Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/30/18

Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
934 PM CDT Sat Sep 29 2018 .DISCUSSION...Water vapor imagery shows the upper trough axis from southwest Texas into northern Coahuila. Shower activity has lingered this evening over the Brush Country in weakly divergent flow aloft over this area. But showers have shown a diminishing trend over the last hour. Will keep low chance PoPs for the rest of the evening for western Brush Country. Also, along the coast where low level convergence is slowly increasing and moisture remains high in this region. Lowered PoPs to slight chance across the northern counties for rest of this evening. Latest HRRR and 12Z HREF show convection should increase in low level convergence zone along the coast overnight, similar to last night. Weak divergence aloft ahead of the slow moving upper trough will aid in development also. No changes to the PoP forecast for overnight. Wind speeds have lowered along the coast to below SCEC but still in that range over the Gulf waters. && .PREVIOUS DISCUSSION... /Issued 649 PM CDT Sat Sep 29 2018/ DISCUSSION...See Marine section for update wind speeds to SCEC range for this evening for most of the coastal waters. See Aviation section for 00Z TAFs. AVIATION...Isolated convection will continue for a couple of hours from northwest of Beeville to near Laredo. High resolution models again depict activity will diminish for the latter part of the evening hours. VFR conditions will exist except for MVFR ceilings/vsbys near convection this evening. MVFR ceilings are expected to develop over the coastal plains from 06-08Z and over the Brush Country toward daybreak. Expect convection will again develop near coastal convergence zone during the overnight hours with MVFR vsbys expected with convection. IFR vsbys will be possible in heavy rain with thunderstorms. The activity will move inland during the morning hours and become more scattered by the afternoon with activity reaching LRD area by 16Z Sunday. MARINE...Onshore flow has been elevated after convection over the coastal waters has diminished. Wind speeds will be in the SCEC range for most of the evening for the coastal waters except for the northern bays. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 73 85 75 87 75 / 50 60 40 40 20 Victoria 72 84 71 87 73 / 40 60 40 50 20 Laredo 72 84 73 89 74 / 30 50 30 30 20 Alice 72 85 73 88 74 / 30 60 20 40 20 Rockport 74 83 75 86 77 / 60 70 50 50 20 Cotulla 71 85 71 88 73 / 20 50 20 30 10 Kingsville 73 85 73 88 75 / 40 60 30 40 20 Navy Corpus 75 85 77 86 77 / 60 70 50 40 20 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ TMT/89...SHORT TERM
Area Forecast Discussion
National Weather Service Duluth MN
634 PM CDT Sat Sep 29 2018 .SHORT TERM...(This evening through Sunday) Issued at 328 PM CDT Sat Sep 29 2018 The FGEN generated area of precipitation has been diminishing some in strength this afternoon per area radars and the latest version of the RAP shows weaker FGEN into the evening compared with earlier model runs. We still expect some precipitation across the southern third of the CWA this evening, some of which could be a rain and snow mix. However, since the precipitation rate may be weaker than earlier, more may fall as rain versus snow as observed earlier. A trough and shortwave will also move through the area tonight providing more lift for light precipitation and we have the highest POPs over far northeast Minnesota. Lows tonight will be in the lower to middle thirties for most areas. As the trough departs on Sunday, high pressure will build in briefly and bring an end to any lingering light precipitation. Highs will be in the mid forties to around fifty. .LONG TERM...(Sunday night through Saturday) Issued at 328 PM CDT Sat Sep 29 2018 Sporadic precipitation chances through the extended with a warm up mid week followed by a return to cooler than normal temperatures late in the week heading into the weekend. A weak high will build over northern Minnesota and northwest Wisconsin Sunday evening into Monday morning. The high will quickly slide into Ontario while a trough lifts from the Northern Plains into the Upper Mississippi River Valley on Monday. Despite the high, skies will remain partly to mostly cloudy with increasing cloud cover heading into Monday morning. Most areas will see rain become likely Monday morning. Initially precipitation will start out as all snow along the International Border down to the Eveleth area. By mid morning precipitation will change over to all rain. The low associated with the trough will quickly exit the region and precipitation should come to an end by Monday evening. Sunday night lows range from the upper 20s to the upper 30s. Highs on Monday will be in the 40s. High pressure will nudge itself into the region through Tuesday from Quebec. Flow aloft will gradually become southwesterly which will advect warm 850 hPa air into the region. By 00Z Wednesday 850 hPa temperatures will range from +3 degrees Celsius to +15 degrees Celsius. Skies will remain mostly cloudy across the region. Tuesday highs range from the upper 40s to the upper 50s. A more substantial trough will dig into the Northern Plains from British Columbia Tuesday evening into Wednesday morning. At the surface this will develop a broad low over the Northern Plains and northern Central Plains. The warm front associated with the system will lift through late Tuesday night through Wednesday afternoon. This will bring us the warmest readings of the extended with highs ranging from the mid 50s along the International Border to the low 70s across southern portions of northwest Wisconsin. The latest ECMWF and GFS guidance show a few hundred to nearly 1000 J/kg of CAPE over eastern portions of Minnesota and northwest Wisconsin. Decided to introduce thunderstorm chances, but somewhat skeptical this much instability develops with as much cloud cover in the forecast. The low will exit the region Wednesday evening into Thursday morning as the trough lifts into Ontario. High pressure will briefly build in on Thursday before another round of precipitation moves in on Friday. Flow aloft will become northwesterly which will advect cold air into the region and bring the cooler temperatures back to the Northland. Highs on Friday range from the low 40s to the low 50s. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 631 PM CDT Sat Sep 29 2018 VFR with light winds and isolated light precip - mainly in the form of rain. Expect MVFR to become more prevalent overnight as low level moisture advects into the region. No IFR in TAFs but it may be possible especially in areas where precip has been occurring today. A return to VFR Sunday. && .PRELIMINARY POINT TEMPS/POPS... DLH 35 49 38 44 / 40 10 10 60 INL 35 45 30 47 / 50 0 0 20 BRD 36 50 38 47 / 20 10 20 60 HYR 36 51 39 48 / 40 10 10 60 ASX 37 51 39 47 / 50 20 10 60 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ SHORT TERM...Melde LONG TERM...WL AVIATION...Wolfe
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1032 PM EDT Sat Sep 29 2018 .SYNOPSIS... Forecast will be dominated by high pressure with some chance for isolated showers at times over the mountains. Winds will be light, and temperatures will remain above normal and humidity will remain unseasonably high. && .NEAR TERM /THROUGH SUNDAY/... As of 1015 PM EDT Saturday: Updated pops again to increase along the Blue Ridge. Showers have anchored on the terrain and while the gauges we have up there are reporting only about 1" in the last 3 hours, some radar estimates are indicating upwards of 2" and so certainly isolated locations have received more. With the anchoring on terrain, issued an SPS earlier but opted to do a Flood Advisory and will continue to watch rates. HRRR not doing a great job with this convection and so not sure if its diminishing trends are to be believed. Otherwise, lower clouds should be able to reconsolidate and become widespread again with areas of fog as well. Sunday morning minimum temperatures will be warm for late September, on the order of 10 deg F above normal. Morning clouds will give way to mixed sun and developing shallow convective clouds as Sunday wears on. The llvl flow will remain weak from the east to southeast as ridging aloft builds atop the SE CONUS. At this point, there remains the possibility of isolated diurnally fired tstms limited to mainly within the axis of high blyr dwpts acrs the sw cwfa and into the mtns. Maximum temperatures should be similar to today, slightly above normal. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... As of 2pm EDT Saturday: Short term forecast is dominated by a flat ridge over the South that changes little Monday and Tuesday. This will lead to continued above normal temperatures and low chances for precipitation. Surface ridge is also fairly stable through Monday and Tuesday, running northeast to southwest well east of the Appalachians. Surface ridge is far enough eastward to limit cold- air-damming effects, but easterly surface flow is expected Sunday evening, becoming more southeasterly Monday night as ridge moves a little farther eastward. Winds should be fairly light in any case, at 5 to 10 kts. Easterly to southeasterly flow will keep some Atlantic moisture in the area, supporting dewpoints, and giving low temperatures 10 degrees above normal. Highs will run 5 to 10 above normal. Forecast soundings show that, despite decent boundary layer moisture, mid to upper levels are warm, and the atmosphere is well- capped, leading to practically no chance of convective activity. Only chances for significant precipitation Monday and Tuesday are isolated showers in the mountains, where upslope low-level flow may be sufficient for some isolate, though weak, showers. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... As of 2pm EDT Saturday: Upper ridge over the South remains the dominant feature Wednesday through Friday. A weak disturbance that crosses the top of the ridge (and has the strongest dynamics well north of the area) may enhance changes for precipitation over the mountains Wednesday evening, but soundings are otherwise forecast to remain capped and convectively stable. Once this disturbance passes, the ridge recovers on Thursday what little strength it lost, and even strengthens late in the week. Surface ridge will remain well east of the mountains, giving continued fairly light winds, and continued southerly to southeasterly flow that will keep dewpoints elevated. The result will be continued low chances for precipitation with unseasonably humid and warm conditions, with highs 10 degrees above normal and lows 15 degrees above normal. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... At KCLT and elsewhere: Still not much in the way of convection near any of the TAFs but KCLT, so will keep VCSH there through 02z. The moist easterly flow will continue overnight and expect another round of MVFR cigs developing in the next few hours, dropping to IFR in most places overnight (KCLT may remain MVFR). Vsby at KAVL likely to drop to LIFR, and cannot rule out at least brief LIFR cigs at all but KCLT. Slow improvement after daybreak Sunday, and though isolated convection is possible again Sunday afternoon, not enough to include in any TAFs at this point. Outlook: Drier conditions are expected from Monday thru at least midweek, as high pressure dominates over the Southeast. Confidence Table... 02-08Z 08-14Z 14-20Z 20-00Z KCLT High 100% High 83% High 83% High 100% KGSP High 97% Low 49% Med 69% High 100% KAVL High 82% Med 76% High 88% High 89% KHKY High 95% Low 59% High 80% High 100% KGMU High 97% Med 63% Med 70% High 100% KAND High 98% Med 67% High 93% High 100% The percentage reflects the number of guidance members agreeing with the scheduled TAF issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ SYNOPSIS...TS NEAR TERM...CSH/TDP SHORT TERM...WJM LONG TERM...WJM AVIATION...TDP
Area Forecast Discussion
National Weather Service Jacksonville FL
743 PM EDT Sat Sep 29 2018 .UPDATE...Radar imagery shows a primary convective cluster nearing our northwestern counties, with no convection ending everywhere else. HRRR shows cluster continuing a few hours over our northwestern counties, then fall apart. Have adjusted hourly POP/Weather grids to reflect this. Otherwise clear to partly cloudy skies with low temperatures in the lower 70s well inland, mid 70s I-95 corridor, upper 90s coast. && .AVIATION...VFR conditions next 24 hours. Latest guidance is not showing much in the way of potential for fog or low clouds...though patchy shallow fog possible around dawn near some TAF sites. && .MARINE...Onshore flow and long period swell will continue to build Sunday into Monday time frame. East winds 10-15 knots and seas 3-6 ft into early Sunday with Small Craft Exercise Caution (SCEC) headlines tonight. E-NE winds increase to 15-20 knots by Sunday Night into Monday with combined seas into the 4-8 ft range and expect will eventually need Small Craft Advisory (SCA) flags for the offshore waters and SCEC headlines for the nearshore waters that will continue well into next week as high pressure builds north of the waters. Rip Currents: Long period swells will continue to build and expect High Risk of Rip currents for all beaches on Sunday into early next week. Surf/Breakers will build into the 3-5 ft range by late Sunday into Monday. && .PRELIMINARY POINT TEMPS/POPS... AMG 72 88 70 87 / 40 60 10 40 SSI 77 85 75 84 / 20 50 60 70 JAX 73 88 74 85 / 10 30 40 70 SGJ 77 87 76 85 / 10 20 50 70 GNV 72 91 72 89 / 10 20 10 50 OCF 71 92 72 90 / 10 10 0 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Wolf/Zibura/Sandrik
Area Forecast Discussion
National Weather Service Medford OR
719 PM PDT Sat Sep 29 2018 .DISCUSSION...After a long, hot, dry, fiery, and smoky summer, rainfall has reached the Rogue Valley! The last measurable rainfall was a meager 0.01 inches on July 15, and amounts this evening in the Rogue Valley have ranged from a few hundredths of an inch to 0.29 inches of rain. This came from one of a handful of thunderstorms in the forecast area...developing over Southern Jackson County and moving northward towards Butte Falls. Cloud to ground lightning has been minimal so far, as expected, with about 28 strikes so far, mostly in Douglas County. Other areas west of the Cascades have received generally less than a tenth of an inch of rain from isolated to scattered showers. Models show more rainfall through the evening, mainly from Jackson/Siskiyou/Eastern Douglas County and eastward. Many areas will see a quarter inch or more of rainfall through Sunday morning as the upper low opens up and pushes eastward. We`ve increased precipitation chances tonight, but amounts still look good. Please see the previous discussion below for more details on the next chance of rain. && .AVIATION...For the 30/00Z TAFs...Along the coast and over the coastal waters...VFR with areas of MVFR cigs in showers with isolated thunderstorms will prevail into this evening, then the MVFR cigs will spread with local IFR cigs/vsbys near the coast. Any thunderstorms will end this evening. Showers will end Sunday morning and conditions will improve to VFR by Sunday afternoon. Over the remainder of the area...VFR conditions in showers and isolated thunderstorms with areas of higher terrain obscured will prevail into this evening. The thunderstorms will end this evening but showers will continue into Sunday morning with isolated MVFR cigs developing. The showers will end Sunday morning, and conditions will improve to VFR by Sunday afternoon. && .MARINE...Updated 700 PM PDT Saturday 29 September 2018...Showers and even an isolated thunderstorm are possible through this evening as an upper level low moves through the area. South winds will persist through Monday, strongest Sunday afternoon and evening. Winds will approach small craft advisory strength, but should remain below criteria. Seas will remain below criteria as well, but could be a bit chaotic due to a southerly wind wave combined with an 8 second northwest swell. Winds will return to northerly by early Tuesday, but will remain below small craft conditions. Seas will also remain below criteria through mid-week, then begin building as northwest swell moves into the waters Wednesday into Thursday. /BR-y && .FIRE WEATHER...Updated 200 PM PDT Friday, 28 September 2018...The upper low that is expected to bring our first wetting rain in quite some time is knocking on our doorstep. Showers are already moving up along the California coast with Arcata already reporting 0.09 of an inch of precipitation in the past 3 hours. This area of showers should hold together enough as it moves north and affect western Siskiyou County later this afternoon. At the same time gusty winds are already occurring in the Shasta Valley with the strongest winds near Weed. Winds are also increasing over the ridges west of the Cascades and portions of the eastside. The good news is relative humidity is higher compared to yesterday at this time. Gusty winds will continue into this evening, but the combination of winds and relative humidity will remain below Red Flag Criteria. Despite this, we`ll continue to headline the winds and low relative humidity in the fire weather forecast. There`s good agreement showers will start to increase in coverage between 4-6 pm pdt with scattered to numerous showers and isolated thunderstorms starting between 6-8 pm pdt mainly west of the Cascades. There may be enough instability for scattered thunderstorms from about Crater Lake north, but this will be accompanied by moderate to occasionally heavy rainfall at times. Given the convective nature of precipitation, rainfall amounts could vary greatly depending on where your at. The best chance for 0.25" or more rainfall is expected along and near the Cascades, Siskiyous, and Marble Mountains. Wetting rainfall (>0.10") is also likely across much of southern and western Siskiyou County, southeastern Josephine County, Jackson County, eastern Douglas County, and portions of western and northern Klamath County. Note the rainfall amounts mentioned are expected from this evening until around midnight. Showers will continue into the overnight period as the upper low moves overhead. However the focus for heavier precipitation will shift east, primarily from the cascades east. Altogether, we expect lightning coverage to be isolated, except from around Crater Lake NP northward including portions of FWZs 623, 617, 624, and 611, where scattered coverage is expected. Due to the expectation of temperatures 15-25 degrees cooler than yesterday and RHs 20-50% higher, and because any thunderstorms that do occur will produce significant wetting rainfall, this does not appear to be a RFW lightning event. While isolated thunderstorms are possible anywhere from the Cascades west to the Coast Range, the greatest chance of them is in a swath from western Siskiyou County north- northeastward into northern Klamath County. The upper low will weaken as it moves overhead tonight, then will shift east of the area late Sunday morning and afternoon. Could not rule out showers Sunday morning, but most should be confined to the Cascades east. Sunday afternoon looks dry as upper ridging builds into the area with temperatures similar to today. There`s fairly good agreement among the models showing another upper low phasing in with a northern branch upper trough on Monday. Several impulses are expected to move from southwest to northeast into our area on Monday over northern California and possibly southern Oregon so we could pick up a bit more rain on Monday. The upper low will continue to move south just west of the Bay area in California Tuesday. Ahead of the low the models show precipitation moving from south to north in northern California and this combined with upslope flow could enhance precipitation rates in the favorable upslope areas near Mount Shasta. However this is not completely clear due to differences in the details depicted by the models. Oregon should stay mainly dry Tuesday, but isolated showers could slip though near the Siskiyous. Beyond Tuesday, the operational models show the the upper ridge portioned near 150w with a northwest flow along with upper level disturbances moving southeast in the northwest flow over our area. it`s not a pattern that is conducive to significant rain. In fact depending on exactly where the upper ridge to the west sets up, we could actually stay mainly dry with not much more than hit and miss light showers. Of note, the GFS ensemble means show a general troughiness over our area with the upper ridge centered around 150W and another upper ridge in the southeastern U.S. One thing we can say with confidence is no significant warm up is expected for most of next week. Precipitation chances will have to be monitored and confidence on the specifics should increase as we get into next week. -Petrucelli && .PREV DISCUSSION... /Issued 303 PM PDT Sat Sep 29 2018/ DISCUSSION...Winds have gusted to around 40 mph in the southern end of the Shasta Valley, and over high terrain east of the Cascades, including Summer Lake. Showers are on tap for later today and tonight. While at the time of this writing there have been no rainfall observation in the Medford CWA yet, much of Humboldt County has received around 0.10" today and radar shows a steady band of showers approaching western Siskiyou County, so it`s only a matter of time. The main upper low driving this weather change looks to be centered near 40.5N/125.5W and will continue trekking northeastward over the next 12 hours. Expect showers to develop from southwest to northeast, first in western Siskiyou, then coverage should spread into the southern Josephine and Jackson Counties, then up to the Umpqua Divide and the Cascades. Higher terrain will receive more precipitation than lower lying areas due to the convective nature of this system, but the duration and fact that the bulk of precipitation over the west side is expected at night (thus with higher RH at lower levels) should set the Rogue and Illinois Valleys to accumulate around 0.10" to 0.20"... while ridges in the Cascades and Siskiyous could see closer to a half inch. HiRes models continue to indicate potential for a quarter inch of precipitation in parts of the Upper Klamath Basin, so decided to maintain that part of the forecast, with some reservations. Most GEFS members are well below, but the HRRR has been depicting the track of the low better than the GEFS, so opted to lean more towards the HRRR. Precipitation will probably start within the next few hours in the southwestern portion of the forecast area (western Siskiyou County) and over the highest peaks of the Cascades, then expect the bulk of precipitation before midnight for the Cascades and westward roughly before midnight, then later heavier precipitation will be more focused east of the Cascades. It`s possible that some of the showers will produce lightning strikes. The main threat for lighting will be in the Cascades and west of the Cascades, though it can`t be ruled out east of the Cascades. While thunderstorms can produce erratic winds, showers should mostly mitigate the threat of fire starts from lightning strikes. Of note, since this will be the biggest rainfall in months, safe driving practices will be important. Oil buildup from the past several months will cause slippery roads when rain begins to fall, and likely increased accident rates. Take it slow on the roads today and tomorrow, especially when traveling around corners and going downhill. Sunday will be a bit of a transition day, with light showers tapering off by the afternoon and brief ridging. Clouds will largely clear up by the afternoon and high temperatures will be near normal. Monday into Tuesday, another low will approach the central California coast, bringing potential rain to northern California. There`s uncertainty as to how far north precipitation will propagate, so stuck with chance and slight chance pops for the time being, but if nothing else expect substantial cloud cover Monday into Tuesday. Cloud cover should suppress Monday highs a few degrees, and keep overnight lows Monday night into Tuesday morning a few degrees warmer than the previous Monday morning. The forecast becomes more uncertain Wednesday into Thursday... the latest few runs of the EC and GFS show the low continuing eastward Wednesday with possible wrap-around showers over northeastern California. Then the low will fill as it heads into the Great Basin and a dirty ridge will build from the north, bringing a slight warm up towards the end of the week. -McAuley && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...None. $$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
904 PM PDT Sat Sep 29 2018 .SYNOPSIS...Scattered showers will continue across the far North Bay overnight through Sunday morning. Otherwise expect dry and seasonable weather for the Bay Area to finish out the weekend. The next front will slowly approach on Monday with increasing clouds and southerly winds. Rain showers will develop Monday night into Tuesday for most areas and possibly linger into Wednesday for the South Bay and Central Coast. Dry weather should return late in the week and into next weekend. && of 9:04 PM PDT Saturday...Upper low now over far northern California brought some rain to the North Bay today into this evening. For the most part rain appears to have ended but lots of left over clouds remain along with lingering spotty showers possible overnight. Was considering removing the morning shower chances in the North Bay with the 00z nam fairly dry. However the rap and hrrr mesoscale models indicate shower chances will continue across Marin/Sonoma on Sunday morning in cyclonic onshore flow. However the rest of the Bay Area should enjoy partly cloudy skies with highs mid 60s to mid 70s to wind out the weekend. Attention will quickly turn to next incoming trough. Monday should be mostly dry as the front slowly approaches from the west with increasing southerly winds and thickening clouds. However a nice day overall with highs in the 70s and some downslope southeast flow possible across the region with no marine layer. Will let mid shift peruse over all the 00z guidance but may need to cut back on the Monday pops given the incoming and slower west trajectory of the upper low. Light rain should develop most coastal areas late Monday night and biggest impacts would be for a wet Tuesday morning commute. The 00z nam then shows the trough dropping south along the Central Coast and tapping into some deep moisture with a possible 1 inch tpw plume setting up over the Central Coast Tuesday night into early Weds. Will await the full gfs and ecmwf before fine tuning those details. 18z gfs suggests drying beyond that but the 12z euro did keep the trough axis too close for comfort. The new 00z euro will be arriving shortly and will update the long range overnight based on that input. && .DISCUSSION as of 2:00 PM PDT Saturday... Rain has returned to the forecast area due to the arrival of a cool, moist and somewhat modest 559dm 500mb upper level low. This upper low is currently centered less than 50 miles northwest of Cape Mendocino and is set to move ashore north of the Cape over the next few hours. Earlier in the week, this upper low was conjoined with a high pressure circulation several hundred miles offshore in a Rex block, a feature which acts as a barrier in the mean westerly atmospheric flow. Over the last few days, the Rex block broke up, allowing for this low pressure system to advance towards the California coastline. This storm system was forecast to mainly impact the North Bay, and so far it has done so. It is fair to say that previous forecast precipitation amounts underestimated this system, given that Stewarts Point 0.21" (nearly all between 11am and noon), 0.18" at both Point Reyes seashore and Sea Ranch, 0.17" at Cazadero, and 0.15" at Mt Tamalpais. Locations east of the Sonoma coastal range in the North Bay have picked up lesser amounts -- to the range of a few to several hundredths. Additional lighter rain showers accumulations are possible over the next 24 hours as this upper low transitions through Northern California. Otherwise for today, the positioning of this upper level low has mixed out the marine inversion due to cooler air aloft. The Fort Ord and Bodega Bay profilers showed the the marine layer pushing well beyond 3500 ft in depth earlier today, generally a sign the marine inversion is no longer present to cap the cooler, moister air in the marine layer. Temperatures are running a bit higher than forecast and versus 24 hours ago given slightly weaker cold air advection and less cloud coverage than previously anticipated. Temperatures should level off sooner this afternoon than yesterday, however, as the upper low moves closer to the area. For tomorrow, the upper low will exit the area, allowing for slight warming by the afternoon. More widespread rainfall is forecast to arrive early in the work week as a cooler, wetter, more organized low pressure system advancing towards the region. Short and medium term forecast models are in good agreement that widespread rainfall is possible for the area, however, they continue to show a moderate amount of disagreement regarding the amount. Broadly, first expect to see lighter warm sector rain showers to precede the heavier rainfall. These lighter showers will move ashore as early as Monday morning through early Monday afternoon, bringing light accumulations. So far, the highest skill/resolution models show the heavier rain band beginning to move ashore over the North Bay overnight Monday before spreading southward into Tuesday morning. Models show some disagreement regarding the orientation of the main frontal rain band, with some models suggesting a more west to east aligned while others show the more typical northwest to southeast line. As for amounts, the afternoon forecast package will continue to feature a slightly wetter forecast -- with local amounts in the higher terrain ranging from 0.75" to around an inch, 0.25 - 0.66" for most urban locations (with lesser amounts in rain shadowed locations and more on wet side of terrain/closer to the coast), and less than 0.20" for the drier remote locations inland areas. One potential snag to watch for is how much the trajectory of the upper low changes as a secondary vorticity maxima enters and rounds the base of the trough -- which could cause the trough to dig farther southward while offshore instead of pushing inland. This storm is expected to be in the beneficial range as far as impacts go -- mainly serving to moisten up the extremely dry fuels (dead trees, grasses, ground detritus, etc) that often spark late fire season concerns. The new water year begins October 1st, which may coincide with the first rainfall of the season. The 2017-2018 water year came in below seasonal normal, with most climatological stations in the region reporting somewhere between 66-80% of normal rain accumulations. Last year, San Francisco picked up its first measurable rainfall on October 19th, at 0.29". The current forecast calls for closer to 0.50" for San Francisco over the first two days of the upcoming water year. This forecast value will likely continue to change as the storm system comes into better focus over the next couple of days. && of 5:57 PM PDT Saturday...Light rain, low ceilings, IFR carrying over into this evening and overnight over the North Bay. Visibilities quite likely lowering to LIFR-VLIFR in the North Bay due to fog, mixed with occasional light rain, tonight and early Sunday morning. VFR-MVFR elsewhere tonight and Sunday. Vicinity of KSFO...VFR. Wind near 10 knots from the south and southwest. Runways likely to remain dry. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR. South to southwest winds becoming light southeast tonight. Onshore wind resumes by Sunday afternoon. && of 08:45 PM PDT Saturday...Chances of showers will continue across the waters due to an upper low that will be making its way into the Pacific Northwest tomorrow. Southerly winds will persist through Tuesday as a second upper low moves through the waters and exits to the south. Once the upper low passes, winds will shift back out of the northwest. More widespread showers are forecast Monday night and Tuesday that will be associated with that second upper low. Expect southerly swell generated by Hurricane Rosa to increase through Monday. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...None. $$ PUBLIC FORECAST: RWW AVIATION: Canepa MARINE: Canepa Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Pittsburgh PA
936 PM EDT Sat Sep 29 2018 .SYNOPSIS... Clouds will diminish as evening approaches. Dry and warmer weather is expected for Sunday and the start of the new week. && .NEAR TERM /UNTIL MIDNIGHT TONIGHT/... Mid clouds are pushing eastward across Ohio in zonal flow aloft. These clouds continue to erode somewhat as they move east. 00Z KPBZ sounding supports this, with dry air above 850 mb. Think that clouds will eventually increase more over the northern CWA as opposed to the south, which is suggested by HRRR soundings and satellite trends. Have tailored the sky grids to show a north-to-south gradient. Left in patchy valley fog for now, although this could become iffier, especially north of Pittsburgh, depending on eventual cloud coverage. Areas that remain clear will remain susceptible due to cooler air over the relatively warmer rivers. Temperatures will end up near climatology for the most part. && .SHORT TERM /SUNDAY THROUGH MONDAY/... Due to an expanding ridge Sunday into Monday, precipitation chances in our area will remain low; rainfall will be mainly focused to the north of Lake Erie. However, above climatological temperature averages near the order of 10 degrees is expected Monday with that building upper level ridge. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Expect that warming trend to continue through the week as the southern upper ridge expands. Precip chances will be shortwave dependent, with the best chance expected Tuesday through Thursday. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Clear sky at the start of the TAF period. Clouds will move in overnight, especially across southeast Ohio and areas north of PIT. The timing and extent of the clouds will determine the extent of valley fog somewhat. Think FKL/ZZV will be spared the thickest fog due to arrival of clouds before fog can become too dense. Kept a period of IFR/LIFR at HLG/AGC/DUJ/MGW as cloud coverage there remains more uncertain. Confidence is moderate at best, and some adjustments are likely with the 06Z forecast. Any fog that does develop should lift by 13-14Z. VFR conditions will then prevail thereafter, as remaining clouds should remain above 3500-4000 feet. Light southeast wind will veer towards the SSW with time on Sunday. Outlook... Restrictions are likely for Monday night and Tuesday as another shortwave trough approaches, and crosses the region. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$
Area Forecast Discussion
National Weather Service Springfield MO
555 PM CDT Sat Sep 29 2018 .SHORT TERM...(This evening through Sunday) Issued at 228 PM CDT Sat Sep 29 2018 A warm front was moving north through the area today with partly cloudy skies and increasing southerly winds. At 2pm, the warm front was roughly along the US Highway 54 corridor in Central Missouri. A definite increase in moisture was occuring with dewpoints ranging from the lower 60s at JLN to around 50 at VIH. Air temps were responding nicely into the lower and middle 70s. Much like the last few nights, areas of fog are expected to form mainly south and east of Springfield where winds will be lighter and less cloud cover will occur. Generally used a blend of the RAP and other high res models which shows good potential for visibilities to drop below 1 mile, perhaps less than 1/2 mile by morning. Later shifts will need to monitor for a potential fog advisory if confidence increases in dense fog production. The NAM shows some signal of light drizzle overnight west of SGF however inspection of soundings and isentropic forecast shows the best chances of this will be further west into Kansas closer to the 850mb low level jet, however it is something to watch. Any fog/low cloud cover will likely burn off shortly after sunrise. Increasing mid level heights and thicknesses will lead to temperatures in the low to middle 80s for most locations on Sunday. .LONG TERM...(Sunday Night through Saturday) Issued at 228 PM CDT Sat Sep 29 2018 Next week is looking very warm with summer time high pressure anchored over the southeast US. A subtle piece of energy looks to move along the western periphery of the high on Monday and may create a few showers across the southeast half of the area however it will likely not amount to much. The strong mid level high is forecast to retrograde slightly west, closer to the area from Tuesday through Thursday, this will allow for a strong fetch of southerly winds to continue with 850mb temps reach 16-18C. Using these temps with 850mb climatology for this time of year would correlate to high temps easily reaching the middle to upper 80s. High temperatures may need to be adjusted upwards in later forecasts. Dry weather is expected during the mid week timeframe under this pattern. From Thursday on into next weekend, several strong disturbances look to move out of the southwest US and move close to or just north of the area. A front will also interact with these disturbances to produce showers and thunderstorms. There is disagreement with the timing and placement of the waves that come out of the southwest, however with time, unsettled weather will return to the area given an increasing southwest flow aloft. CIPS extended analogs for the days 6-12 timeframe favor high percentages for above average temperatures and above average precipitation. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 551 PM CDT Sat Sep 29 2018 VFR conditions for now across the area. Surface ridge was well to the northeast and have seen winds veer to the south today behind a warm front. The increase in moisture and light wind over the eastern Ozarks could lead to some fog development towards morning which some of the models are hinting at. Have dropped Branson down into MVFR towards 10-12z, but have kept fog out of SGF/JLN for now and will monitor visibility trends during the evening. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ SHORT TERM...Burchfield LONG TERM...Burchfield AVIATION...Lindenberg
Area Forecast Discussion
National Weather Service Shreveport LA
1018 PM CDT Sat Sep 29 2018 .SHORT TERM.../Tonight through Sunday/ The evening sfc analysis indicates a weak sfc bndry (pseudo warm front) extending from near the Red River of N TX SE across E TX in VC of the I-20/I-30 corridors, to along the I-20 corridor of N LA. To the N of this bndry, the cirrus shield has been notably thinner, with patchy FG developing across portions of SE OK/adjacent sections of SW AR, where temp/dewpoint depressions are very small. However, within the breaks of the cirrus, areas of stratocu have redeveloped across portions of E TX, with additional development expected overnight across much of E TX/SE OK, and well as portions of SW AR/Wrn LA. Meanwhile, a weak shear axis extending from SE and Deep E TX NE into Ncntrl LA will continue to slowly lift N overnight, as a well defined shortwave trough over SW TX continues to shift E into S TX. Areas of -SHRA over S LA within a high PW environment characteristic with PW`s of 2.0-2.2 inches over S LA, is also progged to slowly spread N into Cntrl LA overnight as well, with the HRRR and 00Z NAM both suggesting that isolated -SHRA may eventually spill N into the Srn sections of N LA as well as adjacent areas of the Lower Toledo Bend Country prior to daybreak. Have added slight chance pops late tonight for the aforementioned areas, and also beefed up pops a bit for Lower E TX/Ncntrl LA as sct convection should quickly increase by mid to late morning over these areas as the shortwave trough to our W enhances large scale forcing across Deep E TX/N LA. The high chance pops for the afternoon generally along-S of I-20 still looks good, with this convection gradually diminishing late in the day as it enters Srn AR. Have also toned down the FG wording tonight for just SW AR/SE OK given the very low temp/dewpoint depressions and thin cirrus, with some minor tweaks to the forecast min temps as well. Zone update already out...grids will be available shortly. 15 && .PREV DISCUSSION... /issued 652 PM CDT Sat Sep 29 2018/ AVIATION... MVFR cigs ranging between 2.0-3.0kft will persist this evening over much of E TX/Wrn LA, with cigs expected to lower to IFR after 08Z over E TX, with even some LIFR cigs and vsby reductions possible across the TYR/GGG/LFK terminals. MVFR cigs should linger overnight across Wrn LA, and eventually develop/spread NNE into portions of SW AR, affecting TXK after 06Z, and possibly ELD after 12Z. These cigs will begin to slowly improve by late morning Sunday, although MVFR cigs will likely persist through the afternoon across E TX/Wrn LA, as sct convection is expected to develop by mid and late morning across Deep E and SE TX/Cntrl LA, and spread N across much of E TX/N LA through the afternoon. Have inserted VCSH mention at 16Z for LFK, before prevailing SHRA at 18Z with some vsbys restrictions possible. Have also carried VCSH mention for the TYR/GGG/SHV terminals after 18Z, with this convection expected to gradually diminish during the evening. Can`t rule out isolated thunder, but low confidence precludes mention attm. VFR cigs should return to SW AR by afternoon, and remain VFR at MLU through the end of the TAF period. Lt/Vrb winds tonight will become ESE 4-7kts after 16Z Sunday. /15/ && .PRELIMINARY POINT TEMPS/POPS... SHV 69 83 70 88 / 10 50 20 30 MLU 66 84 69 90 / 10 40 20 40 DEQ 64 83 68 85 / 10 20 10 20 TXK 64 82 68 84 / 10 30 20 30 ELD 63 83 68 87 / 10 30 20 30 TYR 70 80 69 84 / 10 50 20 30 GGG 69 80 69 86 / 10 50 20 30 LFK 70 79 70 87 / 10 50 20 40 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 15
Area Forecast Discussion
National Weather Service Tucson AZ
400 PM MST Sat Sep 29 2018 .SYNOPSIS...Isolated to scattered showers and thunderstorms mainly south to west of Tucson Sunday, then widespread showers and occasional thunderstorms Sunday night through Tuesday. Expect heavy rainfall at times, especially west of Tucson. Lingering moisture will provide isolated to scattered showers and thunderstorms Wednesday into Friday. Cooler than normal temperatures will occur during the upcoming work week. && .DISCUSSION...Mostly sunny skies across southeast Arizona this afternoon with a few to scattered vertically-challenged cumuloform clouds across the area. However, isolated to scattered showers and thunderstorms extended from northern Sonora Mexico into west central Sonora Mexico. Several HRRR solutions have hinted at the possibility of an isolated shower/tstm early this evening as far north as southern sections of this forecast area. However, have maintained single digit PoPs for tonight with the expectation that any measurable rainfall will remain south of this forecast area. The National Hurricane Center 2 pm MST advisory regarding Hurricane Rosa stated the center was located near 21.4N/118.7W, and was moving toward the north near 12 mph, and this motion is expected to continue tonight. A turn toward the north-northeast with increased forward speed is expected Sunday. On the forecast track, the center of Rosa will approach central and northern Baja California peninsula on Monday. Based on various 29/12Z numerical weather prediction model solutions and per coordination with neighboring WFO`s, there were no significant changes to the inherited forecast regarding rainfall potential associated with increased moisture across southeast Arizona ahead of tropical system Rosa. Based on the latest NHC forecast track, Rosa`s path as a decaying tropical system is still projected to generally remain west of this forecast area into Tuesday morning, with the system becoming a remnant depression late Tuesday morning over west central Arizona. At any rate, the official forecast continues with isolated to scattered showers/tstms developing Sunday especially south to west of Tucson, then widespread showers with occasional thunderstorms Sunday night into Tuesday. The models suggest that a vort max ahead of Rosa will initiate showers/tstms Sunday, and another leading vort max will continue showers/tstms Sunday night into Monday. The "remnants" of Rosa and associated rainfall appears to move northeastward across the area Monday night into Tuesday. Based on the various 29/12Z models and neighboring WFO`s, only very minor changes were made to expected rainfall totals through Tuesday. The heaviest rainfall amounts are still forecast to occur west to northwest of Tucson. As such, the Flash Flood Watch with respect to timing and area coverage remains unchanged from the previous midnight shift. Please see AWIPS product PHXFFATWC / WMO HEADER WGUS65 KTWC / for detail. A break in any significant rainfall appears to occur Tuesday night and perhaps into Wednesday as subsidence occurs behind the departing remnants. However, additional showers/tstms should yet occur Wednesday into Friday as an upper trough moves eastward across the Great Basin and eventually into the Four Corners region. The operational GFS was more amplified with this upper trough versus the deterministic ECMWF which accounted for a generally wetter GFS scenario for later in the week versus the ECMWF. The upshot for Wednesday through Friday is for a continuation of isolated to scattered showers/tstms. A slight chance of showers/tstms also continues into next Saturday, especially northeast of Tucson. High temps Sunday will remain at least a few degrees above normal, the cooler temps will occur Monday. High temps Tuesday into next Saturday reflect only very minor daily changes, and will be below normal through that period. && .AVIATION...Valid through 01/00Z. Isolated -SHRA developing Sunday morning south to southwest of KTUS, then isolated to scattered -TSRA/-SHRA across southeast Arizona Sunday afternoon. The bulk of this activity should occur south to west of KTUS followed by more widespread coverage after the valid period; or, Sunday evening into Monday. Otherwise, scattered clouds mostly 10k-15k ft AGL into Sunday morning, then cloud decks generally 6k-12k ft AGL Sunday afternoon. Surface wind variable in direction mainly less than 12 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Expect isolated to scattered showers and thunderstorms mainly south to west of Tucson Sunday, then widespread showers with isolated to scattered thunderstorms Sunday night into Tuesday. The heaviest rainfall will favor locales west to northwest of Tucson. Thereafter, isolated to scattered showers and thunderstorms mainly east of Tucson Wednesday into Friday. A slight chance of showers and thunderstorms continues next Saturday mainly northeast of Tucson. Gusty south to southwest winds should occur Tuesday into Tuesday evening. 20-foot winds will be terrain driven mainly less than 15 mph at other times. && .TWC WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Monday morning through late Tuesday night for AZZ501-502-505-506. && $$ Francis Visit us on Facebook...Twitter...YouTube...and at