT WED MAY 22 2013

GENERAL FCST FOR THE SHORT-TERM IS FAIRLY SIMPLE. UPR TROF FM THE
NRN PLAINS WL SHIFT EWD ACRS THE AREA AND PHASE WITH SOME ENERGY
DIGGING SE FM CANADA...RESULTING IN STRENGTHENING CYCLONE
TRACKING ACRS SRN WI THIS AFTN/TNGT. THAT SYSTEM WL BRING A
WIDESPREAD SOAKING RAIN TO MOST OF THE FCST AREA THIS AFTN/TNGT.
MAIN CHALLENGE IS WORKING IN THE FCST DETAILS.

JUST SOME LINGERING LGT SHRA OVER THE FAR N EARLY THIS MORNING.
OTHERWISE...THE FCST AREA EXPERIENCING A LULL IN THE PCPN. SFC
BOUNDARY WAS OVER NRN WI AT 05Z...BUT HAS SINCE SLIPPED SWD ALONG
THE LAKE AND BAY. FOG...SOME OF IT QUITE DENSE...WAS OVER THE LAKE
AND BAY. THE PASSAGE OF THE BOUNDARY ALLOWED THE FOG TO ADVECT
INLAND...WITH VSBYS NOW AS LOW AS 1/4 SM AT TIMES AT THE GRB
AIRPORT. THINKING IS THAT THE REAL DENSE FOG WL BE CONFINED
FAIRLY CLOSE TO THE WATER...AND WON/T BE WIDESPREAD ENOUGH TO
WARRANT AN ADVISORY. WL COVER WITH AN SPS...WHICH IS ALREADY OUT.

STLT IMAGERY ALREADY SHOWED EXPANDING AREA OF COLDER CLD TOPS
LIFTG NE ACRS IA/SERN MN. NOT MUCH IN THE WAY OF RADAR RETURNS
WITH THIS FEATURE YET...BUT IT SHOULD EVENTUALLY EVOLVE INTO THE
COMMA HEAD THAT WL PIVOT ACRS THE AREA LATE TDA/TNGT. RAN POPS UP
TO CATEGORICAL IN THE SE 2/3 OF THE FCST AREA. UPPED PCPN AMNTS
CONSIDERABLY FM PREV FCST. ALTHOUGH INSTABILITY WL BE LIMITED...
THERE MAY BE ENOUGH TO GENERATE SOME THUNDER THIS AFTN/EVE.
CARRIED SOME THUNDER IN THE FCST...BUT LIMITED IT TO ISOLATED
COVERAGE. MAX TEMPS WL PROBABLY OCCUR MID-DAY...BEFORE RAIN
BECOMES WIDEPSREAD.

WINDS WL INCR LATE TDA AND THIS EVENING. SOME CONCERN WE COULD
HAVE ONE OF THOSE SITUATIONS WHERE STG NE WINDS CAUSE WATER TO
BACK UP THE BAY TOWARD THE MOUTH OF THE FOX RIVER. ON THE OTHER
HAND...THE LIMITED POTENTIAL FOR THUNDERSTORMS SHOULD PREVENT
EXCESSIVE RAINFALLS. ALSO...DIDN/T GET MUCH RAIN IN E-C WI
YDA...SO AT LEAST WE AREN/T STARTING WITH HIGH FLOWS COMING INTO
THE MOUTH OF THE FOX.

PCPN SHIELD SHOULD START TO PUSH TO THE SE AFTER MIDNIGHT. SHUT
DOWN PCPN IN FAR N-C WI BY LATE TNGT. KEPT IT GOING OVER FAR E-C
WI EARLY FRI...THOUGH IT SHOULDN/T LAST TOO LONG INTO THE MORNING.
STG SUBSIDENCE AND THE ARRIVAL OF DRIER AIR SHOULD SCOUR OUT CLDS
FM NW-SE FRI MORNING. DESITE THE EXPECTATION OF NR FULL SUN FRI
AFTN...TEMPS AND STG NLY WINDS WL MAKE IT FEEL CHILLY FOR LATE
MAY.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 425 AM CDT WED MAY 22 2013

BELOW NORMAL TEMPERATURES WILL CONTINUE INTO THE MEMORIAL DAY
WEEKEND THEN TREND AT OR SLIGHTLY ABOVE NORMAL FOR EARLY NEXT
WEEK. THURSDAY NIGHT WILL BE COLD WITH A WIDESPREAD FROST OR
FREEZE NORTH AND WEST OF THE FOX VALLEY. A HARD FREEZE SHOULD BE
EXPECTED FOR LOCATIONS NORTH OF A WAUSAU TO MARINETTE LINE. LATEST
NUMERICAL GUIDANCE SUGGEST TEMPERATURES IN OUR TYPICAL COLD SPOTS
LIKE LAND O LAKES...TOMAHAWK AND MERRILL COULD DROP DOWN INTO THE
LOWER TO MIDDLE 20S. WITH SUCH A DRY AIR MASS IN PLACE...CLEAR
SKIES AND LIGHT WINDS...WOULD NOT BE OUT OF THE QUESTION THAT LAND
O LAKES DROPS INTO THE UPPER TEENS. LEANED TOWARD THE COLDER
GUIDANCE NORTH AND WEST OF THE FOX VALLEY DUE TO WINDS BECOMING
LIGHT AND VARIABLE AFTER SUNSET. ACROSS THE FOX VALLEY THE WINDS
WILL REMAIN UP A BIT LITTLE LONGER DURING THE NIGHT...THEREFORE
TEMPERATURES SHOULD FALL INTO THE MIDDLE TO UPPER 30S. WOULD NOT
TAKE MUCH IF WINDS WENT CALM FOR A WHILE THAT THIS REGION
APPROACHED 32 DEGREES. WILL LET DAY SHIFT HAVE THE PRIVILEGE OF
ISSUING THE FREEZE WATCH. DESPITE TEMPERATURES IN THE 20S AND 30S
THURSDAY NIGHT...HIGH TEMPERATURES WILL CLIMB BACK INTO THE LOWER
TO MIDDLE 60S AT MOST PLACES ON FRIDAY. AFTERNOON RELATIVE
HUMIDITIES WILL DROP TO 10 TO 20 PERCENT ACROSS THE NORTH...AND 20
TO 30 PERCENT ACROSS THE SOUTH.

MODELS CONTINUE TO DIFFER ON NORTHWARD EXTENT OF THE CLOUDS AND
PRECIPITATION LATER FRIDAY NIGHT INTO SATURDAY. HAVE LOWERED MIN
TEMPERATURES DUE TO SLOWER ARRIVAL OF THE CLOUDS. FROST IS LIKELY
AGAIN FRIDAY NIGHT ACROSS PORTIONS OF NORTH-CENTRAL AND FAR
NORTHEAST WISCONSIN. GFS BUFKIT SOUNDING VERY DRY ON SATURDAY...
THUS WOULD ONLY EXPECT SPRINKLES ACROSS OUR FAR SOUTHWEST. THE
DIFFERENCES IN THE MODELS CONTINUE FOR THE REST OF THE MEMORIAL
DAY WEEKEND AS GFS/CANADIAN TRY TO EDGE PRECIPITATION BACK INTO
OUR SOUTHWEST COUNTIES AT TIMES ON SUNDAY INTO MEMORIAL DAY. THE
ECMWF ON THE OTHER HAND DRIVES THE FRONT WELL SOUTH AND KEEPS US
DRY THROUGH TUESDAY. DID NOT MAKE MUCH CHANGES TO THE SUNDAY
THROUGH TUESDAY PERIOD DUE TO THE UNCERTAINTY ON THE DIFFERENT
MODEL SOLUTIONS. WOULD HAVE PREFER ED TO REMOVE PRECIPITATION
SUNDAY AND MEMORIAL EXCEPT OVER OUR VERY FAR SOUTHWEST.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 425 AM CDT WED MAY 22 2013

LIFR CIGS ACRS THE N THIS MORNING...AND SOME LIFR/VLIFR
CONDITIONS IN FOG NEAR THE LAKE AND BAY. THOUGH SOME IMPROVEMENT
IS EXPECTED...OVERALL POOR FLIGHT CONDITIONS WL LINGER ACRS THE N
INTO TNGT. POOR FLIGHT CONDITIONS...MAINLY DUE TO LOW CIGS...WL
DEVELOP ACRS THE REST OF THE AREA AS WELL THIS AFTN/EVE. MAY NEED
LLWS DUE TO VERY STG NE FLOW JUST ABOVE THE SFC OVER E-C WI
TNGT...WL MAKE ISSUANCE TIME DECISION ON THAT.
&&

.MARINE...
ISSUED AT 425 AM CDT WED MAY 22 2013

WITH HIGH-END SMALL CRAFT ADVISORY WINDS LOOMING JUST ON THE
HORIZON...OPTED TO START THE SMALL CRAFT ADVISORY IMMEDIATELY AND
JUST WRAP THE CURRENT MARINE FOG EVENT INTO IT. DETAILS AND
EXPECTED CONDITIONS WL BE SPELLED OUT IN THE FCST AND MWW
PRODUCT...SO OPTED TO KEEP ACTUAL HEADLINE SIMPLE.
&&

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

$$

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