054 FXUS65 KTFX 081800 AFDTFX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1200 PM MDT Wed Oct 8 2014 .UPDATE... A lot of high level moisture is affecting central and northern Montana and one change for the update was to increase cloudiness in these areas at least for the rest of this morning. Also isolated/scattered showers are moving into north central Montana and have changed the forecast from isolated to scattered showers near the Canadian border. As for high temperatures..due to cloudiness and upslope flow this afternoon lowered highs over the northern east slopes 2-3 degrees. Blank && .AVIATION... UPDATED 1800Z. Weak high pressure is holding over the region. Lower levels will remain dry and surface winds generally light. VFR conditions will prevail through the next 24 hours. && .PREV DISCUSSION... /ISSUED 522 AM MDT Wed Oct 8 2014/ The upper level ridge which has been centered over the interior Western US has begun to flatten in response to shortwave energy moving into western Canada, with flow aloft becoming more westerly through the end of this week. Weak shortwave and upper level jet energy will move east along the US/Canadian border today resulting in more cloud-cover over North-Central MT with a few isolated showers possible, mainly near the Canadian border. A shortwave trough, currently seen in water vapor satellite imagery approaching 130W this morning, will move into the Northern Rockies late tonight and across MT Thursday. ECMWF model is strongest with this feature, but also appears to be the best initialized in comparison with satellite imagery, so increased pops/coverage of isolated showers for Thursday across central MT. Temperatures will remain about 5-10 degrees above seasonal averages through the remainder of this week. Hoenisch Friday night through Wednesday...Relatively weak flow aloft will be over Central Montana Friday night but a shortwave will be moving through the Pacific Northwest. A surface lee trof should develop along the Rockies ahead of this shortwave and bring brisk surface winds to the region. Moisture associated with the shortwave will cross the Rockies Saturday...and possibly along with a chance of a thunderstorm over the Northern Rockies. Heights aloft will be rising again by Saturday night. However, the northwest flow aloft will remain unsettled and some chance of showers will continue into Sunday. A high pressure ridge will be in place by late Sunday but the models diverge a bit at this point. The GFS begins to break down the ridge by Sunday night ahead of a strong low pressure low over the Eastern Pacific. However, the ECMWF sharpens and strengthens the ridge before dropping the trof over the Pacific Northwest early Tuesday. The GFS solution would bring moisture over the Rockies Sunday night and move across Central Montana by Monday, and the GEM shares the more westerly flow solution of the GFS. The ECMWF, however, would keep the air mass dry and warmer. Disturbed west flow aloft will keep the region unsettled through Tuesday night. A weak high pressure ridge will build Wednesday but the flow will remain unsettled and chance of precip over the higher terrain will continue as well. Zelzer && .PRELIMINARY POINT TEMPS/POPS... GTF 68 44 64 43 / 10 10 20 10 CTB 64 42 64 41 / 10 20 20 10 HLN 74 46 67 42 / 10 0 10 10 BZN 72 40 67 37 / 0 0 10 10 WEY 64 30 64 29 / 0 0 0 10 DLN 73 41 68 39 / 0 0 10 10 HVR 64 37 63 39 / 10 10 10 10 LWT 70 42 62 41 / 10 10 20 20 && .TFX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ weather.gov/greatfalls www.twitter.com/NWSGreatFalls www.facebook.com/NWSGreatFalls