990
FOCN45 CWWG 171200
SIGNIFICANT WEATHER DISCUSSION ISSUED BY THE PRAIRIE AND ARCTIC STORM
PREDICTION CENTRE OF ENVIRONMENT CANADA AT 7:00 AM CDT THURSDAY JULY
17 2025.
ALERTS IN EFFECT...AIR QUALITY ALERTS FOR PARTS OF ALBERTA,
SASKATCHEWAN, MANITOBA, AND NWT. FOG ADVISORY FOR IGLOOLIK.
HEAT WARNING FOR PARTS OF THE SOUTHERN NT.
SYNOPTIC OVERVIEW...THE 00Z UPPER ANALYSES REVEALED A LOW OVER
NORTHERN QUEBEC, A TROUGH OVER THE SOUTHEAST B.C. INTERIOR, AND A
RIDGE FROM ALASKA TO THE EASTERN PACIFIC.
THE SURFACE ANALYSIS SHOWS LOW PRESSURE OVER NORTHERN HUDSON BAY,
HIGH PRESSURE FROM THE EASTERN PRAIRIES TO THE WESTERN ARCTIC, AND
LOW PRESSURE OVER WASHINGTON STATE.
DISCUSSION...
PRAIRIES...THERE WILL BE A COUPLE OF CONCERNS THIS FORECAST PERIOD.
FIRST, OF COURSE, IS SMOKE. THE MAIN FIRES OF NOTE CONTINUE TO
FUMIGATE DOWNSTREAM REGIONS AND THE AREAS AFFECTED WILL DEPEND ON THE
WINDS. WITH ONE OF THE HIGH CENTRES OVER THE EASTERN PRAIRIES, MOST
OF THE SMOKE WILL LIKELY BE MOVED OFF TO THE EAST. THIS MEANS THAT
SMOKE FROM THE FIRES IN THE BISSETT REGION OF SOUTHERN MANITOBA WILL
PRIMARILY AFFECT THAT REGION AND THEN NORTHWESTERN ONTARIO.
SMOKE FROM THE FIRES IN NORTH-CENTRAL SK AND MB WILL AFFECT A SWATH
ABOUT 200 KM WIDE FROM BUFFALO NARROWS TO ISLAND LAKE, WITH SOME
SMALL VARIATION NORTH AND SOUTH OF THIS SWATH. SMOKE BULLETINS HAVE
BEEN UPDATED TO REFLECT THIS LIKELIHOOD.
THE OTHER CONCERN THIS FORECAST PERIOD IS SEVERE THUNDERSTORMS.
SEVERE THUNDERSTORMS ARE EXPECTED TO FORM THIS AFTERNOON IN SOUTHERN
ALBERTA AND MOVE INTO SOUTHWESTERN SASKATCHEWAN THIS EVENING. MLCAPE
WILL BE 500-1000 J/KG AND EBWD AROUND 40 KNOTS, LEADING TO PRIMARILY
A HAIL THREAT. CLOSER TO THE UPPER TROUGH AXIS, IN SOUTHEASTERN AB, A
FUNNEL CLOUD THREAT ALSO EXISTS. ALSO IN THE VICINITY OF THIS TROUGH
WILL BE RAINFALL AMOUNTS SURROUNDING THE AREA OF CALGARY, RANGING
FROM 5-25 MM TODAY BEFORE THE SYSTEM DEPARTS TONIGHT.
NT...SMOKE CONTINUES TO AFFECT A NUMBER OF COMMUNITIES IN THE NT AND
AIR QUALITY ALERTS REMAIN IN EFFECT TO REFLECT THE MOST IMPACTED
REGIONS.
THUNDERSTORMS ARE ONCE AGAIN FORECAST THROUGH MUCH OF THE WEST.
STORMS WILL BE SLOW MOVING AND THERE IS SOME POTENTIAL FOR LOCALLY
HEAVY RAIN. BEST CHANCE TODAY FROM ROUGHLY THE LIARD REGION TO
WESTERN GREAT BEAR LAKE, AND THEN EAST THROUGH NORTH SLAVE REGION.
HEAT WARNINGS REMAIN IN EFFECT FOR AREAS SOUTH OF GREAT SLAVE LAKE.
THE COMMUNITIES OF HAY RIVER AND FORT RESOLUTION ARE LIKELY TO BE
SPARED THE WORST OF THE HEAT THANKS TO LAKE BREEZES GENERATED BY
GSL, HOWEVER FURTHER INLAND WILL NOT BE AS FORTUNATE. CONDITIONS
WILL IMPROVE ON SATURDAY.
NU...THE SYSTEM OVER NORTHERN HUDSON BAY CONTINUES TO DECAY WITH JUST
A FEW SHOWERS LINGERING AROUND BAFFIN ISLAND AND KIVALLIQ. WITH WEAK
FLOW SETTLING OVER THE AREA, REMNANT CLOUD, DRIZZLE, AND FOG WILL BE
THE MAIN ISSUES FOR THE NEXT FEW DAYS.
END/CARLSEN/PIMISKERN
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