Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/12/17

Area Forecast Discussion
National Weather Service Gaylord MI
1148 PM EDT Wed Oct 11 2017 .UPDATE... Issued at 957 PM EDT Wed Oct 11 2017 Surface ridging in control of our weather tonight, bringing clear skies to much of the area. However, still a band of lower clouds rotating west along and south of the M-55 corridor. Some clearing noted back across Lake Huron, and would expect to see some of this cloud deck erode in the coming hours. Any clearing will be short-lived, as slowly veering winds bring an extensive area of low clouds to our south back north very late tonight, and especially on Thursday. Latest guidance trends much more aggressive swinging these low clouds north, and fully expect much of the area to be completely cloudy by later Thursday. Have trended the forecast to this more aggressive scenario, and as such, have lowered highs a few degrees Thursday. && .NEAR TERM...(Tonight through Thursday) Issued at 255 PM EDT Wed Oct 11 2017 ...Remaining showers ending late afternoon/early evening... High Impact Weather Potential...None. Pattern Synopsis/Forecast...Surface low continue to make its way thru Ohio this afternoon...while strong high pressure is center along the Ontario/Quebec border. Northern edge of the large swath of rain that developed north of the surface low center is slowly exiting out of our SE CWA as the low pushes toward the Atlantic coast. Clouds are steadily diminishing across our NW CWA as even the upper level moisture/cloud cover begins to depart on the backside of this system. Temps have struggled to warm out of the 50s so far today due to thick clouds and precip. Both the NAM and the RAP pull the last vestiges of shower activity out of our far SE CWA just before 00Z this evening...with clouds quickly diminishing behind the back line of precip as drier air thru the column filters into the region. Gradient remains sufficiently tight for dry easterly low level flow to help preclude fog development tonight. Thus...expect mainly clear skies for our entire CWA for late evening and overnight. Low temps will cool mainly into the low to mid 40s. Thursday will begin with mainly clear skies for much of our CWA before some low cloudiness begins to push back northward into our CWA as low level flow shift to the SE ahead of our next approaching system. Cannot rule out a slight chance of a shower across our SE CWA as well in the afternoon. High temps will warm into the low to mid 60s across our entire CWA. && .SHORT TERM...(Thursday night through Sunday) Issued at 255 PM EDT Wed Oct 11 2017 ...Periods of unsettled weather through this weekend... High Impact Weather Potential: Periods of soaking rain Friday night and again Saturday night-Sunday. Rain may fall heavily at times Saturday evening into early Sunday along with increasingly gusty winds. Can`t rule out a few rumbles of thunder Sunday and depending on the timing, strength and placement of the system...perhaps the potential for a few severe storms. Pattern Forecast: Quite the active pattern setting up across the central U.S. late this week through the upcoming weekend. Despite light/scattered shower activity possible Thursday night into early Friday, focus revolves around the Friday evening through Sunday timeframe. Low pressure rapidly trekking across northern Manitoba/Ontario Thursday night into Friday is expected to drag an elongated cold front across northern Michigan Friday night. This boundary will become stationary across Lower Michigan during the day Saturday providing the focus for a stronger mid level wave and associated deepening surface low to track along as it emerges from the Intermountain West/Plains. Still plenty of uncertainty exists this weekend with respect to low pressure strength, timing and track. However, the potential is becoming likely for periods of rain across much of northern Michigan...potentially heavy at times. Primary Forecast Concerns/Challenges: Gauging precip potential throughout the forecast period with precedence put on the Friday night through Sunday timeframe. Increasing clouds from south to north Thursday afternoon will continue right into Thursday night with perhaps a few showers developing as a result of lingering low-mid level moisture and a weak northeastward moving boundary. This activity is expected to curtail by Friday morning; however, additional rain chances arrive from the northwest Friday evening. Aforementioned elongated cold front is expected to gradually cross northern Michigan Friday night with showers becoming likely over eastern Upper and northwest Lower Friday evening...gradually transitioning along and east of I-75 overnight. Wouldn`t be shocked to see showers continue for some early Saturday; however, a lack of guidance consistency with respect to the placement of the stalling cold front yields decreased confidence to overall precip coverage during the daylight hours Saturday. The stalled boundary across central/southern Lower Michigan gradually begins to lift northward as a warm front Saturday afternoon as low pressure deepens across the Mississippi Valley and progresses northeastward into the western Great Lakes. Rain is expected to become likely once again Saturday evening continuing into Sunday...potentially falling heavy at times as PWATs rise to nearly 1.50 inches (+1 to +3 standard deviations for mid-October). GEFS ensemble means suggest upwards of 1.00-2.00 inches of QPF through the Saturday evening-Sunday time frame across northern Lower...slightly less in eastern Upper. Again, low confidence prevails in terms of the small scale details at this juncture, but there`s at least a small threat for a few rumbles of thunder just given the degree of moisture and dynamics with this system. Given the progged 150+ kt jet structure aloft and the amount of effective bulk shear (in excess of 60 kts) late Saturday night-Sunday morning, a conditional severe weather threat can`t be ruled out either (despite very limited instability)... although the better threat of that may remain downstate and into the Ohio Valley. Precip chances gradually diminish Sunday, although increasingly gusty winds and cooler temperatures ushered in on the back side of the departing low may prove to be enough to start lake processes with scattered lake effect rain showers continuing across the typical NW flow lake effect zones of northwest Lower and eastern Upper. Trends continue to suggest the brief cold spell should be just warm enough (but maybe not by much) to prevent any snowflakes from mixing in across the higher terrain. .LONG TERM...(Sunday night through Wednesday) Issued at 255 PM EDT Wed Oct 11 2017 High impact weather potential: Minimal. Cold air behind Sunday`s departing system is rather fleeting as heights aloft begin to rise during the day Monday. Any lingering light/scattered lake effect rain activity is expected to come to an end during the day Monday. Another system early next week is expected to pass by just to our north; however, high pressure over the midsection of the CONUS should provide mainly dry conditions locally with gradually moderating temperatures. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1142 PM EDT Wed Oct 11 2017 Mostly clear skies through much of the overnight across most of the area. Extensive area of mvfr/ifr cigs just clipping Manistee, but is expected to scatter out early this morning. Additional mvfr/ifr producing overcast will sweep north across all taf locations by later today, with low cigs and areas of drizzle expected this evening. Light east winds will turn southeast with time. && .MARINE... Issued at 255 PM EDT Wed Oct 11 2017 Winds and waves will continue to reach SCA criteria across our Lake Huron nearshore areas tonight and Thursday thanks to persistent easterly onshore flow north of low pressure tracking north of the Ohio Valley. Remaining rain near Saginaw Bay will diminish late this afternoon and come to an end...with dry wx expected for the rest of tonight and Thursday morning. Additional chances of showers will develop Thursday afternoon and night for much of our nearshore areas. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY until 6 PM EDT Thursday for LHZ345>349. LM...NONE. LS...NONE. && $$ UPDATE...MB NEAR TERM...MR SHORT TERM...MG LONG TERM...MG AVIATION...MB MARINE...MR
Area Forecast Discussion
National Weather Service Des Moines IA
620 PM CDT Wed Oct 11 2017 .SHORT TERM.../Tonight through Thursday/ Issued at 325 PM CDT Wed Oct 11 2017 The main forecast concern was focused on stratus deck lingering into tomorrow and with the drizzle/fog potential early Thursday morning. Leaned toward the latest runs of the RAP, HRRR and ESRL HRRR for cloud cover location as they have a good handle on the current trends across the state. Strong inversion develops this evening and looks to trap the low level moisture/stratus deck into the morning Thursday, particularly across the eastern half of the CWA where the stratus currently resides. Confident that the eastern portions of the CWA will remain under the low stratus through at least 12z Thursday, with it lingering and trying to dissipate b/t 12-15z when the WAA begins to develop. The real tricky part is the central sections of the forecast area, from north to south from around Lamoni through Des Moines northward through Ames to Kossuth County. This is currently the western edge of the stratus and the question remains if and how far the stratus retrogrades back west-northwest this evening. In this location, have patchy fog mentioned as a few the hires models keep the stratus as is or erodes it slightly eastward allowing for radiational cooling to setup and thus fog to develop. Concerned that the western third of the CWA will see fog develop overnight with the radiational cooling setup in this location. Dew point depressions do become less than 5F to even 0F by around 09z Thursday and the latest runs of the HRRR/RAP and even the ARW/NMM suggest fog developing by around 09z. Timing of the WAA the west prior to 12z Thursday will determine if this will hold off the radiational fog to development. Across the east, there is very weak lift in the saturated column per MCW to ALO soundings and kept mention of drizzle overnight. Low confidence with any measurable precipitation at this time and currently left out any pops. .LONG TERM.../Thursday night through Wednesday/ Issued at 325 PM CDT Wed Oct 11 2017 A cold front will enter northwest Iowa Thursday night then will continue to move slowly southeast on Friday. The initial airmass will begin dry as the boundary arrives though mid-level moisture advection will arrive during the day on Friday which will help enhance precipitation chances over mainly the northern Iowa. Precipitation chances would settle south Friday night as the boundary moves into northern Missouri. Moisture depths though would support light rain or even drizzle in some areas. A strong short wave will move into the Nevada/Utah region Friday night and move east into the Western Plains on Saturday. This will create increasing southwest flow aloft and will help lift the surface boundary back north. In addition, this flow will bring strong low and mid-level moisture advection to the southeast half of Iowa. PWAT values will increase to near 1.75 inches by Saturday afternoon or near 250% of normal. Warm cloud depths will be near 12.5 kft and the setup is good for an efficient rain producing system. The southeast portion of the forecast area is currently outlooked for severe weather by SPC on Day 4. As of now, the threat for severe weather looks conditional on if the clouds can break and temperatures do recover. Any severe weather threat should be relegated to the far southeast including the Ottumwa and Bloomfield areas. The precipitation will quickly end Saturday night. The wind will increase behind the boundary as cold advection arrives and the pressure gradient increases as low pressure intensifies to the north. Wind gusts over 35 mph are possible and may reach wind advisory criteria for a brief period. High pressure will arrive during the day Sunday and will diminish the wind gusts by the afternoon. Currently have low temperatures in the upper 30s for Sunday night. May not be low enough at this point and could have frost potential by Monday morning. Current forecast low dew points are in the lower 30s over northwest Iowa and lows may approach the dew point values. Generally dry and warmer conditions Monday and Tuesday as high pressure moves southeast and southerly winds return. && .AVIATION.../For the 00Z TAFS through 00Z Thursday evening/ Issued at 620 PM CDT Wed Oct 11 2017 MVFR/IFR conditions over the east may expand back to the west overnight. This will need to be monitored. If the stratus does not move back in, then some patchy fog may develop and bring local MVFR visibilities to areas mainly west of I-35. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Podrazik LONG TERM...Donavon AVIATION...FAB
Area Forecast Discussion
National Weather Service Quad Cities IA IL
242 PM CDT Wed Oct 11 2017 .SYNOPSIS... Issued at 240 PM CDT Wed Oct 11 2017 Storm system that brought widespread soaking rain to much of the cwa yesterday was in the Ohio Valley region. Cyclonic flow as far west as central IA/eastern MN, combined with the moist ground, has kept low stratus in place all day. As a result, temperatures were on the cool side with afternoon readings only in the 50s to around 60. && .SHORT TERM...(This Evening through Thursday) ISSUED AT 240 PM CDT Wed Oct 11 2017 Forecast focus on clouds and possible drizzle. Tonight: Weak surface ridge comes across the cwa providing very light winds. This will be tough to scour out the clouds considering forecast soundings indicate a strenghthening inversion at 850 mb. This will keep the low level moisture from the recent rainfall trapped below the inversion. Therefore, the widespread low stratus is expected to remain in place. Also, soundings indicate a classic drizzle scenario with very dry air above the inversion, and weak omega in the stratus layer, which the HRRR picks up on. For now will keep the mention of patchy drizzle and patchy fog in the grids. Later shifts can monitor for the possibility of more widespread drizzle if the forcing is a bit stronger in the sub-inversion layer. Due to the low stratus, there won`t be much of a diurnal spread in temperatures, with lows in the lower 50s. Thursday: Low stratus to remain in place for much of the morning, then skies should clear from west to east during the afternoon. High pressure ridge will shift to our east with warm air advection kicking in (southerly winds), which should allow for the stratus to gradually erode. Maximum temperatures will push into the 60s, which is normal for mid October. .LONG TERM...(Thursday Night through Wednesday) ISSUED AT 240 PM CDT Wed Oct 11 2017 Main forecast concern for the long term forecast are the chances for thunderstorms this weekend and with it the chance for heavy rain and severe weather. After this front this weekend, the rest of the long term looks dry and more seasonal as far as sensible weather goes. Friday...the return of warmer temperatures and boundary layer moisture is expected as the mean flow turns southwest. H85 flow will advect in warmer more moist air. H85 convergence is expected to be just north of the CWA as a weak wave ripples through the flow. This will be enough to initiate showers and some thunderstorms across the northern CWA Friday evening. As this convection continues through the overnight, the effective warm front will be pushed south into our CWA. Rain from Friday night across the area, may set the stage for hydro concerns on Saturday. Friday night, instability will be low, however deep layer shear is conducive for midlevel storm rotation. Any midlevel rotation would lead to increased rainfall across the area along with possibly the isolated elevated hail storm. The threat for severe weather is low on Friday evening. Saturday, major questions remain as to where the effective warm front is. A strong short wave is expected to approach the area later in the day into the evening. At the same time a low is expected to move across the boundary. Short of a negatively tilted trof, wherever the warm front is Saturday morning is probably where it will stay. Shear is quite strong along this boundary and would lend itself well to low level storm rotation. Any storm near this boundary will likely have a threat to become severe. The next question is whether or not we will have a lull in the precip and cloud cover on Saturday. If we dont have a lull, convection will likely increase with the sfc low. If there is a lull, the threat for severe weather will increase. Another concern is the stalled boundary with PWATs near 2 inches. Near continuous H85 flow will feed convection plenty of moisture. Areas near and north of the warm front could see heavy rain on Saturday. With the rain we had yesterday along with the forecast rain for Friday, hydro issues could become an issue with possible rises on area rivers along with potential flash flooding. There are a lot of possibilities with the forecast for this weekend. Regardless, now is the time to start paying attention to this forecast. Additional model runs will lead to more confidence in a forecast solution. Past Saturday, cooler and drier air is expected without a good chance of precip through mid next week. && .AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon) ISSUED AT 148 PM CDT Wed Oct 11 2017 IFR/low MVFR cigs this afternoon then IFR/ocnl LIFR cigs/vis tonight into Thursday morning. North to northeast winds less than 10 knots through tonight, then becoming south on Thursday. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Haase SHORT TERM...Haase LONG TERM...Gibbs AVIATION...Haase
Area Forecast Discussion
National Weather Service Houston/Galveston TX
857 PM CDT Wed Oct 11 2017 .DISCUSSION... Surface analysis has high pressure over the Ozarks NE towards the Great Lakes. Ridge axis then extends back to the SW into Texas supporting light northeast winds over SE Texas. Favorable radiational cooling conditions should allow for temperatures to fall into the low 60s for most of the area with a few spots of upper 50s. Low temperatures in the 60s/70s will be confined to the coast. Temperatures increase to summer time levels over the weekend with a cold front late Sunday/Monday to bring back fall conditions. Overall forecast looks on track and only adjustments were for ongoing temperature/dewpoint trends. Overpeck && .PREV DISCUSSION... /ISSUED 629 PM CDT Wed Oct 11 2017/ AVIATION... Dry air and northeasterly flow will keep us in VFR throughout the period. Winds will slowly gradually veer and become easterly or even a bit south of easterly by the end of the period. However, the pressure gradient will be loose and winds will be light, mitigating impacts of the wind shift. Indeed, the gradient may be so loose that winds will be fairly light and variable, particularly overnight. Luchs PREV DISCUSSION... /ISSUED 352 PM CDT Wed Oct 11 2017/ DISCUSSION... Other than a few clouds over the southern counties, skies are clear with temperatures in the upper 70s to low 80s. Skies will remain mostly clear tonight with dew points in the 50s and calm winds, bringing low temps tonight down into the low to mid 60s. Onshore flow returns tomorrow, bringing dew points back into the 60s and warming temperatures into the mid-80s. Models agree that the upper level ridge which began to build into the area last night will remain centered over the Lower Miss Valley. This will drive the higher moisture and greater precipitation chances further south into the Texas/Mexico border through Saturday, leaving us mostly dry through the rest of the week except for a few offshore showers. The biggest rain chance over the next few days will be associated with the seabreeze during the day Saturday and Sunday as southwesterly winds bring higher moisture along the coast. The next big weather change will come with the passage of the next cold front. Timing of the frontal passage seems to have slowed down with both the 12Z GFS and Euro indicating passage closer to 12Z on Monday with higher chances of rain on Sunday night ahead of the front. In its wake will be cooler and drier air with dew points from the low 60s near the coast to the upper 40s farther inland and temperatures in the upper 70s to low 80s for the remainder of the week. 22 MARINE... Winds have continued to weaken as high pressure slides in from the NW, and the pressure gradient over the region slackens behind the cold front that moved through SE TX earlier this week. Seas are still ranging between 2 to 4 feet but are expected to continue lowering to 1 to 3 feet by Thursday. Early Thursday morning, could see some isolated shower development in the western waters. Short term guidance such as the HRRR and RAP13 show this development beginning around 06-09Z, and then moving these showers towards coast but dissipate before making their way on land. Onshore flow should return to the forecast late work week, bringing with it an increase in moisture. Next real feature that will impact the marine zones will be the next wind shift behind the cold front expected to impact SE TX late Sunday into Monday. Wind speeds should once again increase behind the front and become more northerly, along with seas also rising between 3 to 5 feet late Monday into Tuesday. Hathaway && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 62 87 67 90 69 / 10 10 10 10 10 Houston (IAH) 64 87 68 90 70 / 10 10 10 10 10 Galveston (GLS) 73 84 77 87 77 / 10 10 10 10 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...39
Area Forecast Discussion
National Weather Service Wilmington NC
923 PM EDT Wed Oct 11 2017 .SYNOPSIS... Unseasonably warm and humid weather will continue through Thursday. A weak cold front will reach the Carolinas late Thursday, with relatively drier and slightly cooler weather heading into the weekend, but continuing unseasonably warm. Fall-like weather should arrive next week as a stronger cold front moves through. && .NEAR TERM /THROUGH THURSDAY/... As of 930 PM Wednesday...Temperatures are dropping almost exactly in line with prior forecast rates. I have made some minor decreases in forecast cloud cover overnight based on current satellite imagery, but not enough to significantly alter the forecast. Discussion from 730 PM follows... 500 mb high pressure centered along the Gulf Coast and surface high pressure centered just offshore continue to provide late summer-like weather across the Carolinas. 850 mb temps near +18C are above the 95th percentile for this time of the year, as are precipitable water values around 2.20 inches. Low-level winds will become quite light overnight, but should still not allow good enough radiational cooling to keep from setting more record warm low temperatures for the date. Forecast and record warm lows for late tonight, October 12: Wilmington: forecast 73, record warm low temp 73 in 1990. Florence: forecast 72, record warm low temp 70 in 1983. N. Myrtle Beach: forecast 73, record warm low temp 68 in 2010, but records only began in 1999. Lumberton: forecast 72, record warm low temp 65 in 2011, but records only began in 1999. A modest subsidence inversion around 6000-8000 feet aloft is helping today`s cumulus clouds persist as altocumulus this evening. Some of these clouds will persist overnight, and will be joined by low stratus and areas of fog late, especially inland. A very weak upper disturbance over east Tennessee and the NC mountains will drift down into the Sandhills region late tonight, and the latest RUC shows late-night showers developing with this feature. I`ll leave the late night 20 PoP in for this feature in the Lumberton vicinity as forecast soundings do show elevated instability persisting overnight when layers from 2000-5000 feet are considered. Low temps are forecast to reach 72-74 for most areas, little changed from the previous forecast. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 230 PM Wednesday...Weak backdoor type cold front will drop south through the area late Thurs. Looks like this will remain the focal point for some shwrs/iso thunderstorms into early Thurs evening. With the loss of heating and lack of any real upper level support, expect activity to diminish through Thurs late eve leaving a very moist low level column up through the first few thousand ft. Northeast to easterly flow behind weak cold front leaves a continuous flow of low level moisture off of the Atlantic into Fri. The winds should kick up behind the front slightly which should lead to the development of low stratus toward daybreak on Fri which should lift through the aftn leaving a layer of strato cu across the area Friday aftn. The limited sunshine and slight modification of the air mass will produce temps closer to the lower end of 80s...a good 5 degrees above normal for most places. Pcp water values should drop closer to 1.5 inches or below on Fri behind the front, mainly west of I-95 corridor and north of local area. The boundary may linger just south of area with convection possible Fri aftn in slightly more moist and unstable air mass over SC or mainly NE SC coastal areas. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... As of 230 PM Wednesday...Temperatures will be well above normal through the weekend into early next week with H5 ridge across the Southeast United States. The ridge is shown to break down early next week which could open the door to a cold frontal passage and a much cooler airmass for Tuesday and Wednesday. However, the H5 pattern becomes less amplified by early next week creating some doubt that the front will move through late Mon/Tue as currently advertised by the GFS. A slower progression of the front would carry rainfall chances into Tuesday as well. Followed a blend of MEX/ECE max and min temperatures Sat-Monday but leaned toward the warmer MEX temps Tue-Wed time frame. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 00Z...VFR conditions should persist through 05Z before some fog begins to develop inland. Rich moisture and light winds overnight will favor the development of low stratus and fog inland, with a lesser potential down at the coast. Our latest forecast brings IFR conditions into the FLO/LBT airports by 09Z, but the potential for IFR is currently too low to include at the ILM, CRE, or MYR airports. Conditions should improve to VFR across the area between 13-15Z Thursday with another round of scattered showers and t-storms developing again during the day. Extended Outlook...MVFR/IFR conditions are possible during the mornings Friday and Saturday from ceilings and/or reduced vsby from fog. Scattered showers are expected each day which could produce brief MVFR/IFR conditions. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 930 PM Wednesday...High pressure off the coast will maintain a light southerly wind and dry weather overnight. Seas currently 2-3 feet are primarily due to an 8-second southeast swell. Models are in excellent agreement and no weather surprises should occur tonight. SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... As of 230 PM Wednesday...A weak cold front will drop south across the waters late Thursday into early Friday. SW winds will shift NE overnight Thursday with a slight brief increase behind the front through Friday, but overall not expecting winds greater than 10 kts . Seas will continue to run right around 3 ft through the period. LONG TERM /SATURDAY THROUGH MONDAY/... As of 230 PM Wednesday...Weak high pressure will prevail at the onset of the long term period. The high will shift offshore allowing winds to veer from a northeasterly direction Saturday to a southerly direction during Sunday. A cold front is expected to approach the waters during Monday but the GFS may be too fast translating into a longer period of southerly winds. Seas are expected to average 3 ft or less through the period && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...SRP AVIATION...TRA
Area Forecast Discussion
National Weather Service Elko NV
241 PM PDT Wed Oct 11 2017 .SYNOPSIS...Dry conditions will continue through Thursday however there may be some smoke from the California fires blowing our way, reducing visibility at times across the northern part of the state. A storm system will bring a chance for rain and snow showers to northern Nevada Friday through early Saturday. && .SHORT TERM...Clouds are increasing across the Pacific Northwest ahead of a low pressure system approaching the coastline. Its been a rather mild day today with relatively light winds...some occasional gusts in the 20s. A band of high cloudiness is quelling temperatures for now but max temperatures still reached into the 60s across the board, northern and central Nevada. In the short term, there will be a low pressure system dipping into the Great Basin, bringing some shower activity mainly to northern Nevada, and a brief cold snap. Tonight through Thursday night. Dry weather will continue. Presently smoke from the California fire situation is making its way into the Winnemucca area, reducing visibility at the Winnemucca airport. Its possible it will decrease visibility all along Interstate 80 tonight as the southwest flow aloft increases ahead of the incoming low pressure system. High temperatures will generally make it into the 50s. Low temperatures will be in the 20s. Friday through Saturday morning. Low pressure will provide at least a glancing blow to northern Nevada and it will likely be a quick hitter. At this juncture, precipitation chances will be highest across northern Nevada, noting that there is potential for more spread further south with the identification of two upper low circulations within the mean trough over Idaho and Montana. Snow levels will be dipping to near 6000 feet so Interstate 80 in the Pequops will get dusted with snow as the front moves through. High temperatures will generally make it into the 50s. Low temperatures will be in the 20s. Saturday afternoon. Dry conditions reappear. Models indicate a clean exit of the trough, moving it as far as Colorado and Wyoming by late afternoon. Then the cold air will begin to move into the CWFA. High temperatures will be in the 40s. .LONG TERM...Saturday night through Wednesday. Sunday morning will be quite chilly across the area with many locations in the teens and lower/middle 20s. After that, a slight warming trend will commence with highs rising back into the 60s/70s for northern/central NV. There are hints of the middle to end of next week becoming active, but confidence is low at this time. More of something to keep in the back of your mind if making plans to travel or enjoy the outdoors. && .AVIATION...VFR expected next 24hrs for KTPH/KELY. Smoke is quite dense this aftn ahead of a weak frontal bndry. This will continue for KWMC at least until early evening with IFR/MVFR conditions. KEKO should see smoke arrive by later aftn or early eve. Vis may drop to MVFR, but confidence is lower since the HRRR models breaks the smoke down as it moves east. Otherwise, gusty winds Southerly to westerly winds will continue. && .LKN WATCHES/WARNINGS/ADVISORIES...None. && $$ 92/94/94
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
728 PM CDT Wed Oct 11 2017 .UPDATE... 728 PM CDT Northeast flow continues this evening but ever so gradually easing. The low clouds are locked in, with local AMDAR soundings indicating a moisture depth of 4,500-5,000 ft, with the upper 1,500 ft of that or so within the inversion. That`s not good for any clearing possibly through much of tomorrow with the incoming light winds under the surface ridge. The drizzle and patchy light rain in northeast and north central Illinois is now mainly driven by lake-induced instability. With flow easing and veering slightly more east overnight, and a tad more drier air, the intensity and coverage of drizzle should wane overnight. Cannot rule out a few spits lingering into early morning close to the shore based on forecast RAP profiles. MTF && .SHORT TERM... 1259 PM CDT Through Thursday... The system responsible for last night`s rain is lifting away from the region. Any lingering showers should come to an end through the afternoon today, but an expansive area of low stratus will remain in place through tonight and likely, through tomorrow as well. Latest forecast sounding suggest that some drier air will overspread the nearly saturated lower levels late tonight and tomorrow, bring a chance for some patchy drizzle and for the late night into early morning hours. The blanket of stratus will also limit the diurnal temperature trends with temps topping out today in the low 60s. Lows tonight are expected to be in the low to middle 50s, but highs tomorrow should only be a couple degrees higher than today, reaching only the low 60s. && .LONG TERM... 241 PM CDT Thursday night through Wednesday... Main concern in the extended is multiple rounds of rain Friday night into Sunday. After an above average end to this week, next week starts with more seasonal temperatures and a slow warm up through mid week. Dry weather is expected Friday as the upper level ridge hangs over the region. Warm air advection will also result in high temps in the low to mid 70s. Cloud cover will play a big part in how efficiently we warm Friday with more cloud cover leading to cooler temps. Precip forms to our north and west along an upper level vorticity streamer Friday evening. Showers and a couple of embedded thunderstorms spread across the region Friday night. A surface low surges from northwest Missouri to Quebec Saturday afternoon to Sunday afternoon. The low`s warm front lifts through the region Saturday bringing another surge of warm air. High temps will range from the low 70s along the IL/WI state line to around 80 south of I-80. Morning showers dissipate, but I`m expecting scattered afternoon showers to form within the warm sector. GFS suggests CAPE and shear values that could support strong to maybe severe storms. Similar to many systems lately, CAPE will be the limiting factor for severe storms. PWATs will be well above average at around 2 inches, and this much liquid could lead to heavy rain. The line of showers and storms pushes east of the forecast area Sunday morning or early afternoon along with the low`s cold front. Northwest winds and a push of cooler air follow the front with highs Sunday in the 60s. Sunday night looks particularly blustery as a secondary upper level trough and cold pool spread across the region. Wind gusts around 25 MPH are possible. Lows in the low to mid 40s are expected. The upper level trough should only produce precip over the lake early next week. The dry period continues through mid next week under high pressure. Temps also climb into the upper 60s by mid week as well. JEE && .AVIATION... For the 00Z TAFs... IFR stratus, fog and drizzle are expected to persist overnight, and are the main aviation forecast concerns through this TAF period. Surface low pressure continues to pull away from the area across the Upper Ohio Valley early this evening. A weak surface trough lingers across central IL/IN however, with moist east-northeast low level flow off the lake resulting in persistent low cigs and intermittent light rain/drizzle. Forcing for producing precip should continue to weaken this evening, allowing a decrease in intensity of precip and somewhat better IFR/MVFR vsbys...though do expect a very gradual decrease in cig/vis conditions into solid IFR overnight. Vsbys around 3SM and cigs 600-700 ft are likely by morning. Low level winds will turn light southeast Thursday, and will eventually shift a warm front north of the area by afternoon. This should result in a gradual improvement back to VFR vis and MVFR cigs. Ratzer && .MARINE... 241 PM CDT Kept current Small Craft Advisory as is as winds and waves will slowly subside through tonight. Low pressure over Ohio weakens as it continues east, and high pressure spreads over the Great Lakes this evening. East winds diminish this evening and veer to southwest by Thursday night. A stationary front over the southern end of the lake Friday night will lead to north winds to the north of the front and southerly winds to the south of the front. The next surface low forms over northwest Missouri Saturday afternoon. The low`s warm front surges two thirds up the lake before the low passes over the lake Saturday evening/night. Wind gusts up to 30 kt are expected. Winds become north to northwest behind the cold front and gales are expected Sunday. High pressure spreads over the Great Lakes Sunday night and then passes south of the lakes Monday night. West to southwest winds 10-20 kt are expected early to mid next week. JEE && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...IL nearshore waters until 5 AM Thursday. Small Craft Advisory...IN nearshore waters until 11 PM Wednesday. && $$ 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
National Weather Service Melbourne FL
846 PM EDT Wed Oct 11 2017 .UPDATE... GOES-16 water vapor imagery combined with the most recent RAP analysis indicates a significant punch of low- to mid-tropospheric dry air advecting across the area. As a result, radar is nearly void of returns this evening, save for an isolated shower or two and some weak convergent signatures over the marine waters. Moisture in association with a wave over the Bahamas will build across our southeastern zones late tonight, so will maintain a low chance for showers over portions of the Treasure Coast waters as well as Martin and St. Lucie counties closer to sunrise. && .AVIATION... Generally VFR with northeast winds increasing after sunrise Thursday. Building moisture through the day on Thursday will support an increased coverage of showers, especially KVRB-KSUA corridor. && .MARINE... Tonight/Thursday...ENE/NE winds approaching 10-15 kts with 15-19 kts offshore/south of Sebastian Inlet. Seas building to 3-5 ft nearshore and 5-6 ft offshore overnight, up to 7 feet by Thursday afternoon. Cautionary statements in effect for the offshore marine legs tonight and will likely be needed over the nearshore waters on Thursday. && .HYDROLOGY...Moderate to Major flooding continues along the upper and middle St. Johns River basin. Limited rain chances through mid week will allow for river levels to remain fairly steady, or show very slow decreases through this period. Higher rain chances are expected From late Thursday or Thursday night through this weekend. Difficult to pin down rain amounts, however any locally heavy rainfall over the basin will aggravate standing water concerns and temper the slow decline of water levels. && .PRELIMINARY POINT TEMPS/POPS... DAB 69 86 73 86 / 0 10 20 40 MCO 69 89 73 88 / 0 10 20 50 MLB 74 87 78 87 / 10 30 50 60 VRB 75 86 77 86 / 10 50 60 60 LEE 71 89 71 90 / 0 0 10 30 SFB 70 88 72 88 / 0 10 20 50 ORL 71 89 73 88 / 0 10 20 50 FPR 75 86 76 86 / 10 50 60 60 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Ulrich/Pendergrast
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Wed Oct 11 2017 .SHORT TERM...(This evening through Thursday) Issued at 355 PM EDT WED OCT 11 2017 Water vapor imagery and RAP analysis show a trof over the western CONUS with axis just inland. Downstream ridging extends from the central Plains to northern Ontario. A shortwave is moving across southern Lower MI toward the Lower Lakes. In its wake, abundant low cloudiness lingers back to se MN/east half of IA, and these clouds will be the main fcst issue heading thru the short term part of the fcst. Sct-bkn lake effect stratocu has been streaming off northern Lake MI into far s central Upper MI/ne WI today. These clouds are now dissipating under moderating air mass and daytime mixing. There were some clouds off Lake Superior into the Huron Mtns and the Keweenaw earlier in the day as well. Otherwise, abundant sunshine has been the rule this aftn across the area. For the most part, temps have risen into mid 50s to lower 60s. A shortwave ejecting from the western trof will reach Saskatchewan/Manitoba on Thu, supporting a deepening sfc low lifting ne into Manitoba. With sfc high pres shifting to Quebec, flow btwn these 2 pres centers will increase across Upper MI tonight/Thu. Although centered to the e, the sfc high pres will ridge back toward the Upper Lakes thru Thu morning, and this will keep low-level flow more out of the se, delaying the advection into Upper MI of the aforementioned low clouds lingering back across southern WI into adjacent MN/IA. However, the development of an upslope lake modified/moistened se flow off Lake MI into the radiationally cooled w half or so of the fcst area should lead to the formation of stratocu/stratus later in the night. Will probably see quite a bit of cloudiness over roughly the w half of Upper MI on Thu as additional cloud cover from the s moves into the area. Areas that see downsloping under s to se winds have a better chc of seeing breaks for sunshine. Clouds will increase into the eastern fcst area in the aftn. Min temps tonight will be higher than last night due to stirring winds and eventually some clouds. 40s should generally be the rule though there will be some 30s in the traditional cold spots and a few locations along the lakeshores may not drop blo 50F. Cloud cover will hold back temps from their potential on Thu. Highs of 60- 65F should prevail. .LONG TERM...(Thursday night through Wednesday) Issued at 418 PM EDT WED OCT 11 2017 Only significantly impactful weather in the long term is gusty winds and more so large waves/lakeshore flooding issues Sun into Sun night. Focusing in on those impacts, models continue to agree that a strong shortwave will drive a deepening SFC low from near Green Bay, WI at 06Z Sun to the SOO around 12Z Sun. The low is modeled to be in the 995-1,000mb range as it moves nearby. This will lead to gusty NE winds early Sun that will turn N then NW through the day and evening. At this point it looks like some areas near central and eastern Lake Superior could see gusts up to 40mph, so nothing too significant there. The bigger issue may be lakeshore flooding/beach erosion as NE-N waves over south-central and eastern Lake Superior are forecast to be around 10 feet Sun into Sun night. Lake Superior water levels are 6 inches higher than this time last year and 2 inches below the October record high. Last we used 14 foot waves as a benchmark for a lakeshore flood advisory, but we may need to flex that down given the elevated lake levels. At this point, don`t expect significant flooding, but certainly will see beach erosion issues if the forecast holds up. Will highlight in the HWO/EHWO for now. Pulled wind maxima from over the south-central and eastern lake to land since model resolution doesn`t handle that well at that time period, and that (along with re-running winds gusts) was the only change made to the blended initialization. It is possible that some snow may be seen inland from Lake Superior Sun night in the colder air behind the system and as another shortwave moves through, but only trace accumulations would be possible at most and only on grassy surfaces. Otherwise, blended initialization handled things well and impacts are none to minor. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 745 PM EDT WED OCT 11 2017 VFR conditions will prevail at KIWD/KCMX/KSAW thru this evening. Late tonight into Thursday morning, advection of low-level moisture/clouds from the south and southeast as well as upslope flow off Lake MI will lead to MVFR cigs developing. The ceilings may mix up a bit higher, possibly VFR at times Thursday; however, the ceilings will likely drop back down after sunset. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 355 PM EDT WED OCT 11 2017 ...NE to N gales possible east half of Lake Superior on Sunday... Tightening pres gradient btwn high pres to the e and low pres tracking ne to s central Canada will lead to an increase in winds to generally 15-25kt across much of Lake Superior tonight thru Thu night. Winds will diminish slightly for Fri/Fri night as weakening cold front associated with low pres tracking to Hudson Bay moves across the Upper Lakes. New low pres will then lift ene along the frontal boundary this weekend, passing across the Great Lakes Sat night/Sun morning. Depending on the strength of the low, there may be a period of NE to N gales on Sun over the e half of Lake Superior. Winds should be down to mostly under 20kt by Mon. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...Titus AVIATION...KEC MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
730 PM CDT Wed Oct 11 2017 .UPDATE... Issued at 730 PM CDT Wed Oct 11 2017 Several modifications made to the near term forecast. We upped lows tonight, given the clouds are going nowhere, per the light mean 950-900mb flow from the north. Also raised cloud percentages considerably all areas, with some breaks expected over the Ozark Foothill region. Held on to the clouds longer farther west into the CWFA for Thursday as well given the continued weak flow. This will result in lower highs, especially from SW Indiana into the KY Pennyrile over to the Ohio River. The NAM and RAP are the only models that seem to have a handle and were followed closely. We generally don`t concern with fog unless vsbys are at or below 1 mile. This an little observable sfc/blyr convergence through 12z means drizzle is unlikely (stays north of the area). Patches of insignificant P6SM drizzle can`t be ruled out entirely. So just a dry, cloudy overnight forecast. CN && .SHORT TERM...(Tonight through Friday night) Issued at 311 PM CDT Wed Oct 11 2017 Stubborn deck of low level stratus has maintained a firm hold on much of the area today. It is a fairly shallow layer with soundings showing the depth less than 1000 feet. Some clearing has worked into Carter/Ripley Counties and a fast erosion of the clouds is occurring just to our south in Tennessee. The question is how far north does this clearing make it before halting for the day. The northward extent should be reached within the next hour or so, with the rest of the region socked in through the night and into the morning tomorrow. There may even be some southward expansion of the clouds after dark. Guidance is hinting at good fog potential overnight, but with wind staying up just enough and clouds in place, wouldn`t expect widespread fog. Stuck with the patchy fog mention for most areas. May even be some light drizzle, especially in our northeast counties late, closer to the surface trough pivoting through Indiana. Clearing should begin to progress from southwest to northeast through the morning hours tomorrow, but clouds may stick fairly tough through much of the afternoon in the Evansville Tri-State area. With some sunshine, temperatures should warm nicely back around 70/low 70s. If clouds linger longer in the east, forecast highs may be too warm tomorrow. Upper level heights rise on Friday in response to ridging building north from the southeast U.S. This in combination with southerly winds on the backside of surface high pressure will push temperatures around 80 by Friday. .LONG TERM...(Saturday through Wednesday) Issued at 311 PM CDT Wed Oct 11 2017 Fairly high confidence in extended forecast with near record warmth on Saturday replaced with cooler air early next week. We only have one shot at precipitation during this time period, and that comes in on Sunday into Sunday evening. Upper level ridging will be in place over the southeast U.S. to start the period, with an 850 thermal ridge extending into our area on Saturday. This will lead to well above normal temperatures, close to records in the mid to upper 80s. (Record highs are 88 in Paducah, 87 in Cape Girardeau, 90 in Evansville.) On Sunday, shortwave energy moves across the Great Lakes region with a cold front pushing into our area. The overall forcing and dynamics aren`t near as impressive as they are further to our north, but should still see a decent shot of some rain move from northwest to southeast Sunday into Sunday evening. Still some subtle timing differences with the 12z GFS remaining a bit faster with moving the precipitation out. Instability looks marginal at best, so kept in only slight chance of thunder with this system. Surface high pressure builds back into the region on Monday and persists for much of next week. This will result in temperatures closer to normal or even a touch below normal for this time of year. Highs may not make it out of the 60s for many locations on Monday before rebounding into the low 70s Tuesday into Wednesday. With the high expected to be overhead on Monday night, temperatures should drop off nicely with MOS guidance hinting at even some upper 30s possible in our northern counties near Mt Vernon, IL. Won`t go quite that cold yet, but did nudge lows down a degree or 2 from what the blend generated, into the mid 40s. && .AVIATION... Issued at 650 PM CDT Wed Oct 11 2017 Low level moisture will cause aviation headaches over the next 24 hours. Cigs are mainly MVFR and should stay that way through tonight and Thursday. Any potential IFR conditions early Thursday morning look to be short-lived. The chance of clearing on Thursday afternoon appears to be low, but there remains a potential for VFR conditions during the afternoon. Winds will be light and variable. Fog should not be too much of an issue due to cloud cover. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ SHORT TERM...SP LONG TERM...SP AVIATION...MY
Area Forecast Discussion
National Weather Service Blacksburg VA
741 PM EDT Wed Oct 11 2017 .SYNOPSIS... A cold front will approach then cross the area overnight. Thursday into Friday, a nose of high pressure will work its way south along the lee of the Appalachians. This wedge will give way on Saturday in advance of another cold front, which in turn will cross the region on Monday. && .NEAR TERM /THROUGH THURSDAY/... As of 741 PM EDT Wednesday...Surface low analyzed near Pittsburgh extends a surface cold front southwestward through central WV. Warm and conditionally unstable air mass lies ahead of it across the forecast area, though a fair amount of southwest/west- southwest surface wind exists limiting convergence/convective coverage. May see some increase along the frontal boundary as it moves into eastern WV in the next hour or two, though past few runs of the HRRR have become less and less enthused on those prospects. Generally reduced PoPs areawide but kept any mention of isolated to scattered PoPs across WV and in our southern Shenandoah and central VA Piedmont counties through late evening. Air mass remains unstable enough for a couple thunderstorms though that will be waning with sunset. In fact the surface front largely clears the forecast area prior to midnight. Also made some adjustments to cloud cover. Late-afternoon visible/infrared imagery depicted an expansive blanket of post- frontal stratus, its eastern extent currently across central KY and eastern OH. Recent RAP and 18z NAM BUFKIT RH profiles show shallow saturated layer atop a strong subsidence inversion at Beckley setting in after around 2 AM. So I did opt to increase sky cover significantly from eastern WV into the western part of the New River Valley and the Mtn Empire in VA. At least some stratus associated with developing post-frontal wedge in eastern VA may potentially intrude as early as the pre-dawn hours in Buckingham, Appomattox and Charlotte Counties. So much of the area should be beginning to turn at least partly cloudy. Previous near-term discussion issued at 230 PM follows... A frontal boundary lifted slowly north during the course of the day, and is currently positioned across the eastern panhandle of West Virginia, eastward into the Delmarva Peninsula. A cold front was approaching our region from the west, located currently from roughly central Ohio, south into eastern Kentucky and Tennessee. Across the forecast area, very warm temperatures with high dew points for this time of the year cover the area. Instability was noted across the entire area, with the greatest over Southside Virginia and neighboring north central North Carolina. Over the past few hours, showers have been developing over this area, with the greatest concentration currently over central Pittsylvania County, VA. Heading into the evening, the activity will continue across the southeast portion of the area, but is expected to also increase across the northwest with the approaching, and subsequent arrival, of the cold front. Isolated thunderstorms cannot be ruled out, especially over the southeastern parts of the area. The bulk of the precipitation will end by midnight, with lingering showers across the far northeast section of the area through sunrise Thursday. There will be a slight chance in airmass, as somewhat lower dew points arrive behind the cold front. However, conditions still will remain above normal for this time of year. Low temperatures will range from the mid to upper 50s across the mountains to the lower to upper 60s across the Piedmont. During the day Thursday, the cold front will continue progressing out of the area, all the while a nose of high pressure works its way south along the lee of the Appalachians. Anticipate a northeasterly flow to advect low level moisture into the region prompting plenty of cloud cover and light rain/drizzle/fog expanding in coverage across primarily eastern sections of the forecast area. By sunset, the light rain/drizzle is expected to have expanded southwest into the Foothills of North Carolina. The far western sections of the area will remain outside this building wedge of high pressure and experience little or no precipitation. High temperatures will range in the 70s, with the coolest readings across the northern and northeastern sections of the area. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... As of 210 PM EDT Wednesday... Strong wedge in place Thursday night and Friday with abundant moisture from the surface through about 5000 feet AGL. Mid and upper levels will be dry. No question about overcast sky over the mountains and through the foothills and piedmont. Western edge of clouds will be just west of Lewisburg to Bluefield to Boone. Not as obvious is the occurrence and amount of any light rain. Isentropic lift and upslope better over eastern slopes of the central Appalachians on Thursday night than on Friday night when the lift shifts into the southern Appalachians. Will have the highest probability of rain overnight Thursday night. Wedge and low moisture erode on Saturday. Winds become more southwest on Saturday night. Clouds will keep temperatures nearly steady on Friday but anticipate enough peaks of sun on Saturday to result in warmer temperatures. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... As of 200 PM EDT Wednesday... Models starting to come into better consensus with the timing and location of a synoptic scale trough crossing the eastern United States Sunday and Monday with the ECMWF on the slower side of the solutions. Strong cold front crosses the Mid Atlantic region early Monday and both GFS and ECMWF showing good upper diffluence ahead of the front on Sunday night. Most favorable location for thunderstorms ahead of the front on Monday will be in the piedmont of Virginia and North Carolina based on the timing of the front. Rest of precipitation will be post frontal. ECMWF consistent in showing 850MB temperatures behind the front dropping into the +4 to +8 range. Precipitable water values drop well below one half inch. Air mass begins to moderate Wednesday. Expect low level winds up to 30 knots with pressure rises on 2 to 5MB/3hr behind the front with decent cold air advection so will be increasing the winds on Monday afternoon and Monday night. As high pressure moves in Tuesday winds will diminish. && .AVIATION /23Z WEDNESDAY THROUGH MONDAY/... As of 741 PM EDT Wednesday... VFR initially as we await the approach and eventual passage of a surface cold front which as of this writing was located across central WV. May see isolated to widely scattered showers or even a thunderstorm as this feature sweeps across the airspace through 03z. Potential for MVFR visibilities in showers which affect any specific TAF; treated as prevailing VCSH mainly for western terminals with TEMPO MVFR showers. Expect a deterioration in flight categories for the after- midnight and overnight hours behind the cold front. Conditions begin to deteriorate earliest at Lewisburg and Bluefield with post-frontal IFR to LIFR stratus; patchy areas of fog with MVFR to IFR visibility possible pretty much anywhere but most likely where rainfall occurred today. While stratus in the west begins to erode Thursday morning to a VFR deck, we then start to develop wedge conditions for Thursday with high likelihood of MVFR to LIFR ceilings along with areas of drizzle or light rain for sites within and east of the Blue Ridge and Alleghany Highlands. Some guidance brings these conditions into Lynchburg as early as mid- morning; general trend is for a westward deterioration in flight categories through the day. Winds begin west/southwest 4-6 kts then become northwest with FROPA through midnight; winds steadily continue to veer overnight to a northeasterly direction 4-8 kts on Thursday. Extended Aviation Discussion... Sub-VFR conditions will continue across central and eastern parts of the area Thursday afternoon through Friday night. Saturday, the lee side wedge will give way to increasing southwest flow ahead of our next synoptic scale upper trough and associated cold front. This will allow for more areas to experience VFR conditions, a trend that will continue into Sunday. Sunday night into Monday, a substantial cold front is expected to cross the area with scattered showers and some storms. Sub- VFR conditions are expected to accompany the stronger showers/storms. Also, in the wake of the cold front, lingering moisture in the west will likely manifest as some upslope sub- VFR ceilings Sunday night into Monday morning. && .CLIMATE... Record high temperatures for Wednesday October 11th... Roanoke......89...1919 Lynchburg....89...1919 Danville.....90...1954 Blacksburg...80...2010 Bluefield....80...2010 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...DS NEAR TERM...AL/DS SHORT TERM...AMS LONG TERM...AMS AVIATION...AL/DS CLIMATE...JH
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Thursday) Issued at 241 PM CDT Wed Oct 11 2017 19Z water vapor imagery shows an upper trough over the Pacific Northwest with a flat upper ridging along the Gulf Coast. This leaves a dry west southwest flow aloft over the central plains. At the surface, a ridge axis was sliding east of the area as high pressure weakened. The forecast for tonight and Thursday is for continued dry weather as there is little or no forcing within the flow aloft and dry air in mid and upper levels. The main concern is for some possible ground fog. Some of the forecast soundings show the boundary layer saturating overnight and there should be relatively good conditions for radiational cooling. The question is whether there is enough moisture in the boundary layer. The RAP and NAM show surface dewpoints holding around 50 overnight. Except for areas where the stratus has lingered, dewpoints have mixed out into the lower and middle 40s. So am a little hesitant to buy into the forecast soundings boundary layer moisture. Winds will likely be light, but there should be enough of a gradient for winds to keep from going calm. So at this point any ground fog looks to be in the typical low lying areas near bodies of water. Lows tonight should fall into the mid 40s. For highs Thursday, have trended them warmer. Models prog pretty good low level warm air advection with 925MB temps warming to around 21C across central KS. With good insolation, think highs will be in the middle 70s to near 80. .LONG TERM...(Thursday night through Wednesday) Issued at 241 PM CDT Wed Oct 11 2017 Initial upper wave pushing east across the northern Plains settles a cold front into the area late Thursday night, with all guidance agreeing it will hang up across the area for the next few periods as it becomes parallel to the mid- and upper-level flow. Initially, the mid and upper layers are rather dry, but will need to watch depths of the cloud layer and persistent low-level frontogenesis for drizzle and perhaps a few showers behind the front in the north and west Friday and Friday evening before moisture depths rapidly increase, with PW values in the 1.5-2 inch range Friday night into Saturday evening. Elevated showers and thunderstorms will likely increase Friday night into early Saturday and play a large role in severe weather potential for Saturday afternoon and evening. Areas that stay in relatively clear air will likely see ML CAPE values around 1200 J/kg and strong low- and deep-layer shear, though mid-level lapse rates and low-level CAPE are not impressive. Secondary front surges through Saturday night with the remainder of the weekend looking dry. With the very high PW air for this time of year and low-level baroclinic zone nearly stationary for a period or two, there are ingredients in place for heavy rainfall as well, though not too dissimilar to last weekend, overall forcing for persistent ascent is not apparent. The front`s location across the area also creates wide spreads in high temperature potential for Friday and Saturday. Expect a much tighter gradient than currently forecasted, with locations in the north and west more likely to be cooler as opposed to warmer than depicted. Modified surface anticyclone settles in Sunday night and presents a good environment for radiational cooling, though nature of this airmass suggests anything more significant than a frost would be unlikely. After a cooler Sunday, temperatures should modify into the midweek as weaker zonal to northwest flow pattern builds overhead. Differences increase in the pattern around Wednesday with models struggling in how to handle energy in the fast jetstream over the northern Pacific Ocean, but rich moisture availability is very hard to come by locally and keeps the Monday to Wednesday periods dry. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 612 PM CDT Wed Oct 11 2017 Have kept a VFR forecast going for the period. Some models continue to pick up on radiational fog development tonight, especially at TOP/FOE by early morning. For now, expect if anything is to form it would be shallow and in low lying areas. Southerly winds begin to pick up tomorrow after 18Z with gusts up to 23 knots seen near MHK. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Wolters LONG TERM...65 AVIATION...Heller