Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/25/18

Area Forecast Discussion
National Weather Service Boise ID
826 PM MDT Fri Aug 24 2018 .DISCUSSION...Smoke has decreased and visibility improved as far south and east as Missoula/MT to Boise to Burns/OR, about as forecast by HRRR smoke model, although a little later than that forecast. Further improvement is indicated this evening as far south as Sun Valley to Rome/OR, but south of there the smoke will continue. Smoke is forecast to return north Saturday to all but our northernmost counties, but then retreat south again to at least the Snake River Saturday evening and possibly even farther south Sunday. Upper trough over our area will be reinforced Saturday and again Sunday, each surge bringing cooler air into our area. Monday should be our coolest day since at least July 3. No updates for now. && .AVIATION...Tonight and Saturday south of a KBNO-KSNT line layers of wildfire smoke aloft and local MVFR/IFR visibilities at the surface along the ID-NV border and in the KTWF area. Mainly VFR elsewhere. Surface winds variable 10 kts or less through Saturday morning becoming west 10-15 kts Saturday afternoon. Winds aloft near 10k feet MSL west 15-25 kts. Sunday outlook...Mainly VFR. Areas of wildfire smoke. Breezy west to northwest winds in the afternoon. Slight chance of showers over the mountains of Baker County Oregon and west central Idaho Sunday afternoon. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday...Early afternoon satellite pics showing the back edge of thicker smoke extending from central Harney county into Valley county. Do expect areas east of this line to see visibility improve through the evening as northwest winds and mixing help to thin out smoke near the surface. However, skies will not completely clear as southwest winds aloft continue to favor smoke transport from CA/OR fires into far southeast Oregon and southwest Idaho. Dry and seasonable conditions persist on Saturday as a trough axis remains positioned west of the area, keeping the area under southwest flow. A couple of smaller short waves will cross the region late Sat/Sun, increasing clouds and bring a slight chance of showers to the mountains of Baker county and the west-central Idaho Sunday afternoon. Elsewhere, conditions remain dry, with passage of the upper trough bringing breezy and cooler conditions for Sunday. LONG TERM...Sunday night through Friday...Upper level trough remains in place through the extended period with reinforcing waves moving through the region. The best chance for any precipitation looks to be late Sunday into Monday for areas near and north of a line Baker City to Stanley. Breezy conditions are also expected with the passing shortwaves. Next deeper trough will arrive late next week, though the timing on this varies quite a bit among the models and thus confidence remains low. Temperatures will remain mild and below normal. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ SHORT TERM...DG LONG TERM....JS/JS AVIATION.....JS
Area Forecast Discussion
National Weather Service Columbia SC
740 PM EDT Fri Aug 24 2018 .SYNOPSIS... High pressure centered near the mid-Atlantic Coast will be shifting farther off the coast over the weekend. Moisture will gradually increase over the weekend into next week in an onshore flow circulating around the high. Near normal temperatures will increase slightly next week as an upper ridge builds over the region. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Dry high pressure will ridge into the forecast area from the north and northeast through tonight. The dry air mass associated with the ridge will bring low humidities and slightly below normal temperatures. The temperature guidance was consistent. Expect lows tonight in the lower and middle 60s. The NAM and GFS MOS support winds northeast about 10 mph diminishing to 5 mph or less this evening. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Upper trough northwest of the region will lift northeastward through Saturday. Upper ridging across the southeast will remain, although there may be a slight weakness across the area Saturday night into Sunday. At the surface, high pressure should remain through the weekend, with main surface front still south of the cwa. High pressure should still remain strong enough over the area Saturday though to keep conditions dry and temperatures below normal. Saturday night will remain dry and cooler than normal. For Sunday, a return flow may begin to bring moisture back into the area, along with the possibility of isolated showers/storms across the southeastern cwa. Temperatures will begin to warm back up to near normal for Sunday. && .LONG TERM /MONDAY THROUGH FRIDAY/... Through the week, upper ridging still expected to remain over the Southeastern States, with a flat upper flow pattern off to the north. May be a slight weakening again late in the week as another shortwave trough moves north of the region. For the most part, surface high pressure will remain centered over the western Atlantic for much of the week. This will allow for a continued southerly return flow of moisture back into the forecast area. It will also result in a slight increase in isolated to scattered afternoon and evening convection from Tuesday onward. Temperatures will climb back to being slightly above normal, with highs back in the lower and middle 90s and lows in the lower and middle 70s next week. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR conditions generally expected through the 24-hr TAF period. High pressure over the Mid Atlantic states extending into the area with weak trough offshore. The pressure ridge will be shifting more offshore during the period. Air mass remains dry this evening. Some thin high clouds mainly to the west overnight. The low level east flow will increase a bit toward morning in the CSRA which may result in an increase in low-level moisture. The latest Lamp guidance and HRRR still indicate low threat for fog. Stratus possible in the CSRA with increase low- level jet toward morning. Will continue forecast for scattered low-clouds near AGS/DNL otherwise mainly clear overnight. Scattered cumulus during Saturday afternoon with continued northeast winds 5 to 10 knots. EXTENDED AVIATION OUTLOOK... There will be an onshore flow circulating around offshore high pressure. Low-level moisture associated with this pattern combined with nocturnal cooling may result in areas of stratus and fog during the early morning hours. Upper ridging will limit the thunderstorm chance. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
National Weather Service Kansas City/Pleasant Hill MO
1056 PM CDT Fri Aug 24 2018 .Discussion... Issued at 417 PM CDT FRI AUG 24 2018 Tonight`s forecast challenge will be the potential for severe thunderstorms developing this evening across north central and northeastern portions of the CWA. Latest convection allowing models can`t come to agreement on if convection will develop tonight.There are a few severe parameters coming together after sunset tonight; southwest low level jet of 45kts redevelops, plenty of instability with MUCAPE values 2500-3500 J/Kg, and a weak boundary setting up over the Iowa/Missouri state line. On the other side of the coin, the strongest upper level support will remain in Iowa and combined with a decent cap (temp 10c at 700MB) across Missouri, the threat of severe thunderstorms remains in question. While the HRRR is not at all impressed with the possibility of severe weather, the Nested NAM is all in on strong thunderstorms developing along a weak boundary along the Iowa/Missouri boarder and then pushing southward into Missouri. Have opted to go with a compromise. After 02Z, expect thunderstorms to develop along the state line and march southward into north central and northwest Missouri. While widespread severe weather is not expected, isolated severe thunderstorms are still possible. Additionally, PWAT values will be 2+ inches, which will provide heavy rainfall in some areas. All convection will weaken and eventually dissipate through the evening as the line approaches I-70. Lastly, patchy fog is expected to develop just before sunrise in low lying area over the northern 1/4 of the CWA. This weekend, brutal August heat will return. Expect above normal temperatures with highs in the mid-upper 90s and humid conditions to produce heat indices approaching 105F. With that said, a Heat Advisory has been issued for the Kansas City Metro area for tomorrow and Sunday.Take extra precautions, if you work or spend time outside this weekend. If possible, reschedule strenuous activities to early morning or evening. By late Sunday into Monday morning, a short wave will provide a slight chance of precipitation for the extreme northwestern counties in the CWA, but the next decent chance of showers/thunderstorms should arrive Tuesday into Wednesday as weak cool front will struggle to push through Missouri. && .Aviation...(For the 06Z TAFS through 06Z Saturday Night) Issued at 1056 PM CDT FRI AUG 24 2018 VFR conditions will persist through the forecast period, except in low-lying areas across northwest Missouri where some patchy fog may develop Saturday morning. Otherwise, skies will be mainly clear and winds will remain out of the southwest. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Heat Advisory from 11 AM Saturday to 7 PM CDT Sunday for KSZ103>105. MO...Heat Advisory from 11 AM Saturday to 7 PM CDT Sunday for MOZ020- 028-029-037. && $$ Discussion...32/Otto Aviation...Laflin
National Weather Service Eureka CA
256 PM PDT Fri Aug 24 2018 .SYNOPSIS...Seasonable temperatures will continue through early next week as a series of upper-level troughs impact the West Coast. Smoke will continue to linger around the area through tonight. && .DISCUSSION...Northerly winds will continue to increase through tonight across the coastal waters. In response to the winds, coastal stratus has become nearly eradicated along most of the northwestern California coast. The lone area still lingering is south of Cape Mendocino. Smoke from wildfires in southern Oregon is observed in visible satellite imagery moving southward down the coast, so introduced this area into the forecast. Additionally, areas of smoke continue to linger around the forecast area this afternoon. HRRR smoke guidance shows the smoke moving out of the forecast area tonight. Otherwise, seasonable, to slightly below normal, temperatures will continue as a series of upper-level troughs continue to impact the West Coast. A more potent upper-level trough digging through the area towards the end of the work week will bring small chance of rain, but confidence is low. && .AVIATION...The marine layer remained manifested along the North Coast into afternoon. A "weakish" frontal/trof boundary pushed across the area today and mostly cleared out much of the expansive stratus field, allowing clouds to scatter out at CEC by late morning. Elsewhere, a substantial amount of low clouds continued over the inner coastal waters. At 1 Pm, ACV ascended from IFR to MVFR by reporting CIG010 even as VIS Satellite showed BINOVC in the stratus deck. Satellite and webcam indicators keep scattering and partial clearing on track through mid-late afternoon at ACV with low clouds expected to return overnight. Guidance has CEC in sort of a mixed bag overnight although the patchy cloudy solution seems more probable at this writing time. Interior areas: Tops of the marine layer was a tad bit lower this morning. Therefore, morning IFR low clouds at UKI were the result of light southerly flow advected from the south. Elsewhere, smoke (FU) and haze (HZ) from various wildfires continued. /ta && .MARINE...Northerly winds will continue to increase through tonight. A Small Craft Advisory remains in effect for the outer waters through Monday afternoon, with Small Craft Advisories coming into effect this evening across the inner waters. Localized near gale force gusts are expected near and downwind of Point Saint George and Cape Mendocino tonight, but the area is too small in coverage for any additional products at this time. Seas will begin to trend down early next week as the northerly winds begin to wane Monday. && .FIRE WEATHER...A brief period of gusty northeast winds will be possible late tonight over the ridge tops of interior Del Norte County as a weak upper-level trough passing through the area. Otherwise, onshore flow will yield normal to slightly below normal temperatures area-wide for much of the next week. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory from 6 PM this evening to 6 PM PDT Saturday for PZZ450-455. Small Craft Advisory until 3 PM PDT Monday for PZZ470-475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Grand Rapids MI
1158 PM EDT Fri Aug 24 2018 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 257 PM EDT Fri Aug 24 2018 Unsettled and changing weather conditions will continue over the area through the weekend and into early next week. A round of light rain/showers over mainly the northern parts of the area early this evening will move out of the area. More widespread rain with some embedded thunderstorms move in after midnight tonight. Showers and low clouds will linger through midday Saturday before increasing sunshine in the afternoon. For Sunday, a hot and sunny day is on track with good chances of thunderstorms developing in the afternoon with more widespread rain possibly continuing through the Sunday night timeframe. The first half of next week continues with periodic rain chances each day. && .UPDATE... Issued at 822 PM EDT Fri Aug 24 2018 Little question a line of thunderstorms will cross our area during the pre-dawn hours of Saturday. I increased the risk for thunderstorms from chance to likely for the storms before sunrise. We have the right entrance region of upper jet around the closed upper low helping the cause of deep layered lift. Precipitable water values rise to near 2.00 inches and we are on the nose of the 1000/850 moisture transport vectors. The most unstable cape rises to between 1000 and 1500 j/kg south of I-96 during this time. Numerous runs of the HRRR and RAP model continue to show this line of storms in the 4 am to 6 am time frame. So in increased the risk for thunderstorms overnight. The previous shift already had 100% chance of rain, so not much change there. I don`t believe the storms will be anything close to severe but we more than likely will see rainfall rates over over 4" per hour for at least a short time in many areas south of I-96. && .SHORT TERM...(This evening through Sunday night) Issued at 257 PM EDT Fri Aug 24 2018 Another weak upper low moving through the high plains will keep our weather unsettled for the next few days. A first round of showers trying to cross the lake this afternoon is encountering very dry in-place air. As a result, precip is having a hard time reaching the ground so far in many areas. Even though this first round of rain will not be too significant, it will help set the stage for another more widespread round of rain overnight tonight as the upper low itself moves through to our north. Rainfall amounts around a half inch are likely across most of the area by the time things taper off Saturday morning. With continuing warm and moist air advection Saturday, along with building high pressure behind the departing low, clouds will be slow to diminish tomorrow morning, but eventually the sun should break out and some storms are possible by tomorrow afternoon mainly east of I-69. For Sunday, plenty of sunshine to start the day will take advantage of the warmer airmass to send temperatures into the upper 80s at most locations. With upper level high pressure well to our south, the capping inversion likely won`t be strong enough to hold off convection, so there could be some strong diurnal thunderstorms that develop Sunday afternoon. Another threat from the high pressure being fairly far away will be the threat of overnight MCS development moving into our area Sunday night into Monday morning. This will be monitored closely over the next 24-36 hours. .LONG TERM...(Monday through Friday) Issued at 257 PM EDT Fri Aug 24 2018 Unsettled weather stays in the area for next week as fairly zonal flow will allow numerous embedded shortwaves to move through the Great Lakes. Depending on the exact timing of these shortwaves, we could see storms fire off nearly any day. This far in advance, it is still too uncertain to say with confidence whether any of these shortwaves will come through at the right time to take advantage of diurnal heating. Temperature for the first half of the week will be above-average in the 80s, but should begin to moderate back to the high 70s for the latter half of the week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1130 PM EDT Fri Aug 24 2018 Mainly VFR conditions with isolated MVFR/IFR will gradually deteriorate to MVFR and eventually IFR during the early to mid morning hours Saturday as lower clouds and rain and thunderstorms move in from the west. Thunderstorms will gradually exit from west to east mid to late Saturday morning but conditions will remain IFR due to lingering low clouds. Conditions will only slowly improve to predominantly MVFR Saturday afternoon and evening. A few showers may linger and also redevelop into Saturday afternoon and evening with an isolated storm also possible. However there is not enough potential to warrant mention of those in any of the terminal fcsts at this time from Saturday afternoon through the evening. && .MARINE... Issued at 257 PM EDT Fri Aug 24 2018 South winds of 15 to 25 knots are creating hazardous conditions for small craft and swimmers from Holland to Manistee today. Waves in the 5 to 8 ft range can be expected to slowly diminish after midnight tonight. These general conditions are expected to only slowly improve through Saturday afternoon as the winds swing around to the southwest during the day. At this time it does look like the winds will remain strong enough to warrant adding in the remainder of the zones to the small craft advisory for the daytime tomorrow. By Saturday evening, winds across the area will drop off significantly, but a renewed push of southwest winds on Sunday afternoon/evening could cause conditions to again approach advisory levels. && .HYDROLOGY... Issued at 257 PM EDT Fri Aug 24 2018 River levels are running around normal for this time of the year, with no flooding into next week. Rain is expected this afternoon and evening with another round overnight. Rainfall of up to around a half inch is possible. Additional rainfall is possible on and off all of next week. Locally heavy rain is also possible, but flooding should be limited or nonexistent. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Beach Hazards Statement through Saturday afternoon for MIZ037- 043-050-056-064-071. LM...Small Craft Advisory until 5 PM EDT Saturday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...AMD SHORT TERM...AMD LONG TERM...AMD AVIATION...Laurens HYDROLOGY...63 MARINE...AMD
Area Forecast Discussion
National Weather Service Lincoln IL
838 PM CDT Fri Aug 24 2018 .UPDATE... Issued at 838 PM CDT Fri Aug 24 2018 Minor updates made this evening to account for a slower progression of thunderstorm chances into areas NW of I-55 through midnight. Current storm development has been minimal in the region, although a supercell in north-central IA could be the start of an MCS forecast by various hi-res models in the eastern half of IA, set to propagate into central IL in the late evening and overnight hours. Last few HRRR runs have featured the closest resemblance to current thunderstorm activity, yet fail to develop any strong organized MCS and simply move some scattered weaker thunderstorms into central IL overnight and southeast IL Saturday morning. Meanwhile, the 18Z NAM nest propagates a strong MCS into western IL by midnight, although it appears this will be at least delayed. As far as severe storm potential, an axis of strong surface based instability is currently analyzed from south- central into north-central IA, forecast to weaken and advect eastward while becoming elevated overnight. This, along with 40-50 kt sfc- 6km bulk shear would favor a hail threat for areas west of I-57, but have minimal wind threat. SPC continues a marginal risk of severe storms in this area. The severe weather threat will lessen with eastward extent across central IL as the upper level trough pushes eastward into a less unstable region, cooled by extensive cloud cover in an overall cooler air mass. Current temperatures are already in the mid to upper 60s, but don`t expect any further cooling as 10-20 mph of south wind and low cloud cover continue in most areas. && .SHORT TERM...(This evening through Saturday) ISSUED AT 324 PM CDT Fri Aug 24 2018 Vigorous upper low noted on 20z/3pm water vapor imagery over Minnesota will be the main weather-maker across central Illinois over the next 12-24 hours. A surface trough associated with this feature will interact with a destabilizing airmass to trigger scattered thunderstorms across central/eastern Iowa this evening. Latest upstream satellite/radar mosaic is mostly dry for the time being: however, mesoanalysis shows MLCAPEs of 1000-1500J/kg across central/western Iowa. All CAMs suggest this will be the area for storm development over the next few hours, with the storms tracking eastward into the Illinois River Valley toward midnight...then across the remainder of the KILX CWA overnight. Have adjusted PoPs to go with dry weather across much of the area through the evening, with high chance to likely PoPs along/west of the Illinois River by late evening. Have spread high chance to likely PoPs across the remainder of the area overnight. Will see some lingering showers/storms across the E/SE Saturday morning, followed by dry conditions across the board by afternoon. With rapidly rising upper heights and increasing amounts of sunshine, high temperatures will range from the middle 80s near the Indiana the upper 80s and lower 90s further west. .LONG TERM...(Saturday night through Friday) ISSUED AT 324 PM CDT Fri Aug 24 2018 Late summer heatwave will unfold early next week...with high temperatures expected to top 90 degrees Sunday through Tuesday. Thanks to the recent rainfall, surface dewpoints will hover in the lower to middle 70s...producing maximum heat index values in the 100-105 degree range each afternoon. While these numbers are below advisory criteria, may eventually need to issue a Heat Advisory for much of the CWA...mainly due to the prolonged nature of the heat. 12z Aug 24 models continue to show MCS activity along the northern periphery of the building ridge Sunday night: however, it appears this activity will remain north of central Illinois across the Upper Midwest into the Great Lakes. The next significant chance for rain will hold off until late Tuesday into Wednesday as a short-wave trough begins to flatten the prevailing ridge. Models are in fairly good agreement with this process, with both the GFS and ECMWF suggesting rain chances increasing across west-central Illinois as early as Tuesday...and especially Tuesday night and Wednesday. After that, a cold front will settle southward into the Ohio River Valley by Thursday...shifting the best rain chances further south. After hot temperatures in the lower 90s on Tuesday...readings will drop into the lower to middle 80s behind the frontal boundary by Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 637 PM CDT Fri Aug 24 2018 A period of thunderstorms is likely overnight as a line or cluster of thunderstorms develops over southeast Iowa this evening and and moves southeastward. Timing is still uncertain, but have VCTS included in TAFs starting 04-07Z and ending 11-12Z, although this timing may have to be adjusted later as thunderstorms develop and start their movement. In advance of this feature, MVFR and some IFR cigs are in place across the region, with some improvement spreading from south to north. Behind the thunderstorms, a period of MVFR cigs is possible especially along the I-74 corridor terminals, gradually thinning in coverage and lifting in height through the afternoon into the VFR category. Winds S 10-15 kts, shifting to SW 10-15 kts around 12Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...Barnes LONG TERM...Barnes AVIATION...37
Area Forecast Discussion
National Weather Service Louisville KY
1026 PM EDT Fri Aug 24 2018 .Forecast Update... Issued at 1025 PM EDT Fri Aug 24 2018 Hi-res models are suggesting a little more coverage of showers overnight. GFS and RAP time-height sections do show some lift in the saturated mid-level air moving over us now, so have bumped up pops for late tonight a little. Kept isolated thunder in the north, where lift is a little more deep...closer to shortwave rotating around the Midwest. Updated products out shortly. && .Short Term...(This evening through Saturday) Issued at 350 PM EDT Fri Aug 24 2018 Weakening complex of showers continues to make slow eastward progress through Indiana and western Kentucky this afternoon. This low pressure system will continue to rotate eastward over the Upper Midwest tonight. This afternoon, surface low pressure was analyzed over western Minnesota with a surface high now over the Mid-Atlantic coast. The main SW LLJ axis of warm, moist advection was over Missouri and Illinois this afternoon, but PWATs over central KY and southern Indiana will steadily increase overnight through Saturday morning. The ongoing area of showers is expected to eventually diminish over central KY by 00-03z this evening. Higher rainfall amounts are still expected along and west of I-65. Between 06-18z Sat, the 25-30 kt LLJ will take on more of a WSW orientation across Indiana and northern Kentucky. Between 4-8 AM EDT Saturday, scattered showers and thunderstorms developing upstream are forecast to move over southern Indiana and north-central Kentucky. Rain chances will be lower south of the Western KY/Bluegrass Pkwy on Saturday, but isolated showers and storms will still be possible throughout the first half of the day. We`ll see improving conditions Saturday afternoon as the system pulls off to the northeast. Until then, mostly cloudy skies are likely tonight through Saturday morning. Highs on Saturday will reach the low to mid 80s. .Long Term...(Saturday night through Friday) Issued at 230 PM EDT Fri Aug 24 2018 By Saturday evening the upper level shortwave trough axis will be just east of Central KY as it continues NE. But enough moisture and instability remain for rain shower chances overnight Saturday and throughout Sunday, mainly north of I64. SREF, GFS and CMC agree with a wet Sunday. Can`t rule out a stray tstorm during this time frame as sufficient CAPE and PWATs are accompanied by decent lapse rates. No severe weather is expected, though a brief period of isolated heavy rain can`t be ruled out. By Monday, ridging stretching from coast to coast across the southern U.S. will allow enough instability for our CWA to experience diurnal chances of showers and tstorms through Tuesday.Conditionally unstable lapse rates, moderate buoyancy and ample moisture suggest some storms could produce heavy rain. Gusty surface winds around 20kts possible with DCAPE values around 1000 J/kg and 20-25kts below 850mb. Upstream, another trough over the northern Rockies will makes its way towards our area. Any chances of organized convection will be best with this feature on Wednesday and Thursday. GFS suggests MUCAPE values of 2917 J/kg with PWATs of 1.81 inches. But with little shear, expect more heavy rain than severe weather at this point. As this trough exits, it will leave a weak boundary to our north susceptible to shortwave propogation to our area on Friday. Another chance of showers and tstorms possible then. && .Aviation...(00Z TAF Issuance) Issued at 720 PM EDT Fri Aug 24 2018 Upper low over the upper Midwest earlier induced the system that is bringing fading light rains to the region now. Those rains should continue to dissipate, but a weak low-level jet will pick up over our area, especially north of the Ohio. This should generate additional showers around daybreak, perhaps also a rumble of thunder. Best chances, prob30`s all, are in the I-64 corridor terminals. Conditions should improve in the afternoon, with little rain chance. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...RJS Short Term...EBW Long Term...CG Aviation...RJS
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
835 PM CDT Fri Aug 24 2018 .UPDATE... 835 PM CDT A breezy, drizzly evening uncommon for August will continue, with the likelihood of isolated to scattered showers and storms overnight. The severe threat is fairly limited, though a couple elevated hail-producing storms could develop in the CWA. Some tweaks to timing and forecast coverage of thunderstorms were made, to mainly slow down and shorten the duration, as well as ease the chances some. This evening finds a surface warm front draped southward across eastern Iowa and eastern Missouri, branching from a low in southern Minnesota. Broad warm and moist advection is occurring over and to the northeast of this feature, including isentropic ascent in the lowest levels over the CWA resulting in stratus and patches of drizzle. A more focused 25-30 kt low-level jet is pointed into northwest Illinois per 00Z soundings and VWP data. While the 00Z DVN sounding did show moistening and warming of the layer below the elevated mixed layer (EML) since 18Z, there is still appreciable CIN to be overcome, with most unstable parcel CIN of over 100 J/kg. This will likely result in storm coverage overnight being less than originally expected, and this is also favored in the lack of a pronounced short wave feature and just more of general height falls at our latitude. This still should certainly be enough to spark some storms, and IR imagery indicates accas clouds streaming over northwest Illinois. The HRRR has supported isolated to scattered activity developing in or near north central Illinois and developing east, as opposed to a more solid convective area moving in from our west. With the EML present within the hail growth zone and effective shear in that layer of 40-50 kt, there is a conditional threat of a couple elevated supercell storms that could becoming hailers. The marginal risk from SPC for the IL CWA covers that well. Otherwise, southerly winds will still show sporadic gusts to 25 mph at times through early overnight, and the combination of these and the clouds will keep temperatures nearly steady the remainder of tonight. MTF && .SHORT TERM... 244 PM CDT Through Tonight... The main forecast highlights tonight focus around the potential for a round of eastward moving scattered thunderstorms, particularly from mid evening over north central IL through the overnight hours across eastern IL and northwestern IN. The main concern with these storms will be hail and heavy rain. While some areas across eastern IL are experiencing some breaks in the cloud cover at this time, it appears that low clouds will shift back over the area late this afternoon and definitely for tonight. Thunderstorms appear probable to develop to our west across portions of IA late this afternoon into early this evening. This will be in response to a mid-level impulse currently seen in water vapor imagery shifting eastward into northern IA along the southern periphery of the parent upper tough in place across the Upper Midwest. The storms will then shift eastward into northern IL during the mid to late evening hours, and into eastern IL and northwest IN later this evening and overnight as this disturbance and the associated lower-level moisture transport axis shifts into the area. Expect the possibility for some stronger storms with this activity tonight, possibly even into the Chicago metro area. Very steep mid-level lapse rates were sampled in the special 18z DVN RAOB and this will likely aid in updraft intensity with these elevated storms tonight. For this reason, hail (some possibly in excess of 1" diameter) looks to be the primary severe concern tonight. Heavy downpours are also likely with these storms, as they are likely to be very efficient rainfall producers. The storms will shift out of the entire area by daybreak Saturday, though low clouds and possibly some fog look to linger into Saturday morning. KJB && .LONG TERM... 241 PM CDT Saturday through Friday... Saturday will begin the significant warming trend with warm/humid conditions which should persist through the middle of next week. Some lingering showers and the possibility of some isolated thunder should linger into Saturday, mainly for the far eastern portions of the CWA as the upper level trough tracks east into the Central and Eastern Great Lakes and sswly low level flow sets up persistent/deep warm/moist advection. For Saturday, temperatures should rebound into the middle 80s with dewpoints climbing into the low 70s. Have generally trended to a dry forecast for the area on Saturday, with the exception of some lingering sct shra/tsra over the far ern portions of the CWA. However, there is the chance for some sct shra/tsra through the diurnally favored hours given the increasing heat and humidity, but weak upper ridging and an elevated warm layer may inhibit convection. Sunday through Tuesday should be the warmest days of the period with the highest dewpoints with periods of dewpoints in the middle 70s. Heat Index values should reach or slightly exceed 100 F during this period. There should also be periodic chances for thunderstorms as a series of shortwaves ride over the apex of the upper ridging. The greatest chance for more widespread thunder should be Tuesday evening as a cold front crosses the region. Following the frontal passage, in a cooler/drier air mass associated with sfc high pressure will building in behind the front keeping the region dry through at least Thursday. && .AVIATION... For the 00Z TAFs... 633 pm...Forecast concerns include cigs through late Saturday morning...winds this evening and thunderstorm potential late this evening into early Saturday morning. Cigs have been steadily lowering late this afternoon with ifr over much of northwest IL. These ifr cigs will slowly spread across the rest of the area this evening...aided by light rain/drizzle which is now developing across parts of the area. This light precip may continue through mid/late evening but confidence for its duration is low. Cigs will remain ifr into Saturday morning...possibly lowering to lifr west of ord/mdw. Cigs will then begin to lift late Saturday morning and are expected to scatter by mid/late Saturday afternoon. Ifr visibilities are possible with any showers or drizzle this evening. An upper wave is expected to allow scattered thunderstorms to develop late this evening and overnight...possibly developing over the terminals as trends currently show. Previous timing of 06z- 10z or so looks ok but as trends emerge may need to include tempo thunder for the Chicago terminals. These storms may produce heavy rain and low visibilities. Showers may lingering through sunrise as the bulk of the thunder potential shifts east of the terminals. Southerly winds are expected to remain gusty for much of this evening with a slow diminishing trend. Gusts 20-25kts for the next few hours are possible with gusts expected to diminish by the early morning hours when directions will shift more to the south/ southwest. Winds will then shift more southwesterly later Saturday morning with some gusts possible mid/late morning into early afternoon. A lake breeze is possible near the shore Saturday afternoon but is currently not expected to reach ord/mdw. cms && .MARINE... 241 PM CDT Low pressure deepening over the Upper Missouri Valley and high pressure slowly sliding off the Mid-Atlantic coast is tightening the pressure gradient over the lake, with 20-25 kt sustained winds and 30 kt gusts. The relatively stable boundary layer should help prevent the stronger winds aloft from mixing down to the surface, but occasional Gale Force gusts will be possible through the remainder of this afternoon and into this evening. Some of the larger/taller craft may experience Gale Force winds that may not mix all the way down to the lake surface. Lighter south and southwest winds will prevail over the weekend as the pressure gradient relaxes. The next period of strong southwest winds up to 25-30 kt looks to be Monday night and Tuesday ahead of a cold front. After an extended period of SSW winds, a sharp shift back to N or NE for later next week following the frontal passage. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006 until 1 AM Saturday. IN...None. LM...Small Craft Advisory...IL nearshore waters until 4 AM Saturday. Gale Warning...LMZ777-LMZ779 until 9 PM Friday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
847 PM CDT Fri Aug 24 2018 .UPDATE... Issued at 835 PM CDT Fri Aug 24 2018 A strong cap has really hampered any kind of convective initiation so far this evening across southern Iowa. Upper-air sounding out of KDVN at 0000 UTC showed a very distinct capping inversion from 850 to 775 hPa. Given this strong capping across eastern Iowa and central Illinois, have reduced PoPs into the chance category. Any activity overnight that does develop overnight in the presence of broad warm/moist advection would probably would be very high-based showers/thunderstorms. If this type of activity were to materialize, marginally severe hail would be a possibility across portions of west-central Illinois and northeast Missouri. Gosselin && .SHORT TERM... (Through Late Saturday Afternoon) Issued at 335 PM CDT Fri Aug 24 2018 Primary concern for the short term is chance for severe thunderstorms tonight. Short range guidance, particularly the RAP, is showing increasing MU and 850mb computed CAPE this evening over parts of northeast Missouri and west central Illinois. This increasing instability coincides with the passage of a warm front which is lifting through eastern Missouri into western Illinois, and a strengthening low level jet over eastern Missouri and Illinois. Additionally, an H5 shortwave currently over western Iowa will be moving east toward the Mississippi River around the base of the larger mid-upper level circulation centered over Minnesota. GFS, NAM and RAP develop precipitation this evening over northern Missouri or southern Iowa as the shortwave moves through and the low level jet increases moisture convergence and isentropic lift. However convection allowing models are inconclusive on areal coverage and location of where the storms will develop. Have generally followed the model consensus for PoPs tonight with thunderstorms developing during the evening over northeast Missouri and west central Illinois and moving southeast overnight. Looks like instability will be maximized around 850mb and the 850mb computed CAPE off the RAP is in excess of 2500 J/Kg over northeast Missouri and west central Illinois. This combined with 30-40kt of 0- 6km shear will be enough to promote organized convection...possibly rotating discrete storms or line segments with large hail. Not sure what the wind threat will be as these storms will be elevated at least initially. Current thinking is that the storms will move southeast to near the I-70 corridor before sunrise Saturday morning, and continue into far southwest Illinois and possibly into parts of southeast Missouri after sunrise. Storms should be weakening as they move southeast as they move away from the strongest instability, and any line segments will probably break up into individual cells as well. Expect any lingering rain to e ending by late morning. Attention then turns to the building heat. Southwest flow will bring increasing heat and humidity to the mid Mississippi Valley on Saturday afternoon. 850mb temperatures of 20-23C build across the region which mixes down to low to mid 90s. With dew point temperatures pushing the low to mid 70s, heat index values will be in the 100-104 degree range. This will be the first of a string of hot days...especially for the heat- sensitive St. Louis Metro area. Therefore, have coordinated with the long term forecaster for this afternoon and issued a heat advisory for the STL Metro. Carney .LONG TERM... (Saturday Night through Next Friday) Issued at 335 PM CDT Fri Aug 24 2018 The focus will be oppressive heat and humidity from Sunday through Tuesday, turning to pops for the rest of the forecast period. Sunday continues to look like the hottest day of the period as an upper level ridge moves in from the south and south/southwesterly surface flow near the surface advects warm, moist air into the CWA. This will allow temperatures to surpass 90 degrees throughout the forecast area. With dew points in the 70s, expect heat index values to reach or exceed 100 in most areas, with the St. Louis Metro seeing values approach 105. Dew points will back off slightly on Monday, keeping heat index values just above 100. Late Monday into Tuesday, the upper level ridge begins to push off to the east ahead of an approaching trough. This will be associated with an uptick in pops, mostly across the northwestern portion of the CWA during the day on Tuesday. The ECMWF is a little faster and bolder with its precip chances than the GFS, but have gone with a blend between the two solution and kept lower pops for this time and area. This will keep the extreme heat at bay over northeastern portion of the CWA, but for the southeastern two-thirds of the CWA that will not likely be impacted by rain and associated cloud cover, heat index values will again rise to around 100. Due to heat index values reaching 100 or higher Saturday-Tuesday for the St. Louis Metro and surrounding counties, have gone with a heat advisory for duration. This may need to be adjusted for intensity over the weekend. Rain chances will increase across the CWA Tuesday evening and overnight ahead of an approaching cold front. The front will slowly move south through the CWA on Wednesday, and will mark the end of the oppressive heat for the remainder of the period, as highs will fail to get above 90. The front should clear the area Wednesday evening, but stall and keep lower pops across the CWA for Thursday. Westerly flow will settle in over the area for Friday, and guidance has a shortwave embedded in this flow pass through the Midwest. The GFS and ECMWF solutions differ in the strength and path of this shortwave, but confidence in either solution this far out in the period is low, so will stick with blended pops for now. Elmore/Tilly && .AVIATION... (For the 00z TAFs through 00z Saturday Evening) Issued at 638 PM CDT Fri Aug 24 2018 Main concern for tonight will be on chances of thunderstorms and low-level wind shear. Lots of uncertainty with respect to how thunderstorms will develop and evolve overnight tonight. Will be watching upstream across north-central Missouri and southern Iowa the next few hours but current expectation is for scattered storms to develop across this region over the next couple of hours and head southeastward. Maintained VCTS groups at terminals for now, starting first at KUIN late this evening, KCOU just after midnight, and metro terminals around 3-4AM. Threat of storms should move southeast of the terminals by late Saturday morning. In addition to the possibility of thunderstorms, other concern is for LLWS at KCOU/KSUS/KCPS as southerly winds lighten up at the surface and winds around 1500 feet AGL increase to around 35 knots out of the WSW. SPECIFICS FOR KSTL: Lots of uncertainty with respect to chances of storms affecting the terminal late tonight. Maintained VCTS group from 0900 to 1400 UTC Saturday for now given uncertainty. Threat for storms should shift southeast of KSTL by mid morning on Saturday with VFR conditions and a light southwest wind for the remainder of the valid TAF period. Gosselin && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Heat Advisory from noon Saturday to 7 PM CDT Tuesday for Jefferson MO-Lincoln MO-Saint Charles MO-Saint Louis City MO-Saint Louis MO. IL...Heat Advisory from noon Saturday to 7 PM CDT Tuesday for Calhoun IL-Jersey IL-Madison IL-Monroe IL-Saint Clair IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Medford OR
816 PM PDT Fri Aug 24 2018 .DISCUSSION... No changes to the forecast tonight into tomorrow morning. The fires remain very active over our region. The Klondike and Watson Creek Fires developed pyrocumulus clouds this afternoon suggesting they will remain very active into this weekend. In fact, some of the smoke from the Klondike fire appears to have made it up to around 600 to 500 mb as it moving with the 500 mb flow. Anyways, overnight temperatures will trend cooler compared to last night. Look for the marine layer to push in along the coast and make it into the Willamettte valley tonight, but stay out of the Umpqua valley. See the previous discussion below for more information beyond tonight and early tomorrow. -Smith && .AVIATION...For the 24/18Z TAFs...Along the coast, conditions are VFR this afternoon. Expect areas of MVFR/IFR cigs to develop this evening into tonight. This will mainly affect areas from Cape Blanco north. South of Cape Blanco, offshore NE winds should allow VFR to prevail. Although, local IFR cigs are possible near KBOK late tonight into Saturday morning. Inland, across the Umpqua basin, expect VFR through the TAF period. Elsewhere, inland, wildfire smoke will continue to produce periods of MVFR visibilities. -Clarstrom && .MARINE...Updated 200 PM PDT Friday 24 August 2018...A thermal trough will strengthen along the coast this afternoon and evening then remain in place this weekend. This will result in gusty north winds and steep seas, especially for the waters from Cape Blanco south. Additionally, a small area of gales is possible south of Brookings between 5 and 20 nm from shore late this afternoon into this evening. North of Cape Blanco, periods of steep seas and winds gusting to small craft advisory levels are likely this evening and tonight and again Saturday evening and night. On Sunday, expect seas to become less steep north of Cape Blanco as winds lower slightly and northwest fresh swell with a dominant period of around 9 seconds builds into the waters. South of Cape Blanco, small craft advisory level winds and seas will continue. Monday, the thermal trough may strengthen again bringing small craft advisory winds and seas to most the waters. Winds and seas are expected to lower Tuesday into Wednesday. -Clarstrom && .FIRE WEATHER...Updated 300 PM PDT Friday 24 August 2018... Temperatures will remain moderate through the weekend, although Saturday will be warmer and drier followed by a cooler Sunday. Recoveries will be good, except for some moderate recoveries well east of the Cascades. The northern portions of zones 615, 616, and 617 may see some light precipitation Saturday night into Sunday night, but amounts will be very light in areas that get any precipitation. A digging trough over the Pacific Northwest will bring gusty winds to the east side Sunday. This, combined with low relative humidities, will bring conditions approaching, but not meeting, Red Flag Warning criteria Sunday afternoon and evening. Modoc county will see the worst conditions. -Stockton && .PREV DISCUSSION... /Issued 301 PM PDT Fri Aug 24 2018/ DISCUSSION...A dry cold front moved through last night, and conditions are cooler than yesterday at this time. Temperatures are about 10 degrees lower than yesterday, and these at or below normal readings should stick around through Monday. The main impact to the forecast area continues to be smoke. There has been notable improvement in air quality across the forecast area, especially north and west of Medford. The HRRR smoke model has been a little optimistic in clearing out the smoke in valleys, and the new Ramsey Fire is bringing new smoke into the Rogue Valley this afternoon, so improvement has been slow to occur. The big question is how much smoke will the Ramsey fire create this afternoon, and where exactly will it go. Current indications are that heavy smoke pushes south-southwest from the Ramsey fire into the Rogue Valley this afternoon. Also, Brookings will see some smoke from the Klondike fire the next several days because of the developing thermal trough and northeast winds. Curry County has been added to the DEQ`s Air Quality Advisory as a result. Switching gears to other weather impacts, as pieces of energy rotate from the northwest through the forecast area over the next week, marine cloud duration and coverage at the coast and West Side will ebb and flow. The clouds that pushed inland to the West Side this morning will be less significant Saturday morning. Then, a potent shortwave trough will push through Saturday night and should bring in another push of marine layer clouds to the coast and West Side into Sunday morning. Models suggest another push of marine clouds Sunday night. Then, a warming trend is expected Monday and Tuesday as the main upper trough pushes to the east and the area is subject to southwesterly midlevel flow. Both the EC and GFS operational models suggest showers are a possibility on Wednesday afternoon. There is some instability as well, but since this is the first synoptic model run that the GFS has featured negative Lifted Index values, we haven`t added any thunderstorms to the forecast for now. An even more significant upper trough arrives Friday, and this brings with it a better chance for some rainfall. Both the EC and GFS operational models bring some precipitation into the forecast area (mainly along and west of the Cascades) on Friday, but GEFS data shows minimal chance for a tenth of an inch of rain with the trough late next week. In any case, it will bring another round of cooler conditions and likely help clear out any smoke that enters into the picture again between now and then. -Keene && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Monday for PZZ356-376. Small Craft Advisory until 5 AM PDT Sunday for PZZ350-370. $$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
Issued by National Weather Service Los Angeles/Oxnard CA 805 PM PDT Fri Aug 24 2018 .SYNOPSIS...Mainly dry weather conditions with temperatures at or slightly below seasonal averages will persist over the region through next week. Look for night and morning low clouds which will dissipate over inland areas each afternoon while only partial clearing is expected near the coast. && of 8:00 PM PDT Friday...Primary short term concern continues to be smoke and associated poor air quality being transported into the region from fires to the north, especially northern portions of Sonoma and Napa counties. Satellite imagery also showing low clouds and fog making a quick return this evening across many coastal areas. 00Z Oakland sounding showing marine layer has shrunk to around 1400 feet, down almost 1000 feet from this time yesterday. The Fort Ord profiler also confirms some reduction of the marine layer this evening. The marine layer is expected to deepen to at least 2000 feet by Saturday morning, with low clouds and fog expected to spread well inland, including the Salinas River Valley. Overall synoptic pattern changing little through early next week, as upper level trough will generally prevail across the West coast. Slight height rises will be felt across the forecast area over the weekend as some weak ridging builds into Southwest California. The slightly higher heights and slightly weaker onshore flow will lead to some reduction of the marine layer depth this weekend, especially southern portions of the forecast area. This in turn will lead to slight warming and drying across interior sections over the weekend, with warmest interior portions of Monterey and San Benito counties climbing into the 90s. While temperatures are expected to nudge downward early next week, a warming and drying trend will be possible by late next week as high pressure aloft rebuilds over the southwestern states. && of 4:30 PM PDT Friday...for 00Z TAFs. Most areas have cleared out this afternoon, but clouds are expected to return late this evening. Most areas have seen at least 6 miles of visibility this afternoon as the smoke was slightly less of a factor than expected. Tomorrow is expected to be similar with most areas clearing in the late morning/early afternoon. Smoke is not expected to be a factor in visibility in most areas tomorrow, although the North Bay may be an exception to that. The experimental HRRR smoke model shows some smoke lingering in the North Bay so KSTS may see some reduced visibilities. The stratus is expected to return once again Saturday night. MKK Vicinity of KSFO...MVFR ceilings are expected to return late this evening as the stratus moves back in. Haze and smoke are not expected to be a factor this evening, but confidence is low on this. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VIS Sat shows stratus moving towards MRY quickly this evening bringing MVFR conditions and SNS will likely follow shortly after that. Tomorrow clearing is expected around midday again and smoke is not expected to be as much of a impact as today. && of 08:00 PM PDT Friday...Moderate northwest winds will affect the northern outer waters through Monday night. Winds will also be breezy through the Golden Gate Gap through Saturday afternoon. Otherwise, generally light winds will prevail through Wednesday. Light northwest swell around 3 to 6 feet is anticipated through the forecast period. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...SF Bay && $$ PUBLIC FORECAST: Gomberg AVIATION: EKA MARINE: Sirard Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Spokane WA
437 PM PDT Fri Aug 24 2018 .SYNOPSIS... Expect cooler weather for the weekend. It will remain mostly dry through Saturday with just an isolated mountain shower possible. Wild fire smoke from British Columbia will cover parts of eastern Washington and north Idaho. There is a possibility of some much needed light rain by Sunday into Monday before another stretch of dry and seasonably warm conditions returns by the middle of the next week. && .DISCUSSION... Tonight through Sunday: Expect cooler temperatures with continued smoke concerns as an upper level trough remains over the Inland Northwest. Breezy west to southwest winds will continue through this evening from the lee of the Cascades and Columbia Basin before tapering off. A weak shortwave in the flow aloft brushes along the BC and N Idaho border by this evening and could produce isolated mountain convection. Any activity would be short lived and decrease early this evening. As the upper trough settles over the region, another shortwave rolls along the BC/WA border Saturday afternoon and brings a small chance of mountain showers. Instability looks weak and lightning chances look low. Winds will be lighter, but afternoon and evening westerly gusts are possible. By Sunday, the next in a series of shortwaves is expected to carve out the upper trough a little more aggressively and bring an increased chance of mountain showers to the region. The Cascades may see light showers, while the mountains of northeast Washington into north Idaho stand to see a better chance of showers. Expect more cloud cover and even the potential for light showers from the valleys of northeast Washington into the Palouse. Breezy westerly winds will redevelop Sunday afternoon especially in the Cascade valleys into the Columbia Basin. The upper trough will also reinforce the north to northwest flow aloft and send waves of smoke southward from BC. Visible satellite shows the current smoke deck covering much of eastern Washington, and since midday today, the surface winds have mixed it to the surface with degrading visibilities and air quality, especially along and north of I90. The HRRR smoke model reflects this trend and shows increasing smoke overnight across north central and northeast Washington, while the southern Basin, Palouse and LC Valley should see limited amounts of surface smoke. The smoke models continue this trend through the weekend. Although increased precipitation upstream in BC should help with a decreasing trend of smoke for the region. More noticeable point will be temperatures, which will feel autumn-like. Expect highs in the 70s Saturday, and then cooling down to the mid 60s to mid 70s by Sunday. /rfox. Sunday night through Friday: The pattern change should be pretty much in place at this point in time with large trof over the northwest Sunday night that gains a positive tilt with its slow exit to the east/southeast into Monday. The positioning of the exiting trof will leave a positively tilted ridge up in British Columbia which will focus a northwest flow into Eastern Washington and North Idaho Monday that lasts until possibly Tuesday that may morph into zonal (west to east flow) Wednesday. Still from Tuesday on into Friday there is enough clutter in terms of synoptic and smaller scale timing of shortwaves that could result in a more active pattern resulting in additional frontal passages Thursday and Friday. Still the overall trend is a general longwave trof lingering in place through this entire interval supporting a forecast consisting of below normal temperatures with the warmest portion of the forecast occurring Wednesday in association with the zonal flow transitioning to a warmer southwest one ahead of the discussed small scale clutter of the active pattern depicted in that part of the workweek. As far as how wet the passage of the synoptic and smaller scale disturbances will be well the trend has been for "not very" since moisture doesn`t seem to be in great abundance with the entrance and departure of the low over this weekend, however a moisture tap from the pacific extending over and around the Cascades in place Wednesday night into Friday which could aid in precipitation production associated with any of the smaller scale disturbance passages during that time interval. Otherwise the continued nuisance associated with the northwest flow Sunday night into Tuesday will be how much wildfire smoke gets transported down from British Columbia. For now smoke and haze continue to be mentioned. /Pelatti && .AVIATION... 00Z TAFS: Winds will be breezy at times this evening across KGEG/KPUW/KLWS/KEAT. Conditions have been deteriorating this aftn across KGEG/KSFF/KCOE/KMWH/KEAT and will likely get worse overnight before things start to improve Sat aftn. MVFR conditions are expected, but could see some localized IFR vis. && .PRELIMINARY POINT TEMPS/POPS... Spokane 51 74 50 68 51 71 / 0 10 0 20 40 20 Coeur d`Alene 49 74 49 68 50 70 / 0 10 0 20 50 30 Pullman 46 74 47 66 48 70 / 0 0 0 20 50 40 Lewiston 52 80 55 72 55 76 / 0 0 0 10 40 30 Colville 45 75 44 69 46 75 / 0 10 0 40 50 10 Sandpoint 44 73 45 66 46 68 / 0 10 0 40 50 30 Kellogg 45 71 45 65 46 65 / 0 0 10 40 60 70 Moses Lake 48 76 50 73 52 79 / 0 10 0 10 10 10 Wenatchee 55 77 56 73 54 79 / 0 0 0 10 10 0 Omak 52 78 54 73 52 80 / 0 10 0 20 40 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
Area Forecast Discussion
National Weather Service Reno NV
230 PM PDT Fri Aug 24 2018 .SYNOPSIS... Near average temperatures continue, with a few degrees of cooling for the early part of next week. Dry conditions, with typical afternoon and evening breezes are expected through Saturday. Breezy winds and critical fire weather concerns increase for Sunday, as a trough approaches the region. No precipitation is expected for the next week. && .DISCUSSION... The pattern over the next week will feature cooler temperatures and periods of breezy conditions, as a series of troughs move through the region. With high temperatures only in the 80s for warmer valleys, these will be the coolest conditions the region has experienced since the end of June. To put this into perspective, however, we are still talking temps near to just a couple degrees below normal. Winds are the greatest concern, with Sunday looking to have the strongest winds, as peak gusts reach 30-40 mph. This will bring choppy conditions on area lakes, possible turbulence for aviation, and increased fire danger. Fire Weather Watches remain in effect for much of the region. Please see the fire section below for additional details. The other concern will be winds kicking up dust and impacting the Black Rock Desert, with the worst conditions likely to be on Sunday. Smoke from ongoing wildfires in northern California and Oregon has drifted across portions of northeast California and northern Nevada. Based on the current satellite image trends and latest HRRR smoke runs, this smoke is likely to increase for areas from approximately I-80 northward overnight. It may appear a bit hazy elsewhere, especially in Alpine and Mono Counties downwind of the Donnell and Lions Wildfires. -Dawn && .AVIATION... Typical southwest to west afternoon and early evening winds can be expected today and Saturday, with gusts peaking around 20-25 kts. Stronger winds are anticipated for Sunday, with surface gusts of 25- 35 kts. This may bring turbulence and localized areas of blowing dust. This is especially true for those flying into the Black Rock Desert on Sunday, where surface dust may produce a decent amount of obscuration. Otherwise, smoke and haze are likely to increase for areas north of I-80 overnight tonight (possibly including the Black Rock Desert). This may bring some surface visibility reductions and terrain obscuration, with further reductions to slantwise visibility. Farther south, the Donnell and Lions Wildfires do not appear to be producing quite as much smoke, but some haze and slantwise visibility reductions are not out of the question for portions of Alpine and Mono Counties. Elsewhere, light haze is possible throughout northern CA/NV. -Dawn && .FIRE WEATHER... No significant changes were made today, with Sunday still forecast to bring relatively widespread critical fire weather conditions to the region. The area of greatest confidence is still in west-central Nevada, where wind gusts of 30-40 mph are expected to combine with relative humidities in the single digits to low teens. A Fire Weather Watch remains in effect for the region on Sunday. However, at higher elevations, winds and poor recoveries could begin Saturday night and potentially last through Sunday night. Next week, winds will be a little breezier then recent weeks as a trough of low pressure remains over the west coast. It`s possible that critical fire weather conditions will re-develop midweek, but it`s a little too early to say which day that might be. -Zach && .REV Watches/Warnings/Advisories... NV...Fire Weather Watch from Sunday afternoon through Sunday evening NVZ450-453-458-459. CA...Fire Weather Watch from Sunday afternoon through Sunday evening CAZ270>273-278. && $$ For more information from the National Weather Service visit...
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday) Issued at 333 PM CDT Fri Aug 24 2018 Early afternoon water vapor imagery shows center of upper low over southern Minnesota dry air following across southwestern Nebraska and northern Kansas. Very isolated elevated showers continue to move across the northern counties but as the trough axis exits believe this will become even less frequent. A weakly-defined modified cold front was sinking south into northern Kansas with lower to even middle 70 dewpoints ahead of it, though visible satellite imagery showing very little cumuliform development ahead of it. Latest RAP analysis is keeping significant CIN to mix-layer parcels in place and any model producing convection along over the next few hours is hard to find. Will continue with very low PoPs along the boundary, though ML CAPE values of 2000-3000 J/kg and effective shear around 40 knots would supply an environment for an organized storm. Main convective concerns over the next several periods are via elevated ascent. The moisture plume over southern Kansas may become more active again tonight as modest upglide increases again through the 310 to 315 K layer. Models do vary somewhat on precip potential, but went ahead with small chances south of Interstate 70 late this evening into early Saturday morning with guidance struggling with the early-day activity. Instability aloft is meager in the higher moisture and should keep any rainfall amounts light. Main other item of interest tonight is fog potential with light winds and little cloud cover behind the stalling boundary, though the weakest winds should be in northeastern areas where precip has been less intense in recent events. Potential looks too low at this point for inclusion with still some wind in the boundary layer on latest RAP forecasts. Highs Saturday should still be able to reach the lower to middle 90s as south winds return, with somewhat cooler readings more likely in southern locations where mid and high cloud may persist. .LONG TERM...(Saturday night through Friday) Issued at 333 PM CDT Fri Aug 24 2018 id-level isentropic lift returns in mainly western areas Saturday night as stronger zonal flow resumes over the northern Plains. Instability remains low here too. Another round or two of elevated convection is possible Sunday night and Monday night as the next upper wave digs into the north-central states. 850 mb temps in the lower to middle 20s Celsius and gusty south to southwest winds still keep potential for rather warm daytime temps with low to mid 90s still expected though persistence of any precip into the daytime hours yields somewhat reserved confidence. The cold front associated with this wave passes in the Tuesday to Wednesday periods and could present a surface-based convective threat though many questions exist on its timing and how previous precipitation will impact its pre-frontal environment. Another elevated warm/moist-air advection regime could develop in the Wednesday night to Friday periods for still more chances for convection. Post-frontal temps should not fall too far before rising above normal again late in the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 608 PM CDT Fri Aug 24 2018 Expect VFR conditions to prevail through the period. The only potential issue would appear to be patchy fog around TOP after 08Z with light winds and high humidities. That said, boundary layer mixing remains present albeit weak overnight so will not include at this point. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...65 LONG TERM...65 AVIATION...Omitt
Area Forecast Discussion
National Weather Service Tucson AZ
906 PM MST Fri Aug 24 2018 .SYNOPSIS...Abundant moisture will remain in the area through at least Saturday with a threat of heavy rain producing thunderstorms at any point through Saturday evening. Sunday into Monday drier air will begin to limit thunderstorms and allow for warmer temperatures. The middle the week should be dry and warm before moisture tries to return again next weekend. && .DISCUSSION...Scattered showers and thunderstorms were still ongoing late this evening after several areas received heavy rainfall today. Most of the Tucson area received some rain this evening, with a few spots reporting .5 to .75 of an inch. Latest HRRR solution suggested that most of the rain, mainly light, will remain across Pima county tonight before dissipating by daybreak. That said, will keep the Flash Flood Watch going until midnight even though the threat had diminished across Cochise, Graham and Greenlee counties. Made some minor adjustments to the POP values east and west of Tucson for the remainder of tonight. Otherwise, the forecast looked in good shape. Please refer to the additional sections in this product for more details. && .AVIATION...Valid through 26/06Z. SCT-BKN clouds around 8k-12k ft AGL across much of the area, although cloud bases could drop to 4-5k ft AGL around heavier convection. Conditions then improve overnight before another round of SHRA/TSRA develops Saturday afternoon. Surface winds remain less than 12 kts through the period with the exception of stronger gusts near TSRA. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Deep moisture continues to provide favorable conditions for thunderstorm development into the weekend. Some storms will be capable of producing very heavy rainfall in a short period of time. The pattern then shifts next week allowing for drier conditions with warmer temperatures. Terrain driven 20-ft winds persist at less than 15 mph, except in and around thunderstorms where strong outflows may occur. && .PREV DISCUSSION...Saturday we will still have near record amounts of PW, at least across the eastern half/two thirds of the area and as usual, if we get enough sunshine it will be an active day with convection and local heavy rains. We may have a bit less instability to help out though. By Sunday, the light SW flow should have eroded a good amount of our moisture aloft for much lower PW values, actually back down to more "normal" levels. This would favor scattered convection generally east of Tucson that afternoon and shutting down after sunset. The situation will likely be similar on Monday and both days should have high temperatures near normal again. The middle of the week into Friday favors dry and warm with the upper level high in a less favorable position for storms and drier air aloft. Then next weekend there is a chance that we start returning to southern flow with some moisture increase once again. && .TWC WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until midnight MST tonight for AZZ502>515. && $$ Visit us on Facebook...Twitter...YouTube...and at