Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/04/17

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
550 PM MDT Sun Sep 3 2017 .AVIATION... 00Z TAF CYCLE Isol to Sct TS and SH will shift southward during the eve hrs. SAF/LVS/AEG and ABQ could potentially be impacted. Biggest impact would be gusty outflow wind to at least 40 kt. A particularly stronger cell could affect SAF with even higher gusts early eve. Most of the activity should die off by midnight or shortly after. Hit and miss drier cells will affect western and northern areas Mon afternoon. Gusty winds will remain the main impact with that activity. 50 && .PREV DISCUSSION...300 PM MDT Sun Sep 3 2017... .SYNOPSIS... High pressure aloft will dominate northern and central New Mexico this week. Showers and storms will be focused over the northern and western high terrain through Labor Day with temperatures near to above average. A vigorous cold front remains scheduled to plunge into northeast and north central New Mexico Monday night, then advance south and westward to the Continental Divide Tuesday on gusty northeast to east winds. The front will spark showers and storms along it`s path with locales along and west of the central mountain chain more likely to be affected Tuesday, while the east experiences cooler and more stable conditions. Thereafter, isolated to scattered showers and storms will be focused over the northern and western high terrain. High temperatures over the east will rebound by Thursday. && .DISCUSSION... Less cumulus overall compared to this time yesterday afternoon but isolated storms have developed sooner than yesterday over the highest terrain of the northern mountains. Models indicate there will be a few more developing as the afternoon progresses but how far south through central NM and for how long they will persist is where there is some model disagreement. RAP13 and HRRR seemed a bit over enthusiastic with Saturday`s convection, so not confident activity will hold together through the evening and into the overnight hours as depicted, reaching the Lower Rio Grande Valley and South Central Mountains. Decided to pencil in some dime sized pops into those areas though dew point at KABQ has fallen into the upper 30s and similar values stretch southward. Therefore any shower or storm would likely be more gusty and dry with lightning than rainy. Labor Day will feature mainly afternoon and evening showers and storms over the western and northern high terrain. Temperatures will be above average. A cold front is expected to push into north central and northeast New Mexico Monday night then spread south and westward on vigorous northeast to east winds. High temperature guidance for northeast NM on Tuesday varies by about 10 degrees, went with a blend with a little more weight given to the warmer ECMWF mos. The west will remain above average temperature-wise with potential for showers and storms but the east will see highs about 5 to 15 degrees below average Tuesday, and will be more stable, which would diminish potential for convection. Hazy skies look to persist through mid week at least though there may be some temporary improvement with the gusty winds expected with Tuesday`s front. Went with mostly generic mountains pops for mid to late this week as the upper high wanders around the central and southern Rockies. Temperatures in the east rebound by Thursday. && .FIRE WEATHER... Weak disturbances embedded in the broad mid-level high pressure system will continue to sink southward over NM this afternoon and Monday with scattered to isolated showers and thunderstorms favoring north central areas, and spottier convection mainly over the mountains farther south. The lower atmosphere is fairly dry so small wetting footprints are expected with erratic wind gusts potentially reaching 50 mph near virga showers and drier variety thunderstorms. High temperatures are expected to vary around 4 to 10 degrees above normal on Monday with falling humidities across the east. Haines of 5 is also expected across the northwest two thirds of the forecast area. A pocket of poor ventilation may linger across the east central plains on Monday before improvement there Tuesday. Look for showers and thunderstorms to increase in coverage and wetness Monday night across the northeast as a gusty back door cold front arrives, then Tuesday across central and western areas as the front pushes southwestward to the continental divide. With the broad upper high centered over the Great Basin, these storms will move south and southwestward off the high terrain while lingering into Tuesday evening. High temperatures will fall a few to 10 degrees on Tuesday from Monday`s readings, and as much as 23 degrees farther east, before falling further across central and western areas on Wednesday. Haines Indices will plummet with Tuesday`s front and remain low for the remainder of the week. Poor ventilation will favor the Sangre de Cristo Mountains on Tuesday before spreading to include central areas Wednesday and Thursday. Daily rounds of mainly isolated showers and thunderstorms will favor the mountains Wednesday through the end of the week as the Great Basin high pressure system migrates southeastward over NM. Humidities will generally trend downward and temperatures upward after Wednesday causing wetting footprints to shrink. && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Gaylord MI
1147 PM EDT Sun Sep 3 2017 .UPDATE... Issued at 1023 PM EDT Sun Sep 3 2017 Earlier diurnal convection in eastern upper MI has faded out. Next precip event starting to take shape upstream. Surface wave along incoming cold front is over the western tip of Superior. Showers are developing in the warn advection zone e-ne of the low, over central/northern Superior, with precip developing se-ward with time. Light showers will re-enter the picture in eastern upper MI toward or just past midnight. Better rain chances will arrive from the nw after 3 am, as the cold front/surface wave and stronger mid-level forcing arrive. Some embedded, non-svr storms with this activity. Shower chances could get as far south as M-72 by 8 am. Unfortunately, per recent HRRR guidance, could be a couple of waves of activity impacting the Straits region through 8-9 am. HRRR runs have not been particularly consistent though, so not going to place a ton of confidence in any one solution. UPDATE Issued at 436 PM EDT Sun Sep 3 2017 A few showers have been able to develop in interior eastern upper in lake breeze convergence. Fcst soundings revealed a cap at around 15kft with at most 200j/kg. Guess that was enough. Will run them until daytime heating fades. && .NEAR TERM...(Tonight through Monday) Issued at 307 PM EDT Sun Sep 3 2017 High impact weather potential: None. Pattern synopsis and forecast: Early this afternoon, morning low clouds have been thinned and lifted into a scattered cumulus field as drier air swept into nrn Michigan. Temperatures have been responding to the emergence of some sunshine by climbing into the upper 60s and 70s. The focus is now shifting to a shortwave activity across western and central Canada that was inducing low pressure in western Montana and the Dakotas. No precipitation there as the air mass is fairly dry, but spotty showers were seen in south central Canada, ahead of an ill-defined warm front extending east of the low pressure. Mid level clouds were thick north of this warm front, and quickly eyeing eastern upper as they advect eastward from western Lake Superior. The scattered cumulus will fade with loss of heating, and a period of mostly clear skies is expected across the region, with the exception for eastern upper where those mid level clouds are likely to roll in early this evening. These clouds will continue to thicken and lower through the night and Monday morning as the aforementioned low pressure and warm front move into nrn Michigan, which will then be followed by the system cold front. While forcing increase through the overnight and Monday morning, via frontal convergence, WAA and DPVA, instability will be rather minimal with CAPES only a handful of J/kg. While showers are likely, especially in eastern upper in stronger forcing, only a thunderstorm or two seems possible. Much better chances for storms will reside downstate Monday afternoon with diurnal heating leading to much more impressive instability ahead of the cold front. Low level moisture will remain thick enough for nrn Michigan through the day for clouds to hold firm for a good portion of the daylight hours, but some late day clearing is expected, more so across eastern upper. Lows tonight will be fairly mild in the upper 50s and lower 60s. Highs Monday will have a good range from NW to SE as the cold front is moving through, the upper half of the 60s NW to the mid and upper 70s more toward Saginaw Bay in downsloping NW flow. && .SHORT TERM...(Monday night through Wednesday) Issued at 307 PM EDT Sun Sep 3 2017 ...Turning cool with showers at times... High Impact Weather Potential...Minimal. Pattern Synopsis/Forecast...Highly amplified upper ridge/trough pattern will develop over the CONUS towards midweek as a deep trough settles into the Gulf of Alaska. High confidence that this will result in deep longwave troughing entrenched over the Great Lakes region for several days. 500mb heights will steadily fall Monday night into Tuesday, dropping 2 to 3 standard deviations below the mean. At the same time, 850mb temps will fall from +7 to 8C 00Z Tuesday to around +3 to 4C by Tuesday afternoon. Thus, cold air advection will be ongoing through the period, though weakening with time. Some lake-induced rain showers will likely develop given the warm water temperatures and influx of colder air aloft, with further enhancement coming at times from lobes of vorticity swinging through the upper trough. Primary Forecast Concerns...Temperatures and shower chances through the period. Possible thunderstorm or two? Despite the anomalous trough and colder air building in aloft, ensemble data suggests the airmass won`t be /significantly/ cold for this time of the year, as 925mb and 850mb temperatures are only about -1 to -2 standard deviations over northern Michigan. A little more impressive further aloft with 700mb temps at -2 to -3 sigma. Still, considering normal highs for early September are in the low 70s and normal lows in the low 50s, most of the area will be running about 5 to 10 degrees below normal. Showers will be possible at times through the period thanks to the deep trough overhead as well as from lake induced processes given the chilly Canadian airmass and warm lake waters. By no means a terribly dry airmass for early September settling into northern Michigan, as PWATs will only drop to around 0.7 inches...not too far off from the median. As per the usual, tough to pinpoint the timing of scattered showers tied to the upper trough, but Monday night through Tuesday night would be the most favored timeframe. By Wednesday, the trough axis will be pivoting east of our forecast area with heights starting to slowly rise again. Chances for lake-induced showers will gradually increase Tuesday into Wednesday as 850mb temps steadily drop and delta Ts increase. Wind direction veers from WNW Monday night to N on Wednesday, so Lake Michigan will be the main contributer...possibly Lake Superior to a lesser extent (cooler Superior waters only yielding delta Ts around +13C). Looks like favorable low level moisture comes into play both days as well. Wouldn`t entirely rule out a waterspout, but parameters look to only be marginal through the period and not always coinciding well. Would like to see deeper EL-LCL depths, which look to range from 10 to 15 kft at best, depending on the model. Finally, given the ongoing CAA aloft, steep low-mid level lapse rates will yield some instability at times that could result in a thunderstorm or two. This would be mainly along Lake Michigan Monday night and over northeast Lower Tuesday afternoon. .LONG TERM...(Wednesday night through Sunday) Issued at 307 PM EDT Sun Sep 3 2017 Scattered shower activity is possible as we begin the extended period, as a sharp trough extending from Quebec through the Tennessee Valley lifts out of the region through the day Friday. High pressure will begin to build into the region Friday, and remain in control through the weekend, and possibly into early next week. This will bring us quiet weather, with the low temperatures probably the biggest concern as good radiational cooling could bring some chilly nights and perhaps some frost concerns again. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1147 PM EDT Sun Sep 3 2017 MVFR to IFR cigs Monday morning. Incoming cold front will cross northern MI Monday morning. Shower activity is expected ahead of and along the front, with a thunderstorm or two possible as well. Vsbys will decrease as precip arrives, with cigs to follow. MVFR to IFR cigs will be in place Monday morning, with PLN the most likely spot for IFR conditions. Improvement to VFR will take place north to south Monday afternoon. Sw winds will increase tonight, with LLWS also developing. Winds veering nw to n Monday and decreasing. && .MARINE... Issued at 307 PM EDT Sun Sep 3 2017 Sfc low pressure and it`s warm front will lift into the region tonight, tightening the pressure gradient and allowing skies to thicken with clouds. The system cold front follows for Monday morning, resulting in a wind shift out of the NW. Wind speeds will be high enough for widespread advisories later tonight through Monday evening. Winds fall below advisory levels later Monday night and into the work week as large sprawling high pressure slowly moves into the Great Lakes over that time. Showers and possibly a few non-severe storms are likely later tonight through Monday with the low pressure. && .APX WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT through Monday afternoon for MIZ020-025- 031. LH...SMALL CRAFT ADVISORY until 2 PM EDT Monday for LHZ346-349. SMALL CRAFT ADVISORY until midnight EDT Monday night for LHZ347- 348. SMALL CRAFT ADVISORY until 8 AM EDT Monday for LHZ345. LM...SMALL CRAFT ADVISORY until 2 PM EDT Monday for LMZ323-342- 344>346. SMALL CRAFT ADVISORY until 8 AM EDT Monday for LMZ341. LS...SMALL CRAFT ADVISORY from 8 AM to 8 PM EDT Monday for LSZ321-322. && $$ UPDATE...JZ NEAR TERM...SMD SHORT TERM...MK LONG TERM...AM AVIATION...JZ MARINE...SMD
Area Forecast Discussion
National Weather Service Denver/Boulder CO
804 PM MDT Sun Sep 3 2017 .UPDATE... Issued at 758 PM MDT Sun Sep 3 2017 No changes needed to previous fcst. && .SHORT TERM...(This evening through Monday) Issued at 203 PM MDT Sun Sep 3 2017 Strong upper high entrenched over the region with very warm and dry airmass over Colorado. Record breaking heat this afternoon as record high temperature already broken at Denver and trying to break the all time September high of 97 degrees. Integrated PW trends from GPS continue to drop with readings down another quarter of an inch in the past 9 hours. No chance of storms through tonight over plains and even much of the mountains. The only exception would be over Park county with an isolated shower possible through early evening. Main impact tonight and Monday will be the smoke and haze expected to increase over Northern Colorado tonight and Monday. GOES16 Geocolor imagery showing thick smoke over much of Wyoming this afternoon. With the flow aloft and a weak frontal boundary, smoke will be increasing over the northeast plains this evening and overnight. Experiment HRRR concurs with some increasing smoke tonight and this may linger through much of the day on Monday. A bit cooler on Monday in prefrontal airmass before main front poised to move into northeast Colorado Monday evening. Still mainly dry on Monday and maybe just slightly better chance of storms over mountains and higher terrain of Palmer Divide. .LONG TERM...(Monday night through Sunday) Issued at 203 PM MDT Sun Sep 3 2017 Monday night the large upper level ridge of high pressure will stretch from the Pacific Northwest into the Desert Southwest...with an upper level trough of low pressure deepening across the central and eastern United States. A strong short wave on the back side of the upper trough will push a strong cold front across northeastern Colorado Monday night...with north to northeast winds gusts up to 30 mph possible. Moisture with the front looks limited...with inverted V forecast soundings suggesting only light rainfall and gusty winds with any showers and storms that do develop. Tuesday should be cloudy and much cooler across northeastern Colorado due to a stratus deck lingering through much of the day. The GFS has trended warmer with Tuesday`s high temperatures while the NAM12 had trended lower. If the NAM12 is correct...many locations across the plains and Palmer Divide may only have high temperatures in the 60s. The cloud cover and cooler temperatures should also result in a very stable airmass with dry conditions expected. The mountains south of Interstate 70 and the southern foothills should see more sunshine and daytime heating. Therefore...these areas could see a better chance for afternoon and evening showers and storms. The dry air combined with mostly clear skies overnight should allow Wednesday morning temperatures to drop into the 40s across most plains locations. A gradual warming trend is expected Wednesday through Friday as the upper level ridge of high pressure shifts eastward over the Rocky Mountain Region. This may allow some subtropical moisture to flow into Colorado from the south and southwest. The increase in moisture combined with daytime heating should result in increased precipitation chances by late in the work week...mainly across the high country. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 758 PM MDT Sun Sep 3 2017 One bndry has moved across DIA which will keep winds nely the next few hours. Overnight winds may eventually just transition to drainage between 06z and 08z. Meanwhile areas of smoke/haze will spread across the area with visibilities eventually dropping to 3-5 miles late tonight. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...RPK SHORT TERM...Entrekin LONG TERM...Kalina AVIATION...RPK
Area Forecast Discussion
National Weather Service Taunton MA
914 PM EDT Sun Sep 3 2017 .SYNOPSIS... Remnants of Harvey and a Midwest cold front will move through the region this evening. Weak high pressure brings clearing and drier weather overnight. A trend to warmer weather follows on Labor Day and Tuesday. A cold front will slowly push toward the region, bringing showers and scattered thunderstorms with locally heavy rainfall late Tuesday into Thursday. Slowly improving conditions move in during Friday, then continue into next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 900 PM Update... Upper level trough over the region will continue to push to the north and east during the overnight hours. At the surface, surface low is currently located off of Cape Ann and the NH Seacoast. Thus winds will generally be from the west for the overnight as the low moves towards the northeast. Bulk of the showers have moved out of southern New England and into NH/Maine. However on the backside of the low pressure, showers have continue to fester. This is in conjunction with the higher 700 mb moisture moving into the area as well as upper level jet. Added the risk for a slight chc across the CT valley as these showers continue to move into from the Berks. The combination of the westerly winds bringing in drier air, these showers will not last very long and appears that they will dissipate around 3-5z. The other item to watch tonight is the potential for radiational fog. Clearing skies and winds going light in sheltered valley locations could result in some fog. See the MMK is down to 1sm. The only caveat once again is the dry air. Also the HRRR and the NARRE are not pinpoint the fog potential. Still cannot rule out the potential so will mention patchy fog for the overnight hours. The risk for dense fog appears low at this time. Previous Discussion... Drier air moves in behind the departing weather system. Expect clearing skies and winds from the west southwest. Overnight lows in the lower to mid 50s except 55 to 60 in the urban centers and on Cape Cod and the Islands. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Monday... High pressure south of the region extends across our area on Labor Day, with the ridge axis shifting east of us by afternoon. That will allow winds to shift from the southwest. This will provide plenty of sun, with sufficient mixing to reach 850 mb. Temps at that level are forecast at 14C, which would support max temps 80 to 85, with cooler spots in the hills and along the South Coast where winds will come off the water. Monday night... High pressure in place to our southeast with a light south- southwest flow over southern New England. This brings a return of dew points in the 60s. Expect min temps in the low to mid 60s. With temps and dew points close to equal, expect areas of fog to develop. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Warm and humid Tuesday with sct strong t-storms possible across the interior * A slow moving front will bring showers/scattered thunderstorms, locally heavy rainfall Tuesday night into Thursday * Drier conditions Fri and Sat but still the risk of a few daytime showers inland Overview... 12Z model suite continues to signal development of digging H5 long wave trough out of Hudson Bay and Ontario S to the mid and lower Mississippi valley by mid week in response to yet another high amplitude ridge building across the western U.S. Cold front will tend to stall across central and western areas as it becomes parallel to the eastern side of the mid level long wave trough. Also noting Bermuda high extending westward into the western Atlantic, a bit higher than its normal position. This deep SW flow setting up will allow plumes of high PWAT air working toward the region. Continued concern for a prolonged period of heavy rainfall along with the potential for localized flooding/flash flooding. By late this week into next weekend, models and ensembles continue to signal the long wave trough lifting NE across New England, but some question on timing and whether it tries to cutoff across Quebec or the Maritimes. At this point, will continue with previous forecast trend of drying conditions moving in by next weekend as high pres pushes E out of the Great Lakes. Will continue to closely monitor the progress of Irma as it approaches the western Atlantic in the Friday-next Sunday timeframe at least. Details... Tuesday... Dewpoints will continue to rise with the developing SW flow, which should reach the mid to upper 60s during the day. Warm temperatures ahead of slowly approaching cold front out of central NY/PA with forecasted H85 temps remain in the +16C to +18C range, so expect temps to top off in the 80s across most locations away from the immediate S coast. Noting SB CAPEs rise to the 800-1000 j/kg range and K indices rise to 30-35 during Tue afternoon across central and western areas. Otherwise, decent instability also moves in as well as increasing PWATs. However, some question as to how far E the cold front will reach during max daytime heating to bring in the best instability. Could see some strong thunderstorms develop across central and western areas, mainly from about Worcester and Windham counties westward during Tue afternoon and evening. SPC keeps mention of general thunder for now. Tuesday night into Thursday... The upstream mid level trough continues to amplify to the W, causing the cold front to stall across the region with weak low pres waves moving along it. Noting steadily increasing PWATs during this timeframe, upwards to 1.8 to 2 inches by Wed night/Thu with persistent SW flow. So, will start to see training showers/scattered thunderstorms allowing for not only heavy downpours but persistent rainfall for potential of flash flooding. Current thinking is the best shot for this would be Wed into Thu, but exact timing as well as where the training precip to set up remains in question. Forecasting a general 1.5 to 2.25 inches of rainfall, but again could see localized higher amounts. Will see POPs increase to categorical by Wed morning across the western half of the region, but will spread E during the day and continue into early Thu before slowly shifting E. Friday through Sunday... H5 trough will lift NE across New England, which should push the front offshore but timing is a bit in question amongst the model suite. Some showers may linger across portions of the region into Friday, but should end Fri evening with drier air in place. Could still see some diurnal showers on Saturday as moisture lingers across the interior. Carrying a dry forecast for next Sunday for now. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... Tonight...High confidence. Band of showers may bring brief MVFR-IFR CIGS/VSBYS moving E across the region, mainly N of the MA/RI/CT border through 03Z- 04Z, then should dissipate. Otherwise mainly VFR conditions. Leftover W-SW wind gusts up to 20 kt should weaken by around 03Z as well. Otherwise, expect clearing skies and west southwest wind. Monday and Monday night...High confidence. VFR. Areas of IFR cigs/vsbys in fog late Monday night. KBOS Terminal...Moderate to high confidence in TAF. May see brief MVFR-IFR CIGS from around 02Z-04Z with batch of -SHRA moving across. Otherwise VFR. KBDL Terminal...Moderate to high confidence in TAF. Outlook /Tuesday through Friday/... Tuesday...High confidence. Mainly VFR. Will see scattered afternoon/evening showers/TSRA develop across the interior with lower conditions. Patchy fog developing after midnight with local MVFR-IFR VSBYS. Tuesday night through Thursday...High confidence in overall trends, but lower confidence in exact timing and details. Expect areas of MVFR-IFR conditions in showers and sct TSRA, initially focused across the interior through Wed, then shifting slowly E Wednesday night into Thursday. Patchy late night/early morning fog with locally MVFR-IFR conditions each night. Thursday night-Friday...Moderate confidence. Lingering showers/scattered TSRA early Thu night, will slowly push E late Thu night. A few daytime showers may develop across the interior late Fri morning into the afternoon. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/... Tonight...High confidence. East winds in the evening become variable, then shift from the west-southwest. Showers and fog should diminish with the wind shift. Wind speeds of 20 to 25 knots linger much of the night, but trend lower after midnight. Seas 5 to 7 feet linger, mainly on the outer waters overnight. A Small Craft Advisory is in effect through tonight. Monday...High confidence. Southwest winds to about 20 kt. Seas subside through the day, but seas of 5 feet may linger along the seaward edge of our outer waters. Small Craft Advisory lingers on the outer waters through the afternoon. Monday night...High confidence. Southwest winds may reach 20-22 knots. Steady south-southwest wind will help seas re-build to 5 feet on the outer waters and possibly RI Sound. Outlook /Tuesday through Friday/... Tuesday...High confidence. S wind gusts up to 20-25 kt, highest across the eastern outer waters. Seas up to 4-6 ft, highest on the outer waters. Good visibility. Tuesday night through Thursday...Moderate confidence. Persistent S-SW winds may gust to 25 kt at times. Vsby will be reduced at times in showers and isolated thunderstorms. Patchy late night/early morning fog with reduced vsby mainly on the nearshore waters. Thursday night and Friday...Moderate confidence. Winds shift to W Thu night as cold front passes. Showers/isolated thunderstorms will end from W-E mainly around or after midnight, but may linger into Fri across the eastern waters. May see patchy late night fog with locally reduced vsby, otherwise mainly good vsby. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ231>234. Small Craft Advisory until 8 AM EDT Monday for ANZ235-237. Small Craft Advisory until noon EDT Monday for ANZ250-251-256. Small Craft Advisory until 4 PM EDT Monday for ANZ254-255. && $$ SYNOPSIS...WTB/EVT NEAR TERM...WTB/Dunten SHORT TERM...WTB LONG TERM...EVT AVIATION...WTB/EVT MARINE...WTB/EVT
Area Forecast Discussion
National Weather Service Burlington VT
1008 PM EDT Sun Sep 3 2017 .SYNOPSIS... Widespread rainfall will taper off tonight as upper level low pressure pulls east of the region. A brief period of fair and seasonably warm weather returns for Labor Day before a slow moving cold front brings a renewed threat for showers from Tuesday onward into the late week time frame. && .NEAR TERM /THROUGH MONDAY NIGHT/... As of 1006 PM EDT Sunday...Minor update to fine tune steadier rain ending from the CPV into parts of central/northern VT. Based on latest radar trends still thinking steady rain ends across the NEK around midnight with just a few leftover scattered showers. Additional qpf will be a tenth or two at most with highest values over northern VT. Temps remain nearly steady overnight in the 50s with south/southwest winds 4 to 8 knots. All covered well in grids/forecast. Current radar continues to show light to moderate rainfall from the eastern dacks into most of central/northern VT. Utilizing the time of arrival tool has the back edge to precip in the BTV area around 01z...and thru the NEK by midnight. Have tweaked the pops toward this thinking and integrated the latest HRRR model reflectivity progs. Otherwise...additional qpf will range from 0.10 to 0.25...with some isolated higher amounts toward the NEK. Large pictures shows negatively tilted 5h/7h trof with deep 850 to 500mb southerly flow associated with warm conveyor. This deep moisture and favorable upper level divergence pattern is slowly shifting 925mb to 850mb winds shift to the southwest as drier air advects into our cwa. Temps will remain steady or climb a few degrees especially aft the heavier showers move east...with lows mainly in the 50s. Winds and mixing should limit fog potential to higher trrn...where summits are obscured in clouds. Previous discussion below: Widespread showers and periods of steadier rainfall continue across the area as expected this afternoon as the remnant moisture from former Hurricane Harvey interacts with a negatively tilted, though progressive upper trough. Precipitation efficiency is on the higher side of average with current 12-hr MRMS totals generally ranging in the 0.25 to 0.75 inch range as of 200 pm. Global and hi-res model output remain in excellent agreement showing this trough and associated rainfall to continue pivoting through the region through the late afternoon and early evening hours before exiting east with better dynamics. So the idea of conditions trending gradually dry later this evening into tonight looks on track at this point. Low temperatures a consensus blend of available guidance with some bias- corrected MOS output thrown in for good measure offering near steady readings in the upper 40s to mid 50s. This seems reasonable given near-neutral advective processes under developing southwesterly flow. The best weather day over the next 3-5 day period by far will be tomorrow (Labor Day) as weak surface ridging builds across the area under deepening southwesterly flow aloft. This is in advance of another longwave upper trough developing to our west across the Upper Great Lakes. Skies should trend partly to mostly sunny through the day with highest coverage of sunshine across southern counties. High temperatures respond nicely as model-averaged 18Z 925mb temperatures climb into the 18-20C range - mainly 70s to a few spot low 80s in favored warm spots of the Champlain Valley and southern VT. As the boundary layer deepens, southwesterly winds will trend a tad breezy through the day, especially across the western slopes of the Adirondacks into the St. Lawrence Valley where channeled flow will develop. Here mean gusts from 25 to 35 mph will be likely with a few spots hitting 40 mph. While below advisory criteria, this could lead to a few downed branches and an isolated power outage or two as trees remain fully leafed out. By Monday night the upper trough continues to approach from the northwest along with a slowly advancing surface front tracking into the St. Lawrence Valley. Showers will be forecast to overspread our western counties overnight as the frontal zone approaches, with much of VT remaining mainly dry. I did introduce an outside threat of thunder across northern New York after midnight as a band of steeper mid-level lapse rates advects ahead of the boundary into this region. Low temperatures will remain on the mild side as deep southwest flow continues - mainly upper 50s to mid 60s. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 350 PM EDT Sunday...Upper trof digs into the Great Lakes Tues and Tuesday night with height falls while a cold front moves into the region and provide a focus for showers and thunderstorms. The front should be in northern NY around 12z Tue with showers concentrated there. The front will move slowly eastward across Vermont on Tuesday. It looks like southern and eastern VT will destabilize mainly south and east of BTV/MPV. An blend of MUCAPE gives 500-1000 J/kg perhaps a bit higher in the immediate CT river valley around 21z Tue. 0-6km shear will also be in the increase with 30-50kt so a strong to severe storm is a possibility over SE VT in the afternoon or evening. 850 temps will range from near 8C at MSS to 13C at VSF. There will be quite a few clouds with highs on Tuesday will range from the lower 70s at MSS to around 80 at VSF, though if there is enough sun could be a bit warmer there. Instability wanes quickly Tuesday evening with loss of daytime heating but still some chance of showers mainly over SE VT as the frontal movement slows to a crawl over southern VT or MA overnight. Lows mainly in the 50s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 350 PM EDT Sunday...The large scale upper trof becomes established over the eastern third of the country through Sunday with a number of short waves moving through it. This will help to keep the threat of precipitation going over the area through much of the extended along with temperatures trending below normal. The frontal boundary will become quasi-stationary orientated from southwest to northeast over southern New England Wed and be the focus for a potential wave of low pressure moving along it Wed into Thu. As a result, we will see the threat for showers be greatest over Vermont with slightly less chance over northern New York Wed and Thu. Eventually the front moves off the coast as the upper trof axis moves over the area Friday into Saturday with the latest models indicating it cutting/closing off somewhere over the Northeast though the timing and location are a bit uncertain as well as when it moves out. The dynamics and instability associated with the upper trof will enhance the potential for showers. Showers will be mainly driven by diurnal instability with the highest chance in the afternoon and evening hours. With the clouds and precipitation through much of the extended time period high temperatures will generally be in the 60s and lows trending into the 40s to lower 50s. In fact the latest ECMWF shows 850 temps near 0C along with 540dm thicknesses by next Sat which means it may be cooler than what we are forecasting but the GFS is a bit warmer, so we`ll wait and see what later forecasts trends bring including what happens with Irma which is just way too far out to say. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Through 00Z Tuesday...Low pressure continues to produce rain and low clouds across much of the North Country. Mix of IFR to VFR conditions for the first half of the night. Gradual improvement expected after 06Z as system pulls east. Winds mainly south to southwesterly at 3 to 8 kts should inhibit widespread fog development outside of rain showers. Low cigs will be main concern through the early morning hours, at which time expect the low to move far enough east with cigs lifting to VFR after 09Z at all sites but KSLK and KMPV. Expect these terminals to improve to VFR during the late morning. VFR conditions expected throughout the day Monday. During the late morning throughout the afternoon, winds will pick up out of the south southwest at 8 to 15kts with gusts generally between 20 and 30 kts possible. Outlook... Monday Night: VFR. Breezy. Chance SHRA. Tuesday: VFR. Chance SHRA...Slight Chance TSRA. Tuesday Night: VFR. Chance SHRA. Wednesday: VFR. Occasional SHRA. Wednesday Night: VFR. Chance SHRA. Thursday: VFR. Chance SHRA. Thursday Night: VFR. Chance SHRA. Friday: VFR. Chance SHRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...JMG NEAR TERM...JMG/Taber SHORT TERM...Sisson LONG TERM...Sisson AVIATION...KGM
Area Forecast Discussion
National Weather Service Grand Forks ND
1000 PM CDT Sun Sep 3 2017 .UPDATE... Issued at 952 PM CDT Sun Sep 3 2017 The cold front has now passed through the FGF CWA with a brisk northerly wind following closely behind. Winds are settling down nicely as the pressure gradient relaxes further behind the front. A light northwest wind should persist overnight...with the a trailing system likely to bring in some scattered showers through Monday morning. UPDATE Issued at 638 PM CDT Sun Sep 3 2017 No significant updates planned for the forecast package. Updated Aviation Discussion is attached below. RAP analysis at 23z shows a surface low pressure system centered just west of BJI with a trailing cold frontal boundary extending back through Ada, Grandin, and Valley City. Winds turn fairly sharply from the north following frontal passage. At 2330z Radar shows thunderstorms beginning to develop over far northcentral MN ahead of the surface low. CAP strength is slowly eroding near the low and scattered strong thunderstorms remain possible over northcentral MN through early evening. && .SHORT TERM...(This evening through Wednesday) Issued at 341 PM CDT Sun Sep 3 2017 Manitoba short wave forecast to move into southeast Ontario by Mon morning. Short wave will send cooler air into the area tonight and Mon. Upper level jet was across southern Canada with showers occurring over northern Lake of the Woods county. Water vapor loop indicated an upper level ridge was rotating through the area. Showers and storms will be possible mainly on the MN side with frontal boundary moving through. Gusty northwest winds may be possible this evening as cooler air moves into the area. Water vapor loop indicated a short wave over central MAN. Another short wave was located over central BC. 500 hpa height falls mainly over southern Canada today will shift south into the area Mon morning as BC short wave digs into the area and concurrent ridge building occurs over western North America. 140M height falls expected by 12Z Mon over the forecast area and ahead of main short wave. Another upper level jet will occur on the south and west periphery of the BC short wave Mon. light showers are expected to occur in the left front quad of jet. Flow aloft becomes much more northerly Mon night. North flow aloft will remain across the Northern Plains through Wed. .LONG TERM...(Wednesday night through Sunday) Issued at 341 PM CDT Sun Sep 3 2017 It will remain dry through the end of the week as an upper ridge builds into the northern high plains and high pressure at the sfc sits over the Great Lakes. ECMWF/GFS/GEM remain in good agreement with this scenario. Temperatures will rebound back to above normal levels by the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Updated at 958 PM CDT Sun Sep 3 2017 Expect VFR conditions with loight northerly blayer flow across the area through the midnight period. Aft 07Z expect increasing mid level clouds spreading from northern ND southeastward and across the FA through the morning hours. Scattered showers and patchy MVFR CIGS and VSBYS will push through the DVL Basin by 12Z... through the RRV from 10Z through 14Z... and through northwest MN aft 14z. Scattered showers and isolated Thunderstorms are possible across northwest MN aft 16z. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Gust SHORT TERM...JH LONG TERM...Riddle AVIATION...Gust
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
542 PM MDT Sun Sep 3 2017 .SHORT TERM...(Tonight through Monday night) Issued at 332 PM MDT Sun Sep 3 2017 High pressure will remain firmly situated over the western CONUS over the next several days, keeping conditions generally dry and warm. Temperatures will be well above seasonal as a result; at least 5 to 10 degrees. Residual moisture trapped underneath the ridge will continue to be recycled each afternoon, resulting in isolated to scattered showers and thunderstorms over the higher terrain. As has been the trend the past few days, the San Juans will be favored for convection with activity subsiding after sunset. The overnight hours will be benign with mild lows and mostly clear to partly cloudy skies. As northerly flow remains overhead we can expect hazy conditions to persist, generally over areas north of I-70, into Monday. Did not make any alterations to the inherited haze grids coverage wise, though I did extend the duration through 15Z Monday morning in accordance with the latest HRRR smoke dispersion model. .LONG TERM...(Tuesday through Sunday) Issued at 332 PM MDT Sun Sep 3 2017 For Tuesday, the continued area of high pressure will be sandwiched between two upper level troughs - one located over the Pacific Ocean and the other, much stronger trough digging into the eastern CONUS. After the midweek point the high will begin to shift to the southeast as the aforementioned Pacific trough moves inland. Here, extended models begin to diverge on potential solutions with the GFS introducing subtropical moisture underneath the retreating high late Wednesday while the Euro lags behind some 36 to 48 hours. Regardless, the progression of the high further east should allow for moisture to trickle back into the region from the south, so we can expect to see an increased chance for showers and thunderstorms as well as cooler temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 542 PM MDT Sun Sep 3 2017 Storms will be laying down for the night as sunset approaches leaving minimal flight operation concerns over the next 24 hours. Winds should be mainly influenced by the terrain with any cigs aoa 120kft agl. VFR dominates the forecast. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MMS LONG TERM...MMS AVIATION...TGJT
Area Forecast Discussion
National Weather Service Gray ME
1011 PM EDT Sun Sep 3 2017 .SYNOPSIS... Low pressure will lift north out of New England overnight. A shallow ridge of high pressure will move east through the region on Monday. A cold front will approach from the northwest Monday night and will gradually stall over the area on Tuesday. Several weak waves of low pressure will track northeast along the front Wednesday through Wednesday night before the front shifts offshore on Thursday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 10 PM...Forecast still on track for the most part. Heaviest RA should lift NE and out of the CWA by midnight. Latest HRRR runs showing a little bit of surge of showers moving across central NH into central ME, associated with cold conveyer belt of developing low just to the east. These will mainly be light and should be gone by early morning if they survive that long. 7 PM...Tweaking the grids to mach up with current grids, but general forecast thinking remains mostly the same. One more slug of steadier, and maybe moderate to heavy precip moves through during this evening from SW-NE. Any mod-heavy rain will probably not last much longer than an hour in any given spot. Then rain should wind down quickly around mid night as flow shifts to WNW and should dry things out quickly. Previously...Low pressure associated with the remnants of Harvey will lift north through the region this evening. Heaviest of this precipitation currently pushing into southwest New Hampshire and will be overspreading the remainder of the forecast area through the afternoon and early evening. QPF not changing much with a half to one inch still expected for storm totals. Looking for gradual clearing from west to east after midnight as winds kick into the west but shelter valley may hold on to fog and stratus into Monday morning. Lows overnight will range from the mid 40s to mid 50s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Shallow ridge of high pressure will build east through the region on Monday.Looking for a mix of sun and clouds in the mountains and mostly sunny skies elsewhere. Should see temperatures closer to normal with upper 60s to mid 70s north and mid 70s to near 80 south. Cold front will approach from the northwest Monday night bringing increasing clouds to northern zones and a chance of showers toward daybreak on Tuesday. Remainder of forecast area will be just partly cloudy. Lows overnight will range from the mid 50s north to the mid 60s south. && .LONG TERM /TUESDAY THROUGH SUNDAY/... To start the extended the region will be under the influence of an amplifying pattern across North America. Seasonably strong ridge building will occur across Wrn North America and over the Wrn Atlantic. Between those two ridges a trof will deepen across the Ern CONUS. This will set up Sly flow along the East Coast some 2 standard deviations greater than normal. This will keep things mild in general...clouds and precip will keep real warmth from being realized. However deep moisture will be transported up the coast...and that could result in locally heavy rainfall...especially if any elevated convection develops. Forecast soundings continue to show plenty of elevated CAPE...perhaps some surface based Tue depending on thunder will remain in the forecast thru midweek. Because of the large ridges to the E and W...this front will be slow to move. Several rounds of rainfall are possible as weak waves ripple north along it. The upper trof is not forecast to start edging E of the region until Fri or so...and even then the low heights aloft could lead to diurnal showers into the first part of the weekend. Then ridging is expected to build over the forecast area from the W. Looking well beyond the weekend...little has changed regarding the track of Irma. The hurricane remains well out in the Atlantic...with several days to go before any potential impacts to the Lesser Antilles. Its current position in the Atlantic Basin continues to suggest the likelihood of impacts to the Northeast are low...however a SW push over the next couple of days may bring Irma into a more favorable location. Ensemble guidance continues to show a wide range of any forecast you see is low confidence at this time. Continue to follow the National Hurricane Center for the most up to date information...and regardless of eventual impacts or lack thereof from Irma it is always a good idea to review your hurricane preparedness and emergency kits. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Short Term...IFR/LIFR ceilings and vsby overnight. VFR Monday through Monday night. Long Term...An extended period of MVFR or lower conditions is likely to begin Tue. As the front moves into NWrn zones during the day conditions will deteriorate in the mtns first. Coastal locations will likely see VFR conditions linger into the afternoon Tue before deteriorating overnight. Areas of IFR or lower are possible Tue night into Wed as RA intensity increases. Especially during the day Tue and Wed...heating of a moist environment may allow for some isolated TSRA to form...though confidence in more widespread convection is low. && .MARINE... Short Term...Have extended this SCAs into Mon afternoon outside of the bays, as seas will remain high, even if winds hover at or just below borderline SCA. Should see winds drop below SCA in the bays as winds shifts to WNW later tonight. Winds quickly pick up from the SW Monday night, and will likely need SCAs again Mon at some point Mon night. Long Term...Deep SW flow develops Tue ahead of the next front. The pressure gradient may be enough for some 25 kt gusts outside of the bays...but more likely is that seas build to 5 to 7 ft. Hazardous seas look to continue into the latter half of the week before diminishing. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ151-153. Small Craft Advisory until 3 PM EDT Monday for ANZ150-152-154. && $$ SYNOPSIS... NEAR TERM...Cempa/Sinsabaugh SHORT TERM...Sinsabaugh LONG TERM...Legro AVIATION... MARINE...
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
629 PM CDT Sun Sep 3 2017 .SHORT TERM... (Through Late Monday Afternoon) Issued at 328 PM CDT Sun Sep 3 2017 Weak cold front has pushed through the forecast area this morning leaving dry and warm conditions for this afternoon and evening. Warm temps will push to near 90 as most areas will see plenty of sunshine with just scattered high and mid clouds south of I-70 and light winds from the southwest. Dry and warm conditions continue into tomorrow with highs into the mid 90s in the St louis area and low 90s elsewhere. The light southwesterly winds will begin to increase late morning into the early afternoon as a new cold front pushes its way into the region. Precip chances increase as front approaches but will remain minimal through this period. Areas to the west of the Mississippi River look to remain capped so any convection will be limited to the eastern CWA. Walsh .LONG TERM... (Monday Night through Next Sunday) Issued at 328 PM CDT Sun Sep 3 2017 (Monday Night) Convective initiation along the front appears probable by early Monday evening. As alluded to by the short-term forecaster above, initiation appears most likely east of the Mississippi River where combination of weaker capping and stronger mid/upper level forcing for ascent will reside. Development further southwestward along the front, particularly across south-central Missouri, is far more uncertain. Some CAMs such as the NCAR WRF and the ESRL HRRR show very little to no development west of the Mississippi River while the NMM and hi-res NAM show a line of storms all the way into western Missouri. Global models are also split, with the NAM/GFS more bullish with the ECMWF not showing much in the way of storms along the front. Leaned a little bit more toward the ECMWF and ESRL HRRR/NCAR WRF as conceptually it makes the most sense. As alluded to above, the further southwest you get, the weaker the mid/upper level forcing along with more of a capping inversion between 700 and 800 hPa. Therefore have highest PoPs across portions of south-central Illinois during the evening hours. Some weakening of the convection is expected late evening into the overnight hours as instability weakens. However, there could be a few strong to severe storms with the frontal passage during the evening before the expected weakening occurs. Slightly better chances of strong to severe storms would be across the Mississippi River where highest PoPs will reside. Further southwest, a more conditional threat will exist. Gusty winds appear to be the primary threat. Cold front is expected to exit the CWA by 0600 UTC, with a band of frontogenetically enhanced showers possible moving from north to south very late Monday night. Should be a gap of dry weather behind the front however and ahead of this potential band of showers. (Tuesday - Next Sunday) Post-frontal showers will remain a threat into early Tuesday, mainly for portions of southeastern Missouri. After that threat passes to the south, see little to no chance of rain through next weekend. Everything remains on track for the well-advertised period of well below normal temperatures behind the cold front. A reinforcing shot of cold air comes in behind a shortwave trough Thursday afternoon/evening. A broad area of anomalously strong high pressure will remain nearly anchored across the central CONUS, aided by confluent flow aloft. Temperatures will run 10-20 degrees below normal, especially at night with a clear sky, light winds, and very low dewpoints. Made very little changes to temperatures for the middle of the week, and lows likely will still need to be nudged downward in future forecasts. Did however slow down the moderation in temperatures late next week into early next weekend. Gosselin && .AVIATION... (For the 00z TAFs through 00z Monday Evening) Issued at 603 PM CDT Sun Sep 3 2017 VFR conditions are expected for the majority of the TAF period. Initially light and variable winds will become southwesterly overnight ahead of an approaching cold front. Southwest winds will gust to near 20 kts after 12z, then diminish and become northerly after fropa. SHRA/TSRA will develop near the front towards the end of the valid TAF period and may affect KCOU/KSTL/KSUS/KCPS after 21z. Kanofsky && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Medford OR
700 PM PDT Sun Sep 3 2017 .DISCUSSION... Smoke is rampant this afternoon with visibilities in most of the west side valleys around or below a mile. High pressure will continue to remain in control through the Labor day weekend and Tuesday bringing abnormally warm temperatures to California and Oregon. Smoke is having very little impact on temperatures pushing towards 100 degrees in locations outside of western Siskiyou county this afternoon, so the concentration of smoke does matter. Look for most areas to under shoot guidance by about 3 to 5 degrees in southern Oregon where as areas near very active fires in Siskiyou county may undershoot guidance by 10 to 20 degrees tomorrow Monday. We tried to make adjustments to high temperatures in western Siskiyou county for Monday to account for the massive smoke concentrations. High pressure will continue to remain in control but gradually break down as tropical storm Lidia travels up the coast of California Tuesday into Wednesday. Right now, we did introduce a slight chance for thunderstorms Tuesday afternoon and evening. There appears to be a healty amount of instability along the Cascade crest, but forcing is really lacking for Tuesday. The best chance for storms will be Wednesday evening as Lidia becomes negatively tilted just west of Eureka California. This should allow for scatted thunderstorms given enough moisture coming up from the south. The other important things to note here is the 0-6 km shear is showing 45 to 55 knots over southern Oregon. In addition, potential instability near the Cascades are around 2200 J/kg. Given these variables, we`ll really have to keep an eye on some potential for severe thunderstorms. Should be interesting to watch. Thursday into the weekend...Eventually a long wave trough will approach Oregon and Washington. The models differ on what exactly will happen, but in general we can expect temperatures to cool off to around seasonal normals with westerly flow. In addition, both models are bringing a dry cold front to the coast around mid day Saturday. This is good news in a few ways because the west flow and the cold front should be cooler and carry some moisture to help fire fighting. In addition, the flow should be strong enough to help with smoke dispersion if we want to believe with what the GFS is showing. The ECMWF doesn`t show as great of a solution with the long wave staying a bit farther north into Washington. In the end, next weekend is a welcome change of pace in the weather. -Smith && .AVIATION...04/00Z TAF CYCLE...Wildfire smoke will limit visibility to less than 2 miles at times west of the Cascades today (including KMFR/KRBG). Visibility will be as low as only a few hundred feet in portions of the lower Klamath River Valley in western Siskiyou County where vertical mixing will be negligible. However, north to northwest breezes will pick up this afternoon in the rest of the west side valleys, which should raise visibility in some areas, but likely not all locations. The northwest winds should bring some thicker smoke east of the Cascades too, which may impact the terminals at KLMT. Visible satellite imagery also shows that the smoke layer is much thicker than the current cloud layer, with the tops of the clouds being obscured by the top of the smoke. aS THE asos ceilometers are reporting ceilings and some are even showing VV am using the reports as a VV designation for the smoke. A shallow marine layer will redevelop north of Cape Blanco for a few hours late tonight into Monday morning with the potential for IFR fog, but confidence in this is moderate at best. Sven && .MARINE...Updated 305 PM PDT Sunday 3 September 2017...Overall, expect light to occasionally moderate northerly winds today through Tuesday morning, strongest south of Cape Blanco on Monday. Relatively low seas can also be expected during this time frame, though seas will be slightly steeper Monday due to the increased wind speeds south of Cape Blanco. Winds are likely to reverse to light southerly Tuesday with seas then expected to become westerly swell dominated. Seas will likely range from 4 to 6 feet at least into early Friday. && .FIRE WEATHER...Updated 230 PM PDT Sunday 3 September 2017...Hot weather will prevail into early next week. Dense smoke shading will occur in some areas, especially western Siskiyou County valleys, portions of southwest Oregon and around the Umpqua Complex, where it will be markedly cooler. A few of the local RAWS sites in the lower Klamath Valley like Dutch Indy, Sawyers Bar and Somes Bar failed to break the strong inversion and only reached the upper 70s for highs Saturday afternoon and it looks like we`ll have similar conditions this afternoon and early this evening. Typically in this type of pattern, these sites would easily reach into the 100s in the absence of smoke. The water vapor image shows high and mid level moisture moving north along the California/oregon coast. At the same time the visible image shows cu starting to build over the Warners and higher terrain in Fire zone 285 and points south and also in portions of Fire zone 624. On a bigger scale, cu is developing and building over the Sierra Nevada crest and northwestward in east to northeast California. The latest HRRR model shows some returns late this afternoon and evening in southeast Siskiyou county and portions of Fire Zone 285. Currently we have a slight chance for thunderstorms mainly over the higher terrain in Siskiyous, but could not rule out a strike or two in parts of Fire zone 285, so we`ll had a slight chance there. Note: Even though we have a slight chance of thunderstorms this afternoon and evening, there`s a chance the smoke may limit the amount of instability, perhaps enough to preclude thunderstorm development altogether, this is especially the case in Siskiyou County. Tonight, east to northeast winds will develop over the upper slopes and ridges of the Coast Range in Curry and western Josephine Counties and also portions of western Siskiyou County. They`ll be gusty at times and combined with poor humidity recovery will cause critical fire weather conditions. Thus the Red Flag Warning remains. The models also suggest Red Flag warning could be met in portions of Fire Zone 621 including the Miller Complex. Overnight relative humidities will be low enough. It will be a close call on the wind. However there`s a higher concern for winds to exceed criteria near and above 4000 feet. Given the sensitivity of the situation, we`ll lean on the side of caution and issue a Red Flag Warning to include portions of Fire Zone 621. With the upper ridge overhead east of the Cascades on Monday, dry, unstable conditions will develop there resulting in the potential for plume-dominated fire with any existing fires. Therefore we have upgraded the Fire Weather Watch to a Red Flag Warning for fire weather zone 624 for this potential including the Jade Creek Fire. Details on all the Red Flag Warnings can be found at RFWMFR. The models have backed off on the thunderstorm potential late Monday afternoon and evening. Moisture and instability are marginal at best and there is little or no trigger. Also if the smoke remains thick enough, this will also limit the amount of instability further. Therefore have removed them from the forecast. There is a slight chance for thunderstorms in northern California and up the Cascades Tuesday afternoon and evening, but I don`t have a good feel of where or if any storms will develop. Wednesday afternoon through Wednesday night could be problematic in terms of thunderstorms. The models are in fairly good agreement showing the remnants of Lidia getting advected into our region Wednesday. At the same time the upper trough (remnants of Lidia) will become negatively tilted as it moves north in response to the upstream upper trough from the eastern Pacific. The pattern that the models suggest could be one that could lead to a thunderstorm outbreak from Wednesday afternoon through Wednesday night. There is even some evidence that we could get an increase in activity overnight Tuesday. Keep in mind this is not a slam dunk as were still a few days out and the details on this are likely to change, but it`s something that we need to be aware of. The focus for thunderstorms should shift north of our area Thursday and we will end up cooler with a few instability showers mainly west of the Cascades. Next Friday into the following weekend could end up cooler if the GFS is right. The ECMWF shows a cutoff low west ofthe Bay area and a less pronounced trough which would suggest warmer temperatures. -Petrucelli && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning from 2 PM to 8 PM PDT Monday for ORZ624. Red Flag Warning from 8 PM this evening to 9 AM PDT Monday for ORZ618>621. Heat Advisory until 11 PM PDT Monday for ORZ021>028. CA...Heat Advisory until 11 PM PDT Monday for CAZ081-082. Red Flag Warning from 8 PM this evening to 9 AM PDT Monday for CAZ280. Heat Advisory until 11 PM PDT Monday for CAZ080. Dense Smoke Advisory until noon PDT Monday for CAZ080. Pacific Coastal Waters...Small Craft Advisory from 11 AM Monday to 5 AM PDT Tuesday for PZZ356-376. $$ CZS/SBN/MAP
Area Forecast Discussion
National Weather Service San Francisco Bay Area
447 PM PDT Sun Sep 3 2017 .SYNOPSIS...The strong ridge of high pressure that brought two consecutive days of oppressive heat to the region is exiting into the Great Basin today. As a result, a cooling trend has begun, however, above average temperatures will persist for the day. In addition, remnants of Tropical Storm Lidia will begin to spread across our region from the south today into Monday and bring a slight chance of showers and thunderstorms to southern portions of the region. Additional cooling is forecast on Labor Day and into the first half of the upcoming workweek. && of 2:00 PM PDT Sunday...Overnight low temperatures were anything but low last night, with many locations reporting overnight lows similar to or higher than their normal daily high temperature. Temperatures have steadily crept upwards from this warm start so far today for most inland locations, with triple digit readings already coming in from the deepest inland locations. Despite this heat, temperatures inland are generally 3-8 degrees cooler than yesterday. Closer to the coast, temperatures are generally 15 to 35 degrees cooler than the same time yesterday. For example, Linda Mar is 33 degrees cooler (112 vs 79) versus the same time yesterday. Despite this cooling, temperatures are still 5-20 degrees above normal today, thus, an excessive heat warning remains in effect for higher elevation locations and a heat advisory remains in effect for all remaining lower elevation locations through the end of the day. The high pressure ridge responsible for the last two days of oppressive heat is now transitioning out of the area and into the Great Basin. To the south, the remnants of once tropical storm Lidia is replacing the hot, dry air mass under the ridge with a more tropical (yet cooler) air mass. The synoptic scale pattern change will bring many changes to the local weather over the coming days. First, the depth of the marine layer will increase gradually which will create a reservoir of cool, moist air for the onshore winds to advect inland. Marine stratus is not anticipated to return on a large scale until at least Tuesday morning, if not later. Second, temperatures will be much cooler, with the cooling trend beginning today and persisting through the week. Near normal temperatures will return by Tuesday, with below average temperatures coming in for the latter half of the week. Third, the tropical air mass will result in humid and hazy conditions and reduced visibility (especially in conjunction with the smoke). Finally, elevated moisture and energy will promote a slight chance of high based convection starting over Monterey and San Benito counties today, before spreading northward to cover most of the area Monday afternoon through Tuesday afternoon. Nocturnal convection may be possible on Monday night if the core remnants of Lidia remain to the southwest as model guidance currently suggests. The initial mid to upper level moisture and energy on the vanguard of Lidia`s northerly excursion from the south is bringing partly to mostly cloudy conditions to most areas of the Monterey and San Francisco Bay areas. KMUX radar is detecting some minor radar returns within this band of elevated moisture, indicative of the energy in that layer and the convective environment that is arriving. Numerous wildfires continue to burn across northern California, southern Oregon, and the Sierra Nevada today. These fires are generating a tremendous amount of smoke, some of which filtered into the region over the last few days. The latest HRRR smoke model suggests that we wont see much additional smoke arrive locally through this afternoon, however, smoke from both the north and from the east is being modeled to arrive beginning this evening and through the night. As a result, Labor Day will see extremely poor air quality for many locations throughout the forecast area. Be sure to check with your local air quality district or the California Air Resources board for more information. && of 4:30 PM PDT Sunday...Upper level low off southern California is bringing mid and high clouds into the area from the south. Stratus continues to stay well away from the area and will provide another night of VFR. Models indicate increasing mid and high level moisture Monday which could possibly bring a few showers to the Santa Lucia mountains and the MRY Bay Area. Vicinity of KSFO...VFR. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR. Cannot rule out the possibility of a shower in the MRY Bay Area Monday. && .FIRE of 8:50 PM PDT Saturday...Very hot and dry conditions persisted across the entire district on Saturday and elevated overnight temperatures are expected again tonight. In addition, expect very poor humidity recoveries in the hills tonight with RH values expected to remain below 30 percent. However, winds overnight are forecast to be light. Therefore, will allow the Red Flag Warning to expire at 9 pm this evening. Even though the Red Flag Warning will expire this evening, fire weather concerns will continue through at least Sunday evening. Temperatures will be trending downward starting tomorrow, but inland areas and the hills will remain hot and dry. Also, southerly winds will begin to increase across the far southern portion of the district late Sunday and then across most of the rest of the district on Sunday night. Moderate and gusty southerly winds are expected in the hills and locally in the valleys on Sunday night. However, relative humidity values are forecast to increase significantly on Sunday night. Also, increasing moisture from the remnants of Tropical Storm Lidia will result in a slight chance of showers and thunderstorms beginning in the southern portion of the district by Sunday afternoon. These chances will remain across the south through Monday morning. Shower and thunderstorm chances will then advance northward into at least the southern half of the San Francisco Bay Area by Monday afternoon and evening. When thunderstorm chances first develop late on Sunday, the sub-cloud layer will still be very dry and so conditions could be favorable for dry lightning across Monterey and San Benito Counties. But with time the lower levels should moisten and any thunderstorms that develop from Sunday night onward will most likely be accompanied by wetting rains. && .CLIMATE...The following is a list of daily record high temperatures for the next 3 days at the selected cities. San Francisco Bay Area....Sun Sep 3 ..........................Temp/Year ...............Kentfield 104/1950 ..............San Rafael 104/1950 ....................Napa 105/1950 ......San Francisco Dtwn 92/1961 ...San Francisco Airport 93/1961 .........Oakland Airport 95/1961 ................Richmond 89/2004 ...............Livermore 115/1950 ...........Moffett Field 93/1961 ................San Jose 99/1950 ..................Gilroy 104/2002 Monterey Bay Area....... .................Salinas 94/1961 .........Salinas Airport 94/1961 ...............King City 103/1955 The following is a list of All-time record high temperatures for the selected cities. Note the period of record for each individual site will vary from one to the other. San Francisco Bay Area....All-Time Record High ..........................Temp Date ...............Kentfield 112 Jul 11 1913 ..............San Rafael 110 Jun 15 1961 ....................Napa 113 Jun 14 1961 ......San Francisco Dtwn 106 Sep 01 2017 ...San Francisco Airport 104 Sep 01 2017 .........Oakland Airport 104 Jun 14 1961 ................Richmond 107 Sep 15 1971 ...............Livermore 115 Sep 03 1950 ...........Moffett Field 106 Sep 01 2017 ................San Jose 109 Jun 14 2000 ..................Gilroy 115 Jun 15 1972 Monterey Bay Area....... .................Salinas 106 Sep 14 1971 .........Salinas Airport 105 Sep 01 2017 ...............King City 113 Sep 02 1955 && of 4:45 PM PDT Sunday...A southerly flow will persist over the coastal waters through Monday. Remnants of Tropical Storm Lidia will bring a slight chance of showers and thunderstorms to the southern waters early this week. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...Heat Advisory...CAZ006-505-506-508-509-513-516>518-528>530 Excessive Heat Warning...CAZ507-510>512 && $$ PUBLIC FORECAST: DRP AVIATION: W Pi MARINE: Sims CLIMATE: Rowe/Dykema/BAM FIRE WEATHER: Dykema Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Paducah KY
640 PM CDT Sun Sep 3 2017 .UPDATE... Issued at 640 PM CDT Sun Sep 3 2017 The AVIATION section has been updated for the 00Z TAF issuance. UPDATE Issued at 343 PM CDT Sun Sep 3 2017 Enhanced CU taking on more definition near KFAM moving SE. The airmass has become slightly unstable in this area, with lapse rates slowly steepening. One tiny return perhaps NW of our area. There is some convergence in this region as well. The HRRR is not completely in sync with placement. But it is still suggestive of isolated shra (maybe some lightning) through early evening. An update to the very near term portion of the forecast may be required to add the isolated mention. && .SHORT TERM...(Tonight through Tuesday night) Issued at 239 PM CDT Sun Sep 3 2017 Still monitoring weak boundary from KOWB to KSAR for potential very isolated convection through the evening. Until something develops, will leave PoPs silent 10`s for now. Otherwise quiet tonight. Breezy and quite warm Labor Day. May be near Lake Wind Advisory criteria for some areas. Night crew can determine the need. Convective chances arrive with front Monday night and progress south Tuesday, over Tuesday night and cooler with high pressure building in. Used a GFS/EC/NAM blend for timing. .LONG TERM...(Wednesday through Sunday) Issued at 239 PM CDT Sun Sep 3 2017 High confidence in drier and cooler conditions for Wednesday and into the next weekend for the extended forecast period. Regionally blended model guidance a little warmer than expected, so weighted toward EKD MOS, as well as the ECMWF/NAM-WRF guidance for temperatures. Given the drier air mass, diurnal temperature will likely remain in the 25-30 degree. No precipitation expected through extended period. Will be interested to see how NHC handles Irma`s track, given some of the varied model solutions from the Canadian, GFS, and ECMWF for the following week. && .AVIATION... Issued at 640 PM CDT Sun Sep 3 2017 A band of showers has developed along a weak surface boundary. The showers are comfortably south of KEVV and KOWB and are expected to dissipate this evening before reaching KCGI or KPAH. The boundary is expected to wash out overnight as pressures lower across the region in response to a rather strong storm system moving southeast toward the Upper Midwest and Great Lakes. The entire area should see light south winds developing overnight. Winds will veer to southwest with mixing Monday morning, and will become gusty by afternoon. Strongest winds will be at KEVV and KOWB where gusts 20-25kts are expected. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS AVIATION...DRS
Area Forecast Discussion
National Weather Service Reno NV
356 PM PDT Sun Sep 3 2017 .UPDATE... Low level instability associated with very warm temperatures and weak low level boundary forcing is helping to development showers and a few thunderstorms north into western Lassen County late this afternoon. A few cells are also trying to develop in far eastern Churchill County. Will update to account for some isolated development into the early evening hours. && .PREVIOUS DISCUSSION... /Issued 1259 PM PDT Sun Sep 3 2017/ SYNOPSIS... High pressure will provide unseasonably hot temperatures and light winds into the early part of the work week. Areas of wildfire smoke and haze will occur as well. Moisture will increase each day through midweek with showers and thunderstorms spreading north across the Sierra Monday and Tuesday and then into western Nevada Wednesday. A few stronger storms are possible Wednesday afternoon and evening. SHORT TERM... For this afternoon/evening...observed and modeled soundings show a cap to deep convection so thunderstorms are not expected. Latest runs of high-resolution HRRR model do show a few showers possible through this evening for Mono and Mineral Counties and near the crest of the Sierra as far north as the Tahoe Basin. For the upcoming work week, no change to the expected evolution of slowly increasing moisture and atmospheric instability over the eastern Sierra and western Nevada through Wednesday. This evolution means the potential area for isolated showers and thunderstorms for Monday afternoon/evening expands across Mono County into western Mineral County and also north across the Tahoe Basin. Storms are expected to be isolated but a few new fire starts due to lightning are possible. For Tuesday afternoon/evening, an offshore low becomes a bit more of a factor and the slight chance for thunderstorms extends north to the Oregon border and west into central NV. However, southeast flow will still focus the best chances over the Sierra. Wednesday looks like the peak day in terms of intensity and coverage of thunderstorms. As the offshore low moves north along the coast towards the Pacific Northwest, there is potential for weak upper impulses to track north from the Tahoe Basin north across Plumas/Lassen/Modoc/northern Washoe Counties. These impulses could aid in developing a few stronger thunderstorms in those counties. The south to southeast steering flow across the Sierra, western NV and northeast CA also strengthens -- creating an environment that increases the potential for (1) new fire starts because quicker moving cells means less time for a wetting rain over any lightning strikes, and (2) a few stronger storms with up to 1-inch hail, gusty outflow winds and/or flash flooding possible (especially over burn scars and if cells train along the same path). Another possible fire concern for Wednesday is breezy winds: a late day zephyr could create westerly gusts 25-30 mph which could fan any existing or new fire starts, especially along the Sierra front range. JCM LONG TERM...Thursday through Sunday... A stable air mass is expected to begin moving in from the southwest on Thursday, with weak southwest flow aloft bringing in drier air. However, lingering afternoon/evening thunderstorms may still be possible across Mono county and in western NV generally east of highway 95. Friday and Saturday are looking to be drier as the southwest flow continues to push moisture north and east of the area. By Sunday, there is some indication that an offshore low could develop and bring a return of moisture and thunderstorms to the area. Recent model simulations have varied greatly on this feature, and for now we are forecasting a slight chance for thunderstorms across the Sierra and western NV for Sunday afternoon and evening. JCM AVIATION... Areas of Haze and smoke from area wildfires may cause some slight reductions in visibility, especially slantwise visibility for landings and takeoffs. These reductions will be most prominent late in the night and during the morning before heating allows for smoke to mix/vent. Otherwise, VFR conditions will persist. A general increase in afternoon cumulus is expected as moisture works slowly northward around upper ridge. Conditions remain too stable for more than isolated showers along the Sierra this afternoon but instability will increase Mon-Wed with isolated thunderstorms in Mono County Monday spreading farther north each day. Right now Wednesday appears to be the best day for coverage and intensity of storms. && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...