Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/20

Area Forecast Discussion
National Weather Service Burlington VT
1039 PM EDT Sun Sep 6 2020 .SYNOPSIS... On Labor Day, a cold front approaches the region with increasing clouds and strong gusty winds expected through the day. A Wind Advisory is in effect beginning 8AM Monday through 8PM Monday for Grand Isle County, Vermont for wind gusts up to 50 mph possible. A few showers are possible across northwest New York Monday night into Tuesday, but overall conditions remain dry and seasonably warm across the forecast area until the latter half of the work week when better chances for showers and thunderstorms arrive. && .NEAR TERM /THROUGH MONDAY NIGHT/... As of 1033 PM EDT Sunday...The wind forecast remains on track for Monday with strong southerly winds, especially within the Champlain Valley. Slight adjustments were made to the forecast onset time of rain showers across northern New York, now looking like the initial round of showers will begin close to 12z (8am). In addition, slight chance of thunder has been included in the forecast for Monday afternoon, though instability will be limited. Only other adjustments were to tweak the hourly temperatures and dewpoints to match trends in observations. See previous discussion below. Previous Discussion...A wind advisory will be in effect beginning 8AM Monday through 8PM Monday for Grand Isle County, Vermont. Everything remains well on track for gusty south winds to overspread the area Monday morning as a strong, 40-50+ knot 925-850mb low level jet moves overhead. Overnight, winds will remain generally light and variable but as daytime mixing begins Monday morning winds will increase fairly quickly. Most areas should see winds gusting out of the south upwards of 20-25 mph towards 8AM, and remain gusty throughout the day in the 25-30 mph range. Locally, in the Champlain and St Lawrence Valleys, channeled south/southwesterly winds will produce winds in the 20-30 mph range with gusts up to 35-40 mph. Higher gusts upwards of 50 mph are possible over the broad lake including Grand Isle. The core of the strongest wind gusts will occur between 10AM and 2PM. After 2PM, winds will still remain breezy but will gradually diminish as we head towards late evening. Boaters on Lake Champlain should exercise caution if going out on the water tomorrow afternoon as these high winds will cause waves up to 4 to 8 ft. While skies should mostly to partly sunny tomorrow, the HRRR smoke model is showing an area of fairly decent concentration of vertically integrated smoke advecting into the Northeast along this front, therefore will likely see filtered sunshine throughout the day. Still expect highs to reach onto the mid to upper 70s across the area. These increasing winds are in response to a deepening low pressure system moving out of central Canada. Precipitation chances from the attendant cold front will mainly be across St Lawrence and Franklin Counties in New York. This front will move in after 00z, and with any real lack of instability of surface convergence will diminish as it moves eastward. Almost nil chances for measurable precipitation exists from the Adirondacks eastward into Vermont. Across our western NY zones, anywhere between 0.10-0.25" of rain is possible. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 352 PM EDT Sunday...Tuesday should be fairly quiet as we remain under southwest flow aloft. At the surface, a frontal boundary will waver around the international border. A weak upper disturbance will scoot by just to our north during this afternoon, and this combined with the weak front and daytime heating may allow a few showers to develop, mainly over the higher terrain. These will dissipate in the evening as the sun sets. Tuesday`s highs will be in the mid 70s to mid 80s, coolest along the international border near the front. Lows will be in the mid 50s to lower 60s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 352 PM EDT Sunday...The aforementioned frontal boundary will remain nearly stationary near the international boundary through at least Wednesday. Hence expect another afternoon with a few possible showers, especially over the higher terrain. Temperatures will be very warm as well, with mid and upper 80s expected in most spots. The front will make its southward push sometime Thursday into Friday as an upper trough swings across Ontario and Quebec. This will bring the chance for showers and thunderstorms those days, along with cooler temperatures, though both parameters hinge on the exact timing of the frontal passage. High pressure will build over the region Saturday, leading to a dry start to the weekend with seasonable temperatures. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Through 00Z Tuesday...VFR through the period with main aviation concern being LLWS early this morning followed by gusty south winds. High clouds are currently departing eastern VT leaving clear skies across the area until 06z. After 06z, mid-level clouds will approach from the south. There exists a slight chance of low level status on the east side of the Greens for a brief period between 10-12z with light southeasterly flow. However, it was left out of the MPV TAF at this time given the dry ambient conditions and lack of cloud cover upstream. Winds overnight will be generally light and variable, increasing from the south towards daybreak. LLWS will overspread the airspace from west to east beginning at 06z through 13-14z as a 40kt south/southwesterly low level jet moves overhead. Wind gusts will begin picking up by 13-14z, which will limit the LLWS threat; however, turbulence is likely through the remainder of the day, especially within the vicinity of terrain as this low level jet will increase to around 60kt towards 15-18z with surface gusts up the Champlain and St Lawrence Valley up to 30-40kt. Elsewhere, gusts should remain in the 25-30kt range. In addition, rain showers are expected across portions of northern NY from 15z until after 00z Tuesday associated with a passing front. Outlook... Monday Night: VFR. Slight chance SHRA. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHRA, Slight chance TSRA. Wednesday Night: VFR. Slight chance SHRA. Thursday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight chance TSRA. Thursday Night: Mainly MVFR, with areas VFR possible. Chance SHRA. Friday: Mainly VFR, with local MVFR possible. Slight chance SHRA, Slight chance TSRA. && .MARINE... Channeled southerly winds will produce winds in the 25-35 mph range with gusts up to 50 mph possible over the broad lake. The core of the strongest wind gusts will occur between 10AM and 2PM. Boaters on Lake Champlain should exercise caution if going out on the water tomorrow afternoon as these high winds will cause waves up to 4 to 8 ft. After 2PM, winds will still remain breezy but will gradually diminish as we head towards late evening && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Wind Advisory from 8 AM to 8 PM EDT Monday for VTZ001. NY...None. && $$ SYNOPSIS...Lahiff NEAR TERM...Hammond/LaRocca SHORT TERM...Hastings LONG TERM...Hastings AVIATION...Hammond/LaRocca MARINE...LaRocca
National Weather Service Eureka CA
403 PM PDT Sun Sep 6 2020 .SYNOPSIS...Hot and dry weather will continue across inland northwest California this week, with record heat likely today and Monday. Coastal areas will be warm and sunny through Monday, with milder temperatures and cloudier conditions returning during the middle of the week. && .DISCUSSION...Strong high pressure over the NE Pacific is supporting record heat across the interior valleys of northwest California this afternoon, with Ukiah reporting a temperature of 113 degrees and several Lake County locations hovering around 110 as of this writing. While today may prove to be the hottest day of the week, Monday may come close as high pressure continues to dominate the region. The Excessive Heat Warning is unchanged and remains in effect through Tuesday. Meanwhile, most coastal locations have generally been sunny and pleasant as weak onshore flow keeps temperatures around 70 on the North Coast. Moving on to the impending offshore wind event for Monday evening, much of the 12z guidance indicated a slight westward shift in the placement of the potent trough poised to dig into the Great Basin Monday night/Tuesday. As a result, available Hi-Res guidance has trended upward with winds along the ridges of interior Humboldt and Del Norte, spurring greater fire weather concerns for those areas in addition to the Trinity, Lake, NE Mendocino areas which had been the focus for the past several days. Refer to the fire weather section below for details. Winds will subside across the area by Wednesday morning, however hot and dry conditions will persist while slowly moderating as high pressure weakens but remains in control over the West Coast. /CB && .AVIATION...Widespread wildfire smoke is lingering across NW California today. These smoke issues generated MVFR/IFR visibility at KCEC and KUKI. Despite the smoke in the region VFR conditions prevail at KACV. HRRR smoke guidance is suggesting smoke will continue affecting the region with reduced visibilities through Monday. Otherwise, mostly clear skies will prevail for the next few days as high pressure over the region continues to build through the NE Pacific. /ZVS && .MARINE...Northerly winds and steep seas continue across the outer waters. These steep seas from 6 to 10 ft will continue through Monday night for both zones. Small Craft Advisory is in effect for southern outer waters through tonight and northern outer waters through monday night. Conditions across the waters will gradually improve Tuesday as the high currently building over the NEPAC slips overhead and the pressure gradient relaxes, possibly bringing a period of widespread light and variable mixed with rounds of southerly winds Wednesday into Thursday. /ZVS && .FIRE WEATHER...Opted to issue a Red Flag Warning for multiple zones as gusty northeast winds will develop along ridgetops late Monday evening and persist through Wednesday morning. This will combine with poor overnight RH recoveries in the 20 to 35 percent range and afternoon minimum RH values as low as 5 to 10 percent on area ridges to produce critical fire weather conditions across portions of interior Humboldt, interior Del Norte, Trinity, NE Mendocino, and Lake Counties. Winds will subside first across interior Humboldt and Del Norte Tuesday evening, continuing in the other areas through Wednesday morning. Otherwise, hot and dry conditions will persist into the middle of the week with a gradual moderating trend. /CB && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 6 PM PDT Tuesday for CAZ102-104>108- 110>115. Red Flag Warning from 10 PM Monday to 8 AM PDT Wednesday for CAZ264-277-283. Red Flag Warning from 10 PM Monday to 10 PM PDT Tuesday for CAZ203-204-211-212. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until midnight PDT Monday night for PZZ470. Small Craft Advisory until 6 PM PDT this evening for PZZ475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Green Bay WI
606 PM CDT Sun Sep 6 2020 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Monday Issued at 300 PM CDT Sun Sep 6 2020 Trends over the past couple hours are starting to lean towards a quieter near term forecast. While there was a brief period of sunshine this morning, ample cloud cover moved in this afternoon and have kept temps from rising much more. As a result, not seeing much instability build across the area, with the highest MUCAPE readings of 600 to 800 J/kg across central WI. Additionally, fairly impressive cap in place with CIN up to -500 J/kg. Very isolated showers have formed across parts of central and east- central WI (most of which is south of the GRB forecast area) with the closest thunder near Milwaukee. Meso models have had a hard time letting go of convection developing across mainly east- central WI then moving south of the area, however the past couple runs of the HRRR and the 18Z run of the RAP have cut back quiet a bit on the overall coverage and intensity of any shower or thunderstorms development. Have capped PoPs at the chance or slight chance category for late this afternoon and evening, and may lower them a bit more sometime in the next hour if trends continue. Kept thunder mention for now, but confidence is very low on whether that is possible. Of course, if something were to develop, strong winds and large hail are possible given the high shear and continued moisture advection. Tonight...Surface cold front sweeps across the state officially cutting off any chance of precipitation. Have PoPs ending in the far east by midnight. Subsidence behind the front will result in at least a partial clearing of the clouds. Lows are somewhat difficult given the cloud forecast, although with winds remaining gusty do not expect a large drop in temps. Lows are forecast to range from the middle 40s in the typical Northwoods cool spots, to the middle 50s along the lake shore. Monday...Generally quiet weather is expected for most of the day. Cloud cover will vary, with some clearing in the morning, then more clouds moving in by the afternoon in advance of the next weather system. Northwest winds will still be a little gusty in the morning, then subside through the afternoon. Highs will feel more fall-like, ranging from the upper 50s in north- central WI to the middle 60s in the Fox Valley. The chance for showers enters central WI late in the afternoon as the upper level pattern begins to amplify and sets up a more active forecast. .LONG TERM...Monday Night Through Sunday Issued at 300 PM CDT Sun Sep 6 2020 A large upper level trough will bring well below normal temperatures along with a period of rain and possibly some thunderstorms during the middle part of the work week. An extended period of northeasterly winds will also bring the concern for some lakeshore flooding on the bay of Green Bay from Tuesday through Wednesday or Wednesday night. The main change from the previous forecast is the low located across the southwestern CONUS becomes cut off and is no longer associated with the trough affecting the area during the middle part of the week. This will allow a break in the precipitation and the northeasterly winds on Thursday and Friday as a surface high builds in across the western Great Lakes region. The shorter duration of rainfall should hopefully help to limit the amount of areal flooding during the middle of the work week given the shorter than expected duration of the moderate rainfall and a bit lower QPF amounts. The aforementioned cut off low will then eject out of the southwestern CONUS late in the work week, then track towards the western Great Lakes region next weekend. The low will bring additional chances for rain showers and isolated thunder to the region. && .AVIATION...for 00Z TAF Issuance Issued at 605 PM CDT Sun Sep 6 2020 MVFR ceilings and scattered showers should give way to VFR conditions from west to east this evening as a cold front moves across the region. MVFR ceilings could return north of a RRL to IMT line late tonight and Monday morning as cold air moving across Lake Superior produce lake effect clouds in that area. VFR conditions are expected across the region Monday afternoon and evening. && .GRB WATCHES/WARNINGS/ADVISORIES... Beach Hazards Statement through Monday morning for WIZ022-040- 050. Lakeshore Flood Advisory until 1 AM CDT Monday for WIZ022-040- 050-073-074. && $$ SHORT TERM.....KLJ LONG TERM......Kurimski AVIATION.......RDM
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
658 PM CDT Sun Sep 6 2020 .MESOSCALE DISCUSSION... 658 PM CDT We continue to monitor for convective initiation north of I-88, with a few apparent inhibiting factors toward eroding the current cap. There remains a highly conditional risk of severe storms, IF mature convection can develop. The confidence in that occurring prior to 11 p.m. or so is on the lower side, and that`s likely the timing needed to tap into any effective low-level air for some tornado threat. Latest hand analysis along with various satellite and observational data indicate the old outflow boundary from the morning MCS draped from far northwest Illinois to near the southwestern CWA border (just north of Bloomington). This extends northwest to a 1005 mb surface low/triple point area near the Iowa/Wisconsin/Illinois border, with a cold front extending southwest from there to near Des Moines. The low-level air mass has recovered fairly well behind the old outflow and ahead of the cold front, with late day temperatures in the upper 70s to mid 80s and a pool of dew points of lower 70s immediately along/ahead of the retreating old outflow boundary. Visible satellite has yet to show any areas bubbling and in fact there is a large area of more stable 6,000 ft clouds moving into north central Illinois from the west. These look to be right below the cap per the 19Z DVN sounding, and the early data from the 00Z DVN sounding still shows a decent cap near 770 mb likely inhibiting any convective growth. The means to overcome that cap in the next few hours would be strong cooling in that layer which has limited ability due to the lack of a strong short wave and instead just gradual height falls/large scale ascent. Also, lifting and saturating of the moist low-levels would be a way, but again satellite is not showing any imminent signs of convecting. We will continue to watch meso sector satellite data closely to see if any tops can start to percolate, as otherwise the kinematic environment remains quite favorable per regional VWP data for supercellular storms if a few can develop. Later after 11 p.m. or so, convective chances may increase as the cold front approaches and a stronger upper to mid-level jet maximum rounds into Wisconsin. The convergence and forced ascent ahead of that boundary may be enough to moisten/cool the layer of the cap, resulting in scattered convection that would likely be elevated. Also warm advection ascent ahead of that may allow for spotty convection too, such as that that developed in northwest Indiana near 6 p.m. With the very steep lapse rates of around 9C/km in the mid-levels and strong curvature in the wind fields within the 1-6 km layer, there will be a large hail threat with any mature storms. Convection allowing models (CAMs) generally show some convection, but the HRRR and the ESRL HRRR have been fairly consistent showing the main development being along the cold front and not able to deeply convect ahead near the old outflow/pseudo-warm front lifting northward. MTF && .SHORT TERM... 308 PM CDT Through Tonight... The large footprint of a worked-over environment left in the wake of this morning`s convection continues to leave questions about the potential for severe weather this evening, with the low-level and mid-level air mass recovery occurring somewhat independently of each other. 19Z mesoanalysis, model guidance, and ILX RAOB indicate quickly steepening lapse rates above 850 hPA, with a deep layer of 9C/km advecting into the region. This recovery has not been a concern over the past day. What has been, and continues to be, the biggest question for severe storm potential this evening is the ability to sufficiently destabilize the near-surface layer for initiation. Most of the CWA is finally clearing out after mid- level clouds and isolated thunderstorms continued a bit longer into this afternoon than expected across northern Illinois. With that said, the return of a higher surface theta-e airmass has been steadily shifting northeastward early this afternoon, with the theta-e gradient analyzed from just west of the Quad Cities to just west of Springfield, IL. Extrapolation of this observed gradient paired with model guidance indicates most of the CWA should see a nearly full recovery of the low-levels via mainly advection with some assistance from insolation by early this evening. Meanwhile, the kinematic environment is becoming more favorable for organized convection. Low-level winds continue to increase per recent DVN/LOT VWP data showing 45kts/40kts as low as 3 kft. These low-level winds will edge upwards in response to an approaching mid- level wave evident in WV imagery across southern MN into far northwest IA. Rising mixing heights will begin to tap into those stronger winds aloft as the afternoon progresses, with the forecast of gusts in excess of 40 mph to locally 45 mph for a window late this afternoon into early evening remaining on track. Putting this altogether, a highly conditional severe thunderstorm threat exists after 00Z/7pm through the evening hours roughly around and north of the Kankakee river Valley westward toward Peoria. The most significant limiting factor will be the ability for incoming forcing to erode enough of the substantial low-level cap currently in place. If sustained deep updrafts can develop, the environment is favorable for semi-discrete linear segments with embedded supercell structures capable of producing damaging wind gusts and large hail. Additionally, a conditional QLCS tornado/mesovortex threat exists within any convection given impressively curved low-level hodographs producing effective SRH values possibly to 500 m2/s2 early to mid- evening. Marginal low- level CAPE values will be a major detriment to this potential, with a low-level warm nose below 700 hPa limiting low-level vortex stretching. Will still need to closely monitor the fine details of the thermo environment this evening as a kinematic environment like this that is highly supportive for tornadoes leaves some concern. The severe threat will gradually diminish through the night as convection slowly advances SSE through the CWA, ultimately slowing across the far southern CWA by daybreak Monday. Kluber && .LONG TERM... 330 PM CDT Monday through Sunday... The work week continues to present challenges for forecast confidence as well as conveying the forecast in a simple manner. The Labor Day holiday remains looking primarily quiet during the day with rain and some thunderstorm likelihood returning Monday night into Tuesday morning and possibly much of Tuesday for northern locations. The spread in forecast rain chances and temperatures across the forecast area from northwest to southeast grows through midweek, with higher to lower rain chances and cooler to warmer temperatures, in general, from west to east. The cold front will be clearing the far southern forecast area later Monday morning or so, bringing with it most of the thunderstorm chances. With the boundary slowing cannot completely rule out some focus or subtle overrunning in the afternoon in the far south, but for most areas it looks to remain dry through the day and early evening. A strengthening high pressure ridge centered over northern Lower Michigan will squeeze the pressure gradient some into the afternoon resulting in a northeast wind of around 15 mph. This should build waves some into the Chicago shore and climatology would say that we would be at least supportive of a marginal Beach Hazards Statement for rip currents. Have leaned that route for the Chicago shore by mid-afternoon with a Beach Hazards Statement, and then started the Indiana shore under one first thing in the morning behind the cold front. As substantial digging of the jet stream occurs over the Rockies Monday night into Tuesday, the downstream baroclinic zone will inch back northward over the Midwest and tighten. In addition the anticyclonic jet will strengthen over the Great Lakes and across southeast Canada, poising a right entrance region aloft over the area Monday night through Tuesday. With a period of increased low-level moisture transport in the low-level jet layer off the deck, these ingredients should be juxtaposed to support a blossoming area of rain and some thunderstorms Monday night, especially after 10 p.m. or so. MUCAPE values are forecast to climb toward 1,000 J/kg in the southern forecast area and there is some uncertainty on how the best forcing and instability will line up. But the dynamics are supportive of at least a marginal severe threat for hail, and thunderstorm chances all the way to the northern CWA with periodic heavy rainfall. The heaviest rain amounts of 2+ inches on high resolution guidance, such as the 3 km NAM and the HREF, and primarily west of the area but would not be surprised to see some isolated amounts that high by midday Tuesday along/north of I-80. Confidence then lowers significantly and much of that is owing to the digging trough in the west developing a dislodged, closed upper low. The 12Z guidance has wobbled back to the west with this and naturally slowing to eject it. With this being so far west, more of the forecast area is impinged upon by upper ridging and drier air from the southeast during midweek. The active frontogenesis area and 850-700 mb moisture convergence zone shimmies northwest of the area in the GFS and ECMWF, and the upper support from the jet region starts to be lost too. It`s still too early to say a heavy rain threat has diminished during that time, but the potential for a flood threat due to a long duration heavy rain beyond the day Tuesday looks to have diminished some. The temperatures continue to show a large spread across the area thanks to northeast winds, clouds, and some rain in northern areas and potential for less clouds southeast. Forecast values for maximum temperatures on Tuesday-Wednesday have 20-25 degree differences from northwest to southeast for the CWA. The GFS and ECMWF lift the closed low late this week much further west of the forecast area than had been the case 24 hours ago. This shows the common theme in forecasting experience that model handling of closed lows can be very problematic, and naturally lowers confidence. With it being further west, the chance of convection at least lingers further into the week, but it`s also possible we remain dry and actually more mild. MTF && .AVIATION... For the 00Z TAFs... Aviation forecast concerns: * Gusty south-southwest winds near 30 kt this evening. * Brief period of high-end MVFR ceilings early this evening. * Potential for strong thunderstorms late this evening. * Wind shift to northwest with cold front after midnight and to northeast Monday afternoon. Convection and residual cold-pool earlier today has slowed recovery/mixing in low level air mass through the afternoon hours. In the near term, this has primarily worked to limit stronger wind gusts (though still near 30 kts expected into early evening). Slow recovery of boundary layer across northern IL has also made our thunderstorm threat somewhat more conditional later this evening, though the potential still exists and any storms that do develop have the potential to be strong/severe given strong wind fields. Current expectation is that convective initiation will occur over the next 1-2 hours in the vicinity of far northeast IA/northwest IL, then spread east-southeast across the forecast area through the mid-late evening hours. 19Z RAOB from DVN depicted strong cap was still in place at that time, though latest SPC mesoanalysis data suggests this cap was weakening across northeast IA in response to cooling aloft driven by large scale ascent in association with an approaching mid-level wave and surface cold front. Various CAM guidance continues to suggest convective development as discussed above, potentially affecting KRFD area 01-03Z and ORD/MDW area 03-06Z. Further refinement may be needed once thunderstorms actually develop. Of course, if cap remains too strong for significant coverage, thunderstorm potential at any individual terminal would be lower. Otherwise in the near term, a high-end MVFR stratocu deck has developed across northern IL late this afternoon and it looks like this will impact Chicago area terminals for a couple of hours early this evening. Duration should be short lived however, as consolidated warm front and outflow from this mornings storms should lift across the area toward 02Z. Surface cold front is then expected to push east-southeast across KRFD roughly 06-07Z and ORD/MDW 08-09Z, with thunderstorms moving south and east of the terminals by that time. Winds shift to the northwest 10-15 kt with frontal passage, and should remain from that direction into Monday before shifting northeast by mid- afternoon Monday. Daytime should be relatively quiet with dry VFR conditions expected. Northeast winds then look to increase and become somewhat gusty Monday evening with rain showers developing mid-late evening. Embedded thunder not out of the question, though low enough coverage/confidence to not include in TAF at this distance. Ratzer && .MARINE... 308 PM CDT A Gale Warning is in effect for all of our nearshore waters through late this evening. Expecting wind gusts to increase quickly this afternoon, with occasional gusts to around 40 kts appearing possible into the evening hours. Wind speeds should incrementally diminish overnight tonight but will remain elevated and breezy. Long-duration Small Craft Advisory conditions are then in the forecast through the end of the upcoming week with a prolonged period of onshore gusty north to northeasterly winds resulting in building and choppy wave action. Carlaw/Kluber && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006 until 10 PM Sunday. Beach Hazards Statement...ILZ103-ILZ104...3 PM Monday to 7 AM Tuesday. IN...Beach Hazards Statement...INZ001-INZ002...4 AM Monday to 7 AM Tuesday. LM...Gale Warning...nearshore waters until 1 AM Monday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Pocatello ID
130 PM MDT Sun Sep 6 2020 .SHORT TERM...Tonight through Tuesday night. Quite a bit of smoke across central and east Idaho this afternoon. Some of this smoke may clear out early this evening. However, the HRRR shows a strong plume of smoke moving into east Idaho from fires in the western central mountains later this evening and overnight. A lake wind advisory for the American Falls Reservoir remains in effect into this evening with winds expected to decrease overnight. Big changes arrive for Monday in the form of a strong cold front. Ahead of the front, we expect breezy west/southwesterly winds to develop. These winds will be strong enough to reach wind advisory levels. Then around mid afternoon the cold front will push through central and eastern Idaho from the north. Winds will switch to a northerly component and become very strong immediately behind the front. 3km NAM model soundings shows +50kts in the 2000-3000ft layer during the late afternoon and evening across the Snake Plain. Although the sustained winds may hold in the advisory level of 30- 35kts, think there may be a short period as the front spills over the continental divide and into the Snake Plain that we could tap into the +50kt layer and bring those winds down to the surface in the form of gusts. Also, unique is the wind direction, being northerly. Strong north winds are rare across eastern Idaho. There is some concern that trees may be more susceptible to strong northerly winds as opposed to the typical westerly or southwesterly winds. For those reason, we will upgrade the high wind watch to a high wind warning for much of the Snake Plain up to Dubois. Around the high wind warning area, indications are that the northerly winds may be a little less robust, so will encompass the warning area with an advisory. Expect a few light showers to accompany the front as snow levels fall from 12000 feet around midday on Monday to 6000 feet by evening. Snow amounts across central and east Idaho look very light, generally less than an inch so will not issue a winter weather advisory. However, with the falling snow levels we need to think about overnight lows. A freeze watch remains in effect for the upper Snake Plain where Tuesday morning lows in the lower 30s remain likely. The cold air will persist into Wednesday morning where much of the Snake Plain and maybe even portions of the Magic Valley could see lows in the lower 30s. Will hold off on a freeze watch for Wednesday morning for now as we are currently gushing headlines, but something to expect. 13 .LONG TERM...Wednesday through next Sunday...A very chilly morning is expected Wednesday with temperatures at and below the freezing mark for the upper snake plain, Arco desert, Island Park area, east highlands,Stanley Basin, Wood River Area and other valley locations. This may be a very early hard freeze already, but it is just a little to early to make to that call quite yet. Snow showers look to have ended for all areas by Wednesday and clearing conditions are forecast for the remainder of the week. High pressure will gradually build in from the west with mid 70s or low 80 degree temperatures for highs. Similar conditions are forecast over the weekend. ND && .AVIATION...Expect breezy conditions to diminish this evening. Smoke across the region may lower visibilities once again tonight. For now, continuing to forecast vfr conditions but may need to amend. Expect strong winds to develop Monday afternoon across the region with showers possible along a cold front. 13 && .FIRE WEATHER...Red Flag Warnings will remain in effect until 9 pm this evening for much of the area, including 422,410,425,427 and 413. Temperatures are much cooler today compared to yesterday but we will are expected to see similar dry and windy conditions as yesterday. Tomorrow is an entirely different weather set-up and much attention should be paid to it. An abnormally strong back door cold front will pass through our forecast area tomorrow afternoon and evening. Though RH values are marginal for some areas; the winds alone are far too dangerous to ignore. Increasing northerly winds are forecast starting across 411 mid-afternoon then spread quickly into the northern portions of 410 at 35 to 45 mph with gusts around 55 mph. These winds will track southward through 410, 425 and 413 with similar speeds forecast throughout the afternoon and evening. As a result, Red Flag Warnings will be in effect. Ahead of these winds, it should also be noted that strong (But not as strong) westerly winds are forecast around 30 mph with gusts to 40 mph. These winds would occur until the northerly winds take over, impacting 425, 427 and portions of 413. A shower or thunderstorm may accompany the frontal passage, but is likely to be sparse in coverage. High elevation snow also remains in the forecast behind the frontal passage going into Tuesday morning. Cooler temperatures and light winds are in store for Tuesday with high pressure gradually building in from the west. ND && .AIR STAGNATION...Smoke or haze is filtering through Central and Southeast Idaho today; resulting from local and regional wildfires to the west. This smoke/haze will persist through the remainder of the day/evening and again settle under the inversion tonight. A few areas are likely to be spared from seeing much impact though; which would include areas bordering Wyoming/Idaho such as Bear Lake and the Palisades. We would look for conditions to clear late tomorrow after the passage of a very strong back door cold front. ND && .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 9 PM MDT this evening for IDZ410-413-422- 425-427. Red Flag Warning from noon to 11 PM MDT Monday for IDZ410-413- 425-427. Wind Advisory from 2 PM to 11 PM MDT Monday for IDZ051-055>066- 068>071-074-075. High Wind Warning from 2 PM to 11 PM MDT Monday for IDZ052>054- 067. Freeze Watch from late Monday night through Tuesday morning for IDZ052-053. Lake Wind Advisory until 9 PM MDT this evening for IDZ054. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
346 PM MDT Sun Sep 6 2020 .SHORT TERM...(This evening through Monday) Issued at 304 PM MDT Sun Sep 6 2020 Currently...A ridge of high pressure remains in place over the region, which has allowed temperatures to break records at Alamosa, Colorado Springs and Pueblo, where highs so far have been 88F, 97F and 103F as of 2:30 PM, respectively. Elsewhere, temperatures are as hot as expected, with 2:30 PM readings in the upper 90s to lower 100s across the plains and mid 80s to around 90 in the high valleys. Skies are generally clear except for a few clouds over the southern mountains at this hour. Generally north to northwest winds have moved into the plains, which has ushered in some haze from wildfire smoke to the area. Tonight...A back door cold front is expected to move into the region from Kansas, bringing an increase to low level moisture and should help to reduce some of the haze across the region. Forecast soundings show that this low-level moisture is expected to be very shallow, so not expecting any low clouds to move into the area. Lows are expected to be near 40F in the San Luis Valley, which is near average, and the upper 40s to around 60F across the remaining lower elevations, which is slightly above average. Tomorrow...The cold front that moves through overnight is expected to keep temperatures a few degrees cooler across the plains and the I-25 corridor, with highs reaching the low to mid 90s. Meanwhile, the cold front is not expected to affect areas west of the eastern mountains, so highs will likely be similar to today in the mid to upper 80s for the high valleys. Alamosa could see another record high broken tomorrow. The well-advertised trough and associated cold front that will bring a big change to the weather begin to approach the region from the north, which is expected to tighten pressure gradients over the northern portions of the forecast area. As a result, gusty winds and a drop in relative humidity values are expected over the central mountains, La Garitas, northern portions of Sangre de Cristo and Wet Mountains, northern half of the San Luis Valley, and the Wet Mountain Valley. Therefore, have upgraded the Fire Weather Watch to a Red Flag Warning for tomorrow afternoon. It should be noted that although the southern portions of the San Luis Valley, Sangre de Cristo and Wet Mountains, and the eastern San Juan Mountains are included in the zones for the Red Flag Warning, these areas are not expected to reach critical thresholds. .LONG TERM...(Monday night through Sunday) Issued at 304 PM MDT Sun Sep 6 2020 ...Potential High Impact Winter Storm still on track for Tues/Wed but still some uncomfortable uncertainties with the storm track... Models have trended farther west and stronger with the upper low as it drops southward through UT Monday night and closes off near the 4 corners region Tuesday evening. EC is slower and farther west than 12z operational GFS...though the GFS Ensemble Mean seems to split the difference. System continues to drop southward Tuesday night before becoming negatively tilted and lifting slowly northeastward across CO Wed night and Thursday with the operational GFS the farthest east in its northeast track across central CO...while EC is farther west across western CO/eastern UT and the Ensemble mean is somewhere in between. Confidence in the storm track is still low but trends suggest a farther westward track which would shift focus for snowfall west as well. Of course if EC is correct then impacts along the I-25 corridor and southeast plains could be less with best forcing staying a tad too far west. Have gone with a GFS/GFS Ensemble blend for now with WPC QPF grids looking good. As for the sensible weather...still looking at a potent cold front dropping south of the Palmer Divide around midnight and through all of the southeast plains by 3 AM. North winds will gust to 50 mph or greater with 18z hrrr and 12z NamNest suggesting gusts to 60 mph will be possible across El Paso, Pueblo, Crowley county...and Otero counties between midnight and 6 AM Tues. Will have to watch this potential as it is certainly conceivable given the tight pressure gradient and some acceleration southward off the Palmer Divide that a high wind warning may be needed for these areas. Snow fills in behind from north to south with the heaviest hit of snow falling on Tuesday/Tuesday night as strong isentropic upglide sets up across a large portion of our area around the closed low. Snow and a lower elevation rain/snow mix will spill over into the San Luis Valley and southwest mountains during the afternoon as the upper low sinks southward. Temperatures will fall through the day, especially across the southeast plains where a rain/snow mix will be possible during the late afternoon with a shift over to snow possible Tuesday night. Residual warmth in the ground will likely play a huge roll with snow accumulations across the lower elevations though where the heavy snowfall rates occur, there could be a period of impactful accumulations over the Palmer Divide and Raton Mesa region as well as the mountains and valleys to the west. Across the southeast plains as well as southern El Paso and Pueblo counties think the ground warmth will mitigate this somewhat...but its conceivable some advisories will be needed, especially to account for possible higher accums on the western sides of Pueblo and El Paso counties. Some impacts to be concerned about include, tree damage and power outages in and near the mountains with heavy wet snow and strong winds. Roads in and near the high country could become slick and snowpacked, especially Tuesday night. And of course the cold temperatures and snow will likely lead to a premature end to the growing season across the plains for warm season crops. Both Tues night and Wednesday night look to drop below freezing across the plains. Given the slower ejection of the upper low Wednesday and Wednesday night it will continue unsettled with another possible round of precipitation Wednesday evening with either wrap around in the west or a WAA band in the east...again...highly dependent on the storm track. Have kept at least scattered pops in during this period and have extended the Watch through Wednesday morning. System slowly pulls off to the northeast for Friday with the weekend drying out and warming back up. -KT && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 304 PM MDT Sun Sep 6 2020 Mainly VFR conditions are are anticipated over the next 24 hours at all 3 TAF sites (KALS, KCOS, KPUB). Haze from wildfire smoke is anticipated to linger at KCOS and KPUB into tonight, with the potential for MVFR visibilities remaining possible. Winds at KCOS and KPUB also diminish this evening and then remain relatively light through the rest of the forecast period. && .PUB WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM to 8 PM MDT Monday for COZ220- 222>225. Winter Storm Watch from late Monday night through Wednesday morning for COZ058>082-084-087-088-094. && $$ SHORT TERM...CARLBERG LONG TERM...KT AVIATION...CARLBERG
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