Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/10/21

Area Forecast Discussion
National Weather Service La Crosse WI
945 PM CDT Thu Sep 9 2021 .SHORT TERM...(This evening through Friday) Issued at 228 PM CDT Thu Sep 9 2021 A northwest flow regime continues in the region through Saturday, allowing for smaller pops until then. The flow`s associated shortwave troughs pass through the region this evening and will bring increased cloud cover with it. RAP13 850-500mb lapse rates hover from 5-6 C/km while ML CAPE is nearly non-existent in the area. Some models show scattered precipitation from late afternoon to evening today along the Mississippi, but due to the scattered nature and quick dissipation, precipitation is not included in the forecast for this evening. Valley fog is likely Friday morning, as the light wind layer overnight is about 5300 ft according to NAM3KM and HRRR model soundings. Dewpoint depression also looks to be less than 4 degrees in the models further setting the stage for a valley fog event. Otherwise, the upper-level high pressure system over the area will keep the area dry and increase temperatures through Saturday, topping out in the 80s on Saturday. .LONG TERM...(Friday night through Thursday) Issued at 228 PM CDT Thu Sep 9 2021 Pops return late Saturday night into early Sunday morning as a shortwave trough pushes a cold front through the area. Highest moisture transport located in SE Iowa and SW Wisconsin late Saturday night into early Sunday morning, so any developing showers likely to be located in those regions. However, the exact location of the showers will largely be determined by the location of the stationary front to the south, which is uncertain at this time. Higher southwesterly moisture transport ramps up again Monday evening in the same areas. GFS MU CAPE is about 700 J/kg so severe storms looking unlikely with this round of showers. Temperatures will be in the 70s throughout the area. On and off precip chances remain through Thursday as another shortwave trough passes through the area. The location of the swt is uncertain at this point, so best locations for showers are not clear. Working with ensemble model data from Tuesday to Thursday to get the best idea of any weather that will occur until then. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 945 PM CDT Thu Sep 9 2021 Little change in thinking from previous issuance. Surface high pressure will drift east through Friday with winds becoming southerly. While mainly VFR conditions are expected, a period of LIFR fog/stratus continues to look likely at KLSE between 10.09 and 10.14Z given clearing skies, light flow, and low T/Td spreads. Boundary layer flow begins to increase slightly by sunrise, but at this point do not expect this will significantly inhibit fog development. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Dahl LONG TERM...Dahl AVIATION...JM
Area Forecast Discussion...Updated
National Weather Service Billings MT
932 PM MDT Thu Sep 9 2021 .UPDATE... The Red Flag Warning has been allowed to expire as Red Flag conditions are no longer expected. Some light returns have persisted the last few hours from Big Timber to Harlowton west. So far no precipitation has been reported by any stations, but there have been some isolated lightning strikes. These still look like they will decrease in coverage and dissipate by around midnight. With all of the smoke across the area, the temperatures did not get as warm this afternoon, so have adjusted the temperature trends this evening to reflect that. The latest runs of the HRRR do not show the smoke changing, either near the surface or aloft, into tomorrow. Reimer && .DISCUSSION... Tonight through Friday night... Upper ridge in control today, will get suppressed a bit tonight and Friday. The impact of this will be felt more this weekend and next week with cooler temperatures. For the rest of this afternoon and tonight, weak shortwave energy will kick across the area and trigger isolated showers and thundestorms over the western half of the area. Inverted V soundings suggest strong wind gusts with convection. Precipitable water amounts start below 3/4 of an inch, but quickly rise to around an inch this evening. Coverage of showers and storms will be isolated (with most of the activity west and north of the area) but those that do swing across will have potential for gusty winds. Smoke has greatly diminished the heat and mixing potential today. Thus, Red Flag conditions not being realized yet. Still have potential for this late this afternoon and early this evening though. Friday should be another warm day, but smoke could play a role in this again (making things a little cooler and limiting mixing potential). Highs are progged in the mid 80s to around 90 degrees, but smoke could limit that. A cold front will swing into the eastern zones late afternoon, then back into central and western zones Friday evening. Timing of the strongest northeast to east winds with this front looks to be during the evening hours (as humidity levels recover). This combined with smoke limiting wind potential with the front in the first place, and this could decrease fire weather threat somewhat. Will leave the Red Flag in place and will not extend it at the moment. A Red Flag may be needed in the east for the front and the midnight crew will need to take a closer look at that. The chance of showers and isolated thunderstorms increases Friday afternoon and evening as a western trough swings across. TWH Saturday through Thursday... Little in the way of changes for the extended forecast period. Expect to see cooler temps through the period, with shower/thunder potential, but little accumulating precipitation outside of western mountains and near foothills. Expect to see isolated shower and thunderstorm activity persist through Saturday, as the upper trough lifts across the region. Guidance continues to trend this system more to the north, with best precip potential to our north. Zonal flow will take over for next week, with weak shortwaves sliding through the flow. This will help keep temps cooler (around normal), and may bring some isolate showers each afternoon through the week. Strongest waves look to cross the region Sunday night into Tuesday, with another late Wednesday into Thursday. These should bring better potential for showers across the CWA, but little total precip. Although guidance has been fairly consistent with the overall pattern, trending cooler, with this succession of shortwaves/troughs, timing and strength of these systems has been fluctuating significantly in guidance, so changes are possible as we get closer in time. Gilstad && .AVIATION... Localized MVFR conditions due to heavy smoke concentrations are possible tonight into Friday. Poor slant range visibilities can be expected as well. Isolated high based thunderstorms are expected west of KBIL through 06Z, with strong wind gusts to around 40kts possible near any storm. Outside of smoke, VFR conditions will prevail. TWH/Reimer && .PRELIMINARY POINT TEMP/POPS... Fri Sat Sun Mon Tue Wed Thu ----------------------------------------------------------- BIL 061/091 059/078 052/081 054/071 048/072 049/079 048/069 21/K 22/T 00/U 33/W 31/U 00/U 22/W LVM 056/090 052/075 046/080 046/071 042/072 042/077 041/068 22/T 63/T 00/U 43/T 31/U 01/U 22/W HDN 057/093 058/080 050/082 051/072 047/072 045/080 046/070 11/K 22/T 00/U 33/W 31/U 00/U 21/B MLS 059/092 059/075 050/079 055/071 048/071 047/078 049/070 00/K 23/T 10/U 32/W 21/U 10/U 11/B 4BQ 059/093 059/078 052/081 056/073 048/069 048/078 048/070 00/K 11/B 10/U 22/W 32/W 10/U 11/B BHK 059/093 055/072 049/078 054/071 046/069 046/077 048/069 00/K 12/T 10/U 33/W 21/U 10/U 11/B SHR 057/095 056/080 047/082 051/074 044/069 042/079 044/070 01/K 22/T 10/U 23/W 42/W 10/U 11/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Quad Cities IA IL
614 PM CDT Thu Sep 9 2021 ...AVIATION UPDATE... .SYNOPSIS... Issued at 315 PM CDT Thu Sep 9 2021 Gorgeous early September afternoon in progress, with high pressure providing light winds and low humidity while some scattered to broken diurnal cumulus is leading to occasional sun breaks. Satellite also shows a large expanse of wildfire smoke aloft through the Plains and even some into central/western Iowa. The high will move off to the east over the next 24 hrs. Ensuing southerly return flow will begin the warm-up into the upcoming weekend. && .SHORT TERM...(This Evening through Friday) ISSUED AT 315 PM CDT Thu Sep 9 2021 Another very pleasant night is on tap for the area. Lows will be a bit tricky due to likelihood of a period of mid/high level cloudiness late evening/overnight attendant to a passing upper level disturbance, which is currently diving down into northern MN. Regional radar also shows a few showers accompanying this wave. Shower chances are non-zero for the area, but they appear far too low for any mention with soundings depicting a rather shallow moisture layer and considerable sub-cloud dry air. As mentioned cloud trends will play a big role in lows for tonight, and because of this forecast lows were kept near 50th percentile of NBM and generally in the lower to middle 50s. Friday will bring plentiful sunshine, albeit a bit hazy as NW flow aloft shuttles in some western wildfire smoke. Doesn`t look to be too thick per HRRR smoke model and should remain very high up in the atmosphere. Southerly return flow will be developing and strengthening during the day allowing for warmer highs generally in the upper 70s and lower 80s. Dew points will also increase a bit, but still comfortable to slightly noticeable humidity levels expected with a bit of a SE trajectory on winds. .LONG TERM...(Friday Night through Thursday) ISSUED AT 315 PM CDT Thu Sep 9 2021 Main Messages: *Unseasonably warm weather is forecast into early next week. Saturday looks to be potentially the warmest day as highs could reach around 90F to the lower 90s although a greater uncertainty exists on highs due to the potential for thicker wildfire smoke aloft. *A dry pattern is anticipated for most of the outlook area through Sunday. However, there are low chances for showers/storms across the north Sunday afternoon into Sunday night. A cold front may bring better chances for rain across eastern Iowa and northwest Illinois into the middle of next week. Friday night through Saturday A large upper ridge over the Southwest U.S. will shift into the Southern Plains late this week into the weekend. Models show the upper ridge eventually breaking down with flow aloft becoming zonal over the Midwest. A 30-40 kt WSW LLJ juxtaposed to the north of the ridge will advect an anomalously warm EML, characterized by 850mb temps of 24 to 28 C, across Iowa and Illinois later Friday into Saturday (NAEFS is highlighting 850mb temps at 3+ standard deviations above normal). Temps will warm up significantly from those of Friday with upper 80s/lower 90s forecast for Saturday. The wildcard for highs on Saturday will be the magnitude of western wildfire smoke. Latest HRRR smoke model shows potentially dense smoke aloft by Saturday AM, which if occurs and being September could be impactful in lowering highs by a few degrees. It will also become more humid with dewpoints reaching the low/mid 60s by Saturday. Heat indices could potentially be in the low to mid 90s with some areas in the upper 90s. Sunday A weak front dropping into the northern forecast area on Sunday will lead to highs in the upper 70s/low 80s north of highway 30. However, to the south the very warm conditions will hang on with highs in the mid/upper 80s. The front could kick off isolated showers and storms from Sunday afternoon into Sunday. Right now thinking coverage will remain low. Monday On Warm conditions will continue through early next week with highs in the 80s. A front lingering in our northern counties looks to lift back as a warm front by late Monday and could take the rain chances with it for a time while expanding the warm and humid conditions across our north. There is a growing consensus signal for a stronger upper level trough to move through the area heading into the middle of next week. This will sweep a cold front through the area, and focusing greatest rain chances by Tuesday into early Wednesday. Upper level ridging looks to build in by mid to late next week leading to dry and warm conditions. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) ISSUED AT 613 PM CDT Thu Sep 9 2021 Clear skies may occasionally have a some mid clouds passing through well above 10kft through Friday evening, but otherwise, a VFR period with light winds overnight, becoming southeast during the day Friday, and increasing to 10 to 15 kts. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...McClure SHORT TERM...McClure LONG TERM...Uttech/McClure AVIATION...Ervin
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
716 PM CDT Thu Sep 9 2021 ...New Short Term, Aviation... .SHORT TERM... /NEW/ Update: The only real change to the short term forecast was to bring MinTs down a few degrees tonight into Friday morning given the light winds, mostly clear skies and dry air at the surface. Overnight lows will fall into the 60s, though a few of the rural outlying/sheltered locations may briefly dip down into the upper 50s. I also introduced haze into the worded forecast based on satellite observations and HRRR vertically integrated smoke products. At this juncture, I don`t anticipate any substantial reductions in visibility at the surface as most of the smoke will remain above 5,000 feet. There may be more of an orange hue to the sky around sunrise Friday and possibly toward sundown Friday across parts of the area. Otherwise, the remainder of the short term forecast remains unchanged and appears to be on track. Bain Previous Discussion: /Through Friday/ A mild and beautiful day it is today! Following yesterday`s cold front passage, temperatures are in the upper 80s with dewpoints in the 40s across most of the region. While not exactly autumn-like, the lower humidity is certainly appreciated. Winds are beginning to veer out of the southeast which should allow for humidity to increase gradually over the next few days, so today will likely be the driest day (in terms of relative humidity) through the next several days. The dry conditions and clear skies will mean lows tonight should have little difficulty falling into the 60s across the region. This morning, a few rural locations northwest of Fort Worth even managed to drop into the upper 50s, and a repeat of this will be likely again tonight. Friday will be slightly warmer with highs reaching into the low to mid 90s, but low humidity will keep it fairly pleasant overall. Godwin && .LONG TERM... /Issued 345 PM CDT Thu Sep 9 2021/ /Friday Night through Thursday/ Mid level ridging will continue to dominate the Western U.S. through Saturday with warm and dry conditions expected across North and Central Texas. A lack of any significant low level moisture will lead to seasonably cool morning and warm, but dry afternoons through Saturday. With an increasingly active northern stream, several shortwaves will chip away at the stronger ridging over the weekend and we should see a general weakening of the ridge by late Saturday. Meanwhile, a disorganized area of low pressure in the Western Gulf and its associated 2"+ PWs will gradually meander toward the TX Coast during this time. As zonal flow becomes established across the Central and Northern Plains Saturday night, increasing pressure falls in the lee of the Rockies should result in strengthening southerly flow across Texas. This should rapidly pull moisture northward overnight into Sunday morning with dewpoints climbing from the 40s into the mid/upper 60s. Sunday afternoon will feel noticeably warmer as heat indices climb back into the upper 90s. While the ridge will try to become re- established across the Southwest through the middle of next week, it appears that North Texas will remain east of its stronger influence. This should lead to at least some afternoon scattered showers and thunderstorms, particularly across our east and southeast counties through the middle of next week. We`ll have 20-40% PoPs each afternoon during this time with temperatures likely to be influenced by an increase in cloud cover. The ECMWF does show some potential for an organized coastal low in the Monday to Wednesday timeframe which could bring significant rainfall to Southeast Texas. We`ll keep an eye on this as some heavy rainfall could spread into our southeast counties through mid week. Dunn && .AVIATION... /NEW/ /00 UTC TAF Cycle/ VFR will prevail at all TAF sites through the end of the TAF period. Stout ridging overhead will allow for dry conditions; with just some high clouds. Haze from the smoke moving in from the western US wildfires could impact slant-range visibilities, but reductions to surface vsby is not expected. Southeasterly winds less than 10 knots will prevail at all TAF sites throughout the TAF period. Prater/Bain && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 67 93 69 95 70 / 0 0 0 0 0 Waco 65 93 65 95 68 / 0 0 0 0 0 Paris 63 91 64 93 65 / 0 0 0 0 0 Denton 65 93 65 95 66 / 0 0 0 0 0 McKinney 65 93 66 94 67 / 0 0 0 0 0 Dallas 67 93 71 95 71 / 0 0 0 0 0 Terrell 63 91 64 94 65 / 0 0 0 0 0 Corsicana 64 93 64 95 68 / 0 0 0 0 0 Temple 64 94 64 94 68 / 0 0 0 0 0 Mineral Wells 62 93 64 95 64 / 0 0 0 0 0 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
National Weather Service Hastings NE
615 PM CDT Thu Sep 9 2021 ...Short Term Update... .UPDATE... Issued at 614 PM CDT Thu Sep 9 2021 Some comments solely regarding high temperatures tomorrow (Fri): The bottom line: Have nudged down highs 1-2 degrees across the vast majority of the coverage area (CWA) from original late afternoon "forecast package" just issued a few hours ago, and perhaps might not have gone quite "cool" enough. Background/reasoning: We generally don`t "mess with" tomorrow`s (2nd period) temperatures on an evening/swing shift, but after seeing how the extensive smoke aloft wreaked a surprising amount of havoc with our high temperature forecast today (our early AM forecast package ended up 4-6 degrees too warm most areas)...and given that confidence is high that the persistent smoke plume will remain in place and be be very similar tomorrow based on HRRR-Smoke (vertically integrated)...opted to proactively nudge highs down 1-2 degrees for now, and will advise upcoming night shift that this might not have been enough. In other words, while there is zero doubt that tomorrow will be noticeably warmer/hotter than today based solely on a significant increase in the low-level temp profile, feel that the majority of the CWA is probably heading more toward low-mid 90s (at most) instead of mid-upper 90s. The the main exception would be in a few of our extreme southwest counties (especially Furnas/Phillips/Rooks) where upper 90s to around 100 appears more attainable given the drier air/lower dewpoints expected there. && .DISCUSSION...(This evening through Thursday) Issued at 327 PM CDT Thu Sep 9 2021 Satellite continues to show smoke streaming into the area this afternoon. The hazy sky has had an impact on temperatures with highs not getting as warm as initially expected. The HRRR smoke forecast continues to push the band of smoke across the area through tonight. With the upper level ridge expected to continue to the west during the day Friday, expect the smoke to stream through the area tomorrow as well. The ridge drifts a little to the east and would expect temperatures to be a little warmer. In addition, there will be warm advection and warming temperatures at 850mb. This would all lead to temperatures in the 90s for highs tomorrow. The only concern will be how much the smoke could reduce the heating as it has today. Did lower temperatures a little bit, but would not be completely surprised if temperatures were a few degrees cooler than forecast. With that in mind, will continue to keep mention of heat index values out of the HWO, which it is only a small area at this time. Friday night into Saturday the upper level ridge continues to drift to the east and temperatures will be warm for Saturday as well. Friday night a surface low develops to the west/northwest of the forecast area and starts to move into the north Saturday afternoon. Dry weather continues through the day Saturday, but as an upper level wave moves in Saturday evening, there will be a small chance for some showers and thunderstorms Saturday night into Sunday morning. Most of the activity will be in Nebraska. There will be westerly flow across the area for the period Sunday afternoon through Thursday. There are a couple of waves that move through during that period, but the strongest one appears to be Tuesday and Tuesday night when the wave is a little stronger and there is a cold front that moves through the forecast area. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 555 PM CDT Thu Sep 9 2021 VFR expected through the period. Looking at satellite decided to carry a FEW250 layer as smoke from western fires continues to stream into the area. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch DISCUSSION...JCB AVIATION...Beda
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1125 PM EDT Thu Sep 9 2021 .SYNOPSIS... A slow moving cold front will produce several rounds of heavy showers and thunderstorms through early Friday morning as Hurricane Larry passes by well to our east producing high surf. Fair weather gradually returns on Friday through much of the weekend as high pressure slowly crosses the area. Drier conditions expected over the weekend with the exception of a chance of showers over northern areas on Sunday as a cold front crosses the region. Canadian high pressure will build into New England early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Update...S/WV trof is swinging into the region now...and the greatest forcing is expected over the next several hours. This is going to focus mainly over Penobscot Bay and parts of W central ME before moving E. This is where all the moisture transport will be...and localized amounts of an additional 1 to 2 inches remain possible. Slowly things will taper off from W to E overnight. Previous discussion...Latest mesoscale models and radar trends continue to direct the highest moisture content and precipitable water values towards eastern portions of our forecast area overnight in an area of good forcing dynamics. Highest rainfall totals will likely be over the Midcoast region and adjacent areas through early Friday morning where Flash Flood Watches were issued earlier this afternoon and along and ahead of a decelerating frontal system. There has been a rather consistent signal in the model solutions with the evolution of this event with perhaps a slight eastward shift in the rainband maximum axis. The latest HREF and HRRR solutions also suggest a secondary rainfall maximum in the foothills which will need to be monitored closely overnight with the added effects of terrain. Although there may be a rumble of thunder or two, limited the threat for thunderstorms to slight chance during the overnight hours. It will be muggy tonight, however winds will eventually switch to the west. Patchy fog expected in-between the moderate to heavy showers. Coastal splash-over possible as well. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... Heavy showers over the Midcoast region will come to an end Friday morning as drier air pours in across the forecast area from the west. Increasing sunshine, especially over downslope areas will lead to temperatures in the 70s over southern and central locations. Dry conditions will continue for Friday night as high pressure builds towards the Mid Atlantic seaboard. It will be cooler with overnight lows in the 40s across the north and lower to mid 50s across the south which is still seasonably mild for this time of the year. && .LONG TERM /SATURDAY THROUGH THURSDAY/... Overview: High pressure to our south will result in mostly tranquil weather for the upcoming weekend with near seasonable temperatures. A series of weak disturbances passing mainly to our north will introduce a few chances for scattered showers through much of next week but there will be plenty of nice weather mixed in between. Temperatures will remain near to slightly above normal. Impacts: Little to no major weather related impacts are expected through the middle of next week. Some increased surf and rip currents may persist through at least the first half of Saturday from distant Hurricane Larry. Forecast Details: High pressure will be centered across the Mid- Atlantic on Saturday as an area of low pressure approaches the Upper Great Lakes. Our area will be under weak 500 mb ridging, which will allow for partly to mostly sunny skies with near seasonable temperatures into the 70s with 60s across the mountains. Skies on Saturday night will start out mostly clear in all areas but some increase in cloud cover is expected late, especially across the north and mountains. Low temperatures will primarily be into the 50s. Skies will then be partly to mostly cloudy on Sunday with the most cloud cover over the north and mountains as a broad area of low pressure moves across eastern Ontario and Quebec. Scattered rain showers will be possible, especially across the north but overall am not expecting this activity to be very widespread as we will be sitting on the southern edge of the better dynamics and likely will be battling dry air both at the surface and aloft. This low will then allow for a surface cold front to cross through our area on Monday. This front is currently looking rather dry with just an isolated shower possible as it crosses. This front will allow for dewpoints to fall into the 40s to low 50s in most locations on Monday night through Tuesday and this combined with high temperatures on Tuesday only into the 60s to near 70 it will feel like a Fall day. The forecast then becomes more uncertain as we approach Wednesday through the beginning of next weekend as there are large differences in both deterministic and ensemble guidance for both the placement and magnitude of the upper level pattern. The ECMWF deepens a 500 mb trough just to our east, which results in cool conditions as onshore flow develops. On the other hand, the GFS is generally not as amplified, which results in warmer temperatures under weak ridging. The end of next week will feature mostly tranquil weather with near to slightly above normal temperatures. Taking a look at 24-hour QPF individual ensemble members, there remains large differences in amounts but generally it looks like the best window for measurable rainfall will be Tuesday night into Wednesday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Short Term...Areas of LIFR conditions overnight in heavy showers, low ceiling and fog. Areas of VFR conditions expected over far northern and western portions of the forecast area, however there will still be some fog. Gradual clearing will commence later tonight spreading towards the Midcoast region by mid morning on Friday. VFR conditions all areas thereafter which will last into Friday night. Long Term...VFR conditions expected this weekend, although some widely scattered showers may result in brief MVFR conditions across northern terminals late on Sunday. VFR conditions expected next week outside of any shower activity. && .MARINE... Short Term...Have extended the SCAs through 12 UTC Saturday which matches up well with our high surf advisories and adjacent neighbors projects from long period swells from Hurricane Larry. Rain, fog and lowered visibilities will be replaced with gradual clearing on Friday and through the weekend along with diminishing seas. Long Term...Seas will gradually diminish on Saturday, although they will remain in the 4-6 feet range through Sunday. SCA winds are possible late Saturday afternoon or evening through Sunday as a cold front crosses the waters. Winds will then diminish on Monday under high pressure. && .HYDROLOGY... The anticipated lull in showers and embedded thunder today has come and gone with more showers and scattered thunderstorms upstream about to cross the region later this afternoon, this evening and during the overnight hours. Precipitable water values around 1.5" to 2.0" near the Mid-Coast combined with additional dynamics and instability will lead to locally heavy precipitation particularly along and east of I-95 for this event. There could be some localized 4 inches rainfall amounts in the Midcoast region. Any consistent training of showers and thunderstorms could possibly lead to isolated flash flooding. && .TIDES/COASTAL FLOODING... Astronomical tides top out at their highest peak for the month for the next couple days. With building long period waves and some contribution in water levels due to storm surge and the effects of wave setup, expect some splash-over over the next couple days along the vulnerable beaches of York and Rockingham counties. These will mainly be beaches that are oriented towards the east or southeast. Total water levels will likely remain below flood stage. Have noted some significant oscillations on several of the ESTOFS runs at high tide, most likely due to the effect of wave setup. ETSS more conservative with the average of the two models being a most likely scenario. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Flash Flood Watch until 9 AM EDT Friday for MEZ014-021-022- 025>028. High Surf Advisory until 8 AM EDT Saturday for MEZ023>028. NH...High Surf Advisory until 8 AM EDT Saturday for NHZ014. MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ150>154. && $$ NEAR TERM...Legro
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 303 PM CDT Thu Sep 9 2021 Today through Saturday: The narrative through the weekend is no precipitation with warming temperatures. Record high temperatures are possible Saturday, specifically in southeast Nebraska. An upper level ridge currently located over the central Rocky Mountains will drift slowly to the east. The ridge will allow for return flow at the lower levels and theta-e advection. High temperatures this afternoon should peak in the 80 to 85 degree range. For Friday, expect temperatures to be 10 degrees warmer than today. Friday could serve as a signal for how the forecast will perform Saturday. For this forecast issuance, the high temperature forecast for Friday is near the 75th percentile of model guidance. For return flow situations, the 75th percentile is usually a good starting place for the forecast. If temperatures over perform, an adjustment will be needed for Saturday. For Saturday, the forecast is near the 50th percentile of model guidance. This indicates that temperatures could be warmer than expected. Furthermore, 850 hPa temperatures will be near or even above 30 degrees Celsius. An analysis of NAEFS climatology of 850 hPa temperatures show them to be at the maximum of climatology. Using the broad forecasting technique of bringing the 850 hPa temperature down to the surface would result in high temperatures near 100 degrees. All of this combined (forecast at 50th percentile of guidance, 850 hPa temps at climatological record, broad forecasting technique), could result in record temperatures Saturday afternoon. Smoke from the western wildfires is likely to become more visible over the weekend. The RAP smoke model shows that smoke particulate should increase greatly. It`s expected to remain mostly in the upper levels of the atmosphere and would be visible as a haze. Though, on Saturday the RAP smoke model shows an increase in near-surface smoke particulate values. Sunday through Monday: The upper level ridge will breakdown over the weekend as a weak upper level shortwave will flatten it. An attendant cold front is also expected to encroach the forecast area and bring with it a 20% chance for precipitation. The timing of this front has slowed from previous model runs and it doesn`t push as far south. Areas behind the front could see a 10 to 15 degree drop in temperatures. As the front may stall out over eastern Nebraska or western Iowa, there could be a large difference in temperatures from the south to the north. Tuesday, the models are in agreement in a strong trough moving over the northern CONUS. This will result in temperatures near the climatic normal. There will be a few chances for precipitation with Tuesday night and Wednesday morning being the best chance. The cooler temperatures, or in this case, near normal temperatures look like they`ll be short in duration. The Climate Prediction Center has a high probability for temperatures to be above normal for the 6 to 10 Day, 8 to 14 Day, and 3 to 4 Week outlooks. This signal is supported by the ECMWF as it builds an upper level ridge over the central CONUS next weekend. However, the GFS builds one over the East Coast. As is common with extended ranged guidance, time is needed for a consensus to be achieved. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 621 PM CDT Thu Sep 9 2021 VFR conditions to prevail with light winds generally out of the southeast and under 10 kts. Not expecting any smoke impacts in the lower levels/at the surface in this period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Fajman AVIATION...CA
Area Forecast Discussion
National Weather Service Pocatello ID
222 PM MDT Thu Sep 9 2021 .SHORT TERM...Today through Saturday. High pressure breaks down and moves east setting up warm, south southwest flow today ahead of a trough setting up off the west coast. Expect breezy to moderate winds for our northern areas with record to near record temperatures for most of our area. By Friday, tomorrow, an upper level low over OR/WA will bring scattered showers and thunderstorms across the area by late Friday afternoon into the early evening. Saturday expect lingering showers for our eastern areas with breezy, cooler northwest flow behind an exiting system. Expect well above normal temperatures today, record to near record, before becoming below normal by Saturday. Wyatt .LONG TERM...Sunday through next Thursday. Expect mostly dry conditions through the period with brief periods of breezy to moderate winds. Sunday a breezy trough moves over northern ID and Southern Canada elevating the winds over our northern areas, especially the Central mountains. The last couple of model runs have been showing some light precipitation mainly over the Eastern Highlands, from Island Park down to the Bear Lake region. Models are still indicating another mostly dry, breezy trough on Wednesday into Thursday, again impacting mainly the Central mountains. Fire weather highlights may be needed depending on relative humidity recovery. Currently though relative humidity looks to stay ABOVE critical values every afternoon. Expect 70 to 80s with cooler mountain temperatures through the period. Wyatt && .AVIATION...VFR to prevail under mostly sunny skies into the early evening. High clouds to become more prevalent ahead of an approaching system as we get into the overnight and early morning hours on Friday. Precip will move into the area likely by mid- afternoon Friday at KSUN and to the other terminals around 11/00Z so will likely need to add VCTS on the next forecast for KPIH, KIDA, KBYI and KDIJ. Winds will become breezy out of the SW in the 15-20 mph during the afternoon hours with locally higher gusts in and around any storms that develop. McKaughan && .FIRE WEATHER...Red flag warnings remain in effect for Fire Zones 475 and 476 with critically low RHs and gusty winds expected to continue this afternoon. A system moves into the region tomorrow, bringing with it gusty winds but increasing humidity and rain chances. Thunderstorms will be possible during the late afternoon hours and into the early part of Saturday morning. Instability is limited however and confidence in scattered coverage is less than desired. That being said, and after coordination with surrounding offices, have held off on Red Flag issuance at this time but one may be needed on the next forecast package. In this systems wake, temperatures look to be much cooler as we move into the weekend with RHs well above critical levels which should keep fire weather concerns at bay. McKaughan && .AIR STAGNATION...Poor air quality conditions are expected through Friday for Custer county due to wildfire smoke from local and regional fires. There is an Air Quality Alert in effect for Custer county through Friday from the Idaho Department of Environmental Quality. The air quality has been determined by the IDEQ to be unhealthy to sensitive groups, and will remain in effect until air quality has significantly improved. The HRRR smoke model brings regional smoke into the area through Friday, however enhanced smoke inundation in the Central Mountains is expected due to active localized wildfires. Precipitation Friday and northwest flow aloft by late Saturday will help bring better air quality conditions into the area. Wyatt && .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for IDZ475-476. && $$
For frequently asked questions about the Area Forecast Discussion