559
FXCN01 CWAO 310930
MAIN WX DISCUSSION
UPPER LEVEL PATTERN
PRAIRIES UPR TROF SHARPENS AND DEEPENS FORMG NEW UPR CENTRE EARLY ON TO BE OVR
MB/ON BDR BY T+12; THIS NEW UPR LO FRTHR DEEPNS TRACKG THRU NRN ONT/JMSBA/NRN
QC. DEEP LATTDNL FNTL TROF XTNDS SWWD OF NEW UPR LO TO CROSS MIDWEST AND GRTLKS
RGNS. GEM MODLS AND GFS HAVE WORKD VERY WELL IN TANDEM PAST FEW RUNS, WHILE
SLOWR UPR TROF PICTRD IN NAM MODL IS NOT CONSIDRD A VIABLE SOLTN.
NXT MAJOR UPR TROF IN THIS STG ZONAL CURRNT WAS POORLY INTLZD OVR NERN PAC.. IT
WILL MOVE ACRS BC TO CARVE HGTS OVR PRAIRIES PROVNCS BY END OF PD. NO SIG
DIFFRNC IN TIMING BUT UKMET MODL DIGS DEEPER THAN OTHRS.
SYS ONT-QC..
AS MENTIONNED MORE MERIDIONAL TRACK SUGGSTD BY NAM MODL IS REJCTD, IN VIEW OF
CONSSTNCY AND CONSENSUS OF GEM MODLS WITH OTHR FORGN GUIDNCE, ALTHOUGH GEMREG IS
MORE PROGRSSV WITH ITS UPR TROF. ECMWF LIKE GEM'S AND ENSMBL MEAN HAS A DOUBLE
CNTR OVR UNGAVA/LABDR CST BY T48, BUT SLGTLY MORE SLY TRACK; GFS SHOWS LESS
OCCLUDED SYST AND A BIT MORE MERDNL TRACK. SO LONG BAND OF >15CM ACCUM STRTCHG
JUST N OF LO'S TRACK THRU XTRM NRN RGNS OF ON/QC SEEN IN OBJCTV SVR WINTER WX
BASED ON GEMREG , FORMG AN ARC THRU PEAWANUCK - KUUJJUARAPIK - KUUJJUAQ, MAY
NEED ADJSMNT IN TERMS OF N-S LOCATN, BUT SIGNAL APPEARS RIGHT.
SHARP HANGBACK COLD FNT BRINGG COMA HEAD ACRS NRN ONT HAS ALL THE INGRDNTS TO
FORM FNTL SNSQUALLS SWEEPG XTRM NRN ONT AND CNTL QC FM JMSBA TO MANICOUAGAN
RSRVR ACCRDG TO OBJCTV SVR WX ASSESSMNT.
IN WARM SECTR MDT SWLIES TO BRING MILD TEMPS AND GUSTY WINDS ON HALLOWEEN DAY
FOR ONTARIO/SRN QC/SRN NB-NS. SWLIES COULD REACH SVR CRITERIA AS THEY INTENSIFY
OVR NS/GLFSLWRC ERLY THU MORNG.
SFC LO ALG 60N..
AT T48 ENSMBL FCST DISPLAYS SIG SPREAD IN POSN OF SUPPRTG UPR CENTR FM NRN MB TO
JUST S OF GRTSLVLK, AND HINTS AT PRBBLY TWO SFC CNTRS, VC GRTSLVLK AND NRN MB.
IT COULD BE TWO WVS SEPARATED BY SFC RDG POKING THRU CENTL NUNAVUT, AND MODLS
DIFFER ON STRGTH OF THAT RDG (UKMET HAS WEAKEST RDG AND DEEPST LO). IN ALL
INSTANCES NOT A LOT OF PCPN XPCD WITH THIS SYS, PRETTY MUCH ALL LIGHT SNOW
WITHIN A BROAD ENVLP, XCP A MIX OF TYPES AROUND GRTSLVLK IN THE 24-36H PD.
FNTL TROF THRU PRAIRIES..
CONFDNC WAS SHAKEN BY RELTVLY POOR INITILZTN OVR NERN PAC, BUT MODLS SHOW
GOOD CONSENSUS ON AMPLITUDE AND MOTION OF THE UPR TROF. UKMET/ECMWF APPEARED TO
HAVE THE BEST START. UKMET CARVES DEEPER HGTS THRU SK/ERN MT BY END OF PD,
WITHOUT LEADG TO SIGLY DIFFRNT FCST FM GEMREG AT THIS PT. BUT A BETTER PHASING
OF DYNAMICS WITH THERMAL PATTRN COULD BRING MORE ROBUST DVLPMNT, AND WE HAVE
ECWMF HINTING AT A SFC LO OVR ND. NOT MUCH PCPN XPCD OUT OF THIS BUT A BROADER
ENVLOP WOULD VERIFY BETTER, AS WE XPC A SMWHT BETTR DEVLPD SYS THAN CURRNT
GEMREG FCST.
END/GIGUERE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page