Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/09/20

Area Forecast Discussion
National Weather Service Denver/Boulder CO
853 PM MDT Tue Sep 8 2020 .UPDATE... Issued at 837 PM MDT Tue Sep 8 2020 No significant adjustments to the grids at this time. Of note, we tied the record low of 31 for this date at DIA this evening. It also ties the record for the earliest coldest temperature in Denver. It look a little longer for the rain/drizzle to turn over to snow this afternoon, but light to moderate snow finally settled in by this evening as the better mid and upper level moisture filled from the southwest. Bands of heavier snow along the urban corridor, generally in the 1/2 to 1 inch per hour range. So far, here at NWS Boulder we have picked up 3.6 inches of snow. Latest HRRR shows the snow west of Denver and north of I-70 tapering off by midnight, but it should continue overnight for zones 34/37 with favorable southeasterly winds in the mid levels. The focus east of I25 will shift more to the Palmer Divide and eastern plains late tonight into Wednesday morning. No changes to any of the ongoing highlights. && .SHORT TERM...(This evening through Wednesday) Issued at 332 PM MDT Tue Sep 8 2020 A mix of light rain, drizzle and light snow has been spread across northeast Colorado through this afternoon as moist northeast flow has continued into the region. Over the mountains, precipitation has been enhanced by upper dynamic forcing associated with a cutoff upper level low that has developed over east-central Utah. The upper level dynamic forcing and elevated instability moving northward out of New Mexico has produced an area of moderate intensity precipitation over the San Juan Mountains and other central Colorado mountain ranges this afternoon. The northern fringes of this upper lift will extend over the north central mountains and I-25 corridor through this evening. This should enhance snowfall over north central and northeast Colorado well into tonight. Light to moderate snow is expected in the mountains and over the Palmer Divide with lesser amounts of snow over the I-25 urban corridor and adjacent plains. Will be maintaining the Winter Storm Warning and Winter Weather Advisories that were previously in effect for tonight. In addition, a Freeze Warning will continue on the plains. Low temperatures on the plains should be in the mid to upper 20s. Additional snow accumulations in the Front Range mountains and foothills should be 5 to 10 inches. The Palmer Divide should see 4 to 8 inches of snow, and other plains locations will see 2 to 5 inches of snow. After midnight, all of the ingredients for snowfall should begin diminishing and snowfall rates should begin to come down. The Denver metro area may still see some lingering snow over the morning commute, but little additional accumulation is expected. Scattered snow showers will also be possible over the mountains. Weak upslope flow over the plains will hold low level moisture in place leading to only partially clearing skies by late in the afternoon. Temperatures will be much cooler than normal, only reaching the upper 30s and lower 40s on the plains, due to the lack of sunshine. .LONG TERM...(Wednesday night through Tuesday) Issued at 332 PM MDT Tue Sep 8 2020 Models are in very good agreement that the cutoff low will weaken and move northward near the UT-CO border on Wednesday night and Thursday morning. The greatest forcing for ascent will remain well south of the area and there will be less coverage of showers. On Thursday, the low should advance further north into eastern WY. A small jet streak embedded with the low along with increasing mid-level lapse rates, especially over the mountains, will contribute to a higher coverage of showers by afternoon. Isolated storms and another brief period of snow accumulation in the mountains are also possible. Friday, the low should move east across the Central Plains. As it does, flow aloft will turn to northwesterly. Friday afternoon may see isolated showers, mainly in the high terrain, but otherwise no active weather is expected for a while. Saturday, will see more ridging and significant clearing, and Sunday the area will be close to the ridge axis. This will lead to dry weather, but more seasonable temperatures. Monday, long range models agree that another upper level trough should begin to move onshore in the Pacific Northwest. Tuesday, this trough may clip the area as it moves east towards the Great Plains. We`ll likely return to above normal temperatures during this period with a continuation of warm westerly flow aloft. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 837 PM MDT Tue Sep 8 2020 Ceilings and visibilities will be in the IFR/MVFR categories overnight along with light snowfall. Mainly light snow, but localized bands of moderate snowfall with rates 1/2 to 1" per hour possible this evening. Overall, snow accumulations of 2 to 4 inches are expected overnight on elevated and grassy surfaces. Accumulation on pavement should be much lower due to heat stored from this past weekend, more slush vs snow. Snow is expected to taper off Wednesday morning with a gradual improvement in cloud heights and surface visibilities through the late morning and afternoon hours. && .BOU WATCHES/WARNINGS/ADVISORIES... Freeze Warning until noon MDT Wednesday for COZ038>051. Winter Storm Warning until noon MDT Wednesday for COZ033>037-041. Winter Weather Advisory until 6 AM MDT Wednesday for COZ031. Winter Weather Advisory until noon MDT Wednesday for COZ038>040- 042-043-045-046. && $$ UPDATE...Cooper SHORT TERM...Dankers LONG TERM...Direnzo AVIATION...Cooper
Area Forecast Discussion
National Weather Service Boston/Norton MA
1029 PM EDT Tue Sep 8 2020 .SYNOPSIS... Increasing humidity, along with warm temperatures are in the forecast for the next couple of days. A cold front will bring scattered showers and a few thunderstorms Thursday into Thursday with the focus for this activity near and south of the Massachusetts Turnpike. High pressure brings dry and cooler weather Friday and Saturday. Another cold front approaches Sunday into early Monday bringing another round of showers. Dry weather with cool nights and mild days follow the rest of Monday into Tuesday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 1015 PM Update... Adjusted the forecast to bring down visibilities a bit more across the interior. Uncertain on how far west the Dense Fog Advisory will need to be extended, but will save this for the next update when fog expands a bit more. RAP low level RH values are doing well so far, but will need to continue to monitor for future updates. Combined this with the GLAMP guidance to bring down visibilities. Added a bit more drizzle to the forecast, mainly across areas where visibilities are anticipated to be at or less than 1 mile. Rest of the forecast is on track. 735 PM Update... * Areas of dense fog develop through the overnight hours Areas of low clouds and fog were already making their way onto the Cape/Islands early this evening, faster than what most of the guidance was indicating. Given light southerly winds with dewpoints in the 60s coupled with increasing longer nights this time of year, areas of fog and low clouds will continue to expand northwest overnight. We think the low clouds and fog may end up more extensive than much of the guidance indicates based on pattern recognition. This is especially true with decoupling winds; so expect to see areas of dense fog develop and spotty drizzle too. We already issued a dense fog advisory for the Cape and Islands through 8 am Wednesday. This will likely need to be expanded overnight. Previous discussion follows. The synoptic situation is largely unchanged from 24 hours ago, so what we saw last night is likely what we will see overnight. Given the moderately moist low levels and light winds, another round of fog/stratus is pretty much a given. Of course, the devil is in the dense the fog will get? how far inland will the clouds make it? You get the idea. Didn`t make any significant changes to the forecast we had. Fog should be most widespread across coastal areas/eastern MA/CT River Valley, and thinking that the thicker fog will be across SE MA, Cape and Islands. Heck, like this morning, there may even be some light drizzle in those areas as well. Lows overnight will generally be in the 60s, but some upper 50s are possible. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... as of 230pm... 12z short term models still indicate the idea that deeper moisture off to our south will nudge northward later in the day into Wednesday night. Models show an axis of precipitable water values that close in on 2 inches. At the surface, we will see this in the form of dewpoints of 70F or a little higher, especially closer to the south coast. Don`t see a lot of forcing, but with that amount of deep moisture, it doesn`t take much for scattered showers to develop. So have blended in some of the hi-res models to drive the hourly PoP grids, which basically gives us a 20-30% chance of showers Wednesday night across the southern half of the forecast area -- with highest along the south coast and adjacent coastal waters. Some signals of a little bit of instability in the models, primarily from the high dewpoints, so have gone ahead and included a slight chance of thunderstorms mainly along the immediate south coast and offshore. QPF is rather tricky. Given the high precipitable water values, local downpours of 1/2" are possible. But since the chance of precipitation is rather low, the areal average QPF ends up less than 0.10". High temperatures Wednesday will again top out well into the 80s across inland areas, 70s but with an increasingly humid feel nearer the coast. Wednesday night is looking to be fairly muggy in most areas due to those increasing dewpoints with lows in the 65-70F range. You`ll need to go to the higher elevations of NW MA to experience lows in the lower 60s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Highlights... * Humid Thu/Thu night with scattered showers & a few t-storms with the best chance near and south of the MA Turnpike * Much less humid and also cooler Fri/Sat with dry weather * A period of showers is possible sometime Sun into early Mon with a cold front * Dry weather follows the rest of Mon into Tue with cool nights and mild days Details... Thursday... It will be warm and quite humid on Thu ahead of an approaching cold front. This front will bring the potential for a round of scattered showers and a few thunderstorms Thu/Thu night with the focus near and south of the MA Turnpike. The guidance indicates that we may see around 1000 J/KG of Cape develops ahead of the front, so a few thunderstorms are certainly possible. Some guidance also suggests the showers may linger well into Thu night towards the south coast. So while Thu into Thu night will not be a complete washout, the threat for showers and a few t-storms exists with the focus near and south of MA Turnpike. High temps on Thu should be mainly in the 80 to 85 degree range, but it will be humid with dewpoints well into the 60s to near 70. Friday and Saturday... High pressure will build to our north behind the cold front Fri into Sat. This coupled with a wave of low pressure to our south will generate a northeast flow of much less humid & cooler airmass to the region. Dry weather expected over this time too, other than the low risk for a few lingering showers across southeast New England early on Fri. NE winds will hold high temps in the middle to upper 60s along portions of the coastal plain and especially the Cape/Islands on Fri and Sat. Elsewhere, high temps should reach the lower to middle 70s, but with plenty of sunshine and low humidity. Low temperatures late Friday night into early Saturday morning will bottom out well down into the 40s to the lower 50s. Sunday through Tuesday... High pressure moves east of our region on Sun as a cold front approaches from the west. This will likely bring a return to a bit of humidity and another round of showers sometime Sunday into early Mon. This will be followed by another large high pressure system the rest of Mon into Tue, bringing dry weather with cool nights and mild afternoons. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through 00z Thursday...overall moderate confidence in TAFs. IFR-LIFR conditions will overspread much of the region through the overnight hours in low clouds and fog. This process was already occurring across the Cape and Islands and will occur in many areas from southeast to northwest through 08z. Fog/stratus should lift at most TAF locations by 14z tomorrow, but areas near the south coast and especially Cape/Islands may see low clouds and fog flirting with the area into the afternoon. KBOS Terminal...Moderate confidence in TAF. Sea breeze should shift back to the south 01-02z, with another sea breeze developing tomorrow 14-16z. Highest uncertainty is with how low the ceilings and visibility drops late tonight, as BOS may end up being on the edge of the most widespread IFR conditions. Although currently an MVFR forecast, there is a possibility for another round of IFR conditions as we saw early today. KBDL Terminal...Moderate confidence in TAF. Uncertainty exists in exact timing of fog/stratus development overnight. Expected to drop to IFR, but LIFR is possible. Improvement should occur by mid to late Wednesday morning. Outlook /Thursday through Sunday/... Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance SHRA, isolated TSRA, patchy FG. Thursday Night: Mainly VFR, with areas MVFR possible. Breezy. Chance SHRA, isolated TSRA. Friday: Mainly VFR, with local MVFR possible. Breezy. Friday Night through Saturday: VFR. Sunday: Mainly MVFR, with areas IFR possible. Breezy. Chance SHRA. && .MARINE... With a ridge of high pressure across the region, winds will remain rather light for the next couple of days. Biggest concern will be the fog that will become most widespread during the overnight and early morning hours. Visibilities of less than 1/2nm will be most common around and south of Cape Cod. A slight chance for thunderstorms will also be possible for Wednesday night. Outlook /Thursday through Sunday/... Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms, patchy fog. Local visibility 1 to 3 nm. Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Chance of rain showers, isolated thunderstorms. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Friday Night through Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Dense Fog Advisory until 8 AM EDT Wednesday for MAZ022>024. RI...Dense Fog Advisory until 8 AM EDT Wednesday for RIZ008. MARINE...None. && $$ SYNOPSIS...Frank/Nash NEAR TERM...Frank/BL/Nash SHORT TERM...Nash LONG TERM...Frank AVIATION...Frank/Nash MARINE...Frank/Nash
Area Forecast Discussion
National Weather Service State College PA
1108 PM EDT Tue Sep 8 2020 .SYNOPSIS... A nearly stationary frontal boundary will remain stretched along the south shores of Lakes Ontario and Erie over the next few days as a strong upper level ridge expands westward into the Mid Atlantic region. A weak cold front will push south of the area by Friday. Most of the time will feature dry conditions, but a few showers will be possible late Wednesday night into Thursday. Most of the activity is expected to be across the southeast portion of the Keystone state. An upper level trough and associated front are likely to push into Pennsylvania by late in the weekend. This system will bring the potential for some showers and perhaps a thunderstorm on Sunday. && .NEAR TERM /UNTIL 8 AM WEDNESDAY MORNING/... A cirrus and cirrostratus layer will continue to stream north across the eastern two thirds of PA overnight while skies stay mainly clear across the NW Mtns. Weak ridge of sfc high pressure will remain over the area keeping winds light. Some patchy fog is possible late, mainly across the southeast. Lows will be mainly in the 60s. && .SHORT TERM /8 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Weak high pressure will keep mainly dry conditions across the area on Wednesday, with plenty of sunshine and warm temperatures again. Warmest readings likely to be near IPT, given it is a bit drier there, and the southeast areas may have some fog early on. Not seeing much support for high dewpoints across the southeast early on, so cut down on the chance of showers across the southeast some. Sfc based CAPE will be rather minimal and only 400-600 j/kg at the upper end per the latest RAP guidance, so we should see primarily MDT cu across the SE and NW zones will the flattest clouds across the central counties of PA. Higher chance of rain late Wednesday night into Thursday, mainly across the far east, as dewpoints forecast to climb closer to the upper 60s and lower 70s after the day on Wednesday. As was the case today, any showers and storms with the front to the north likely to be on the cool side of the front, unlike the situation on Labor Day. Highs will range from the mid 80s to around 90 degrees. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Latest GEFS and EC are in good agreement depicting a stationary front off the east coast, which will continue to pool moisture from the Carolinas to the northeast into the southern part of PA Wednesday night. A fast-moving and fairly flat shortwave racing east over the aforementioned llvl stationary front may lead to a few showers Wednesday night, and isolated to scattered showers and T-storms Thursday afternoon. PoPs are highest in southeastern PA topping out around 40-45%. A cold front will sag southeast through the northwest mountains during the day Thursday, but mid- level ridging/subsidence and a deep mid level layer of dry air will limit convection to little more than isolated showers as the front passes through. Temperatures will dip by a few degrees on Friday (to near normal) accompanied by ample sunshine and northerly winds. An approaching upper trough and surface low pressure system will move in from the Ohio Valley region for the second half of the weekend as southerly flow ushers in mild and breezy conditions for Saturday and Sunday. A surge of moisture will also bring an increased likelihood of showers and thunderstorms on Sunday, with likely PoPs forecast in northwest PA and only chance PoPs in the southeast. The start of next week appears more tranquil, as a cold front and surface high pressure ushers in near normal temperatures for a couple of days. A few lingering showers are possible Monday but the trend will be drier heading into the middle of next week. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Weak stationary boundary will linger off to our NW, but high pressure over Central PA will keep mainly clear skies and VFR conditions ongoing through Wednesday with just some patchy morning river valley fog possible. Winds will remain light from the S/SE with a thin cirrus veil overhead. Outlook... Thu...Widely scattered showers/tstms and low cigs, restrictions possible. Fri-Sat...Mainly VFR conditions expected. Sun...Lower conditions possible with a chance of showers. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Lambert/Martin NEAR TERM...Lambert/Martin SHORT TERM...Martin LONG TERM...Lambert/Banghoff AVIATION...Martin/RXR
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1153 PM EDT Tue Sep 8 2020 .AVIATION... Low level moisture overriding frontal boundary will maintain low cigs into Wednesday. Scattered showers and a few storms will also lift northeast through the area overnight as a pocket of unstable elevated air is pulled through the area as main upper disturbance lifts to the north of the area. In the wake of this activity, minor vsby restrictions in br/-dz should set in late tonight into early Wed morning. For DTW...low ceilings will persist through the forecast period with some breaks/lifting of cigs late Wednesday. Any shower activity looks to be rather spotty and mainly north/northwest of terminal overnight. .DTW THRESHOLD PROBABILITIES... * High for ceiling 5000 ft or less through Wednesday. && .PREV DISCUSSION... Issued at 407 PM EDT Tue Sep 8 2020 DISCUSSION... A deep stationary baroclinic zone is gradually sloped over Lower Michigan and the Northern Great Lakes this afternoon. The frontal zone will serve as a conduit, bringing active weather to at least portions of the region throughout the next 36 to 42 hours. Main driver for the weather will be episodic waxing/waning of ageostrophic forcing along the frontal zone due to changes in Ontario/Quebec +145 jet streak. The northern Great Lakes and Lower Michigan will remain in an area of preferred right entrance region dynamics. The next significant warm advection surge will funnel through the Saginaw Valley late this afternoon and early evening in response to upper level high retrograding to Ohio and polar vorticity anomaly swinging through Northwest Ontario. For forecast details, on late afternoon and early evening refer to the Update Discussion earlier today. The main item of uncertainty tonight is on coverage of convection, particularly for the central and southern cwa. A portion of NWP solutions suggest a decent coverage across portions of the southern or central cwa in the 01-6Z timeframe. HRRR has been advertising the potential with the ARW offering a more robust solution with a greater coverage. Prefer to err on a more bullish solution given the impressive frontal boundary in place and amount of available moisture to interact with the front. Introduction of drier air aloft from northward migrating frontal zone will provide for steeper lapse rates and MUCAPE development this evening. Latest forecast soundings suggest as much as 1000 J/kg will be available for a time. Low level stability will limit the potential for any strong thunderstorm risk. Potential exists for some localized heavier rainfall due to cell training, but high uncertainty exists given the low QPF in model solutions. For Wednesday, most active weather appears to remain more centered over portions of northern Lower Michigan and northern Great Lakes as very deep anticyclonic flow lifts directly into the cwa. A good signal exists for differential AVA through the area. Models show opaque cloud holding within the baroclinic zone with saturation trapped within the strongly stratified 2.0 to 4.0 kft agl layer. Lowered high temperatures a little despite the ridging. Very strong surface based ridging will then develop over the state on Thursday in response to geopotential height rises. Some uncertainty exists with end timing of precipitation, as could see remnant showers hanging on over the Thumb through Thursday morning. Current forecast reads more optimistic/dry. No real cold advection to speak of as stationary boundary lifts northward as a warm front, therefore and increase in geostrophic/gradient winds is relatively non-existent. That will set the stage for pleasant end of the week weather with very chilly Friday and Saturday mornings. MARINE... A stationary front draped across western Lake Erie will remain stalled in the area for the next few days. Disturbances tracking along the front will bring periodic chances for showers and some thunderstorms through Thursday with the next round moving in this evening and overnight. The best coverage of showers tonight will be across Saginaw Bay and central to northern Lake Huron. Stout northeast winds will persist on the northern side of the front and Small Craft Advisories continue across the Thumb and Saginaw Bay shorelines due to the long fetch and onshore wave action. Gusts will approach or exceed 25 kt at times, especially across the bay. Marine conditions then begin to improve on Thursday as high pressure builds into the Great Lakes. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Lakeshore Flood Advisory until 8 PM EDT Wednesday for MIZ048-049- 054-055-063. Lake Huron...Small Craft Advisory until 11 AM EDT Thursday for LHZ421-422- 441>443. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....DG DISCUSSION...CB MARINE.......CB You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Grand Rapids MI
917 PM EDT Tue Sep 8 2020 LATEST UPDATE... Update .SYNOPSIS... Issued at 211 PM EDT Tue Sep 8 2020 - Showers and a Few Storms Tonight, Light Showers Wednesday - Dry Thursday and Friday, Rain Possible Saturday into Sunday && .UPDATE... Issued at 917 PM EDT Tue Sep 8 2020 Highest pops/most persistent rain showers tonight will be near and north of a Muskegon to Clare line where the 850 mb front warm front is located. South of that line showers should be more scattered to isolated. The highest risk of a tstm overnight will be near and east of an AZO to LAN line where RAP guidance shows 500-1000 J/KG Capes persisting through 12Z. The storms currently entering NW Indiana from the southwest should be arriving along the I-94 corridor toward midnight if they hold together. Main threat with these elevated storms (and any others overnight) would be periods of locally heavy rainfall and a few cloud to ground lightning strikes. && .DISCUSSION...(This evening through next Tuesday) Issued at 211 PM EDT Tue Sep 8 2020 -- Showers and a Few Storms Tonight, Light Showers Wednesday -- This evening will be the last threat for thunderstorms until later Saturday. Otherwise, occasional showers will progress through the region tonight into Wednesday before ending Wednesday night. Chilly early September weather has settled in north of a warm front positioned across north central Indiana and Ohio. Temperatures haven`t move much today out of the 50s to around 60 north of I-94, which corresponds to 20 degrees below normal for most locations. Coupled with on and off rain and a northeast breeze, and one could say it is rather raw outside. Even so, much of our region has been in either a D0 (abnormally dry) or D1 (moderate drought) recently, so the cool and wet weather will help ease the situation. Periods of showers and thunderstorms will continue riding north of the warm front this evening and tonight, with no severe weather expected given their elevated nature. HREF MUCAPE does suggest some thunderstorm potential across southern Lake Michigan and especially near and south of I-96 this evening and tonight. This is where 250-1000 J/kg of elevated instability is shown. Otherwise, general rain showers are expected. Periodic light showers or sprinkles are possible Wednesday with cloudy skies continuing. There will likely be prolonged periods without rain during the day, however. Expect any leftover showers to exit the region Wednesday night. -- Dry Thursday and Friday, Rain Possible Saturday into Sunday -- Medium range guidance is in fairly good agreement that an upper low centered across the SW U.S. will move toward the Great Lakes by this weekend. The low will become cutoff from the northern stream flow across the northern U.S. and spin for a couple days across the Four Corners region before migrating northeast and getting reabsorbed in the westerlies. The precise timing of phasing such as this can be tricky to pinpoint several days out, but ensemble guidance has good consensus on bringing the chance for rain into the region particularly Saturday evening into Sunday morning. Amounts do not look heavy given the progressive nature of the system. ECM mean surface based CAPE looks pretty weak Saturday but maybe just enough to warrant some lightning potential. Mid level winds look strong at 50 kts but we probably won`t have enough instability to realize those strong wind gusts in any deeper convection. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 802 PM EDT Tue Sep 8 2020 Southwest Lwr MI is on the north side of a stationary frontal boundary so expect low cloudiness and scattered showers/drizzle to persist tonight and Wednesday. An isolated tstm cannot be ruled out either. A mix of IFR and MVFR cigs this evening will trend down overnight into early Wednesday to more widespread IFR with some areas of LIFR as well. On Wednesday cigs are expected to gradually lift to mostly MVFR category by 18Z. Northeast sfc winds around 10-15 kts will continue. && .MARINE... Issued at 211 PM EDT Tue Sep 8 2020 Persistent offshore winds will continue through the week and as a result the highest wave action will be across the western half of Lake Michigan. For our nearshore waters, the highest wave action is expected into this evening and Wednesday with 2 to 4 footers likely. Looking ahead, adverse conditions to small craft are possible on Sunday behind a front when winds swing around to the NW and build higher wave action. && .HYDROLOGY... Issued at 211 PM EDT Tue Sep 8 2020 Rainfall over the last 24-48 hours has put a dent in the D0/D1 drought status across much of the region. River levels were very low to begin with and are able to take the runoff with little problem, but Sycamore Creek near Holt will crest near bankfull tonight and the Grand River at Ionia is expected to go above bankfull Thursday given a projected 6 foot rise from its current stage reading as of this afternoon. This crest will translate west toward Kent and Ottawa counties by the end of the week and weekend but no flooding will occur. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...Meade SYNOPSIS...Hoving DISCUSSION...Hoving AVIATION...Meade HYDROLOGY...Hoving MARINE...Hoving
Area Forecast Discussion
National Weather Service Wichita KS
910 PM CDT Tue Sep 8 2020 .UPDATE... Issued at 909 PM CDT Tue Sep 8 2020 Main synoptic boundary has dropped south into ern OK, at this time, but the mid level baroclinic zone continues over the eastern half of KS. Over the top of the boundary, 850h moisture transport axis continues to lead to showers and embedded thunderstorms moving N-NE into SE KS at this time, with a more diffuse area of moisture transport across the rest of the forecast area leading to widely scattered showers and patchy drizzle. Current forecast continues to look on track, with the SE KS area of moisture transport expected to continue with more numerous showers and a few thunderstorms at least until 08-09z. But think as the night progresses, think showers will become the main precip type, as the elevated instability begins to wane or drop further south, so less thunder. The showers could still pose a localized flooding threat for portions of SE KS, given the training of the showers and high precipitable water rates for efficient rainfall producers. The rest of the area will continue to see a more widely scattered shower and patchy drizzle chance, as low layers stay fairly saturated. Could see a slight uptick in the shower coverage overnight, as RAP bufkit soundings suggest that column will become more deeply saturated after 06-09z, which would change the drizzle over to more of a rain. Will send out a quick update, mainly just to freshen the wording. Ketcham && .SHORT TERM...(This evening through Thursday night) Issued at 308 PM CDT Tue Sep 8 2020 Unseasonably cold air will continue to ooze southward tonight into Wednesday with occasional post-frontal drizzle/rain and even bouts of convection. Moderate cape/weak shear within higher PWAT axis along the front will support strong/marginally severe storms and heavy rainfall rates until early this evening across southeast Kansas. Meanwhile, elevated instability within frontogenetic zone further northwest across central Kansas may support scattered convection tonight as well. Otherwise, it looks like record lows and cool highs are in jeopardy for Wednesday across most of the area. The closed upper low will be slow to evolve Wednesday into Thursday across the Four Corners region before lifting out Thursday night. This will keep the area unseasonably cool with periods of rain and chances for convection. Darmofal .LONG TERM...(Friday through Tuesday) Issued at 308 PM CDT Tue Sep 8 2020 The upper low will will continue to lift northeastward across the northern Plains and Upper Midwest Friday through Saturday with upper ridging trying to build in across portions of mid-America by early next week. This is expected to result in a warming trend and return to a drier regime with temperatures trending close to seasonal climo. KED && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 643 PM CDT Tue Sep 8 2020 Expect widespread IFR cigs and MVFR vsbys as shallow cold air on the north side of a cold front has led to lots of low clouds. Also seeing patchy drizzle develop, as the cloud deck continues to lower and saturation increases in the lowest layers of the atmosphere. The only exception will be over SE KS where proximity to the main synoptic frontal boundary may lead to MVFR cigs and possible VCTS due to convection developing along or over the top of the main synoptic front. As the evening progresses moisture transport over the top of the shallow cold air will lead to the drizzle and rain increasing for most locations, with a gradual lowering of the cigs to LIFR in some locations with MVFR vsbys due to the DZ/RA. Kept the aviation conditions very pessimistic for the overnight into Wed, with IFR prevailing as the moisture transport continues over the top of the shallow cold air, for off and on, RA/DZ for the daytime hours on Wed. Ketcham && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 49 54 52 62 / 90 80 80 60 Hutchinson 46 51 47 59 / 90 90 80 50 Newton 46 52 50 60 / 90 80 80 60 ElDorado 50 56 52 62 / 80 80 70 60 Winfield-KWLD 53 59 55 65 / 80 80 70 60 Russell 42 47 44 56 / 100 90 80 40 Great Bend 42 47 45 55 / 100 90 80 40 Salina 45 50 47 59 / 90 90 80 50 McPherson 46 50 47 58 / 90 90 80 50 Coffeyville 60 73 60 73 / 80 40 40 50 Chanute 56 67 58 71 / 80 50 40 50 Iola 55 65 56 70 / 80 50 40 50 Parsons-KPPF 58 71 59 72 / 80 50 40 50 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Ketcham SHORT TERM...KED LONG TERM...KED AVIATION...Ketcham
National Weather Service Wilmington OH
1033 PM EDT Tue Sep 8 2020 .SYNOPSIS... A southerly flow around high pressure will bring dry weather and above normal temperatures through Thursday. Seasonal temperatures return for Friday after a weak cold front drops through the Ohio Valley. Showers and thunderstorms will be possible Saturday and Sunday along the next cold front. && .Update... A frontal boundary has settled across northwest portions of the forecast area with nearly all of the area seeing mostly clear skies at the current time. Within northeast flow north of the front, low level stratus is beginning to move southwestward into the northern fringes tonight. Near this front, the potential for thickening fog is increasing through the overnight hours and will continue into the morning. Visibility guidance (HRRR, SREF, NBM, RAP forecasting sounding) all show locations around the boundary becoming the focus for areas of fog and perhaps dense fog. Have added this mention into the near term forecast update. Further south, radiation fog remains a concerns, especially for river valleys, but there is uncertainty as to how severe fog will get outside of valleys toward morning. Have kept patchy fog from the previous forecast but this may need to be adjusted through the overnight as light southeasterly winds persist south of the front. The greatest threat for thickening fog is likely across the north where recent rains have provided a fresh source of low level moisture. Otherwise, no major changes made to the forecast. Temperatures drop into the low to mid 60s by morning with fog the biggest hazard for the morning commute. .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... High pressure at the surface and aloft is centered along the Mid Atlantic Coast, with a nearly stationary boundary situated to the northwest. The warm and humid airmass over the Ohio Valley is exhibiting a lack of forcing and deep moisture, with FEW to SCT cumulus forming in a shallow layer around 4000 ft, dissipating at sunset. This weather regime should keep precip from developing through tonight. Under mainly clear skies and light winds, patchy fog may develop later tonight in humid near surface conditions. We can expect above normal overnight lows in the lower to middle 60s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Dry weather is forecast to linger through the short term. Though high pressure to the east will weaken by Wednesday night under a moistening southeast flow, it appears that dry air and a lack of forcing will persist over the ILN area, resulting in no precipitation. Abundant sunshine fortified by warm advection will allow above normal temperatures to continue, with forecast highs ranging from the lower 80s northwest, the upper 80s DAY CMH and CVG, up to the lower 90s southeast. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Region will find itself on the south side of a stationary front at the beginning of the period. The front will stretch from the eastern Great Lakes back into the central plains. The front will remain near stationary until the weekend. This will lead to dry conditions for Thursday and Friday. Highs will range from the mid 70s in West Central Ohio to the upper 80s in the lower Scioto Valley. Increasing clouds on Friday will knock a few degrees off the highs for Friday. On Saturday, a strong H5 s/w will swing out of the northern plains into the western Great Lakes. Moisture that has pooled in the deep south will be pulled north on Saturday and will begin to interact with the upper level lift. Showers and thunderstorms are expected Saturday through Saturday night as the s/w swings across the region. A cold front is forecast to push through the region on Sunday, shunting the rain chances off to the east. The highest PoPs are forecast in the southeast quarter of the fa on Sunday. High pressure will build for Monday, bringing highs in the 70s. The high pressure moves quickly off to the east and by Tuesday the region is already on the backside. Highs will be in the 75 to 80 degrees range. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... VFR will continue through this evening under high pressure at the surface and aloft. Went a little more aggressive with the potential for FOG at LUK late tonight into Wednesday morning. Climatologically, light southerly winds and current dewpoint depressions point toward a favorable setup for valley fog in the area. Additionally, trends in fog development near a stalled surface boundary across northern Ohio will have to be monitored closely as the southern extent of the fog may creep close to DAY/CMH/LCK/ILN. For now, have kept mention of BR in 00Z TAF as ground fog should gradually build till morning. At this time, there is low confidence as to the ultimate severity of the fog. OUTLOOK...No significant weather expected. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Coniglio NEAR TERM...Coniglio/McGinnis SHORT TERM...Coniglio LONG TERM...Sites AVIATION...Coniglio/McGinnis
National Weather Service Jackson KY
1123 PM EDT Tue Sep 8 2020 .UPDATE... Issued at 1123 PM EDT TUE SEP 8 2020 Went ahead and updated the forecast to remove the evening wording from the forecast. Temperatures remain on track, so no need to update these. Fog is beginning to form a bit earlier than expected and earlier than the past few nights, so did beef up the fog wording a bit more for the rest of tonight in the valleys. This also means having it start sooner as well. Changes have been saved and sent. UPDATE Issued at 740 PM EDT TUE SEP 8 2020 Forecast is in good shape this evening with the only change to bump up dewpoints through the rest of the evening as they have come up much faster. Otherwise, everything remains on track. && .SHORT TERM...(This evening through Wednesday night) Issued at 354 PM EDT TUE SEP 8 2020 We see surface high pressure parked off to the east and this combined with mid and upper level ridging will lead to mostly dry and warm weather through the period. Tonight we will see a bit more moisture return given the placement of the high and this will lead to an increase in mainly river valley fog. Another night of ridge/valley temperature splits are on order. The question remains just how warm we will get on Wednesday, as we have been cooler today than forecast and we see a similar setup for tomorrow. Given this ran very close to what we had going, but concerned it could still be a little lower if similar 850 mb temperatures are the influence. Also, another factor for cooler highs today could be some upper level smoke present based off of the HRRR smoke product and a hazy look when looking in the sky this afternoon. However this is not forecast to be a factor for Wednesday based of the 12Z HRRR smoke product. There is some indication in the CAMS for a few PoPs in the far southeast toward the VA border by Wednesday afternoon, but the surface trough would tend to lean further east with convection and the more favorable downslope flow out of the east seems less conducive for development as well. Given this have kept the forecast dry, but do have a 10-14 PoP in the this area given the CAMs and increased moisture. None the less expect at least a little more cumulus throughout the region and even some high clouds sneaking in from the east coast disturbance. Wednesday night, we will see skies become mostly clear, as cumulus relents through the early evening. Another night of mainly river valley fog seems reasonable, as we continue to see moisture on the increase. Outside of this we will continue to see some ridge/valley temperature splits going into early Thursday morning. .LONG TERM...(Thursday through Tuesday) Issued at 447 PM EDT TUE SEP 8 2020 Eastern Kentucky will continue to bask in a warm early fall weather pattern Thursday and Friday as temps reach well into the 80s each day under partly to mostly sunny skies. There is a small chance for shower or storms each afternoon over far southeast Kentucky, but even there many places should remain dry. A warm front brings better chances for a few showers and storms on Saturday. Additional shower chances continue Sunday into Monday as a a couple of cold fronts affect the region. Model agreement is generally good through the long-term period. The latest model suite analysis for 12z Thursday continues to show an anomalous ~ 598 dam high SE of Nova Scotia with broad ridging extending SW across most of the eastern CONUS south of the Great Lakes. A col develops in this ridging over eastern Kentucky and central Appalachians on Thursday and persists into early Friday as a weak cool front bleeds southward across the area, eventually stalling near/south of the TN Valley. The upper level col disappears on Friday as surface high pressure nudges in from the north. Meanwhile, the upper level ridging gradually erodes through the day as a broad upper level trough deepens over central Canada and captures a filling cutoff low over the Great Plains. Some shortwave energy, rotating around this low, lifts over the Mid- Mississippi Valley late Friday, initiating a low pressure wave along the stalled front near the TN valley. That surface wave accelerates toward the Great Lakes on Saturday lifting a warm front across east Kentucky. A trailing cold front follows Saturday night/Sunday morning. During the day Sunday, a broad shortwave trough - the last vestige of the cutoff low - passes over the Great Lakes dropping another cold front toward the Ohio Valley. The fronts progress south of the Ohio River is in question as the best upper level forcing is sheared away toward Canadian Maritimes. The sensible weather will feature continued warm temperatures and mostly sunny skies on Thursday. There will be a threat for isolated to widely scattered showers and storms across southeast KY during the afternoon/evening hours ahead of/along the weak cold front. Thursdays highs are forecast to remain on the warm side of normal - in the mid 80s for most but pushing upper 80s near the TN border. Northeasterly winds usher in a slightly cooler air mass behind the front for Friday knocking down highs into the low 80s over northeast KY to the mid 80s further south. A subtle surface trough could again trigger a few afternoon/evening showers and storms closer to the Virginia border. Temperatures and humidity levels rebound slightly on Saturday as the warm front lifts through the area with some scattered showers and storms. The rain chances continue for Sunday into Monday as a couple of cold fronts pass through the region. High temperatures are forecast to reach the mid 80s on Saturday cooling off into the upper 70s to low 80s by Monday. Night lows are expected to range through the 60s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) ISSUED AT 740 PM EDT TUE SEP 8 2020 Mainly VFR conditions will be seen through the period, outside of a period of river valley fog late tonight. Light winds will be seen through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KAS SHORT TERM...DJ LONG TERM...GEERTSON AVIATION...KAS
Area Forecast Discussion
National Weather Service North Platte NE
625 PM CDT Tue Sep 8 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 327 PM CDT Tue Sep 8 2020 Another round of rain and snow is likely tonight. The trigger or forcing is currently moving east through wrn Colorado and should lift through wrn and ncntl Nebraska late tonight. The strength of the forcing across wrn Nebraska could be sufficient for a period of accumulating snow across the wrn Sandhills at elevations near of above 4000 ft. The RAP model is keying on regeneration of strong midlevel frontogensis and periods of strong lift in the DGZ across wrn Nebraska. If the model is correct than periods of rain mixed with snow at times should develop along and west of highway 83 tonight. The upper level energy energy across srn Colorado this afternoon is producing thunder and satellite indicates a robust deformation zone underway. The HRRR echo tops product suggests 25kft tops across swrn and ncntl Nebraska tonight and the NAM shows a few hundred J/KG of elevated CAPE in this area also. The forecast tonight will carry an isolated thunderstorm chance. The forcing should exit wrn and ncntl Nebraska late Wednesday morning with a chance of showers in the afternoon. Periods of light rain are possible Wednesday night associated with weak forcing and continued moist, warm air advection operating on aloft on the front side of a stalled upper level low across the Four-Corners region of the wrn U.S.. The temperature forecast leans on the warmer deterministic based short term model blend for lows in the 30s tonight and Wednesday night and highs in the 40s Wednesday. This is probably the best strategy given the expected overcast skies tonight through Wednesday night dictated by all models. The cloud cover will negate any sort of radiational cooling. Sensible heating from the relatively warm ground should be the dominate force to hold overnight temperatures above freezing. .LONG TERM...(Thursday through Tuesday) Issued at 327 PM CDT Tue Sep 8 2020 Dry weather is possible Thursday as the models indicate no substantial forcing for rain. However, the southerly 850mb-500mb flow is moist. This moisture will be running over a sfc high pressure ridge and the models suggest overcast skies. The last rain chances for this storm system appear to be Thursday night into Friday morning and Friday night as the upper low lifts through the central and northern Plains. Most of this rain will affect north central and areas to the east. Thunderstorms are in place Friday night as lapse rates will steepen in response to warm air advection. Mild, near normal temperatures and dry weather return Saturday through Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 625 PM CDT Tue Sep 8 2020 Low ceilings and gusty winds will continue through the evening regionwide, then conditions slowly begin to improve across northwest Nebraska overnight (including KVTN). Meanwhile, precipitation becomes more steady with perhaps a rumble of thunder across the southwest (including KLBF). A brief transition to rain-snow mix is possible around sunrise. Expect generally MVFR through the forecast period. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
953 PM CDT Tue Sep 8 2020 .UPDATE... Issued at 934 PM CDT Tue Sep 8 2020 Scattered to widespread thunderstorms continue to develop along the front in mid-Missouri with a few storms showing signatures indicating they may be producing small hail. These storms are largely being forced by low level convergence along the front and are tapping into a pool of up to 1000 J/kg of elevated instability. As we head later into the early morning hours, this low-level convergence and instability is expected to gradually tail off, decreasing precip chances across much of the area. That said, lower end precip chances will persist across NE MO and west-central IL where deeper forcing can be found along elevated portions of the front. Hazards associated with current storms appear to be fairly low- end threats for damaging winds, hail, and flooding. The severe threat continues to fall by the hour with diminishing instability, and since these storms are largely elevated, they will have a difficult time mixing strong winds to the surface. As for flooding, several areas have seen multiple rounds heavy rain this afternoon and evening. Fortunately this rain has been spread across several hours, and rain rates limited to about an inch an hour have kept things from getting out of control. BSH && .SHORT TERM... (Through Late Wednesday Afternoon) Issued at 309 PM CDT Tue Sep 8 2020 Primary concern for the rest of this afternoon into the evening is convective trends. Scattered storms have already formed and will be ongoing for the remainder of the afternoon into the evening. A few of the storms will likely be strong to severe as a decent amount of MLCAPE has built up this afternoon. Latest SPC mesoanalysis shows 2500+ J/Kg MLCAPE just south of the cold front, just north of I-44 in Missouri and I-70 in Illinois, though effective shear is pretty weak. Respectable DCAPE values in excess of 1000 J/Kg in this environment is supportive of pulse severe storms with microbursts. The RAP shows the instability weakening considerably after sunset (though MUCAPE remains stout enough for thunder through the night. Convection allowing models suggest the thunderstorm coverage should decrease significantly through late evening and will be generally confined to northern portions of the area by early Wednesday morning. The cold front will continue to drift south, though deterministic guidance keeps the coolest air bottled up across northern Missouri and west central Illinois. This will translate into a warm and humid day again across east central and southeast Missouri into southwest Illinois. There may be some lingering convection on Wednesday morning north of the front in northeast Missouri and west central Illinois...though the low level forcing is weak, and the primary area of moisture convergence is well north of the forecast area over central Iowa. Carney .LONG TERM... (Wednesday Night through Next Tuesday) Issued at 309 PM CDT Tue Sep 8 2020 Guidance is in general agreement that the mid Mississippi Valley will see somewhat cooler and drier weather for Thursday and Friday, although the details are a bit sketchy. The GFS is more aggressive in driving the cold front south into the lower Mississippi Valley than other models, and it looks like it`s trying to keep more low clouds around than the EC or NAM. This translates into 2m temperatures that only get to the mid 60s to low 70s on the GFS while the NAM and EC get back into the low 80s along and south of I- 70...keeping the cooler temperatures in the mid 60s and 70s bottled up in northern Missouri and west central Illinois. Ensemble guidance is leaning more toward the warmer solutions which does lend confidence to the EC/NAM for Thursday into Friday. the large cut off low over the Four Corners Region begins lifting and filling in on Friday, and by 00Z Saturday the GFS and ECMWF have it moving east across the Great Plains as a (mostly) open wave. The resulting surface low drags another cold front into the Mid Mississippi Valley Saturday afternoon. Southerly flow ahead of the front will should be enough to get most of, if not the entire area into the 80s again, with some scattered convection most likely in the afternoon and evening. The airmass behind the front doesn`t look particularly cold at this juncture, however deterministic guidance does show a large and persistent high pressure system building into the Midwest and Great Lakes behind the front Sunday and Monday. The high produces cool and dry northerly flow both days which keep highs in the mid and upper 70s with little chance of precip. Tuesday may be a little warmer as the high drifts east and the flow turns back around to the east/southeast. Carney && .AVIATION... (For the 00z TAFs through 00z Wednesday Evening) Issued at 621 PM CDT Tue Sep 8 2020 Initial concern is with the ongoing convection across the area. The best chance for thunder has pushed southeast of UIN and COU. Further southeast, storms have really filled in just to the west of the metro terminals. I anticipate storms to gradually diminish over the next few hours, but SUS and STL are so close to these heavier storms that it`s likely they will see a heavier storms pass overhead. Therefore I`ve gone ahead and included a tempo group with TSRA at those terminals. Confidence is lower that these storms will reach CPS, so have stuck with VCTS for the time being. As the best shower and storms chances retreat to the northeast, confidence is high that MVFR and eventually IFR cigs will slide further SE, reaching the metro terminals later this evening. Ceilings will gradually lift and scatter out after sunrise tomorrow morning, though some uncertainty remains with regards as to just how long the reduced cigs will hang on. BSH && .PRELIMINARY POINT TEMPS/POPS... Saint Louis 66 86 65 80 / 70 10 5 5 Quincy 55 71 58 73 / 50 20 10 20 Columbia 58 79 60 75 / 70 10 10 20 Jefferson City 61 80 62 78 / 90 10 10 20 Salem 64 88 64 83 / 20 10 0 5 Farmington 63 85 64 83 / 20 10 0 5 && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Midland/Odessa TX
631 PM CDT Tue Sep 8 2020 .DISCUSSION... && .AVIATION... Cold front currently moving through the area... as of 2325z front at INK and north of MAF moving south at about 14kts. North wind with gusts to 35kts with fropa... bldu as low as 1sm. Have thunderstorms over SE NM and Upper Trans Pecos moving east with additional showers and storms developing behind the front across Northern Permian Basin. Have storms mentioned in all TAFs and expect will transition to light rain overnight with development of IFR cigs. && .PREV DISCUSSION... /issued 450 PM CDT Tue Sep 8 2020/ UPDATE... Updated NPW for high wind and issuing new ZFP. DISCUSSION... Have already received an observation from GDP with gusts to 60 mph, have updated NPW to begin High Wind Warning for GDP and Wind Advisory for Culberson County now. Expect high wind there to continue on and off through Wednesday night. PREV DISCUSSION... /issued 245 PM CDT Tue Sep 8 2020/ DISCUSSION... WV imagery shows the upper trough now over eastern UT. Models dig this to the UT/AZ border by 00Z Thu, before ejecting the trough to the upper MS Valley by 18Z Sat. At the sfc, the cold front is just NW of KLUB as per area radars, and appears to be slowing as diurnal heating takes place. Hourly analysis throughout the morning has the HRRR and Nam Nest performing best on the placement/timing of the front, as would be expected over the lwr res models. That said, fropa at KMAF looks to be 02-03Z this evening, although that timing gets defenestrated if convection comes into the mix. Speaking of, the latest HRRR develops convection along a weak dryline up against the higher terrain 19-20Z, w/development along the front 20-21Z, putting everything east of the Pecos, as well as the Stockton Plateau/lwr Trans Pecos, in a warm sector w/dewpoints mostly in the 60s. Forecast NAM soundings to the north of KMAF at 21Z show mlcapes in excess of 3000J/kg w/no cap. Models are in good agreement w/steep mid-lvl lapse rates of 7+C/km from KMAF west ahead of the front, as well as dcapes over 1000 J/kg. Convection along/behind the front should quickly become elevated, and a few severe storms this afternoon/evening are not out of the question. Supplementing this will be a 40kt LLJ set to develop over the lwr Trans Pecos ahead of the front, as well as the right entrance region of the upper jet. One other possibility tonight that`s been absent from these parts for quite awhile will be heavy rainfall. PWATs are running about 2 std devs above normal, and K indices ahead of the front in excess of 35 suggest a potential for heavy rainfall, which is also noted in fairly impressive model QPFs. Temps w/this front continue to frustrate, mainly because the GFS decided to go off on its own, which has messed up the blends quite a bit. Looking at post-frontal temps up north, the GFS can be discounted for now, and the NAM is the favored model for this event. That said, many targets of opportunity have arisen over the next couple of days, and we`ll undercut NBM numbers quite a bit. This should result in record-breaking cold highs Wed afternoon. Temps should stay cool through until at least Friday, when skies begin clearing and sfc flow veers around to the SE. Long range models still develop a weak upper trough between ridges over Texas, which will keep a chances of convection in play each day, and temps below normal for once. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 52 56 50 60 / 80 80 70 70 Carlsbad 44 57 45 66 / 70 30 20 20 Dryden 60 69 56 67 / 60 70 70 70 Fort Stockton 53 61 49 62 / 80 50 50 50 Guadalupe Pass 44 58 43 65 / 70 30 20 20 Hobbs 44 53 44 62 / 90 50 40 30 Marfa 46 65 43 66 / 70 40 40 40 Midland Intl Airport 52 57 49 61 / 80 60 60 60 Odessa 52 58 48 62 / 80 60 50 50 Wink 51 61 49 64 / 80 50 40 30 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...None. TX...Wind Advisory until 8 AM CDT Thursday for Eastern Culberson County-Van Horn and Highway 54 Corridor. High Wind Warning until 7 AM MDT Thursday for Guadalupe and Delaware Mountains. && $$
Area Forecast Discussion
National Weather Service Marquette MI
833 PM EDT Tue Sep 8 2020 .SHORT TERM...(This evening through Wednesday) Issued at 338 PM EDT TUE SEP 8 2020 Water vapor imagery and RAP analysis show a positively tilted mid- upper level trough extending from Quebec to the Great Basin. At the sfc, cold front that passed across Upper MI Sun night is now setup from the Lower Great Lakes to the Southern Plains. Large sfc high pres is centered over MT with one ridge extending e to the northern Great Lakes and a second one nne to nw Manitoba. Closer to home, clouds and rain have spread into Upper Mi this afternoon from convection which initiated earlier this morning over WI and southern MN. Strengthening fgen along the mid-level front in response to upper divergence in the right entrance region of 120+ kt upper jet extending from the eastern Dakotas into Quebec will continue to support rain showers over the southeast half of Upper Mi into this evening. Tonight, Expect pcpn band to diminish and shift farther s and e this evening and overnight, however, there is some question as to how much the mid and high clouds will thin out across the nw fcst area late tonight as satellite imagery still shows considerable mid-high clouds upstream over MN and SD. If this cloud cover stays intact and doesn`t thin out much later tonight, that should prohibit formation of widespread frost. For now, will maintain mention of patchy frost in the grids over the western interior with a few lows getting down in the 33-35F range and will brief the evening shift to monitor upstream cloud trends in case adjustment in temp fcst may be needed. Min temps over the east half will generally be in the lower to mid 40s. Given uncertainty, will end up issuing a SPS for some patchy frost west tonight and then a better chance for widespread frost Wed night. Wednesday, the mid-level front, rather than the surface front, will be the focus for weather over our area. Models indicate another fgen band developing with fgen maximized around 700 mb. This band will lift northeastward across the central and eastern UP resulting in a band of steady rain developing by late morning and persisting through the evening. Still looks like there will be a sharp cutoff to the northwest of this band. Many of the 12Z models trending slightly se with axis of better pcpn and higher (categorical to likely) PoP grids. In updated PoP grids, will keep the Keweenaw virtually dry and only have chance POPs west of a line from roughly Marquette to Watersmeet. Expect a quarter inch or more of QPF across south central where axis of heavier pcpn with the fgen band is expected. With 850 mb temps still progged to be around or just below 0 C and thick cloud cover and pcpn expected, still expecting near- record cold highs across the area Wednesday in the low 50s. Under more persistent rain temps will likely struggle to even get out of the 40s. .LONG TERM...(Wednesday night through Tuesday) Issued at 335 PM EDT TUE SEP 8 2020 Little change to the longterm forecast from the past few days as the cooler pattern continues as a blocked pattern maintains its grip across much of the CONUS. Temperatures look to remain anywhere from 5 to 10 degrees blo normal, perhaps reaching back up towards normal Monday into Tuesday next week...but both deterministic and ensemble GEM, GFS, and EC modeled 500mb height tendencies at the start of next week suggest that "warm-up" won`t last too long. Heights are rising as high pressure is moving into the region on Wednesday night. The high pressure will create the combination of calmer winds and clearing skies across the area through the night, leading to the chance for widespread frost development, a SPS has been issued to cover that. Taking the fcst verbatim at this point, a freeze watch/warning would be warranted for portions of the interior west, with lows falling into the mid to upper 20s, but have opted for the SPS with the frost potential tonight to keep things simple. There is some chance that clouds hang on a little bit, and the eastward extent of the clearing is still up for debate yet. The other question is how much rain falls during the day Wednesday and does that lead to fog development, and with that, freezing fog? Adjusted MOS guidance seems to bite a little bit more on this chance, as well as steep inversions in model soundings(see NAM). For now, will stick with widespread frost wording and not dive into the fog/freezing fog potential. By mid-morning Thursday, high pressure will be into the area with dry weather expected through Friday. Highs near 60 on Thursday and mid 60s on Friday, with some patchy frost Thursday night. The next chance for precipitation is with the advertised cutoff low currently over the intermountain west. Models have the shrtwv moving through the Great Lakes region Saturday evening, bringing widespread rain across the UP. Behind this wave, an associated cold front passes over the UP, bringing a cooldown with breezy conditions on Sunday. Heights rise as a ridge moves into the central CONUS on Monday, bringing a warmup to start the week. Look for highs to be near normal Monday and maybe a touch abv normal Tuesday, in the low 70s...yes this is now abv normal! Models show some discrepancies in the deterministic, but ensembles suggest another cooldown in the latter part of next week, but nothing looks too cold at this point. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 832 PM EDT TUE SEP 8 2020 VFR conditions are expected through the forecast period at KIWD and KCMX. Upslope northeast flow with added Lake Superior moisture will support a period of MVFR cigs this evening and likely again by later Wednesday afternoon as rain chances increase. Even with some improvement expected overnight, cigs should remain at or near MVFR. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 338 PM EDT TUE SEP 8 2020 A quieter period of weather is shaping up for Lake Superior for the next several days as a high pres ridge shifts se, reaching Lake Superior Wed aftn and then lingering across the Great Lakes region Thu/Fri. Winds should be mostly under 20kt. There may be a period of somewhat stronger winds across western Lake Superior on Thu as sw winds increase on the nw edge of the high pres ridge over the Great Lakes. Otherwise, the next potential of stronger winds will occur on Sat as a low pres trough approaches and crosses Lake Superior. There may be some 20-30kt southerly winds ahead of the trough, mainly across eastern Lake Superior, and then possibly 20-30kt nw winds in its wake late Sat night into Sun. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...JAW AVIATION...JLB MARINE...Voss
Area Forecast Discussion
National Weather Service Tucson AZ
219 PM MST Tue Sep 8 2020 .SYNOPSIS...A strong storm system over Utah will bring gusty winds, much cooler temperatures and scattered showers and thunderstorms into Wednesday. Temperatures will slowly warm to near normal by the weekend with a slight chance of afternoon thunderstorms near the New Mexico border. && .DISCUSSION...As of 2 pm the cold front has moved just south of Prescott and continues to plow southward. A line of convection has developed right along the front with one severe thunderstorm warning thus far. Other than that convection has been very limited and the wind has been a bit tamer than forecast. Both likely the result of the heavy smoke laying across the region impacting the heating and resultant mixing. Latest HRRR runs indicating that convection still a decent bet as far SW as Tucson when the front rolls through this evening so have left pops in the forecast for the overnight period with a little adjustment. Weak mid-level cold advection is currently taking place and that will translate to stronger mid and low level cold advection this evening behind the frontal passage. The result will be cooler overnight temps and highs on Wednesday around 8-10 degrees cooler than this afternoon. With the upper low parking itself over Arizona/Utah border through Wednesday night there remains a threat of showers and afternoon/early evening thunderstorms east of Tucson through Wednesday night. At this time the upper low looks to slowly fill and move Thursday into Friday. Left a slight chance of showers and storms for the far eastern areas Thursday as enough moisture and instability should remain, especially if the low is a bit slower, to allow for that. Afternoon temperatures only a couple of degrees warmer Thursday and remaining about 5 degrees cooler than average. Friday through the weekend ridging will follow the departure of the upper low with a rebound in temperatures as a result. The ridge not looking quite as pronounced as earlier with a low level easterly flow undercutting the ridge. This easterly flow may bring enough moisture for a few showers and mountain storms far eastern areas each afternoon through the weekend. Temperatures running within a couple of degrees of normal Friday into early next week. && .AVIATION...Valid through 10/00Z. SCT-BKN 10-15k ft MSL. A slight chance of -TSRA/-SHRA KTUS eastward into Wednesday. SFC wind SWLY/WLY 15-25 kts with gusts up to 35 kts easing to 10-15 kts after 09/05Z. SW winds increasing again after 09/17Z to 10-20 kts through the afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...An unseasonably deep storm system over southern Utah will maintain breezy conditions this evening and again Wednesday afternoon with a chance of some showers and a few thunderstorms from Tucson eastward. Much cooler temperatures will also move in resulting in below normal highs Wednesday and Thursday. A slight chance of residual showers and thunderstorms are possible for eastern areas Thursday but otherwise, mostly dry and gradually warming temperatures are expected Thursday into Friday with generally light winds. This weekend, will be warm with a slight chance of showers and thunderstorms east of Tucson each afternoon through Monday. Winds will be light Saturday with an easterly breeze developing Sunday into Monday. && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Public...Cerniglia Aviation...Rasmussen Fire Weather....Rasmussen Visit us on Facebook...Twitter...YouTube...and at