Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/17/21

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
548 PM MDT Mon Aug 16 2021 .AVIATION... 00Z TAF CYCLE Thunderstorms have decreased in number across far northern New Mexico, but remain scattered to numerous over many central parts of the state. Cells are tending to drift slowly to the south, but some erratic deviations have been observed. Several storms are strong with heavy downpours briefly limiting visibility/ceilings along with small hail and gusty downburst winds. Activity will tend to stay along and south of the Interstate 40 corridor by late evening with much of the activity coming to an end between midnight and the early morning hours. Storms will redevelop Tuesday afternoon over the west central, southwestern and south central mountains of New Mexico, however the number of cells will be significantly less than today. 52 && .PREV DISCUSSION...329 PM MDT Mon Aug 16 2021... .SYNOPSIS... There will be a downtick in the coverage of showers and thunderstorms on Tuesday, then another uptick in the coverage of storms and rainfall intensity on Wednesday as a storm system passing north of New Mexico draws rich monsoon moisture northward over the state. Behind the system, dry air will dominate northern and central New Mexico through the end of the work week. Showers and thunderstorms will then gradually increase in coverage and wetness daily Saturday through Sunday as better monsoon moisture streams over the state from the south. High temperatures will vary from near normal to around 8 degrees below normal through Thursday before warming some at the end of the week. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)... Broad cyclonic flow aloft over the region this afternoon. Several mesoscale or even smaller scale vortices embedded within the rather unusual mid-August flow regime further enhancing the background/thermodynamic environment. This pattern resulted in an early start to our diurnally-driven storms with storm motions generally and slowly toward the south or southeast. 18Z RAP, 18Z NAM12 and recent HRRR runs suggest areas south of I-40 in western New Mexico as well as a corridor from Conchas Dam to Vaughn southward into Lincoln County will be favored for the most widespread thunderstorm coverage into early evening. Isolated strong to briefly severe storms will also be possible for eastern and southern zones. Respectable ML CAPE values in 1000-1500 J/kg range are in place but within a very weakly sheared environment. Thus, severe threat pretty low outside any significant southward-moving outflow boundary or two that would locally enhance shear profile. Axis of a west to east oriented 300mb trough across far northern New Mexico this afternoon will sag southward through tonight and the first half of Tuesday. Models generally support a west-east oriented trough axis nearly stalled across far southern NM by late morning or midday Tuesday. Weak height rises (1-2 dam), associated slight warming aloft and further air mass drying from north to south expected to keep Tuesday`s storm crop much less robust as compared to today for most areas. Still a locally heavy rainfall concern across southern areas closer to the deeper moisture. KJ LONG TERM...(WEDNESDAY THROUGH MONDAY)... An upper level low pressure system passing slowly eastward over the northern Rockies will draw rich monsoon moisture northward over central and western areas on Wednesday with scattered to numerous showers and thunderstorms capable of producing locally heavy rainfall. Storms will move toward the northeast at speeds around 10-20 mph, moderating the flash flood risk somewhat. As the upper low exits eastward across the upper Great Plains, drier air will filter over NM from the west and northwest with only a few thunderstorms possible Thursday and Friday favoring the northern mountains near the CO border. High temperatures will vary from a few degrees above normal across the northeast to as much as 9 degrees below normal elsewhere Wednesday through Friday. The weekend into early next week will feature monsoon moisture gradually increasing from the south with a daily uptick in the coverage of showers and thunderstorms due to consistent troughing over the northwest US and a building ridge of high pressure over the southeast US. 44 && .FIRE WEATHER... There are no significant fire weather concerns through the forecast period. Thunderstorm coverage will remain seasonably favorable through mid-week with perhaps a slightly increase in overall storm activity on Wednesday and Wednesday night following a slight downtick for Tuesday. An unusually deep upper level trough moving into the interior West will eventually force a drier westerly flow over the area beginning Thursday and likely persisting into Friday and Saturday. This drying episode or break in the monsoon pattern could be rather abrupt and potentially significant with minimum humidity values in the upper teens and 20s for much of the north and west. Moisture levels should then steadily recover early next week with a more typical late August thunderstorm pattern developing. KJ && .ABQ WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 10 PM MDT this evening for the following zones... NMZ206>209-220-224>226-239>241. && $$
Area Forecast Discussion
National Weather Service Gaylord MI
1144 PM EDT Mon Aug 16 2021 .UPDATE... Issued at 925 PM EDT Mon Aug 16 2021 Tufty cirrus has lifted up toward the Straits area while thinning. Expect that trend to reverse to some degree later tonight, with partly cloudy conditions generally across the north half of the forecast area. Meanwhile, a 5k-ft stratocu deck is seen over parts of se lower MI. This will expand/develop northward, with increasing clouds late overnight near Saginaw Bay in this forecast area. Min temps generally similar to last night. && .NEAR TERM...(Through Tonight) Issued at 317 PM EDT Mon Aug 16 2021 ...Patchy Fog... High Impact Weather Potential...Minimal. Pattern Synopsis/Forecast...High pressure will once again stay over the region as the upper level pattern stagnates from Fred. The models, which tried to get the moisture into the SE counties, yesterday, have backed off on that idea, leaving the night dry over the forecast area. The only models with something close area the GFS and the SREF. Almost every other model, takes things east into SW Ontario, to the east of us. So with the return flow over the region, there is more moisture in the low levels, but with the light flow over the region, and the expected clearing skies, low temperatures are expected to be in the lower to mid 50s, fog becomes possible, although more patchy, and most of it south of M-72 again. The smoke to the NW and W should begin to move into the E Upper, but probably not in big concentrations. That would be expected more Tuesday night. && .SHORT TERM...(Tuesday through Thursday) Issued at 317 PM EDT Mon Aug 16 2021 High Impact Weather Potential: Minimal... Pattern Synopsis/Forecast: By Tuesday morning...will be looking for Fred to have merged with the flow to our south...sending a plume of moisture northeastward along a more or less NE-SW oriented boundary to our southeast near the Appalachians. Weakly split flow across the central US will leave the splash pool version of troughs roughly across the southern/eastern US...while the deeper end of the pool remains across the northwestern troughing digs into the flow out there. Bermuda high looks to retrograde a tad...moving into the southeastern US through the remainder of the period as Fred dissipates. Additionally...this retrogression will probably keep Grace...and whatever becomes of "Eight" out in the Atlantic...from disturbing our weather patterns here in the Great Lakes too much. In the heights ultimately rise with the approach of the Bermuda high...will look for increasingly warm and unsettled weather through the period...though uncertainty yet remains. Primary Forecast Concerns: Smoke plumes, temps, and rain chances... Satellite imagery today shows a plume of smoke from the western US being advected eastward across the Plains...centered mainly over the Dakotas, with some lower concentrations spreading perhaps even as far east as Minnesota, per Geocolor satellite imagery. HRRR 16/12z smoke model shows the bulk of the smoke staying to our west/northwest in the stronger flow...perhaps getting into the UP by the end of the day. (Don`t be surprised if the wild sunset pictures start cropping up again...though they may not be as wild as some of the days we`ve seen earlier this summer.) As Fred and its associated boundary shifts north-northeastward through the period...with the weakly split flow to our west/southwest...would not be surprised if the smoke stays shunted to our least for a flow over us would be more southerly and largely smoke-free. Even the smoke approaches...will have to keep an eye on it could keep temperatures from getting as hot as expected...and minimize precipitation potential (particularly the typical diurnal stuff)...especially if this manages to make it into the Great Lakes at some point. Will be interesting to watch the differential heating on satellite in the next few days, though...between the areas of smoke and no smoke. Meanwhile...guidance has been pushing precip chances back the last couple days...suggesting that we should end up dry Tuesday now (as opposed to the teeny tiny diurnal pop-up chances I`d discussed in yesterday afternoon`s AFD). With Fred`s boundary and associated moisture plume likely not that far to our southeast...will expect more clouds, similar to today, as we go into Tuesday. There is some uncertainty in where exactly Fred ends up before dissipating completely...though it should get pretty close to the Ohio Valley region as it tracks up the west side of the Appalachians Tuesday/Wednesday. This should ultimately result in weakening the hold of high pressure over our area (the high pressure centered off to our east today, that is)...which should lead to increased return flow...and an increase in moisture over the next couple days or so. Would not be surprised if precip chances began to crop up late the atmosphere becomes more favorable overall (due to increasing heat and humidity)...with perhaps another niblet of energy riding up the flow into the Great Lakes later Wednesday into Thursday...though attm...nothing looks groundbreakingly certain. .LONG TERM...(Thursday night through Monday) Issued at 317 PM EDT Mon Aug 16 2021 High Impact Weather Potential: Minimal attm... Though a lot of uncertainty remains in the forecast beyond`s entirely possible our best rain chances may hold off until the long term. As some shortwave energy lifts northeastward through the Plains late in the week...looks like there is some potential for showers and storms by the end of the workweek or early weekend...though as mentioned, there is a lot of uncertainty attm...particularly with regard to timing and position of the shortwave and it associated surface boundary. Will have to see how this fares...and would not be surprised if the smoke ultimately ends up affecting this as well. We`ll see. Otherwise...the latter half of the week does look warmer and more humid (as mentioned briefly in the short term) flow should be more off the Gulf towards the end of the the environment will tend to be more favorable for showers/storms. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1144 PM EDT Mon Aug 16 2021 IFR fog overnight MBL. Thicker patches of cirrus will remain over far northern lower MI tonight. MBL has already seen fog form, and IFR conditions will be seen off and on thru morning. Otherwise VFR, with surface high pressure continuing to poke in from the east. Light winds. && .MARINE... Issued at 317 PM EDT Mon Aug 16 2021 Tonight through Wednesday...Tonight through Tuesday night, the sfc high that has been over the region, will remain, with a slack gradient, so the winds are expected to be light south winds over the Upper Great Lakes. Winds aren`t expected to change until Wednesday, when the remnants of TS Fred moves up the Appalachian mountains, and light northerly winds would begin over the region, and the upper level systems begin to move through the region again. Wednesday afternoon, is also when we expect the next chance for showers and thunderstorms to begin to move out over the Lakes Huron and Michigan. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...NONE. LS...NONE. && $$ UPDATE...JZ NEAR TERM...JL SHORT TERM...FEF LONG TERM...FEF AVIATION...JZ MARINE...JL
Area Forecast Discussion
National Weather Service Bismarck ND
1039 PM CDT Mon Aug 16 2021 .UPDATE... Issued at 1031 PM CDT Mon Aug 16 2021 Winds gusted to 37 mph at Beach and generally 20 to 30 mph as the area of showers pushed through Golden Valley and Billings counties. Expect winds to drop off shortly, if they haven`t already, so we will be ending the RFW shortly for Golden Valley, Billings and McKenzie Counties. Otherwise, we made some minor changes to pops through this evening and sky cover through Tuesday morning. UPDATE Issued at 822 PM CDT Mon Aug 16 2021 We added some slight chance pops in west central North Dakota. Current forecast track puts an area of showers (currently with some thunder) into west central ND around 8 PM MDT. Not certain at all if these showers will make it to ND, and don`t really care about the moisture. The main issue is the gusty winds that are possible as they move into ND. 7 PM RH at 715 PM MDT is still 16 percent. Worried that we could see some gusty and erratic winds as the showers move into ND. Therefore we have extended the RFW an additional 2 hours over Billings, Golden Valley, and McKenzie counties. Most of the shower activity looks to be confined to Billings county and south, but can`t rule out some gusty winds in southern McKenzie county. There has been some lighting activity so a dry lightning strike can not be ruled out, but the main threat is the possible gusty and erratic winds with the low humidities. RH values should recover enough by the new ending time, 10 PM MDT. The updated RFW has been sent. We cancelled the remainder of the counties in the original RFW as winds and RH will continue to rise and gusty winds here are even more uncertain. To the east we`ve given up on the potential for showers over the southern James River Valley through the rest of the evening. Slight chance pops were dropped here. Otherwise no changes from previous forecast. UPDATE Issued at 607 PM CDT Mon Aug 16 2021 Although winds have not been too strong this afternoon over the northwest and west central, humidities have been, and remain quite low with most areas in the RFW around 10 percent. There are some stronger winds over northeast Montana that could push into the far northwest yet early this evening. No changes to the current RFW with an expected expiration time of 8 PM MDT. Otherwise no changes to the current forecast. We remain close to our daytime highs. Bismarck has reached 102F, breaking the old record of 101F set in 1969. Abundant smoke remains across western and central ND and expect this to continue through the night and into Tuesday. Main impacts are to Aviation with MVFR visibilities. && .SHORT TERM...(This evening through Tuesday) Issued at 226 PM CDT Mon Aug 16 2021 There continues to be multiple forecast concerns through the short term. First, a Red Flag Warning remains in effect for northwestern and portions of southwestern North Dakota through this evening. Stronger westerly winds have been delayed across the area, and have been mainly confined to southern Saskatchewan closer to the surface low centered over east central Saskatchewan. However, this surface low is expected to move east through the afternoon which, in addition to deeper mixing of the boundary layer, should increase winds. We will continue to monitor how conditions evolve. Despite smoke at the surface and aloft throughout the day, the high temperature forecast remains mainly on track, with temperatures maybe not getting quite as high across the far southeast where greater moisture resides. According to the HRRR smoke model, smoke will likely remain across the area into Tuesday with only slight improvements to visibility possible this evening. With the moisture in place across the southeast and a subtle wave passing through in the upper level flow, there will once again be a slight chance for thunderstorms later this afternoon and into the evening across the far southeastern counties. The SPC mesoanalysis page shows the atmosphere remaining capped, contributing to the low confidence; however, if the cap manages to be breached, a couple thunderstorms capable of small hail and gusty winds will be possible given sufficient CAPE and very marginal shear. Lastly, hot temperatures, dry conditions, and gusty winds are once again expected for Tuesday. The best overlap with low humidity and gusty winds tomorrow will be across southwestern and south central North Dakota, where a Fire Weather Watch has been issued. The biggest challenge with tomorrow`s fire weather forecast will be the position and strength of the surface low that develops ahead of the approaching Pacific Northwest trough, as the low will determine the location and strength of the surface winds. .LONG TERM...(Tuesday night through Monday) Issued at 226 PM CDT Mon Aug 16 2021 With the aforementioned surface low and upper trough approaching the forecast area later on Tuesday, our precipitation chances will begin to increase. The best chances for showers and storms will be across the north and west late Tuesday into Wednesday, beginning to overspread the CWA by late Wednesday into Thursday as the front moves through. Forecast highs on Wednesday will remain tricky as the cold front is expected to move through during the day, with 70s possible in the far northwest and 100s possible in the southeast. Nevertheless, cooler temperatures will eventually arrive and linger through the weekend along with the precipitation chances due to continuing southwesterly flow aloft. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1031 PM CDT Mon Aug 16 2021 Smoke will produce periods of MVFR visibilities tonight and into Tuesday across western and central ND. Only scattered high level clouds expected tonight with some increasing high and mid level clouds on Tuesday. Westerly flow at KXWA, KDIK and KMOT and southerly flow at KBIS and KJMS will diminish this evening. A cold front will drop into northern ND Tuesday with surface flow turning northeast to east at KXWA and KMOT. A southerly flow is expected at the southern TAF sites of KDIK, KBIS and KJMS Tuesday. && .BIS WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Tuesday afternoon through Tuesday evening for NDZ018>022-031>035-040>046. Red Flag Warning until 11 PM CDT /10 PM MDT/ this evening for NDZ017-031-032. && $$ UPDATE...TWH SHORT TERM...Gale LONG TERM...Gale AVIATION...TWH
Area Forecast Discussion
National Weather Service Boise ID
916 PM MDT Mon Aug 16 2021 .DISCUSSION...Showers and thunderstorms along the NV border will continue through this evening before tapering off overnight. Storms have produced wind gusts up to 50 mph this evening underneath the storms. A cold front will move through the region on Tuesday morning bringing breezy northwest winds midday into the afternoon. A threat of showers and thunderstorms exists along the cold front Tuesday. Smoky conditions should start to improve on Tuesday morning, before the trough moves overhead from the north. As the trough moves south, it will pull in smoke from the BC fires and smoky conditions should return. No updates to the current forecast. && .AVIATION...Mostly MVFR. Local IFR visibilities and areas of mountain obscuration due to wildfire smoke. Isolated thunderstorms south and east of KBOI, ending by 06z. Gusts to around 40 kts possible near storms. Cold front crossing the area from the west 12z- 18z/Tue. Conditions improving to mainly VFR following front. Surface winds mainly west to northwest 5-15 kts, increasing to 10-20 kts Tuesday afternoon. Winds aloft at 10k feet MSL southwest 20-30 kts increasing to 30-40 kts Tuesday afternoon. && .PREV DISCUSSION... SHORT TERM...Tonight through Wednesday night...Incoming cold front has already begun to clear the smoke out of Harney and Baker Counties. The front will pass through southwest Idaho this evening and south-central Idaho overnight and will clear most of the smoke out of those areas, too, except directly downwind of the fires. There have already been a couple of showers and weak thunderstorms in Valley County this afternoon. These should end late today. Other thunderstorms will form late this afternoon and evening in southeast Malheur County/OR, the Owyhee Mountains, and in Idaho from the Snake River south to the Nevada border. HRRR indicates strong wind gusts possible in Owyhee County with these thunderstorms. Tuesday will be partly cloudy, windy, and 10 to 20 degrees cooler than today, and much less smoky. A chance of showers and thunderstorms will develop in eastern Valley County/ID Tuesday afternoon and spread into south-central Idaho and Owyhee County Tuesday evening. Wednesday will be another 10 degrees cooler than Tuesday as the upper trough closes a low right over Idaho, with showers continuing in Valley County, with snow even possible above 8500 feet. Northwesterly flow around the low will begin to spread smoke in from Oregon again and it may get into Idaho Wednesday night. LONG TERM...Thursday through Monday...Temperatures will remain below normal through the period as a series of troughs cycle over the Pacific Northwest. Valley locations will see temperatures consistently in the 80s. The threat of showers/thunderstorms over higher terrain of southwest Idaho remains through the remainder of the period. The active pattern may help to scour out smoke that re-enters the area. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ DISCUSSION...KA AVIATION.....JT PREV SHORT TERM...LC PREV LONG TERM....AL
Area Forecast Discussion
National Weather Service Charleston SC
918 PM EDT Mon Aug 16 2021 .SYNOPSIS... Deep tropical moisture will persist through mid week as Tropical Cyclone Fred passes to the west and Atlantic high pressure remains to the east. Weak troughing should then persist later this week through early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Showers are developing along the Georgia coast about 1-2 hours earlier than expected, so near-term pops were adjusted to reflect this. The forecast is on track, otherwise. GOES-E and KTLH/KEVX radar data at 17/01z show the center of Tropical Storm Fred inland just north of Mariana, Florida. Southeast South Carolina and Southeast Georgia will becoming increasingly influenced by Fred`s cyclonic circulation through the night as it moves steadily north/northeast into far southwest Georgia/southeast Alabama. Showers have remained fairly light early this evening with isolated tstms producing pockets of locally heavy rainfall. Guidance is pretty unanimous in the depiction of showers/tstms redeveloping later this evening and especially overnight as low- level wind fields increase coincident with a pronounced low- level jet and shortwave energy increasing from the south during the early morning hours Tuesday. High-res guidance suggest there could be several bands of heavy rain developing after midnight with most of the activity poised to affect the region from coastal Georgia into much of southern South Carolina through daybreak as UVVs with the approaching shortwave intensify. Instability will also be on the increase as dewpoints rise and warm/moist air advects inland from off the Atlantic. Pops 60-90% look on track later tonight. There is a potential for intense rainfall rates with any feeder bands that develop, but it does appear most of the heavier convective elements will remain progressive. The latest RAP high-res output suggest PWATs could surge as high as 2.50-2.65" within any feeder bands, which could further increase rainfall rates. However, as the center of Fred gains latitude, there is a possibility that convective training may become more of an issue as sunrise approaches, especially in southern South Carolina. This will need to be watched as an increased risk for flooding could materialize in these areas. At this point, the risk for flash flooding still looks to low to hoist a Flash Flood Watch, but trends will be monitored. A non-zero waterspout/tornado threat could also develop within any heavier convective elements as surface winds look back relative to the mean flow atop the boundary layer overnight. This could provide just enough low-level helicity to produce an isolated waterspout or tornado. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... TC Fred will make its closest pass to the Georgia and South Carolina coastal areas on Tuesday, passing up through far western/northwestern Georgia per latest NHC forecast...with a slight easterly shift in the forecast track. As this occurs, deep tropical moisture plume (and semblance of a TC feeder band) will get drawn northward into the SE Georgia and South Carolina region with PWAT values approaching 2.5 inches later tonight through Tuesday. Along with increasing larger scale forcing for ascent associated with the tropical system, widespread showers/storms will be ongoing Tuesday morning particularly across the SE South Carolina counties with the band lifting northward in time. Precip coverage may tend to diminish some later in the morning and into the afternoon as the initial moisture plume/feeder band gets drawn further up the coast, although some additional bands of showers/storms are likely to develop and swing through the region as we get into the daytime heating cycle. It`s difficult to get too specific with pop timing/placement, but the overall forecast idea will be for high pops in the morning followed by a secondary increase through the afternoon. Of course, the biggest impact will be from the widespread heavy rainfall/flooding potential given the recent localized heavy rains that we have already seen and especially during the morning commute hours Tuesday. Overall (larger scale) rainfall amounts of 1 to 3 inches still appears to be a reasonable target given how quickly the deep moisture plume/feeder band slides up through the region. But some localized amounts in excess of 3 inches will likely occur. Am not inclined to hoist any type of flood watch product at this time. But a small handful of short-fused flood advisories will likely be needed late tonight and Tuesday. Along with the heavy rainfall threat, given the slight eastward shift in the TC storm track and increased low level flow, a window of stronger effective bulk shear and low level helicity values may creep north-northeastward into the SE Georgia counties and largely west of the I-95 corridor in South Carolina. Latest SPC outlooks keep the higher (marginal-slight) risks for severe just to our SW and W of our CWA through Tuesday, which is fine. But I suspect later shifts tonight and into tomorrow will need to keep an eye on storms. Precip chances/coverage/rainfall amounts will taper off somewhat for the Wednesday/Thursday timeframe, back to the typical tendency for increased chances in the afternoon. And after our relatively "cooler" stretch of weather, temperatures will rebound back closer to normal readings (upper 80s to around 90). && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Subtropical larger scale ridging is expected to re-establish itself along the SE Atlantic coast into the Gulf of Mexico during the latter half of the week, although still projected to get flattened to some degree across the Deep South as stronger westerly flow/lowering mid level heights spread into the northern tier of states. Some rebounding of upper level heights/ridging may take shape across the eastern CONUS later in the weekend into early next week as the upper level ridge propagates westward a bit into the lower Mississippi River Valley. We lose the tap of deeper tropical moisture, which should bring lowering rain chances overall. That said, enough moisture remains across the SE in the presence of developing low level troughing through the central Carolinas into Georgia to keep periodic convection active in the coastal waters, and diurnally driven showers and storms inland. Temperatures will largely run around or perhaps slightly above climo highs/lows through the period. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... Showers/tstms are expected to impact all 3 terminals later tonight into Tuesday morning as Tropical Storm Fred moves into southwest and eventually western Georgia. Showers could develop as early as midnight then steadily expand/spread north as the night progresses. An especially nasty area of showers/tstms could impact KCHS and KJZI prior to daybreak where vsbys could drop below alternate minimums at times. Prevailing showers with TEMPO groups for tstms will be highlighted at various times, but most of the activity should end at the terminals by mid/late morning. One last feeder band could impact the airports early /mid-afternoon, but VCTS will be included during this time as there are still some timing/coverage unknowns. Extended Aviation Outlook: Periodic flight restrictions will continue through the week owing to shower/thunderstorms, especially Tuesday into Tuesday night, as TC Fred migrates northward west of the region. && .MARINE... Tonight: A Small Craft Advisory has been issued for the Georgia offshore waters for seas of 5-6 ft. Seas at 41008 continue to climb and are now running just above 5 feet. Latest WaveWatch10 output shows 6 ft seas remaining in the Georgia offshore leg through about 12z Tuesday. Otherwise, winds will remain 15-20 kt with seas 4-5 ft over all other zones with 10-15 kt with gusts to 20 kt in the Charleston Harbor. Showers/tstms will redevelop over the waters overnight. Low vsbys to 1 NM or less will be possible in pockets of heavy rain. Gusts 35 kt or greater could also occur. Special Marine Warnings may be needed at some point. There is even a low-end risk for an isolated waterspout or two. Tuesday through Saturday: Stronger southeasterly winds are anticipated for Tuesday into Tuesday night as TC Fred migrates up through far western/northwestern Georgia and into the eastern Tennessee Valley. Still some potential for 6 foot seas to develop in the outer Georgia waters Tuesday, although wind gusts and seas are expected to largely remain just below small craft advisory criteria, topping out in the 15 to 20 knot range with slightly higher gusts, and seas 3 to 5 feet. Winds weaken and veer more southwesterly for the remainder of the week with no significant concerns at this time. Rip Currents: Modest onshore flow, astronomical influences from the upcoming perigee, and the presence of some swell energy will combine to produce a moderate risk of rip currents at all beaches through Tuesday. && .HYDROLOGY... A few more rounds of heavy rainfall will impact southeast South Carolina and southeast Georgia into Tuesday night. Overall rainfall totals of 1 to 3 inches are expected through Tuesday night, with locally higher amounts likely. Heavy rainfall persisting over the same areas for extended periods may lead to minor flooding, especially in low-lying and poor drainage areas. A risk of flash flooding may develop in urban coastal areas such as Downtown Charleston if heavy rain falls around the times of high tide. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for AMZ374. && $$
Area Forecast Discussion
National Weather Service Dodge City KS
620 PM CDT Mon Aug 16 2021 ...Updated Aviation Discussion... .SHORT TERM...(This evening through Tuesday) Issued at 324 PM CDT Mon Aug 16 2021 A weak mid level vorticity max has been moving south across central and western Kansas today. By mid afternoon, latest RAP analysis showed it along or just north of the Oklahoma border. Water vapor imagery is showing mid level subsidence spreading south into the forecast area. Based on this and latest radar and visible satellite trends, it appears that any significant convection through the late afternoon and early evening hours will be confined to areas south of the Oklahoma border. Will keep some small pops for thunderstorms along and just north of the border late this afternoon and early evening. Thunderstorm chances may linger into late tonight in areas toward central and south central Kansas as a low level jet redevelops and veers out through the late night hours. Locally heavy rainfall is possible again given the location of the plume of higher PW`s into central Kansas. As we move into Tuesday, the vort max/weak mid level circulation moves east into eastern Kansas with weak mid level ridging developing over southwest Kansas. Thunderstorm chances will be fairly low after today moving into mid week. .LONG TERM...(Tuesday night through Monday) Issued at 324 PM CDT Mon Aug 16 2021 Broad, weak upper level high pressure will spread over the central CONUS through the first few days of the extended period. While isolated thunderstorms cannot totally be ruled out, we should remain dry with with seasonal high temperatures in the lower 90s. A fairly strong upper level storm system that is currently dropping into the Pacific Northwest this afternoon will continue to close off and move slowly east through the northern Rockies through mid week. This system will swing out across the northern and central Plains on Thursday. An associated surface cold front should move through western Kansas by Thursday afternoon into Thursday night and should bring scattered thunderstorms to central and southwest Kansas. Highs on Friday will remain a little cooler, generally in the 80s across the area. Behind this system, upper level flow becomes more west to southwest over the central Plains. Another disturbance could bring a chance for thunderstorms to the area through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 606 PM CDT Mon Aug 16 2021 Gusty south southeast winds will decrease to around 10 knots over the next couple of hours. BUFR soundings indicating late day clouds over the southwest kansas at or above 5000ft AGL will also dissipate by or shortly after sunset. Will need to monitor the potential for patchy fog between 11z and 14z Tuesday but at this time the probability of this appears too low to include into the 00z Tuesday TAFS. South southeast winds will increase to around 15 knots between 15z and 18z Tuesday. && .PRELIMINARY POINT TEMPS/POPS... DDC 65 91 66 92 / 20 10 0 0 GCK 62 92 64 93 / 10 10 0 0 EHA 62 92 63 93 / 10 10 0 0 LBL 62 92 64 93 / 10 10 0 0 HYS 64 90 66 91 / 10 10 0 0 P28 68 91 69 93 / 20 20 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Gerard LONG TERM...Gerard AVIATION...Burgert
Area Forecast Discussion
National Weather Service Des Moines IA
621 PM CDT Mon Aug 16 2021 .DISCUSSION.../Tonight through Monday/ Issued at 359 PM CDT Mon Aug 16 2021 Forecast Highlights: -- More of the same today, some fog possible southeast tonight. -- Gradual increase in heat and humidity through Thursday. -- Smoke returns to Northwest Iowa Tuesday. -- Thunderstorm chances return later in the week. TODAY THROUGH TUESDAY: Upper level trough looks to remain in place over the state through much of the day Wednesday with a pattern change finally taking place Wednesday night into Thursday. Any chances for precipitation before Wednesday seem rather slim with little moisture or forcing. Thus, the main concerns for today and tomorrow will be increasing heat and humidity Tuesday and the return of smoke from western wildfires into the state, mainly effecting northwest into western Iowa on Tuesday during the daytime hours. The HRRR smoke model suggests lighter concentrations at the surface and more smoke aloft, especially over northwest Iowa. For the rest of today, expect another pleasant afternoon with high temperatures in the low to mid 80s and dew points in the 50s to low 60s. Overnight lows will once again be in the upper 50s to 60s with some possibility for fog in the far southeast that could drop visibilities temporarily around daybreak Tuesday. Some moisture return into Tuesday afternoon will cause dew points to rise back into the upper 60s to low 70s, the return of the humidity pushing heat indices back towards 90 in western Iowa with high temperatures Tuesday afternoon in the mid to upper 80s. WEDNESDAY AND BEYOND: The mid-level trough that will bring our next system starts to push east from the Pacific Northwest into the Inter- Mountain West on Wednesday. Southerly surface flow ushering in some WAA and theta-e advection into the area will push high temperatures in to the upper 80s to low 90s with heat indices in the low to mid 90s on Wednesday afternoon. Additionally, some scattered convection could be possible on Wednesday, mainly associated with peak heating, but any storm chances look to be isolated at best. With the scattered/isolated nature of any possible convection, chances are too low at the moment to introduce mention over NBM forecast. Conditions on Wednesday will become a bit breezy by the afternoon with 10 to 20 knot gusts. A surface low pressure and associated cold front move will across the Northern Plains on Thursday as the aforementioned mid-level trough continues to move east across the Inter-Mountain West, arriving in our area Friday or Friday night. Models are fairly consistent in introducing scattered convection into our area on Thursday night but still differ on arrival timing and movement of the mid-level system Friday into Saturday. What does seem likely is a window of precipitation on Friday that may linger into some of Saturday and could bring some decent rainfall to the area, but the quasi-perpendicular motion with respect to the boundary should help alleviate any hydro issues given our recent dry spell as well. Another system looks to arrive Sunday into Monday keeping additional chances for storms/precipitation around through the weekend. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 619 PM CDT Mon Aug 16 2021 Mainly VFR conditions through the period with southerly winds. There are low chances for fog, particularly near KOTM but at this time probs are low enough to exclude from the forecast. Some cumulus development is expected by Tuesday afternoon but all bases are expected to be above 3 kft. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...KCM AVIATION...Donavon
Area Forecast Discussion
National Weather Service Grand Forks ND
1000 PM CDT Mon Aug 16 2021 .UPDATE... Issued at 1000 PM CDT Mon Aug 16 2021 Dry, breezy, and mild conditions are still expected overnight, with no impactful weather. On Tuesday it should be hot, but we`ll monitor trends overnight to gauge potential smoke impacts on max temps. There is a signal for isolated thunderstorms Tuesday during peak heating along the surface trough (southwest to northeast orientation over our area), but this potential is complicated by lack of organized forcing aloft and smoke impacts on stability parameters. For now only chances were to near term trends this evening. UPDATE Issued at 709 PM CDT Mon Aug 16 2021 Temperatures are starting to drop after late afternoon highs near in the 90s (lower than forecast due to smoke by 3-5F), while smoke layer aloft continues to lead to filtered sun as it slowly sets. Smoke and clouds may have a similar impacts Tuesday, but I`ll hold off on adjustments until later to get a better handle on trends. A mild night is still forecast. Smoke layer remains primarily aloft minimal impacts at the surface expected as flow remains west-southwest (closer thick smoke producing fires are still north and east of our CWA). Near term adjustments made, otherwise forecast is on track for tonight. && .SHORT TERM...(This evening through Tuesday night) Issued at 340 PM CDT Mon Aug 16 2021 As surface high pressure tracks eastward across the Great Lakes surface low pressure is steadily digging into the western Dakotas, with a moderate low level south-southwesterly flow extending up through the Central Plains states into and across our Northern Plains region. Near the surface, a mid-Dakota dryline marks the boundary between much lower dewpoint air over portions of central and western ND and the more humid air over eastern ND and western MN. And at the mid levels, a more westerly flow aloft has ushered in a new wave of smoke from western U.S. wildfires. The smoke layer now having advanced over eastern ND and much of northwest MN has taken the top edge off the high temperatures expected for the day. Along the eastern edge of the smoke layer, from Baudette down through Fergus Falls and into Sisseton, bands of cumuliform clouds are trying to develop... but suffer from a good focusing mechanism. Further west, the smoke layer and generally impeded heating is further suppressing cumulus development there. As a result, there is still a possibility for an isolated shower and thunderstorm from the far southern RRV up through the Lake of the Woods from the late afternoon into the evening hours. CAMS have been steadily decreasing this threat over time, and latest HRRR has all but eliminated that chance. Thus we can expect a steady wind to persist through the overnight with a moderate H8-H7 flow aloft... and overnight low temperatures maintaining from the upper 60s to lower 70s. And on Tuesday, expect a remake of today, with gusty south-southwest winds near the surface and daytime highs ranging in the 90s. .LONG TERM...(Wednesday through Monday) Issued at 340 PM CDT Mon Aug 16 2021 The mid to late week period is marked by steadily increasing chances for showers and thunderstorms in eastern North Dakota and northwestern Minnesota. Temperatures will peak through midweek and then cool through the late week and weekend after a cold front makes its way across the area on Thursday. Guidance continues to struggle with the pattern change that is imminent in the late extended term period. More agreement is present in rain chances starting in the middle of the week this week and continuing through the weekend. A cold front will move through the area late on Thursday, and drop high temperatures from the mid 90s, prior to frontal passage, down into the lower 70s after frontal passage. The chances for thunderstorms and showers increase until we reach the weekend due to the upper level trough passing through. The greatest chance for decent rainfall amounts will be on Friday of this week, with PWATs trending above normal and chances for QPF greater than 0.1" (in 24 hours) exceeding 70% depending on which ensemble you choose to view. Definitely starting to see the signals for a decent rain event (which we desperately need), but details are still fuzzy and confidence is low on the specifics. Given the upper-level flow after the trough moves through at the end of the week, ensemble guidance is hinting at more systems passing through the area, keeping our rain chances on the up and up into the start of next week. Some are showing a ridge building in in the southeast, which could push us out of more zonal flow and halting our rain chances, but we will have to see what unfolds as we approach the weekend at this time. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 709 PM CDT Mon Aug 16 2021 VFR conditions should prevail with smoke layer aloft persisting through the TAF period, but creating minimal impacts at the surface. Southerly winds decrease some this evening becoming gusty again during the day Tuesday. A low level jet transitioning eastward tonight may result in a period of low level wind shear 35-40kt across parts of northwest MN before sunrise Tuesday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...DJR SHORT TERM...Gust LONG TERM...AK AVIATION...DJR
Area Forecast Discussion
National Weather Service Glasgow MT
815 PM MDT Mon Aug 16 2021 .DISCUSSION... ...High fire danger and hot temperatures will remain a concern into Tuesday for Northeast Montana... 800PM UPDATE: Update to the forecast this evening was to mainly remove the Heat Advisory for all but the far southwest counties and remove the Lake Wind Advisory. PoPs/Thunder were updated to increase across the south where thunderstorms were rolling through. Winds are expected to calm rapidly this evening, but will come roaring back to life by mid-day tomorrow. SMoke and Haze is projected by GLAMP/NBM to subside near the surface over the next 9 hours but is immediately overridden by the HRRRSmoke which places the smoke back over nemont tomorrow. Did a blend of these 2 products starting with GLAMP and twisting it into HRRRSmoke after about hour 9-12. GAH AFTERNOON UPDATE: Hot and dry conditions will continue across much of the region into Tuesday before a cold front comes down from Canada. With the slow arrival of the front, have extended the Red Flag Warning and Heat Advisory across some of the southern zones through Tuesday. A Lake wind advisory may also be necessary in the late afternoon after the front crosses Fort Peck Lake. Also of concern, particularly for Fire Weather concerns will be the potential for mostly dry thunderstorms with strong gusty winds developing along the southern boundary of the CWA late this afternoon and continuing east overnight. MORNING DISCUSSION: Hot and mainly dry conditions will continue today with the western U.S. upper ridge over the area. Temperatures will be in the mid 90s to low 100s for highs. West winds will develop this morning and increase to 15 to 25 mph this afternoon. With RH as low as 10 percent, it will lead to very high fire danger. Isolated thunder is also possible in the southwest late this afternoon and this evening. HRRR guidance continues to indicate that haze and smoke will remain over the area today and tonight in varying degrees with lower visibility and poor air quality at times. Will keep Red Flag Warning in effect for all Fire Weather Zones through midnight tonight. Will keep Heat Advisory in effect for the south this afternoon and evening. Will issue a Lake Wind Advisory for Fort Peck Lake from noon to 8 pm today. A weak wave could give the SW zones an isolated thunderstorm late this afternoon and this evening. A cold front approaches the area tonight and moves south and east across the forecast area during the day on Tuesday and reaches the North Dakota border Tuesday evening. The front will be early enough in the day in the NW that temperatures will cooler for highs but late enough in the afternoon or early evening for the SE to be as hot as today. The SE will have one more day with highs near 100 and may need another Heat Advisory on Tuesday. Will hold off for now to see where the models handle the timing of the cold front. An upper trough will drop SE into the Pacific NW on Tuesday and a wave on SW flow aloft Tuesday Night will bring rain showers to Phillips and Petroleum Counties and points west while the remainder of the forecast area will have chances for showers possible thunderstorms with the lowest chances in the east where dry slotting is expected. Temperatures will be much cooler with highs in the 60s west and 70s east on Wednesday. An upper trough moves through Montana Thursday and Friday with cool temperatures and chances for showers. Another trough over the weekend could bring more chances for showers. && .AVIATION... LAST UPDATED: 0215Z FLIGHT CAT: MVFR-VFR. DISCUSSION: Smoke from western wildfires will continue to hamper visibility across the region tonight into Tuesday. Visibility will vary between 3SM and P6SM depending on how thick the smoke. An incoming cold front and increasing chance of showers will begin to clear the smoke from the northwest by Tuesday morning. WIND: Calming to light and variable late this evening through tonight. Increasing to 10 to 20 kts Tuesday afternoon with direction varying based on placement of a frontal passage. LLWS: Low level wind shear is possible 02 - 08Z Wednesday morning behind the passage of the cold front. /GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT Tuesday for MTZ122-137. Red Flag Warning until midnight MDT tonight for MTZ120-134>136. Heat Advisory until 9 PM MDT Tuesday for Dawson...Prairie... Wibaux. && $$
Area Forecast Discussion
National Weather Service Green Bay WI
1029 PM CDT Mon Aug 16 2021 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Tuesday Issued at 201 PM CDT Mon Aug 16 2021 Another quite late summer day across central and northeast WI. Satellite imagery at 18Z showed daytime cu had developed across much of the area once again. A few sites were also starting to see southerly gusts to around 15 to 20 mph. Similar to the past few days, expect clouds and occasional gusts through early this evening, then both will dissipate as the sun sets. Tonight...Upper ridge and surface high pressure will provide mainly clear skies and light winds. Used a blend of the best performing guidance for low temps and adjusted for local effects. This brings lows down into the 50s, with the typical cool spots in the upper 40s. Tuesday...Have been watching the smoke across Minnesota and the Dakotas advance slowly east today. The HRRR smoke model (which has been fairly reliable this summer) indicates smokes will start to drift over western and northern WI by tomorrow afternoon or evening, not quite reaching the Fox Valley or east- central WI yet. This smoke is expected to remain aloft so surface air quality should remain okay for tomorrow. Meanwhile, expect another day with daytime cu and a few afternoon wind gusts. Highs will be fairly uniform in the upper 70s to low 80s area wide. .LONG TERM...Tuesday Night Through Monday Issued at 201 PM CDT Mon Aug 16 2021 Weak blocking pattern of the upper winds is expected though Thursday, keeping mostly dry weather across the region. Temperatures and dewpoints will slowly increase with south winds. Highs will be 5 to 10 degrees above normal by Thursday. There is a slight chance of a shower Thursday afternoon or evening ahead of the 850mb warm front, but left it out due to relatively dry air below 700mb. The chance of showers and thunderstorms will increase Friday and Saturday as an upper trough approaches from the Plains States. The ECMWF has been consistent in bringing the front through Saturday, and the Canadian model is even a little slower. The GFS brings some activity in Friday, even though it does not bring the surface front through until Saturday morning. Think the best chance of showers and thunderstorms is Friday night through midday Saturday. Temperatures will be a few degrees high than normal. SLightly cooler and drier air should arrive Sunday and Monday as the front exits the area. && .AVIATION...for 06Z TAF Issuance Issued at 1024 PM CDT Mon Aug 16 2021 Based on current low temperature/dew point depressions in several locations, it appears that patchy fog development will occur overnight, especially between 09z-13z/Tuesday. Confidence is not high that it will form at the TAF sites, but will probably add a TEMPO group at MTW and RHI, and leave it out for the remaining sites. The persistent pattern of daytime cumulus clouds and south winds continues for Tuesday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....KLJ LONG TERM......RDM AVIATION.......Kieckbusch
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1043 PM CDT Mon Aug 16 2021 .SHORT TERM... (Through Late Tuesday Afternoon) Issued at 228 PM CDT Mon Aug 16 2021 An elongated ridge stretching from high pressure centered over New England remains over the Midwest today. The ridge is sitting under a broad trough of low pressure aloft in the mid and upper levels. Richer low level moisture is making some inroads back into the Mid Mississippi Valley today with some low 70s dew point temperatures creeping up into southern Illinois. Deterministic guidance continues to print out light QPF early this evening, and again on Tuesday due to what appears to be weak low level moisture convergence along and east of the Mississippi River. High resolution convection allowing models (CAMs) also show isolated- widely scattered convection over parts of the CWFA this evening and tomorrow, with the HRRR being the most aggressive both in coverage and strength of the convection. The HRRR`s performance hasn`t been stellar of late, and the low level dry tongue on the western periphery of the ridge is right where it blows up I`m discounting the HRRR at this time. Otherwise the slight chance/low chance PoPs in the current forecast for early this evening and tomorrow over parts of Illinois into southeast Missouri (tomorrow afternoon) look very reasonable. Actually, I really like deterministic RAP depiction of where the precip will fall, and that it won`t last too long after sunset due to loss of diurnal heating. Temperatures tonight through Tuesday night should continue to warm a couple of degrees each period as the airmass associated with the lingering surface ridge continues to modify. Carney .LONG TERM... (Tuesday Night through Next Monday) Issued at 228 PM CDT Mon Aug 16 2021 The upper level pattern remains relatively unchanged through midweek. The remnants of TS Fred lift northeast through the Appalachians toward the eastern Ohio Valley and coax the weak trough over the Midwest into Great Lakes Region by Thursday. Another more vigorous trough dips into the Intermountain West by late Wednesday where it lingers until early Friday when it`s picked back up by the mean westerlies. The resulting lee side cyclogenesis creates a low- level low pressure system which moves through the Northern Plains Friday and into Canada Friday night. The upper flow over the Mid Mississippi Valley remains zonal at best, even slightly anti- cyclonic, so the cold front attached to the surface system fails to penetrate to far south into Missouri and Illinois. None-the-less, it does look like the best chance for precipitation will be on Friday and/or Friday night ahead of the cold front as it moves into Iowa and northwest Missouri. The front might make it down to the I- 70 corridor before it stalls, and then lifts back to the north on Sunday as another trough sweeps through the Northern Plains and a 5940+ meter 500mb ridge builds over the lower Mississippi Valley. This ridge has the potential to bring us the warmest weather in the next 7 days. Bottom line is that the weather looks fairly unexciting, typical August with isolated-scattered storms possible each afternoon, with Friday probably having the best shot at rain ahead of the cold front. Temperatures look typical for mid August...upper 80s to low 90s with lows in the upper 60s to low 70s. As mentioned above, Monday may be our warmest day under the influence of the strong upper ridge to our south. Current thinking is that some parts of the are will warm into the mid 90s Monday. Carney && .AVIATION... (For the 06z TAFs through 06z Tuesday Night) Issued at 1041 PM CDT Mon Aug 16 2021 VFR flight conditions are expected to prevail through the forecast period at all local terminals. Some model guidance suggests that fog development is possible during the early morning hours, but confidence remains high that this fog, if it does develop, will stay away from all local terminals. Otherwise, diurnal cumulus will develop near mid-day tomorrow. Brief, isolated showers are still possible near KSUS, KSTL, and KCPS during peak heating, and it now looks like showers may also occur near KJEF and KCOU. However, confidence remains low in their occurrence, so I have continued to leave mention of them out of the TAFs for now. Elmore && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 69 87 71 90 / 10 10 10 20 Quincy 64 83 66 86 / 5 5 5 10 Columbia 65 86 66 88 / 5 10 10 10 Jefferson City 65 87 67 89 / 5 10 10 20 Salem 68 84 69 87 / 20 20 20 20 Farmington 64 85 66 88 / 5 20 10 20 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Melbourne FL
850 PM EDT Mon Aug 16 2021 .DISCUSSION... Current-Tue...TC Fred made landfall earlier this afternoon near Cape San Blas in the FL Panhandle. It will continue to advance northward and weaken tonight and into Tue. Convection finally got going late today from collisions between the ECSB/WCSB -- convective outflows across the central peninsula. Highest concentration of activity lies across the I-4 corridor with some additional development southward toward Lake Okeechobee. Movement is toward the N/NNE at 15-20 mph. Some of these storms may press towards the east coast before dissipating. Primary threats remain occasional to frequent cloud-to- ground lightning, torrential downpours, and gusty winds to 35-45 mph. Activity will diminish thru mid to late evening, possibly hanging on a little after midnight is the latest HRRR is to be believed. Overnight lows continue warm in the M-U70s with conditions humid. Moist airmass remains in place through Tue, which will again lead to above normal coverage (60pct) of showers and storms into the afternoon. Sea breeze will be able to push inland, as low level S/SW flow remains rather light, with highest coverage of convection focused across the interior through late day where boundary collisions are favored. It will remain quite humid, with highs in the L90s across much of the area, and peak heat index values 100- 105. && .AVIATION...Sea breeze/mesoscale boundary collisions across the interior of ECFL will gradually diminish thru mid-late evening as they advance N/NE. Some may make it back to the coast. Will handle with tempo groups as necessary. Tempo MVFR CIGs/VSBYs invof convection. Light SE/SSE winds tonight gradually becoming ESE near the coast with sea breeze formation and slow penetration inland. On Tue, ISOLD-SCT SHRA/TSRA possible in the late morning and early afternoon, followed by a east/west coast sea breeze collision near the inland terminals, increasing coverage to SCT-NMRS into the evening. && .MARINE...Overnight-Tue...SERLY winds relaxing to around 15 kts offshore overnight, diminishing to 8-14 kts areawide on Tue, then increasing toward 15 kts again late in the afternoon north of the Cape. Will end the Cautionary Statement for offshore north of Sebastian Inlet with mid-evening Coastal Waters Forecast issuance. Seas 3-4 ft, possibly up to 5 ft well offshore the Volusia coast overnight will average 2-4 ft on Tue. ISOLD-SCT convection over the local waters overnight into Tue. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Sedlock/Watson/Haley
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1100 PM CDT Mon Aug 16 2021 .UPDATE... Issued at 1100 PM CDT Mon Aug 16 2021 Updated for aviation discussion below. && .SHORT TERM...(This evening through Tuesday night) Issued at 233 PM CDT Mon Aug 16 2021 The forecast issues in the short term are the return of elevated smoke to the area, and the elevated fire weather conditions. Aloft, the western ridge will expand to the northeast into the region. Surface high pressure to our east and surface low pressure to our west will keep us with southerly low level flow through the short term which will advect heat and humidity into the region. This will spell the end to the very comfortable dew point temperatures that we have been enjoying. Dewpoints in the western CWA have increased well into the 60s, while west central Wisconsin is still in the 50s. Tomorrow afternoon dewpoints will rise further with the entire forecast area expected to have dewpoints into the mid 60s. Along with the increased moisture, temperatures rise as well, with high temperatures in the low 90s for most of our Minnesota counties and in the mid to upper 80s for our Wisconsin counties. Elevated smoke is visible on satellite moving into northwestern Minnesota and HRRR vertically integrated smoke has the thicker smoke reaching the northwestern CWA this evening and continuing to spread southeast across the area, reaching the Twin Cities Metro tomorrow morning. The smoke looks to remain elevated, so impacts may just be haze and pretty sunrises and sunsets. Fire weather concerns continue in the short term, with elevated fire weather conditions today and tomorrow for northern parts of the forecast area. Minimum RHs only fall into the upper 30s and 40s this afternoon and Tuesday afternoon with breezy southerly winds. These conditions, when combined with the dry vegetation, could lead to the rapid spread of any wildfires that are able to start. .LONG TERM...(Wednesday through Monday) Issued at 233 PM CDT Mon Aug 16 2021 With forecast models continuing to converge that the late week system arrives Friday, Wednesday and Thursday are expected to be dry and hot. Each day, highs will be in the upper 80s to lower 90s while overnight lows will only drop to the mid 60s and lower 70s. The Twin Cities heat island will likely remain above 70 both Wednesday and Thursday night. We will also feel quite "muggy" as southerly flow advects additional moisture northward into south-central MN and western WI. Dewpoints are forecast to slowly climb into the mid to upper 60s by midday Thursday. With these factors in mind, there is a chance a Heat Advisory for the Twin Cities metro area may be needed in future forecasts. While skies are expected to be nearly cloud- free until Thursday evening, elevated smoke from wildfires in the western US and Canada will create a thick haze. Have increased sky grids through Wednesday night to account for this. Overnight Thursday, cloud cover will build from the west as the thoroughly discussed upper-level trough approaches the Northern Plains. Guidance mostly agrees that as the negatively-tilted trough swings through the Northern Plains, a surface low will develop somewhere over the Dakotas. This low is forecast to deepen and travel northeast into central Canada with a cold front extending southward into the central CONUS. Timing discrepencies between forecast models still exist (with the GFS being the fastest) but general consensus is the cold front sweeps through MN and WI during the Friday to Friday night time period. As such, 40-60% PoPs throughout Friday seem warranted. Heaviest QPF is likely to be far off to the northwest near the surface low and greater synoptic scale forcing (per guidance). However, accumulating QPF is also possible with the likely showers and thunderstorms being forced along the cold front. Models are generally hinting at a few tenths to an inch of rain across the CWA, though locally higher amounts may be possible with any convection. Also, if the frontal passage is delayed until Friday evening, Friday`s highs could again be in the mid to upper 80s. One could hypothesize that this extra daytime heating may lead to stronger convection but forecast confidence is currently much too low to delve any farther. After the cold front passes, highs for the weekend will drop to the mid 70s to lower 80s. Have opted to leave area-wide 30-40% PoPs lingering for Sunday as long-range models suggest a 2nd shortwave approaching the Northern Plains. However, much uncertainty also exists with this feature. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1100 PM CDT Mon Aug 16 2021 VFR conditions will continue. The two main concerns are still smoke aloft and, in Minnesota, a persistent south wind. The gradient is tighter as you go farther west, and gusts around 18 kts will be possible in western MN overnight. Meanwhile, western WI may have winds of only about 5 knots, since the influence of the high pressure in the northeast extends as far west as Wisconsin. Gustiness should be more amplified by late morning Tuesday. As for the smoke, little change is anticipated. Finally, some cumulus will form again Tuesday afternoon. KMSP...No additional concerns. /OUTLOOK FOR KMSP/ Wed-Thu...VFR. Upper level smoke. Wind S 10-15 kts. Fri...Mainly VFR. Chance SHRA/TSRA/MVFR. Wind S 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ UPDATE...TDK SHORT TERM...CEO LONG TERM...CTG AVIATION...TDK
Area Forecast Discussion
National Weather Service San Francisco Bay Area
550 PM PDT Mon Aug 16 2021 .SYNOPSIS...Today should be the last day of hot conditions across the interior before temperatures trend cooler by midweek. Dry, gusty offshore winds expected to bring increased fire weather concerns Tuesday night into Wednesday for the interior North Bay Mountains and portions of the East Bay Hills. && of 02:30 PM PDT Monday...Less coastal stratus this morning across the North Bay which has allowed Santa Rosa to finally break the 90 degree mark. It`s also toasty again in the East Bay with Livermore and Concord reporting 91 and 95 at this hour, respectively. More triple digit heat likely for our typical hot spots including Cloverdale, Lake Berryessa, Pinnacles, and Parkfield. Meanwhile, coastal areas remain in the 70s as the marine layer continues to hover around 1600-1800 feet deep. And now we focus on the pattern change and the elevated fire weather concerns. An upper level trough will be tracking across NorCal on Tuesday which will help usher in cooler air to make our temperatures more seasonable for the rest of the week. Tuesday night into Wednesday, that trough will nudge eastward and this is where fire weather concerns arise. On the back side of that trough, north to northeast flow will be enhanced creating dry, gusty offshore winds. Our highest confidence of this occuring is across the hills of Napa County, however, the hi-res WRF and NAM models do suggest that increased winds could spread into the interior terrain of Sonoma County as well as into the East Bay hills of Alameda and potentially Contra Costa counties. Wind speeds are forecast to be sustained at 10-25 mph with gusts peaking 30-40 mph...up to 50 mph across the highest peaks. In addition, the WRF is also showing very low RH values Wednesday morning down to around 10 percent. Dry conditions and gusty winds coupled with record dry fuels all contribute to the elevated fire weather concerns we have for midweek. Thus, we have issued a Fire Weather Watch for Tuesday night into Wednesday. SPC has included our area in their fire outlook for Day 3 and we will be monitoring future model runs to see if the watch needs to be upgraded to a warning and/or expanded in time or area. If you live in the areas of concern, please ensure that you have a plan should a wildfire quickly spread near your community. The trough will linger to our east into Thursday, but there is some discrepancy in the models. The GFS moves the trough more progressively away from our region while the ECMWF keeps the trough more stationary over the Great Basin. As stated above, the trough will be the dominant influence on our weather for the rest of the work week. Once we have gotten past the time of fire weather concern, then the weather will be mild with seasonable temperatures and typical marine stratus. && of 05:40 PM PDT Monday...For the 00z TAFs. Current satellite imagery shows mostly clear skies across the area, with stratus having retreated well offshore. VFR conditions prevail at all terminals, though some smoke and associated haze have drifted into the district from the various wildfires in northern California. Latest HRRR model surface smoke forecasts show an improving trend tonight and then minimal smoke presence through the remainder of the TAF period. Profiler data show a marine layer depth of around 800 feet at Bodega Bay, increasing to near 1500 ft at Fort Ord. Have delayed stratus ceiling onset a bit from previous TAF package as models did not anticipate present degree of clearing over coastal waters. Moderate onshore winds will continue into the first part of the evening, though stronger in the vicinity of KSFO where an Airport Weather Warning has just been issued. Winds aloft will also increase across the North and East Bay with 25-35 kt winds at 1,500 to 2,000 ft AGL. This may create some LLWS issues as this increase is anticipated around when surface winds are forecast to diminish (~05z-08z). Models show the strongest winds aloft over the North Bay. Vicinity of KSFO...Airport Weather Warning for winds gusting at times to a bit over 35 kt through around 8 pm PDT this evening. Onset of MVFR ceilings presently projected to occur during the late night hours. KSFO Bridge Approach...similar to KSFO, though winds not quite as strong. Monterey Bay...IFR ceiling onset presently expected to occur during the mid to late evening hours, then continue through the night and well into Tuesday morning. && of 02:15 PM PDT Monday...Gusty northwest winds over the coastal waters tonight. The strongest winds are expected over the northern outer waters and along the coast at the typical coastal jet locations where near gale force gusts will be possible. Gusty westerly winds are also forecast through the Golden Gate gap and through the Delta this afternoon and evening. Winds will further strengthen Tuesday afternoon into early Wednesday morning, particularly over the northern waters where gale force gusts are expected. Light southerly swell persists as Hurricane Linda churns in the southeast Pacific along with a weak northwest swell. Steep short period northwest waves also continue at periods of 7 to 9 seconds. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...SF Bay until 3 AM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 AM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Mry Bay until 9 PM && $$ PUBLIC FORECAST: Bingaman AVIATION: Blier MARINE: AS Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Reno NV
314 PM PDT Mon Aug 16 2021 .SYNOPSIS... Winds will be gusty Tuesday with high fire danger and travel and recreational impacts as a cold front moves through the region. Temperatures will fall to well below normal by Wednesday behind the front, rising back to around seasonal normals by late week and for the weekend. Major smoke relief from northern California fires is anticipated Wednesday and Thursday under north to east flow. && .DISCUSSION... Very isolated light showers and a couple thunderstorms (in-cloud lightning observed) have developed from southern Douglas and Lyon counties south through Mono and far western Mineral counties as Sierra cumulus development pushes away from the crest in westerly flow aloft. Expect a few thunderstorms into this evening south of Highway 50, with perhaps a cell or two east of Highway 95 to the north of Hwy 50 as westerly flow pushes out into that area later today. Hi-res simulations show thunderstorm outflow winds up to 40- 50 mph out in the Basin and Range...which is quite possible given DCAPE exceeding 1500-1800 J/KG per the latest SPC mesoanalysis, especially if any storms can at least briefly build an elevated core. Any storms should dissipate by around sunset. Turning to Tuesday, the main forecast concern revolves around a dry cold front poised to push through northeast California and western Nevada in the afternoon and overnight into Wednesday. The main concerns with the front are related to fire danger as well as lake recreation (choppy lakes) and hi-profile vehicle travel as wind gusts of 30-45 mph are expected in the afternoon and evening. Secondarily, temperatures are expected to fall off 5-10 degrees for most areas, perhaps up to 15 degrees north of Susanville and Gerlach. This will push highs down to near average for most spots, slightly below average across far northeast CA and northwest NV. Wednesday, temperatures fall off additionally with highs topping out well below normal in the 70s to lower 80s. Also, wind flow is expected to shift to a north and northeast direction as weak high pressure builds into the region. This should allow smoke to finally be greatly reduced (shown in latest HRRR smoke runs) although the easterly flow will become an issue on the slopes to the southwest and west of Sierra fires. Note that low temperatures in the low to mid 30s are possible for Sierra valleys Thursday morning. Temperatures rebound towards seasonal averages late week (peaking Friday) as the upper low responsible for Tuesday`s cold front moves away from the region. Unfortunately, a return to westerly flow could bring back in smoke once again. Bleh. For the weekend, temperatures look to remain blunted at near or slightly below average as another wave moves by to the north and possibly pushes a dry cool front into the region. -Snyder && .AVIATION... Widespread smoke and haze continue to be the primary contributors to lowered SFC and slantwise VIS across the Sierra and western NV. Even if/when the main terminals go VFR, slantwise visibility may still be heavily reduced due to smoke layers extending from area wildfires. Smoke conditions look to improve greatly Wednesday behind a cold front. Thunderstorm chances continue into this evening for eastern Mono County out into Mineral, Lyon, Churchill, and Pershing counties (less than 20% chance). Gusty outflow winds to 40 kts or so will be possible near thunderstorms. Afternoon breezes enhanced by an upper short wave trough and cold front look to be stronger Tuesday afternoon than today. Widespread gusts 25-35 kts, locally 40 kts, are on tap for increased turbulence. Winds diminish to much lighter northerly Wednesday. -Snyder && .FIRE WEATHER... ...Breezy this afternoon/evening... ...RED FLAG WARNING issued for Tuesday afternoon and evening with gusty dry winds for the entire forecast area... ...Much cooler Wednesday with shifting winds... A few thunderstorms remain in the forecast late this afternoon and evening, for Mono-Mineral into west-central Nevada. Storms will be on the dry side with gusty outflow winds up to 50 mph. Southwest winds increase this afternoon for northeastern California and far northwest Nevada ahead of an approaching cold front. This cold front and associated mid-level shortwave trough are pretty significant for this time of year. As gradients tighten up this afternoon and evening we will see winds gusting up to 30 mph for many areas north of I-80, with a few hours of critical fire weather conditions in some localized areas. Since we are not expecting a widespread critical event today, we will only be headlining the winds and focus the Red Flag Warning on the strong winds Tuesday. The main event will be on Tuesday afternoon-evening with a long period of gusty winds 35-45 mph across the Sierra, northeast California, and western Nevada. The Fire Weather Watches have all been upgraded to Red Flag Warnings for Tuesday, along with the additions of the Tahoe Basin and Southern Mono County into the Red Flag Warnings. Most areas will see 3-8 hours of Red Flag conditions tomorrow, with some midslope areas seeing up to 12 hours of critical conditions. Winds may be slow to drop off Tuesday night as signatures for decent cold air advection are evident and support continued breezy conditions into the overnight hours. Also, specifically for the Sierra crest and the Dixie Fire, winds will shift easterly with downslope potential west of the Sierra crest. Gradients will support gusty winds along higher terrain and continued strong ventilation through the overnight hours into Wednesday morning. -Hoon && .REV Watches/Warnings/Advisories... NV...Red Flag Warning from 11 AM to 11 PM PDT Tuesday NVZ420-421-423-429-458. Lake Wind Advisory from noon to 10 PM PDT Tuesday NVZ001>004. Heat Advisory until 11 PM PDT this evening NVZ001-003>005. CA...Red Flag Warning from 11 AM to 11 PM PDT Tuesday CAZ270-274-278. Lake Wind Advisory from noon to 10 PM PDT Tuesday CAZ071>073. Heat Advisory until 11 PM PDT this evening CAZ070. Red Flag Warning from 11 AM to 11 PM PDT Tuesday CAZ271-272. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
1010 PM EDT Mon Aug 16 2021 .SYNOPSIS... Weak frontal boundary in the region combined with southerly flow of tropical moisture will keep threat of showers and storms around into midweek, while Fred moves from the Florida Panhandle toward the Tennessee Valley and Central Appalachians. Once Fred moves by midweek, look for a return to typical August weather to end the week. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 1010 PM EDT Monday... ...A few lingering showers overnight along with areas of dense fog. The remnants of Fred move in by Tuesday afternoon and evening... Overall coverage of shower and storm activity continues to wane over the CWA as this update. Made some adjustments in regards to PoPs to account for this as our heaviest precipitation lifts north into the Shenandoah Valley as shortwave energy chugs east. Hi-res guidance such as the NAM3km, HRRR, and ConShort all depict isolated to scattered coverage overnight into Tuesday morning. Meanwhile Tropical Storm Fred sits down across the southern Georgia and Alabama border per the 8 PM update from NHC. The storm has a forward motion out of the north northeast at 10 mph and is progged to become a depression sometime Tuesday afternoon and evening as it enters the central Appalachians/Great Smoky MOuntains region. A lull to start Tuesday morning will give way to numerous showers and storms by Tuesday afternoon as the outer feeder bands of Fred work in. Some storms could be strong to severe with weak MLCAPE values and strong low level shear pushing north into western North Carolina and southwest Virginia. As a result an isolated tornado cannot be ruled out along with gusty winds out of any storms that may form. The bigger concern will be heavy rainfall and localized flooding concerns. PWATS per the 12z sounding at RNK were around 1.6 and look to increase to around 2 inches by Tuesday afternoon and evening. Flash flood guidance sits between 1.5 to 2 inches in the west to right around 2 inches in the east. Efficient rain producing storms combined with repetitive days of rain will help further confidence in flooding concerns. A widespread swath of 2-4 inches looks to blanket the area with lesser amounts out east over the Piedmont and amounts of 5 inches or more over the North Carolina mountains/foothills. Overnight temps tonight will remain 60s with highs in the mid to upper 70s to around 80 Tuesday afternoon. Previous discussion... Scattered showers and storms continue through this evening. More heavy rain and severe weather threats Tuesday... Not much has changed over the last the few days as a weak frontal boundary remains stalled just to our north allowing deep southerly moisture to funnel in. The trend looks to continue as upper level ridging over the central Plains region has yet to buckle and our upper level trough sits firmly overhead. As a result, it`s another evening of slow moving showers and storms. Most of the activity is confined to our west across southern and central West Virginia where better low level convergence can be found closer to the front. Another area that continues to see activity is down across the North Carolina mountains/foothills back into the Virginia Southside/Piedmont where localized flooding cannot be ruled out as storms train over some of the same locations this evening. Most of this activity is driven by Tropical Storm Fred to our south and spokes of shortwave energy that continue to pivot through before the system actually arrives Tuesday. For that reason the Weather Prediction Center, will keep a Slight Risk for excessive rainfall in place for areas along and west of the Blue Ridge with a Marginal Risk out east tonight. This area expands on the Day 2 outlook for the entire region with the exception of the North Carolina mountains where a Moderate Risk for excessive rain will exists. PWATS are on the order of 1.7 to 2.0 inches this evening with an expected increase Tuesday as more tropical moisture moves in. With that said, there is increasing confidence for flooding concerns. Not much has changed per this update in regards to rain amounts per the earlier forecast package. A widepspread swath of 2-4 inches are likely in most locations with localized amounts of 6 inches or more across the North Carolina mountains/foothills region. On top of this the risk for severe weather will become an issue as we head into Tuesday afternoon and evening. One or two strong storms are not out of the question this evening into tonight but overall instability has been limited with showers/clouds earlier in the day. Much of the same can be said for Tuesday morning with the threat for severe weather likely to move in late Tuesday afternoon and evening per latest hi-res guidance. NAMnest, HRRR, and RAP guidance diminish activity overnight with lingering showers, low clouds, and fog left in it`s wake. By Tuesday evening low level shear increases as Fred works up into the eastern Tennessee River Valley/central Appalachians region. For that reason, the Storm Prediction Center highlights the southern Blue Ridge, New River Valley, and North Carolina mountains/foothills region in a slight risk for severe weather. These areas have the best bet to see an isolated tornado with just enough spin in the low level as Fred brushes by to the west. Elsewhere a marginal risk for severe weather remains in place with an 2% probability of an isolated tornado and 5% probability for wind as the main concerns. Temperature wise we look to remain tropical. Overnight lows will range from the low to mid 60s over the mountains with mid to upper 60s out east. Highs Tuesday will remain in the low to mid 70s under the clouds and bands of showers in the west with values closer to 80 east of the Blue Ridge. Areas that do see the sun will increase the risk for severe weather late Tuesday into Wednesday as some of the outer bands of Fred feed in. Confidence remains moderate in the near term. Some discrepancies remain in the models per the placement on where the heaviest rain will set up and where the core of Fred will actually. go as it makes it`s way toward our region. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 230 PM EDT Monday... Remnants of Fred to bring widespread rainfall and possible flooding, with showers lingering late into the workweek. Better agreement in place this afternoon among the weather forecast models, with the consensus taking the remnants of Fred northward across far western Virginia and through West Virginia on Tuesday night. As such, little change in the previous forecast philosophy, including expected rainfall amounts. With the center of Fred passing just west of our area, strong southeasterly windflow will develop Tuesday evening, drawing Atlantic moisture across the Blue Ridge into the higher terrain of the mountains. That upslope flow will enhance rainfall amounts in the vicinity of the Blue Ridge, making for areas of heavy rain. Highest amounts are expected across the Highlands of North Carolina, where locally 6 or more inches will be possible, while widespread amounts of 2 to 4 inches are in the forecast for the remainder of the mountains and foothills. With this in mind, the main concern given the recent dry conditions will be more for the possibility of localized flash flooding along creeks and streams where training of rain bands develops. River flooding is less likely as water levels in the larger rivers remains below normal. The other concern with this system will be the slight chance of storms producing damaging winds and even the remote chance for a brief tornado. Weather forecast models indicate enough shear in the low levels to support this, mainly south of Highway 460, however the storm will be passing our area during the overnight, limiting the amount of instability and therefore the severe threat. Even with the system moving away to the northeast on Wednesday morning, believe areas of heavy rain/localized flash flooding and a few severe storms will be possible in any trailing bands that become stalled/situated across the Piedmont. Something to watch for as we get into the early afternoon hours as temperatures there warm into the 80s. Scattered showers and storms are expected across the lower Mid- Atlantic Wednesday night through Thursday night as waves of energy move across in the general west-to-east windflow. With no change in airmass to clear out the tropical moisture from our region, expect muggy conditions under partly to mostly cloudy skies. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 300 PM EDT Monday... Less rainy and more summertime pattern returns to end the week... Little change in the forecast thinking for the weekend, as weak upper-level disturbances move across the Great Lakes region, while the southeast ridge tries to build along the Atlantic Coast. Will be enough upper-level support for continued afternoon showers and thunderstorms through the weekend. Humid conditions expected with temperatures near normal throughout the forecast period. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... As of 815 PM EDT Monday... Sub VFR flying conditions overnight into Tuesday as scattered showers and storms continue to pivot through... A healthy supply of tropical moisture continues to funnel in on deep southerly flow leading to a continuation of showers and storms between the TAF sites this evening. Rain will remain heavy at times with locally gusty winds in and around any thunderstorms that may form. For now left TEMPO groups in for ongoing convection that remains around KLYH and KBLF. These will run from 00z/8PM to 02z/10PM as ongoing convection continues to surge north and eventually weakens where our weak wedge remains in place. Elsewhere light to moderate rain showers will continue to pivot through with a lull likely sometime after 06z/2AM at all TAF locations per latest hi-res guidance. Moderate confidence remains in that statement based upon the fact of increasing moisture leading a stray to a few leftover showers, low clouds, and fog as shortwave energy pivots east. As a result, expected VFR to predominantly MVFR conditions in areas where it is not raining this evening. IFR to LIFR conditions are expected n areas of convection and fog. This will be the general theme overnight as cigs/vsbys start to drop especially after midnight. Any area that do see shower and thunderstorms activity will once again have a shot at fog. Highest confidence for this remains at KLWB where IFR fog looks to occur between the 9-13z window. Fog has also been mentioned at KROA, KLYH, KBCB, KBLF, and KDAN as each of these TAF sites received rain from earlier this afternoon/evening. Fog looks to mix out Tuesday morning with ceilings slowly lifting by mid afternoon. Winds look to remain light and variable for the start of the TAF period. General direction will be from the east and southeast before increasing Tuesday afternoon. Highest winds will be across the mountains Tuesday afternoon into Tuesday night as the remnants of Fred move in. Low to moderate confidence in ceilings, visibilities, and winds during the TAF period. Some timing issues in regards to a lull in the shower/storm coverage as well. Extended Aviation Discussion... The wet weather pattern is expected through midweek, then afterwards, still at least diurnal driven storms, but looks like less coverage, though models vary on this, so confidence is low beyond Wednesday. Showers and thunderstorms look to be more numerous Tuesday afternoon into Tuesday night as remnants of Fred move along/west of the Appalachians. So overall anticipate the worst aviation day to be Tuesday, then a slight improvement after Wednesday. Areas of fog are possible overnight with Sub-VFR conditions. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PM/WP NEAR TERM...ET SHORT TERM...NF LONG TERM...NF AVIATION...ET/KK/WP
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
754 PM MDT Mon Aug 16 2021 .UPDATE... Issued at 748 PM MDT Mon Aug 16 2021 Showers and a few thunderstorms moving eastward across southeastern Montana and northern Wyoming are occurring in an area of enhanced lift associated with an upper shortwave and surface front. Have added PoPs to parts of northeastern Wyoming and far northwestern South Dakota. && .DISCUSSION...(This Evening Through Monday) Issued at 143 PM MDT Mon Aug 16 2021 Upper air analysis shows broad upper ridging across the western CONUS today. At the surface, high pressure sits to our east and a surface low moves in from the west. In addition to smoke aloft, we continue to see areas of near surface smoke restricting visibility throughout the forecast area. Have kept mention of smoke in through Tuesday based off the HRRR model. With that ridging still in place, expect another hot day Tuesday, with highs reaching over 100 for most of our plains counties. With breezy conditions and RH values dipping to near 10 percent for much of the region Tuesday, have added some fire weather headlines. Red flag warning in effect for our NE WY counties, while our western SD counties are in a fire weather watch for Tuesday. As far as precipitation chances go, some CAM models do show potential for isolated thunderstorms in south central SD this evening, with some weak shortwave energy coupled with good low- level moisture, if the cap does break. With ML Cape values around 1000-1500 J/Kg and 0-6km shear around 30 kts, any storms that are able to develop in south central SD may have potential for severe tonight. As we progress towards mid-week, ridge slides eastward and upper trough develops over the west coast. By Wednesday, an upper low and associated cold front move towards the area. Timing of the cold front make highs for Wednesday a bit tricky, as the GFS and ECMFW time fropa a bit slower than the NAM and Canadian models. Following frontal passage, winds will shift out of the north and cooler temps do move in. Models do show some storms/showers moving in behind the front, currently around Wednesday evening and into Thursday. Right now, instability looks week, but PWATs near 200%, so chance of severe is low, but could see some areas of heavy rain mid-week. Approaching the weekend, the upper trough digs into the rockies and eventually and upper low moves through the northern plains around Friday/Saturday, bringing more potential for active weather. && .AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening) Issued At 519 PM MDT Mon Aug 16 2021 Areas of MVFR VSBY in smoke will continue overnight with some improvement during the day on Tuesday. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Fire Weather Watch from Tuesday morning through Tuesday evening for SDZ319>326-328>335. Red Flag Warning from 11 AM to 8 PM MDT Tuesday for SDZ327. WY...Fire Weather Watch from Tuesday morning through Tuesday evening for WYZ318. Red Flag Warning from 11 AM to 8 PM MDT Tuesday for WYZ314>317. && $$ Update...10 DISCUSSION...Dye AVIATION...10