893 FXUS63 KDLH 090834 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 334 AM CDT Mon Sep 9 2019 .SHORT TERM...(Today through Tuesday) Issued at 329 AM CDT Mon Sep 9 2019 The main focus of the short term forecast period continues to be on a round of moderate to heavy rainfall across the Northland, expected to begin this afternoon and continue through the overnight hours, along with a Marginal risk of severe thunderstorms, mainly along and south of a line from McGrath, MN to Park Falls, WI. The main drivers for this shower and thunderstorm activity is a mid-level shortwave that will eject from a longwave trough over the Pacific Northwest, and into our region, along with a low-level baroclinic zone and 925- 850 mb layer frontogenesis that will lift northeastward this afternoon and evening. A 35 to 45 knot low-level jet is progged to develop concurrently with the mid-level shortwave, which will help advect higher values of theta-e and enhance moisture transport. Instability appears to be rather modest, with most-unstable CAPE values in the 500-1000 J/kg range. However, with the strengthening low-level jet, deep layer shear should be supportive of stronger updrafts, in the 40 to 50 knot range. Mid-level lapse rates are somewhat marginal, but could still support some large hail, with values generally in the 5.5 to 6.5 degree C/km range. Damaging wind gusts will also be possible in the strongest thunderstorms. Moderate to heavy rainfall will be likely in some locations. There is a Marginal risk of excessive rainfall, meaning the possibility of localized minor flooding in some spots. However, a portion of the region is in a D0 drought per the latest US Drought Monitor, so the risk of flooding should remain very low. Winds will be fairly strong today, from the southeast, with gusts between 20 to 30 mph in many locations. Highs today should remain well below average, thanks to the cloud cover, rainfall, and an easterly component of the wind, which should advect some lake-cooled air off Lake Superior. Highs today will range from the upper 50s to the lower 60s. Chances of showers and thunderstorms will continue through the evening hours and overnight. Overcast skies should help buoy temperatures in the upper 40s over the Minnesota Arrowhead to the upper 50s to near 60 south. Some of the guidance is progging some heavier rainfall right along the North Shore due to a component of orographic lift from on-shore flow. The aforementioned gusty southeast winds will continue through the evening, with gusts between 15 to 25 mph. The surface low associated with today's shortwave will translate across the region on Tuesday, which will be quickly followed up by high pressure and subsidence, which will act to gradually diminish our chances of showers. Some lingering large-scale forcing will keep some chances of rain showers in the picture Tuesday morning, mainly along Lake Superior. Conditions will gradually dry out in the afternoon hours Tuesday. Westerly flow will help temperatures warm into the lower 60s north to the lower to middle 70s south. .LONG TERM...(Tuesday night through Sunday) Issued at 329 AM CDT Mon Sep 9 2019 The extended will feature several opportunities for showers and thunderstorms, especially through Friday. Confidence decreases quite a bit over the weekend into next week with the GFS and ECMWF offering vastly different solutions with the upper level pattern. A longwave trough over the western CONUS Tuesday evening will move to the Plains/central Canadian provinces by 12Z Thursday. A shortwave will cause shower chances Tuesday night into Wednesday. The Northland will be well north of a warm front and instability will be marginal so we only have low chances for thunder over our southern zones. The best chance for rain into Wednesday will be over our southern zones with the ECMWF keeping far northern Minnesota dry. Cool temperatures will continue into Wednesday with highs in the mid fifties to lower sixties. Gusty off-lake winds will make it feel even cooler near Lake Superior. As the longwave trough approaches the region Thursday, low pressure will deepen and move into eastern South Dakota by 12Z Thursday. The low will move northeast Thursday and be along the northern Minnesota/Ontario border by 12Z Friday. Widespread rain and a few thunderstorms will occur Thursday/Thursday night, then diminish from south to north Friday/Friday evening. Instability isn't very high with this system, but the forcing will be strong, so we do expect some storms, but the threat for severe storms is low. There could be some heavy rain though, and after rainfall from the previous two systems, some flooding could occur. Temperatures Thursday and Friday will remain below normal, with it being coolest on Friday. Confidence in the period from Saturday through Tuesday is lower than average. The GFS is far different than the ECMWF/Canadian. The GFS has an upper trough through the Northern Plains Saturday evening and the ECMWF shows zonal flow. Model differences magnify on Monday with ECMWF forecasting a longwave trough along the west coast and ridging over the central CONUS. The GFS has ridging from the southwest CONUS into Alberta. For now, we have chances for showers/storms Saturday into Tuesday but if the ECMWF ends up verifying, much of that period will be dry and warmer. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 710 PM CDT Sun Sep 8 2019 Broken clouds will remain over the region overnight with occasional MVFR ceiling heights possible, but expecting VFR ceilings for the most part. There is a slight concern that some fog may develop late tonight, mainly at HIB and HYR. With clouds around, not expecting visibilities to drop off too much, but there could be some brief periods of MVFR mainly from 10Z to 14Z. Winds will be light and variable overnight. A developing low pressure system will bring increasing clouds and rain to the terminals from southwest to northeast on Monday. Most models suggest ceilings at most sites will drop to MVFR during the morning to mid day, and then possibly IFR at BRD during the afternoon. Some models are also hinting at some LLWS late in the period, but due to it being at the tail end of the period, left it out of the TAFs for now. Winds will become blustery from the east to southeast with gusts up to 20 kt possible. && .MARINE... Issued at 329 AM CDT Mon Sep 9 2019 The gradient will strengthen over Lake Superior between high pressure east of the lake and low pressure over the Northern Plains. Easterly winds will be on the increase today, building waves into tonight. Small Craft Advisories have been issued for much of the nearshore waters except for portions of the South Shore east of Sand Island. The wind and waves will decrease late Monday night into Tuesday as the low moves into the area. There are still some differences in the track of the low, and for now, we expect winds to be north/northeast on Tuesday, but if the low is faster than expected, they could become westerly for a time. Another stronger low pressure system will cause easterly winds to ramp back up Wednesday into Thursday evening. Some gale force winds will be possible with this low, especially Wednesday night into Thursday evening. && .PRELIMINARY POINT TEMPS/POPS... DLH 58 52 69 51 / 90 100 30 10 INL 61 51 61 48 / 80 100 40 10 BRD 60 59 70 53 / 100 80 10 30 HYR 64 59 76 52 / 90 90 20 10 ASX 64 55 73 51 / 80 100 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Beach Hazards Statement from 10 AM CDT this morning through this evening for WIZ001. MN...Beach Hazards Statement from 10 AM CDT this morning through this evening for MNZ037. LS...Small Craft Advisory from 3 PM this afternoon to 4 AM CDT Tuesday for LSZ146. Small Craft Advisory from 10 AM this morning to 7 AM CDT Tuesday for LSZ144-145. Small Craft Advisory from 3 PM this afternoon to 10 AM CDT Tuesday for LSZ142-143. Small Craft Advisory from 10 PM this evening to 10 AM CDT Tuesday for LSZ140-141. && $$ SHORT TERM...JTS LONG TERM...Melde AVIATION...JS MARINE...Melde