Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/24/20

Area Forecast Discussion
National Weather Service La Crosse WI
745 PM CDT Sun Aug 23 2020 .UPDATE... Issued at 745 PM CDT Sun Aug 23 2020 Evaluating the latest incoming guidance, in combination with todays high temperatures, decided to move Monday`s highs up a few degrees south of I-94. Felt there was enough confidence with a plume of warmer air heading in in the low-levels /1.5-3C warmer at 925mb/ south of the I-94 frontal boundary in the afternoon, today`s warmer-than-forecast highs, and what looks like a capped and clean afternoon. It isnt perfect, and a few items are working against an overachieve: watching the Dakotas convection to shift east and probably not make it to the area, but bring in some morning clouds. The shortwave trough that the convection is currently associated with will shift through in the morning in MN/WI. Also, the thicker smoke will arrive overnight and this might intercept some radiation. Evaluated Monday evening severe weather and it is definitely on track. Has some signals like June 2 of this year with a front moving in from the north, while very warm and capped south of the front (June 2 was the hottest day of summer thus far). Lapse rates aloft are not explosive like June 2 Monday evening, but in the 7.5-8C/km range which is favorable and normalized CAPE is around 0.30 (big hail!). Large hail parameter suggests 2-3" hail possible in the I-90 to I-94 corridor per RAP - seems reasonable. Drier soundings would also support some higher-end wind gusts. The wind shear is a bit better on the front too (versus June 2) with some looping to the hodograph, but low- level shear is lacking so any tornadic activity should be limited. An enhanced risk area from SPC would not be surprising. Current thinking is initiation will happen near MSP, east along I-94(ish) in the later afternoon and storms will shift east- southeastward into WI. HRRR/HRRRX/RAP solutions keep the buggers north of I-94 with a stronger cap in place vs NAMNest 18Z run which convects the front near MSP and drops storms southeast. Definitely an afternoon and evening to be weather aware! && .SHORT TERM...(This evening through Monday) Issued at 225 PM CDT Sun Aug 23 2020 Steepening lapse rates due to diurnal heating combined with weak moisture transport have allowed a few showers/storms to pop up across north-central WI. These should continue to move southeast over the next few hours, diminishing with the loss of daytime heating and increasing ridging aloft. The main hazards are lightning and perhaps some gusty winds and small hail given fairly steep low- level lapse rates near 7 C/km and marginal mid-level lapse rates around 6 C/km. For tonight, mid-level ridging should provide fairly quiet conditions, with light winds and lows in the 60s. There could be some patchy fog in the Mississippi River tributaries, but increasing wind above the surface as the night wears on should preclude much fog development in the mainstem. There might also be some patchy fog across north-central Wisconsin given recent wetter conditions and decent radiational cooling. A small 500 mb perturbation then looks to approach from the west early Monday morning, likely associated with overnight convection in Minnesota. There are some placement differences with this feature, but wouldn`t be totally surprised to see some showers/storms hold together with the forcing, especially across north-central Wisconsin where there is weaker ridging and less low-level dry air to contend with. Given the time of day, lightning and small hail would seem to be the main threats. Heat and storm chances are then the focus for the rest of the day. A subtle boundary layed out across the area will shift northward as a warm front, with increasing WAA/frontogenesis by late afternoon, strongest to the west/just into the northwest portions of the area. Given increasingly warm and moist air, NAM/GFS suggest MLCAPE values well above 3000 J/kg during the afternoon, likely due to dewpoints in the mid 70s in both models. This may be a bit overdone, as 50th percentile dewpoints are in the low 70s, but there should still be a decent amount of instability that builds. There is fairly good agreement that stout capping will be in place, however, which may be tough for any potential convection to overcome until moisture transport ramps up in the evening. Capping should be weakest across north-central Wisconsin where air aloft isn`t so warm, so that area would seem to have the best shot at an isolated shower/storm during the daytime. Thus, it`s currently looking like much of the day should end up dry, humid, and hot (emphasis on that last word). 925 mb temperatures approaching +25C to +30C should translate to widespread afternoon temperatures in the 80s and 90s, with dewpoints in the 70s pushing heat indices near heat advisory criteria in the mid to upper 90s. A few of the warmer valley locations could hit heat indices around 100, but at this time this doesn`t look to be widespread enough to warrant heat headlines. .LONG TERM...(Monday night through Sunday) Issued at 225 PM CDT Sun Aug 23 2020 The 23.12Z models have continued the trend started with previous runs of suggesting a MCS to impact portions of the area Monday night. A short wave trough riding up and over the large upper level ridge looks to move across the Upper Midwest Monday night and produce some weak to moderate pv advection in the 500-300 mb layer. A warm front currently extending across central Minnesota into northern Wisconsin is not expected to move much and will provide a focus for convective development as the wave moves over the area. With good warm air advection south of the front, the baroclinic zone is expected to tighten up resulting in a weak to moderate band of frontogenesis in the 1000-500 mb layer along and north of the warm front. The warm air advection should result in strong isentropic upglide over the warm front with the 23.12Z NAM showing 6 to 12+ ubar/s on the 310K isentropic surface. With this forcing, have increased the rain chances to around 60 percent and these may need to go higher if model signals continue with later data sets. There will also be a risk for severe storms with this activity. A band of 1500-2500 J/kg of ML CAPE is expected to form in the vicinity of the front. Deep layer shear looks to be on the order of 40 to 45 knots along and north of the front, with most of this residing in the 0-3 km layer. As the low level jet/moisture transport increases Monday evening, the shear in the 0-1 km layer will ramp up to maybe as much as 30 knots along and south of the front. This would suggest a threat for damaging winds and large hail and maybe an isolated tornado near the boundary where the low level and deep layer shear can overlap. Locally heavy rains will be possible as well with precipitable water amounts expected to be around 2 inches north of the front and warm cloud depths increasing to around 3.5 km during the evening. The next best chance for more rain looks to come Thursday night into Friday morning. Similar to Monday night, a short wave trough looks to run along the top of the upper level ridge and across the Upper Midwest. However, agreement between the 23.12Z ECMWF and GFS remains poor on the strength of this wave with the GFS being much stronger than the ECMWF. For now, the rain chances have generally been bumped up into the 40 to 50 percent chance range with this system until the models start to show some better agreement. This system will have to be watched for another severe threat as well. Very similar set up to Monday night with a decent CAPE pool developing along the stationary front with good deep layer shear along and north of it and low level shear along and south of the front. Precipitable water axis along the front looks to be between 1.5 and 2 inches as well for another locally heavy rain threat. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday) Issued at 745 PM CDT Sun Aug 23 2020 VFR conditions are expected through the period. However, Monday later afternoon and evening, storms should develop to the north of the airfields. Thunderstorms could affect both airfields in the evening, although KLSE has slightly higher probabilities. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ UPDATE...Baumgardt SHORT TERM...Lee LONG TERM...04 AVIATION...Baumgardt
Area Forecast Discussion
National Weather Service Bismarck ND
923 PM CDT Sun Aug 23 2020 .MESOSCALE DISCUSSION... Issued at 915 PM CDT Sun Aug 23 2020 Thunderstorms were increasing and building back toward the west along ND Highway 36 running from northwest of Jamestown to north of Bismarck, an east to west oriented line. Another line of storms extended also east to west from northern Foster County to near Fessenden in Wells County. These storms are north of the surface boundary that pushed through late this afternoon. These storms were in an area of 2-3,000 J/Kg MUCAPE, 700-500MB lapse rates of about 7.5 C and deep layer moisture flux convergence oriented east to west in the area where the storms formed. Earlier CAMS, specifically the HRRR did show this line developing so it is now followed as the CAM of choice. This would bring weak convection just to the west of Bismarck and Mandan so a low pop was introduced for the next several hours. && .UPDATE... Issued at 550 PM CDT Sun Aug 23 2020 Updated pops and expanded severe risk over the southeast part of the forecast area. Two outflow boundaries were pushing south from the convection near Jamestown. Between the tow, near the North and South Dakota border in Dickey County a thunderstorm formed and underwent explosive growth. A new Storm was now forming on the north side of the original Storm. && .SHORT TERM...(This evening through Monday) Issued at 220 PM CDT Sun Aug 23 2020 Thunderstorms forming and propagating along and behind a cold frontal boundary in moving through central and southwest North Dakota. Frontogenetic forcing continues to extend across into the cold air side of the baroclinic zone late this afternoon. We expect storms to primarily be elevated along and north of the cold front. Strong warm advection across the frontal boundary this evening will feed the convection, and if it aligns into an east west convective line there will be some training possibilities, which suggests a potential for heavy rain this evening in the central James river Valley. We have messaged this in the Weather Story and Hazardous Weather outlook for tonight. Tonights lows will be in the lower 50s north and the lower 60s south. On Monday dry weather is expected. We used the smoke information from the HRRR model which keeps considerable elevated smoke across the region tonight and Monday. Highs will be in the 80s to lower 90s. .LONG TERM...(Monday night through Sunday) Issued at 220 PM CDT Sun Aug 23 2020 The initial H500 pattern with a ridge across the western US will gradually flatten as shortwave energy moves through the northern plains this coming week. This will tend to bing an active pattern with chances for thunderstorms Tuesday through Thursday, and again Saturday and Sunday. There is the potential for strong to severe thunderstorms Tuesday and Tuesday night with better CAPE and Shear with a cold frontal passage. Temperatures will be above normal through Tuesday, then normal or slightly below normal Thursday and Friday. Although warmer temperatures may be seen next weekend, some extended analogues are starting to hint at much cooler weather in the 6 to 10 day period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 915 PM CDT Sun Aug 23 2020 KDIK-KXWA-KMOT will be VFR. Scattered to numerous thunderstorms are forecast from just north of KBIS through KJMS until about 24/08Z. Then MVFR ceilings possible at KJMS between 08Z and 15Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MESOSCALE...JPM UPDATE...JPM SHORT TERM...WAA LONG TERM...WAA AVIATION...JPM
Area Forecast Discussion
National Weather Service Columbia SC
752 PM EDT Sun Aug 23 2020 .SYNOPSIS... An upper trough axis to our west will continue to bring deep moist southwesterly flow over the region through tonight. An upper ridge over the western Atlantic will build into the area early next week. Tropical Storms Laura and Marco are forecast to move through the Gulf of Mexico early next week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Light showers streaming over mainly the southeastern forecast area with PWATs around 2 inches and both the offshore ridge and trough to the west promoting deep SW flow with an influx of moisture along the Gulf Coast courtesy of Hurricane Marco approaching the central Gulf of Mexico. Expect a break in shower activity after sunset. Later tonight, a channel of positive vorticity advection, mainly in the NW forecast area, will keep chances of showers overnight with any precipitation generally light. With continued moisture streaming into the mid and upper levels overnight as well, expect clouds to continue to overspread the forecast area. Temperatures tonight drop to around 70. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... The Midlands and CSRA will be between a Bermuda High off the East Coast and TC Marco moving into the northern Gulf Coast. Deep tropical moisture will continue to stream into the region with southwest flow as PW values remain in the 2.0 to 2.3 inch range early this week. This will result in scattered to numerous showers and thunderstorms Monday and Tuesday. WPC places portions of The Midlands and CSRA in a Marginal Risk of excessive rainfall Monday through Tuesday. Convective activity noticeably decreases due to subsidence north of TC Laura on Wednesday. High temperatures will be below normal Monday and Tuesday due to extensive cloud cover and rainfall with near normal temperatures expected on Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... High pressure aloft builds over The Midlands and CSRA Thursday through Friday in between an upper trough over the Northeast and TC Laura moving into the Western Gulf Coast. Increasing H5 heights will lead to above normal temperatures with highs in the lower to mid 90s and lows in the lower to mid 70s. We should also experience a late summer diurnal scattered shower and thunderstorm pattern. A strong upper trough moving into the Ohio River Valley absorbs the remnants of TC Laura Friday Night through Saturday. The GFS phases the remnants with the upper trough while the EC does not. At this time the TC Laura remnants appear to stay north of the region with a continued chance of showers and thunderstorms through next weekend. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... VFR conditions through the evening then restrictions toward morning with stratus expected to develop. Deep moisture remains in place across the area with ridge offshore and south flow moisture transport in to the area. Still some light rain in the area but likely not to impact terminals this evening. Models suggest higher low-level moisture and a greater potential for more widespread IFR/MVFR stratus toward morning. This is supported by latest HRRR and Lamp. MVFR strato-cumulus may continue through late morning or early afternoon before scattering out by 18z. Moist and weakly to moderately unstable air mass Monday. Guidance indicating scattered to possibly numerous showers and a few thunderstorms may develop near the coast and spread inland during the afternoon. These showers may impact terminals with restrictions at times after 18z. EXTENDED AVIATION OUTLOOK...Scattered mainly diurnal shower and thunderstorm activity through the period. Patchy late night/early morning fog/stratus possible. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Des Moines IA
629 PM CDT Sun Aug 23 2020 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Sunday/ Issued at 253 PM CDT Sun Aug 23 2020 Continued focus on the heat throughout the work week with just some patchy fog possible across the north-northeast early Monday morning. The other concern or uncertainty is the impacts of the wildfire smoke streaming in from the west on Monday and Tuesday. Weak flow and enough low level moisture around to have a mention of patchy fog across the northeast by Monday morning. Similar trend to this morning with the fog developing. Large thermal ridge continues to strengthen over the western two- thirds of the country and keeping Iowa hot through Thursday before the ridge begins to break down by the end of the week. 850mb temperatures by Monday warm to around +25C and there is some mixing that develops tomorrow afternoon. Confident with the mid to upper 90s for highs Monday but with the last several runs of the HRRR continually bringing in the wildfire smoke, uncertainty with how much of an impact his plays on temperatures as well as air quality. Can already see hints of smoke over the Dakotas and western Nebraska via GOESEast satellite trends and it doesn`t appear to be impacting current temperatures attm. At any rate, hot, dry, and a little breezy in the afternoons Monday through Wednesday. Friday through the weekend...a much needed cool down is anticipated during this period but low confidence with any significant precipitation maker with the lingering tropical systems hoarding the main moisture source. && .AVIATION.../For the 00Z TAFS through 00Z Monday evening/ Issued at 627 PM CDT Sun Aug 23 2020 Some potential for fog over northern TAF sites late tonight mainly in the KMCW/KALO vicinities. Otherwise light winds tonight becoming breezy at times on Monday with VFR conditions forecast. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Podrazik AVIATION...Donavon
National Weather Service Eureka CA
253 PM PDT Sun Aug 23 2020 .SYNOPSIS...Warm to locally hot temperatures will occur across interior valleys during the next week. Otherwise, scattered, mostly dry thunderstorms will be possible across the region tonight through Monday evening. Afternoon and evening thunderstorms will remain possible over the far eastern interior through mid-week. && .DISCUSSION...The primary concern through Monday continues to be potential thunderstorm development...particularly late this evening through Monday evening. A decayed tropical system and a mid-level disturbance off the southern California coast will spread moisture north over the region this evening and overnight. The surface to 850 mb layer will be dry, but moistening is forecast to occur near 700 mb, which, when combined with steep mid to upper level lapse rates, will aid in MUCAPE values from 100 to 500 J/kg. Model guidance shows mid-level ascent and an associated moist plume spreading north across Lake and Mendocino counties during the late evening hours, then Humboldt and Trinity counties after midnight, followed by Del Norte county Monday morning. Isolated to scattered thunderstorm development is forecast to be embedded within this plume of moisture. Due to the warm and dry low- level airmass and progressive northerly storm motion, most lightning strikes will be on dry ground and pose a threat for new fire starts. Additionally, due to the dry low- levels, gusty and erratic winds beneath any storms will be possible. Reference the Red Flag Warning and fire weather discussion below for more information. Another concern during the next few days will be high temperatures in southern Mendocino and Lake counties where highs Monday are expected to reach near 100 degrees in valley locations. However, the smoke across many inland areas will act to mitigate high temperatures a bit. Coverage and impacts still do not appear to warrant a heat advisory. The last concern today through Tuesday will be impacts from wildfire smoke. Mid level flow will be rather persistent out of the south- southeast. This should push smoke from fires east and south of the area into most interior locations. Smoke may be dense at times which will impact visibility. Health concerns from the smoke are dealt with by the air quality management districts. Beyond Tuesday, the weather will become more tranquil with temperatures running a few degrees above normal. Isolated thunderstorms will remain possible across the Trinity horn for both Tuesday and Wednesday afternoons. /JMG&SEC && .AVIATION...The stratus proved to be a worthy adversary today in regards to predicting its movement. By midday, the cloud layer began to pull back over the ocean in Humboldt county with IFR conditions at KACV, while coastal Del Norte and KCEC clung on to LIFR Cigs and visibility. For the remainder of the afternoon, the stratus would surge back in before the terminals could improve better than IFR during brief receding movement. Another round of low clouds and LIFR conditions is expected to return once again to coastal terminals this evening. Farther to the south, KUKI experienced some passing smoke with reduction in visibility. More periodic passing smoke can expected through this evening. HRRR Experimental Smoke guidance did fairly well at depicting this, and shows another round possible beginning early this morning. Elevated thunderstorms should form in the vicinity of KUKI this evening, and then progress north and northeast across the forecast area. && .MARINE...Breezy northerly winds will continue across the outer waters overnight, strongest in the Northern Outer waters through Monday. These winds will generally continue through the forecast period, generating widespread steep seas of 8 to 9 feet. Advisory level northerly winds and seas are expected to continue for the outer waters for the foreseeable future. Northerly winds and steep seas will begin ticking up beginning overnight Monday. && .FIRE WEATHER...Isolated to scattered thunderstorms are expected to spread north across the area late this evening though Monday evening. Very dry low levels and moderately fast northerly storm motions will support dry storms. Activity is expected to reach Lake and Mendocino counties late this evening, then Humboldt and Trinity counties after midnight, followed by Del Norte county Monday morning. Have continued the existing Red Flag Warning which runs from late this evening through Monday evening. Storms are possible across the Trinity horn for Tuesday and Wednesday afternoons. After Wednesday, storm chances will decrease significantly. /JMG&SEC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning from 11 PM this evening to 11 PM Monday for CAZ201>204-211-212-264-276-277-283. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 PM Tuesday for PZZ470-475. $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Glasgow MT
840 PM MDT Sun Aug 23 2020 .DISCUSSION... EVENING UPDATE: Going forecast looks fine. Changes were minimal this evening. GAH AFTERNOON DISCUSSION: Zonal flow across the region will maintain warm and dry conditions throughout the area. High temperatures on Monday will be well into the 90s as a brief ridge emerges ahead of trough to the west. Winds stay below critical fire weather criteria, but with fuels still dry and relative humidity staying fairly low, the area is still not free of fire weather concerns. HRRR Smoke model indicates haze from wildfire smoke will clear from NW to SE throughout the rest of the day but will return tomorrow. The Hill Fire by Fort Peck Lake appears to not be as hot on satellite and spot requests and DSS for this fire has decreased significantly. Moisture from the remnants of a tropical system in the eastern Pacific will ride along southwesterly flow aloft, providing much needed relief to the western US, but could also provide the amount of moisture necessary for a few thunderstorms to develop by the time it reaches Montana through midweek. The trough from the west arrives late Monday night and a series of weak shortwaves will mean a few opportunities for moisture this week, but also the chance of dry lightning as the boundary layer remains relatively dry. Monday night low temperatures will be warmer and depending on the time of arrival for the front, could be anywhere from upper 60s to upper 70s. Storm Prediction Center has categorically general thunderstorms for Monday, but marginal chances for severe on Tuesday. Given the temperatures and the limited moisture, the main threat appears to be wind driven. After midweek, temperatures will gradually decrease toward more seasonable temperatures by the end of the week. Lack of model consensus disrupts accuracy in timing and placement of future troughs, however, there is some confidence in the continuation of weak disturbances before the potential of much larger Alaskan low pressure system that may arrive sometime next weekend and last through the weekend. Roxy && .AVIATION... FLIGHT CATEGORY: VFR DISCUSSION: Mainly clear skies and dry conditions will prevail over the area with the exception of some haze caused by smoke coming in from the south due to the fires in California. The smoke is not expected to greatly reduce visibilities at any of the terminals. WINDS: Light and variable overnight into Monday morning, becoming southeasterly at 10 to 15 knots during the afternoon. RMB && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
915 PM CDT Sun Aug 23 2020 .UPDATE... Issued at 915 PM CDT Sun Aug 23 2020 A stray thunderstorm may affect nrn Nebraska overnight. These storms are ongoing across SD this evening. An increase in the low level jet to about 30kts as shown by the RAP model may support a southward turn in the storm motion causing activity to brush northern Nebraska. A forecast update is in place for isolated thunderstorms along and north of highway 20 tonight. && .SHORT TERM...(This evening through Monday night) Issued at 237 PM CDT Sun Aug 23 2020 A slight chance exists for convective thunderstorms early this evening, but confidence is low for widespread storm activity. A surface trough axis, extending through western Nebraska, is the primary focus for uplift. GFS soundings show 850-500 mb lapse rates of about 9 C/km, which indicates the possibility for strong thunderstorms. Aside from the trough and lapse rates, there are few other factors that appear promising for thunderstorm development over the forecast area. Farther north, a cold front moves moves through the Dakotas, but this will be too far out of reach to influence weather in Nebraska. Forecast soundings from the NAM show less than 1000 J/kg of ML CAPE and deep layer shear between 20 and 30 knots. After the trough passes, dew points in the Sandhills and southwest Nebraska will drop to the 50s, with 40s present in the far western edge of the CWA. The eastern Panhandle and northern Sandhills have the greatest chances for precipitation in the early evening. Any storms that do develop will be isolated and are not expected to be severe. The main weather concern for Monday is high temperatures. A ridge currently centered over the Four Corners will build north today and tomorrow. H850 mb temperatures Monday will reach 34C in the western forecast area, translating to temperatures nearing 100F at the surface. Normal highs for late August in the region are in the mid 80s. Meanwhile, smoke from wildfires in the western U.S. will continue to move into Nebraska. While it will not necessarily reduce temperature, it will create hazy conditions throughout the region. .LONG TERM...(Tuesday through Sunday) Issued at 237 PM CDT Sun Aug 23 2020 Hot temperatures will continue Tuesday and Wednesday as the upper level ridge remains settled over the western U.S. Heat index values will be in the upper 90s on Tuesday and the mid 90s on Wednesday. On Thursday, a cold front will move south across the Dakotas into Nebraska, bringing cooler temperatures to the region. Temperatures will be in the 80s through the weekend. Chances for precipitation will also return next weekend as southerly winds bring moisture northward to the Great Plains from the Gulf of Mexico. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 613 PM CDT Sun Aug 23 2020 Isolated thunderstorms may affect nrn Nebraska until 05z this evening. The area of concern is along and north of highway 20 west of Valentine. Otherwise, a strong upper level ridge of high pressure will remain anchored across the Four Corners region of the western U.S.. VFR should prevail across western and north central Nebraska tonight and Monday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...CDC SHORT TERM...Meltzer LONG TERM...Meltzer AVIATION...CDC
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1006 PM EDT Sun Aug 23 2020 .SYNOPSIS... High pressure will slowly strengthen and build in from the east through early next week, before shifting a bit further south by mid week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 10 PM Sunday...Veil of mostly mid with some level clouds continue to stream northeast from the Gulf of Mexico into the Carolinas late this evening. Scattered showers and a couple of thunderstorms from earlier in the afternoon dissipated with loss of heating before dark. Another warm muggy night upcoming with lows mainly in the low/mid 70s. The HRRR model tries to depict some showers approaching the southern coast toward morning, but most of the other high-resolution is dry. Will remove PoPs as think any activity would likely be after 12z in the morning. No other changes to the current forecast. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... As of 330 PM Sunday...Not a huge different from today with a fair amount of mid and high level clouds still expect with highs mainly in the 80s. Highest threat for showers and storms will be roughly in the same area as today, along the southwest part of our area. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... As of 300 AM Sun...High pressure expected to be the main influence in the long term, with hot conditions expected by mid week. Mostly dry weather expected through the beginning of next weekend, when low pressure or a cold front move into the region. Monday and Tuesday...Strong high pressure will be centered off the SE coast Monday and Tuesday, with subsidence and dry air keeping the area mostly dry. However, mid to upper level moisture will continue to stream into the area from the Tropical Cyclones in the Gulf of Mexico, which will lead to some overcast skies (filtered sunshine at best), and chances for some occasional sprinkles. Despite low level heights building, aforementioned cloud cover will limit highs to the upper 80s to around 90. Tuesday could get a little warmer depending on how quickly the high level moisture clears out of the area, and if unfiltered sunshine returns before the afternoon is over. Wednesday through Saturday...An approaching upper level trough over Great Lake/Northeast will squeeze high pressure southwestward on Wednesday, and then high pressure rebuilds over the SE Atlantic Thursday through Saturday. Low level heights will continue to increase during this period and hot temperatures are expected with afternoon highs in the low to mid 90s. With high humidity, heat index values of 100-105 are possible as well. Despite hot temps mostly dry conditions are expected Wednesday and Thursday, with increasing (scattered) chances expected Friday and Saturday as a upper level trough moves across the Great Lakes and a cold front approaches from the NW. There is some chance that the remnants of Laura could push across the area, but there is still high uncertainty with the evolution of that. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Short Term /through 00Z Tuesday/... As of 705 PM Sunday...With any very light precipitation ending soon, conditions will be VFR through the overnight hours and through the end of the TAF cycle at 18Z Monday. Overnight model guidance suggests some MVFR cigs possible briefly prior to sunrise. Given the abundance of mid and high clouds, will continue to leave out of the forecast. Winds near calm tonight, becoming southwest 5 to 10 kts again Monday. Long Term /Monday night through Friday/... As of 315 AM Sun...Mostly VFR conditions expected through the long term as high pressure builds in. Some isolated bouts of early morning fog/stratus will be possible though. && .MARINE... Short Term /through Tonight/... As of 1005 PM Sunday...Winds remain a bit gustier over the Pamlico Sound and some of the central waters, but winds are generally SW 5-15 knots with seas 2-3 feet at late evening. A few 4-footers may be possible over the outer waters overnight. Similar winds Monday with southwest winds 10 to 15 kts, but some gusts toward 20 kts possible late afternoon/evening. As we begin to see the fringe swell from Laura, seas will build to 3 to 5 feet late in the day into the evening. Long Term /Monday through Thursday/... As of 315 AM Sun...Decent boating conditions expected this week, with winds remaining light. Only wildcard will be how much swell builds into the area from distant Tropical Storm (and possibly Hurricane) Laura. Right now, seas are expected to peak at 3-5 feet Monday through Wednesday, with a brief period of 6 feet possible during the peak on Tuesday. Winds will be mostly out of the SW at 5-15 kts, though could briefly increase to 15-20 kts Tuesday night/Wednesday morning, before becoming SW 10-15 the rest of Wednesday and Thursday. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement from 8 AM EDT Monday through Monday evening for NCZ196-204-205. MARINE...None. && $$ SYNOPSIS...MHX NEAR TERM...CTC SHORT TERM... LONG TERM...SGK AVIATION...EH/CTC/SGK MARINE...EH/CTC/SGK
Area Forecast Discussion
National Weather Service Marquette MI
627 PM EDT Sun Aug 23 2020 .SHORT TERM...(This evening through Monday) Issued at 409 PM EDT SUN AUG 23 2020 WV imagery and RAP analysis indicated a mid/upper level ridge from the Southern Rockies through the Central Plains toward the Upper Mississippi Valley resulting in wnw flow into the northern Great Lakes. Farther north, a mid level low was sliding east into northern Manitoba. At the surface, a weak gradient prevailed with weak frontal boundaries northeast of Lake Superior and through north central WI. A weak shrtwv along with MLCAPE values into the 1000- 1500 J/Kg range supported sct shra/tsra through portions of western/central Upper Michigan. With relatively weak 0-6km shear near 20 knots and unfavorable mid level lapse rates, the TS have remained relatively shallow/weak. However, with PWAT values around 1.5 inches, brief heavy rain will be possible along with some small hail. Tonight, expect that the sct shra/tsra slowly moving through central Upper Michigan will gradually weaken this evening with the loss of daytime heating/instability. Otherwise, with abundant low level moisture remaining, dewpoints in the mid 60s, areas of fog are likely to develop again overnight. Min temps should also only fall off into the low to mid 60s. Monday, models suggest that as a shortwave trough and surface low slides through northern Ontario it will drag a weak cold front into Upper Michigan. There is less agreement with the potential for another shrtwv moving into the area from the northern Plains. Nevertheless, expect another round of sct diurnal shra/tsra. With slightly stronger 0-6km shear to 30 knots and MLCAPE values again to near 1500 J/Kg, some stronger or locally svr tsra may be possible. .LONG TERM...(Monday night through Sunday) Issued at 325 PM EDT SUN AUG 23 2020 12z guidance continues to be in good agreement on the dominate upper level features determining flow across the CONUS. Ridging over the western CONUS and the western Atlantic will continue this week and subtle changes in these features will impact how tropical systems in the Gulf of Mexico will impact the southern US and perhaps our region. As these ridges vary in extent and magnitude, the Upper Great Lakes will find itself sandwiched between the western ridge and a deepening trough over eastern North America by mid-week. The pattern looks to flatten out some Thursday, before ridging and troughing amplifies over central and eastern Canada, respectfully, in response to an upper level low digging into the Canadian Rockies for the weekend. Overall, this will allow the muggy conditions to linger, as well as bring a few systems into the region this week. By the weekend, a cooler airmass will filter in. Monday night, early showers and thunderstorms associated with the transiting cold front should be trending downward at around the time the log term period begins. As the front moves through, expect the activity to shift south and any severe threat to come to an end. Until the showers/thunderstorms exit the region, expect localized heavy downpours to still be possible. The front will stall over central WI overnight, which will keep at least low-end chance PoPs in the forecast for the far south into Tuesday morning. Lows should bottom out in the 50s away from the lakeshores, but remain in the low 60s by the water. Tuesday, high pressure will sink southeast over Ontario, landing just northeast of Lake Superior by Tuesday night. This will allow for brief height rises and a break in the humidity. Expect highs to climb into the 70s with maybe stray low 80s in the interior west and interior south. Next round of showers and thunderstorms comes Tuesday evening into Wednesday, as a surface warm front lifts through the region, aided by a few upper level impulses. Accompanied by strong isentropic lift, expecting a good chance of widespread rain across the region to begin overnight Tuesday and continue into Wednesday. As the front lifts through and WAA increases early on, low level cap in the model soundings looks to prevent much in the way of surface- based convection, but elevated values of 500-1000 j/kg could still enable the development of some thunderstorms, especially if the deep shear values of 40-50kts are realized. As the front lifts through Wednesday, theta-e advection and instability look to increase in the afternoon, allowing for some redevelopment along the boundary in the afternoon into the evening, especially in the east. PWATS among the guidance is around 1.5-1.75", with the GFS and EC showing potentially widespread 0.5-1" 24hr QPF and the forecast reflects this general thinking. Thursday, high pressure building southeast over Ontario into Lake Superior behind the outgoing system looks to keep the region dry. However this will be short lived, as upper level troughing looks to begin reestablishing itself over the region. The details are still a little uncertain as the guidance varies, but expecting another shortwave within this flow to move into the region. At the surface, low pressure moving out of the Plains could have some dynamic reenforcement aloft as it moves into the Great Lakes region. Further south, the remains of Laura could be over the middle-Mississippi Valley. Guidance suggesting this position also suggests possible phasing between these systems. Given the uncertain nature and model spread of these features, confidence is low on the evolution of this Thursday night into Friday event. While confidence is low on the details of this event, confidence is high on a cooler Saturday, as the upper level trough allows 850mb temps to fall at or below 10C. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 626 PM EDT SUN AUG 23 2020 Fog will return overnight and take conditions back down to IFR/MVFR at all sites. Conditions improve again Mon morning. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 409 PM EDT SUN AUG 23 2020 Winds across Lake Superior will remain mostly under 20kt Mon thru midweek. A humid air mass over the area combined with some showers moving across the lake has supported fog development across much of Lake Superior early this morning. Will continue the Marine Dense Fog Advisory across much of the lake through 13z. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JP AVIATION...07 MARINE...JLB