Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/13/17

Area Forecast Discussion
National Weather Service Bismarck ND
1003 PM CST Sun Nov 12 2017 .UPDATE... Issued at 951 PM CST Sun Nov 12 2017 Based on largely NDDOT webcam trends through 0330 UTC, cancelled the Dense Fog Advisory for Wells county, but, extended it into Renville and Bottineau counties. Still plenty of uncertainty in how the fog will evolve across the north central, whether it will continue a slow regression north with drier air in southeasterly winds, or if it will hold more solidly as suggested by the 03 UTC GFSLAMP. UPDATE Issued at 757 PM CST Sun Nov 12 2017 Expanded the Dense Fog Advisory to include Burke and Divide counties per observed trends through 0130 UTC and the consensus of the 01 UTC RAP/NBM/GFSLAMP and the 00 UTC HRRR visibility forecasts which favor dense fog focusing into far northwest North Dakota through the night. The fog has been eroding across portions of eastern McLean into Sheridan and Wells counties over the past 1 to 2 hours. Thus, the Dense Fog Advisory may be cancelled later this evening if trends continue for these counties. In fact, the CAMs suggest that drier air with southeasterly winds may erode the fog through Minot by 05-07 UTC. UPDATE Issued at 552 PM CST Sun Nov 12 2017 Little change with this update. Some uncertainty exists how long dense fog will last tonight across Sheridan, Wells and possibly McLean counties with southeasterly winds advecting drier air into the area. The 23 UTC RAP/NBM/GFSLAMP and 22 UTC HRRR within their visibility forecasts suggest the fog for these areas decreasing over the next 1-3 hours. Otherwise, the dense fog is favored by the aforementioned guidance to remain solidly in place across the northwest, and potentially expanding towards the international border of the north central. Modifications to the current Dense Fog Advisory are certainly possible through the night. && .SHORT TERM...(This evening through Monday) Issued at 428 PM CST Sun Nov 12 2017 The main forecast issue in the short term continues to be fog/no fog issues, how dense any fog might become, as well as sky cover. Late this afternoon decided to issue a dense fog advisory for portions of northwest and north central ND, mainly along and north of Lake Sakakawea to the Harvey area. Later shifts may need to expand this advisory. Currently, the surface high pressure center was off to our east in Minnesota/Iowa, with the high pressure axis extending northwestward into the Devils Lake Basin/Turtle Mountains area. Warm advection southerly winds were established over western and most of central North Dakota. Throughout the day, the area of low clouds and fog that developed early this morning persisted until around noon CST over northwestern and into parts of central ND...mainly from McKenzie to Divide counties...east/southeast along Lake Sakakawea...nearly making its way to the Minot area. There was a large temperature spread across our area this afternoon, with lower 20s in the Turtle Mountain area to the lower 50s in parts of the southwest. The short term high res models continue to depict dense fog (visibilities of 1/4 mile or less) in most of northwest North Dakota this afternoon, but by mid-afternoon visibilities there had improved around noon CST with most areas having visibilities above 3 miles. It was only after 3 pm when visibilities began to drop. Some area web cams continued to show some locales with lower visibilities in fog, especially around Lake Sakakawea and a few points north. The evolution of fog expansion is the main challenge for tonight. The high res models indicate the area of low clouds and fog expanding tonight and moving northward. Thus will have a mention of widespread fog across all of northwest and north central ND. The broad ridging aloft continues on Monday, along with southerly winds. Low clouds and fog should erode from south to north on Monday as was seen Sunday afternoon. Highs Monday should again be in the low/mid 50s far southwest, but reach into the 30s in the Turtle Mountains. .LONG TERM...(Monday night through Sunday) Issued at 428 PM CST Sun Nov 12 2017 Deterministic models are in reasonable agreement through mid week. A cold front moves through the area on Tuesday afternoon/evening bringing only minimal precipitation chances and a brief cooldown on Wednesday north and east. Expecting breezy northwest winds late Tuesday afternoon and night mainly across the northeast half of the state. Although there are some differences between the GFS/ECMWF with the next wave that moves through Thursday/Friday, their solutions, especially regarding the position of the northern upper trough, have come into better agreement. We are expecting strong south winds (especially the James Valley to Turtle Mountains and east) and seasonable to mild conditions Thursday. Then the cold front moving through Thursday night with northwest winds developing, and becoming strong on Friday with colder air moving in. Highs Thursday from 30 to 50 northeast to southwest...cooling to highs Friday from lower 20s north to 30s south. Precipitation chances still look best to the north and east of our area. Model consensus is still giving mainly slight chances of light rain or snow for us. The colder air Friday lingers into Saturday, with a moderate recovery in the southwest on Sunday. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 951 PM CST Sun Nov 12 2017 LIFR/VLIFR conditions in freezing fog will continue across much of northwest and north central North Dakota tonight through Monday morning. The fog may continue northwest into Monday afternoon. Otherwise, VFR conditions are forecast across the southwest and south central for the 00 UTC TAF cycle. && .BIS WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 6 AM CST Monday for NDZ001>004-009>012- 021-022. && $$ UPDATE...PA SHORT TERM...JV LONG TERM...JV AVIATION...PA
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
703 PM CST Sun Nov 12 2017 .DISCUSSION...Made a few relatively minor tweaks to the overnight forecast to cover development and potential persistence of precipitation in various locations across Deep South Texas/RGV and the Lower Texas coastal waters. The forecast is tricky to say the least as models are in mixed camps. The 18Z GFS came in with fairly robust vertical motion in the low levels (sub-700 mb) along the coast and over the Gulf waters for most of the night through midday Monday before the energy shifts south by late afternoon. The ECMWF and to some extent recent runs of the HRRR favor evening to overnight development along the edge of the differential diabatic heating zone (it was only in the lower 70s across the Rio Grande Plains while along US 281 it popped into the mid 80s). GFS shows some of this as well even at its solution is more dominated by rainfall over the Gulf. The hunch here is that GFS is picking up on low level (near surface?) speed convergence as the midwestern ridge builds south and pressure rises a bit more overnight than the ECMWF, which shoves its deeper moisture inland sooner. Given the unseasonably "soupy" low level airmass (surface dewpoints in the 70-74 range) it won`t take much to get showers going just about anytime and anywhere...but climatology favors better overnight rainfall (QPF) toward the coast vs. inland and have re-oriented the values that way, while giving a nod for near 0.1" averages over the Hidalgo/Brooks/northeast Starr/eastern Jim Hogg area. Not enought to dent the drought but better than nothing. As for Monday...elected to nudge higher chances toward Brownsville/Port Isabel in line with guidance consensus for the morning hours, while keeping the waters south of Port Mansfield a bit wetter than farther north. The moisture will get a southward shove by late afternoon as northeast surface winds pick up with nose ofthe ridge building southwest from the core in the Ohio Valley, with skies tending toward overcast. 52/BSG && .AVIATION...Similar to the discussion above, TAF forecast is a bit difficult as well. Impacts, however, shouldn`t be - though can`t rule out brief IFR visibility in any locally heavier showers that pass by through the period. Overall, the overnight should be fairly copacetic with mainly VFR mid level ceilings. Elected to throw in a few TEMPO groups for MVFR visibility when it does rain - briefly - since the nature of the rain is rather tropical given the warm/humid low levels. For Monday morning, more of the same; ceilings may touch MVFR but should largely remain in the 3K foot dividing line. By afternoon, the northeast winds pick up a bit...and would not be surprised to see some 20 knot gusts but for now have kept sustained in the 10-13 knot range. May see ceilings settle in lower; for now, held just above the MVFR/VFR line but OVC may be the sense of the sky with a slight "cooling" compared with today. 52/BSG && .PREV DISCUSSION... /issued 244 PM CST Sun Nov 12 2017/ SHORT TERM (Tonight through Monday Night): Mid level ridging remains in place over northwest Mexico, extending east over deep south Texas and the west Gulf. A surface cold front has pushed into central Texas, but it should dissipate as the main supporting high pressure over the plains slides off to the east. Some of the continental high pressure will push out over the north Gulf tonight, however, backing local wind to east or northeast through the short term. Kept chance pops in the forecast for tonight and Monday as coastal convergence and continuing low level moisture support weak shower activity. By Monday night northeast winds will be in control and the deepest moisture will be pushed to the south. Skies should open up a little Monday night but will still be partly cloudy. Warmer than normal temperatures will continue, though not too extreme, with overnight lows still in the mid to upper 60s, about ten degrees above normal, while Monday`s highs in the lower 80s will be about 5 degrees above normal. LONG TERM (Tuesday through Sunday): Most of the upcoming week will be dominated by high pressure in the vicinity at the surface and aloft. The H5 ridge will be building to the southwest, providing drier northwest flow aloft, capping off the atmosphere. At the surface, the ridge will stretch from south Texas all the way to Maine, providing deeper moisture return into south Texas. Temperatures will reach above average each afternoon, rising into the mid to upper 80s. The main weather event is the arrival of the next cold front sometime on Saturday. Models are still differing on timing by a good 12 to 18 hours, but are agreeing on a considerable improvement in temperatures for the latter half of next weekend. MARINE: Now through Monday Night: Moderate northeast to east winds will develop tonight, with slowly building seas across a long Gulf fetch as continental high pressure filters south over the north Gulf coast. The wave models have backed off slightly on the wave heights, with 4 to 6 feet now forecast, instead of 5 to 7, for the offshore waters Monday night. Tuesday through Thursday: Tranquil weather expected for the marine areas for the middle of the week as surface high pressure remains just to the northeast. This keeps the gradient weaker, keeping winds 10 to 15 knots and seas relaxing to around 3 feet. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 71 78 69 81 / 50 60 10 0 BROWNSVILLE 69 80 68 83 / 50 60 10 0 HARLINGEN 69 80 67 82 / 40 50 10 0 MCALLEN 69 81 66 84 / 40 30 10 0 RIO GRANDE CITY 69 81 65 84 / 40 30 10 0 SOUTH PADRE ISLAND 72 77 71 79 / 60 60 10 0 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV
Area Forecast Discussion
National Weather Service Columbia SC
935 PM EST Sun Nov 12 2017 .SYNOPSIS... An approaching cold front will cross the area late tonight into Monday morning. Dry high pressure will return to the region for Monday night through Thursday. Another cold front will arrive early Saturday. && .NEAR TERM /THROUGH TONIGHT/.. Cold front moving into middle TN late this evening. Light showers have developed ahead the front and are now moving into the western Midlands. Little convergence will be associated with the front because of the lingering surface ridging extending into the area from the north. The main rain support will be an h85 jet. The models display the greatest moistures and lift around 100 am especially in the north section. The system is progressive with little time for moisture recovery so we leaned toward the lower guidance rainfall amounts. Expect light amounts of mainly 0.1 south to 0.2 of an inch north. Latest HRRR indicating the light showers moving slowly through the area overnight and moving east of the area by around 14Z Monday. Overnight lows will be mainly in the 40s. && .SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/... Monday...There may be lingering moisture associated with the cold front in the east section early. Otherwise, expect drying behind the cold front. It will be warmer with afternoon sunshine. The guidance consensus supports highs in the lower 60s north to upper 60s south. Lows Monday night will be mainly in the upper 30s to the lower 40s. Generally tranquil weather with seasonable temperatures expected through mid week with broad upper troughing over the eastern part of the country. Surface high pressure will continue to build over the area Monday night through Wednesday in the wake of the departing upper trough off the east coast. 500mb flow will be northwesterly across the forecast area with north- northeasterly low level flow from the surface through 850mb. Atmospheric moisture will be very limited with precipitable water values below 0.5 inches throughout this period leading to dry conditions enhanced by a strong subsidence inversion. A fast moving shortwave trough will move through the Ohio Valley Wednesday and to the Mid-Atlantic coast by late Wednesday night but moisture associated with the system remains to our north or precipitates on the upslope side of the Appalachians with downsloping flow downwind of the higher terrain. Therefore will continue to carry a dry forecast Wednesday night. Temperatures will be near to slightly below normal with lows in the upper 30s to lower 40s and highs in the 60s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... The extended forecast features a transition to near to slightly above normal temperatures for the end of the week as 500mb heights flatten across the southern part of the country with weak upper ridging over the Ohio Valley and Great Lakes region ahead of a digging western upper trough. This upper trough will translate eastward Fri/Sat bringing a cold front through the forecast area sometime late Friday night or Saturday with increasing chances of rain. The most recent medium range model runs have trended a bit slower with ensemble support for slower timing, while the GFS remains the fastest of them. The fast moving nature of this trough/front will limit rainfall potential and overall moisture is not that great with only a narrow band of higher precipitable water (around 1.25-1.50 inches) immediately preceding the front. There is a relatively strong 850mb jet around 40-50 knots which will result in breezy conditions Saturday across the region. Operational models and ensemble timing differences lead to lower confidence in rainfall chances and amounts but Saturday is the most likely time frame at this point. Instability looks minimal but will depend on the timing of the front, with better instability possible if the front moves through later Saturday. High pressure builds into the region in the wake of the cold front Saturday night through Sunday with dry weather expected. Temperatures through the period will near to slightly above normal with highs in the 60s to around 70 degrees and lows generally in the 40s. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... MVFR to IFR CIGS, with MVFR VSBYs at times in light rain, overnight into Monday morning, improving to VFR by midday Monday. Weak surface wedge of high pressure over the western and central Carolinas and CSRA, with patches of light rain across the region. Widespread MVFR CIGS in place over our forecast area (FA), with IFR CIGS still confined just to the NW and N of our TAF sites across NE GA and upstate SC. Frontal boundary back to our NW will move through Monday and scour out the wedge and low cloud cover. In the meantime, patches of light rain expected through early Monday morning, with band of IFR CIGs progressing through the FA as well,along with periods of MVFR VSBYS in light rain and/or fog also possible at times late tonight and early Monday morning. Conditions are expected to improve to VFR by midday Monday. EXTENDED AVIATION OUTLOOK...Dry high pressure is generally expected to preclude aviation concerns during the outlook period. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service Grand Forks ND
919 PM CST Sun Nov 12 2017 .UPDATE... Issued at 919 PM CST Sun Nov 12 2017 No updates needed. && .SHORT TERM...(This evening through Monday) Issued at 247 PM CST Sun Nov 12 2017 Temps are the main issue. Lower clouds in NW MN slowly clearing eastward. Meanwhile high and mid clouds moving east and entering NE ND. In general model RH progs have these handled pretty well. In addition a band of low level RH from west central MN into central/NW ND is lifting back north. It is very thin in nature in E ND but more expansive in NW ND. HRRR has this band lifting north into DVL basin this late aftn/eve, then moving north. Fog in NW into central ND spreading north and should remain west of the fcst area. However HRRR and other various short range models indicate some fog possibly affecting far NW fcst area. Main focus though is west of our fcst area. How much fall in temps tonight in NE ND and far NW MN tonight? Low level cloud cover going away but high/mid clouds moving in. Light south wind. Should drop into the teens in the snowcover area should occur but otherwise not a huge fall off tonight as warm advection gets going in the low levels. Monday will see mid/high level moisture moving through the area and exiting the east. Warmer air moves in...with near 32F for highs in NE ND to low 40s in non-snow areas. .LONG TERM...(Monday night through Sunday) Issued at 247 PM CST Sun Nov 12 2017 By Tuesday, a ridge aloft brings temperatures rebounding to near normal values, with highs in the 30s to 40s and lows generally in the 20s. Warming will be most dominant for areas without remaining snowpack, generally along and south of the Highway 200 corridor. For Tuesday night through early Wednesday, precipitation chances return along and behind a cold front pushing across the Dakotas toward the Great Lakes. Most model guidance suggests that this will be realized mainly as light scattered cold rain, except for locations in counties along the international border that could see light snow mix in overnight and into Wednesday morning. For Wednesday, drier high pressure builds through with a significant cooldown to highs in the 20s to lower 30s. Late in the week, the next hybrid low pressure system brings precipitation chances as it pushes east from the Northern Plains to the Great Lakes. Precipitation chances develop Thursday afternoon and night, with better chances across the forecast area on Friday. At this point, there is poor model confidence in the available moisture content, so will not speculate other than to say snow chances exist, especially for Friday in Minnesota. However there is a signal for stronger winds as a low level jet moves through the area Thursday night through Friday night, so the potential for stronger winds coinciding with snowfall will need to be monitored in the upcoming days. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 648 PM CST Sun Nov 12 2017 There are still MVFR clouds at KTVF and KBJI, and it is not looking like they will move anywhere any time soon. May have to linger them longer into the night. So far the fog has stayed to the west of KDVL, but will have to monitor to see if it expands back into the area tonight. Light winds continue. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Godon SHORT TERM...Riddle LONG TERM...BP AVIATION...Godon
Area Forecast Discussion
National Weather Service Goodland KS
440 PM MST Sun Nov 12 2017 .SHORT TERM...(This evening through Monday) Issued at 154 PM MST Sun Nov 12 2017 Once again main issues to address will be onset, location and coverage of stratus and fog. Morning upper air soundings, surface observations, and satellite showing a moist air mass remains to our and southeast. This has been the same air mass that has been over and near the area since the end of last week. Currently lee side trough is developing as surface ridge has pulled to the east. Tightening gradient and pressure falls seen on analysis and captured by the model output. This is going to cause breezy conditions over the western third of the area. This strengthening southerly flow will pull the saturated air mass back into the region during the night. Through the day the guidance has shown a little tendency to start development a little further west. Hrrr and Rap have been doing the best recently have caught onto this. With latest trends have adjusted fog west through Monday morning from earlier thoughts. Wherever this forms, it will likely become dense since the air mass has not changed. Evening shift will have to pin this down. Fog looks like it dissipates by late morning. However, stratus looks to hang into the afternoon. Even with stratus hanging on longer today, temperatures rebounded nicely. So kept the temperatures near the blend except for the far west which has shown a tendency to be too cool in this pattern. .LONG TERM...(Monday night through Sunday) Issued at 145 PM MST Sun Nov 12 2017 Progressive pattern in place as shortwave troughs move over an upper ridge anchored over Mexico/southern Plains. As a result, no major weather impacts are anticipated. The only mention of precipitation will come on Friday, with a cold front bringing a slight chance for rain showers. Friday may also be windy behind the front. The rest of the period is dry. May see a little fog in eastern areas Monday night/Tuesday morning with lingering moisture associated with the current air mass. Temperatures on Tuesday will be much above normal, return to near normal on Wednesday behind a front, slightly above normal on Thursday, slightly cooler on Friday behind the next front, then near normal next weekend. Normal high temperatures for this time of year are in the lower to middle 50s and normal low temperatures are in the upper 20s. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 440 PM MST Sun Nov 12 2017 For KGLD and KMCK, another difficult forecast pinpointing arrival and departure of stratus and fog this evening through Monday morning. For KGLD currently have sub vfr conditions impacting the terminal around 05z and continuing through 16z with winds from the southeast to south at 8 to 14kts. After 17z vfr conditions return with winds from the southwest around 10kts. For KMCK have sub vfr conditions at the terminal in the 09z-20z timeframe with winds from the southeast to south 10kts or less. After 21z vfr conditions return with winds from the south near 10kts. Updates to the forecast(s) for one or both terminals likely during the evening as conditions warrant. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BULLER LONG TERM...024 AVIATION...99
Area Forecast Discussion
National Weather Service Wilmington NC
902 PM EST Sun Nov 12 2017 .SYNOPSIS... A cold front will bring showers tonight and into Monday morning. Canadian high pressure will slowly build across the Carolinas in the wake of the front. Temperatures will be below normal early in the week, then recover to seasonable levels late week. Below normal temperatures will return with the passage of a strong cold front late next weekend. && .NEAR TERM /THROUGH MONDAY/... As of 900 PM Sunday...Clipper system over the Ohio Valley will move rapidly east and offshore during Mon. System will be followed by cool and dry Canadian high pressure. Guidance not in the best of agreement regarding POPs or QPF for this event with a drier GFS contrasting with a wetter solution offered by the ECMWF and NAM. Leaned on the wetter solution for the NW corner of the Forecast Area with the highest confidence in measurable rainfall, up to categorical POPs. As the showers pivot toward the coast overnight and Mon morning, the higher resolution models are kind of all falling on the band wagon with the risk for rainfall shrinking from S to N as the robust mid-level shortwave begins to weaken and lift out to the N. Given the short duration of meaningful moisture, and the residual dry layer below 1 kft, will keep QPF amounts light, around a tenth of an inch or less. In the wake of this system, showers will end and a modest surge of dry and cool air will follow. Even with thick clouds giving way to increasing sunshine from W to E on Mon, highs will be no higher than the upper 50s and lower 60s. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Shortwave over New England at the start of the period will exit to the northeast Mon night. This transitions the mid-level pattern over the Carolinas back to more progressive or zonal flow. Meanwhile, at the surface, Canadian high over the Ohio Valley at the start of the period will slowly drift east, ending up over New England by the end of the period. This will maintain northerly flow at the surface while aloft the flow will be out of the west-northwest. Precipitable water will remains under half an inch through the period which will keep the region dry. In fact other than some occasional cirrus skies will remain cloud free. Northerly flow will help keep temperatures a few degrees below climo with highs in the lower 60s and lows in the upper 30s to lower 40s. Tue night could see typical cold spots dip several degrees lower as radiational cooling will be more effective. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...Weakening surface high pressure on Wednesday to give way to a cold front and new high Thursday night into Friday. With little to no moisture flux ahead of the boundary and zonal flow aloft expecting no weather with FROPA. So weak and short-lived will be the cold advection associated with the front that Friday`s highs will be slightly warmer than Thursday. High pressure moves offshore Friday night into Saturday not only strengthening the warm air advection but also introducing healthy moisture advection. Healthy cold front to arrive Saturday night or Sunday to bring some rain chances, though overall model consensus is that QPF prospects will be minimal. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As of 00Z...Only moderate confidence with respect to ceilings and visibilities overnight, as well as the timing of precip, if any. Models are not in good agreement, with one model taking us down to LIFR. Think we will probably see IFR conditions, but hopefully visibilities will remain 2SM or better. The HRRR model depicts a narrow band of precip, associated with a weak cold front. The precip should reach the western terminals by 10-12Z. Look for conditions to improve during Monday morning, with MVFR conditions expected by afternoon at the latest. Northerly flow through the forecast period. Extended Outlook...VFR tempo SHRA/MVFR/IFR Mon. VFR Tue-Fri. && .MARINE... NEAR TERM /THROUGH MONDAY/... As of 900 PM Sunday...ENE to E winds of 5 to 15 kt will back to the N around sunrise as a cold front moves offshore. There will be a modest cool and dry northerly surge in the wake of this system with Canadian high pressure slowly building toward the waters beginning Mon. The pressure gradient will begin to tighten on Mon and this will increase wind speeds to 15 to 20 kt by/during the afternoon. Seas will respond, building from 2 to 3 ft tonight to 3 to 4 ft Mon afternoon with some 5 ft seas late across the outermost waters. SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Northerly flow will remain on the high end of the 15 to 20 kt range through the period. High pressure over the Ohio Valley at the start of the period will shift east, moving over New England as the period ends. The high building down the coast will help keep the gradient pinched through Tue night, maintaining speeds approaching 20 kt. Seas 3 to 4 ft with occasional 5 ft Mon night will increase in response to extended period of stronger northeast flow. Seas 4 to 5 ft will become more common Tue with potential for widespread 5 or 6 ft seas and the appropriate headlines late in the period. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...High pressure centered just west of the waters to bring a moderate northerly flow on Wednesday. This flow weakens Wednesday night into Thursday as the high dissipates. A new center of high pressure becomes established well to our north by Friday keeping a northerly component dominant, though NW to NE all seem possible depending on the shape and positioning of the high. No advisories are planned through the period. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...REK/RJD SHORT TERM...III LONG TERM...MBB AVIATION...DL
Area Forecast Discussion
National Weather Service Lincoln IL
908 PM CST Sun Nov 12 2017 .UPDATE... Issued at 906 PM CST Sun Nov 12 2017 The main issues tonight center on the timing and coverage of clearing, and the subsequent formation of dense fog. Fog as actually already started to form under the stratus layer, mainly north of a line from Champaign to Lincoln to Peoria. Utilizing timing tools on the satellite loops shows the clearing line may reach Peoria by 330 am, I-55 corridor by 7-730am, then down to I-70 by early afternoon. However, HRRR updates are indicating a blanket of stratus clouds could remain across all of our forecast area into Monday afternoon. Not ready to shift that far toward slowing the clouds, so have trended slower based on satellite trends. The last couple of runs of the HRRR has also reduced the coverage and eastward extent of dense fog. Have expanded Patchy Fog to cover the current foggy areas, and limited the Areas of Fog to NW of the Illinois river, where HRRR still focuses thicker fog. Can`t rule out the possible need for a dense fog advisory NW of the IL river, but confidence is not high enough to issue that with the evening update. Clearing could help low temps reach or forecast lows in the NW counties, but the delayed clearing along and south of I-72 tonight will create warmer lows there. Have increased low temps across the south by several degrees. The remainder of the forecast looks on track. Updated forecast info is already available. && .SHORT TERM...(This evening through Monday) ISSUED AT 316 PM CST Sun Nov 12 2017 Short-wave trough evident on 20z/2pm water vapor imagery over northeast Illinois will track into Ohio by this evening. Synoptic subsidence in the wake of the wave will lead to clearing skies tonight:however, it appears this will be a slow process. Latest visible satellite imagery shows the back edge of the low cloud shield just now advancing east past Des Moines, Iowa. Based on satellite timing tools, clearing will not arrive in west-central Illinois until around midnight...and may not reach the Indiana border until closer to daybreak. Once skies clear, the potential for fog exists overnight thanks to very light winds and a moist boundary layer. HRRR has been consistently showing widespread fog along/west of the Mississippi River has been trending further east into central Illinois with subsequent runs. Have therefore decided to include patchy fog in the forecast after midnight along/west of a Champaign to Shelbyville line. With low temperatures bottoming out in the upper 20s and lower 30s, there could potentially be a few slick patches on sidewalks and bridges/overpasses for the Monday morning commute. Once any early morning fog dissipates, mostly sunny skies will prevail with high temperatures climbing into the middle 40s. .LONG TERM...(Monday night through Sunday) ISSUED AT 316 PM CST Sun Nov 12 2017 Another mild and dry day will be on tap for Tuesday, with highs reaching the upper 40s and lower 50s. The next approaching storm system will come into the picture Tuesday night into Wednesday as a short-wave trough and its associated cold front quickly swing through the region. All models show FROPA around midday on Wednesday, so have continued to focus highest PoPs late Tuesday night into Wednesday morning. With modest MUCAPE values of 100-200J/kg in advance of the front, have included a slight chance for thunderstorms across the western two-thirds of the KILX CWA late Tuesday night. Once the front passes, rain chances will quickly diminish from west to east by Wednesday afternoon/evening. Dry conditions will prevail on Thursday before the mid-week frontal boundary returns northward as a warm front Thursday night. Model consensus keeps the area largely dry until late Thursday night when showers and perhaps a few thunderstorms develop along the advancing boundary. Big questions still remain for the end of the period...with the 12z Nov 12 GFS continuing its recent slowing trend and the once consistent ECMWF now slowing its solution by nearly 12 hours. The latest GFS features an area of low pressure tracking out of the Plains into southeast Wisconsin by 00z Sat...while the ECMWF takes a similar track with the low arriving in southeast Wisconsin by 12z Sat. Both solutions place central Illinois within the warm sector of the system Friday and/or Friday night...with the potential for thunderstorms. Given considerable model spread, have limited slight chance thunder to mainly during the day Friday...lingering across east-central Illinois into Friday evening. This obviously may need to be adjusted if the slowing trend continues. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 559 PM CST Sun Nov 12 2017 IFR/MVFR clouds will continue through the evening, as a clearing line slowly approaches central Illinois from the west. The center of the upper level low has shifted into far western Indiana, and subsident air flows have started to increase. The subsidence has shut down all precip, but has also set up an inversion that could trap the low stratus clouds a bit longer than the models want to clear it out. Have slowed the clearing by an hour or two, but that may not be enough. Depending on clearing timing and coverage, dense fog could develop from west to east in the wake of the clearing. Have introduced LIFR fog at PIA for now, but HRRR is showing much more widespread VLIFR conditions as far east as DEC. Will monitor cloud trends closely for fog potential. Winds will be a non-factor to aviation, other than to be favorable for dense fog formation. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Shimon SHORT TERM...Barnes LONG TERM...Barnes AVIATION...Shimon
Area Forecast Discussion
National Weather Service Northern Indiana
831 PM EST Sun Nov 12 2017 .SYNOPSIS... Issued at 825 PM EST Sun Nov 12 2017 A mixture of light rain and snow will shift east out of the area well before sunrise. The precipitation may end as a brief period of freezing drizzle east of Interstate 69. and possibly a touch of freezing drizzle will quickly move east by midnight. Lows tonight will be in the upper 20s and lower 30s. It will be dry with a warming trend Monday and Tuesday as high pressure settles over the area. Highs will reach into the upper 40s and lower 50s by Wednesday. Additional rain showers, with even a possible thunderstorm, will move through on Wednesday as a cold front sweeps through the area. Yet another system will bring more rain on Friday. && .UPDATE... Issued at 823 PM EST Sun Nov 12 2017 Updated grids to speed up departure of precipitation, add more of a rain/snow mix with temps falling and surface obs and scattered reports showing snow at several spots. Back edge of precip was moving along at a decent clip, with HRRR showing everything clearing near/just prior to 6Z. Have sped things up as a result and may not be fast enough. Still a chance of precip ending as some freezing drizzle in eastern areas as low level lift continues but ice production lost aloft. && .SHORT TERM...(This Evening through Monday) Issued at 405 PM EST Sun Nov 12 2017 Ramping height falls centroid to 80-90 m/12 hours through the Ohio Valley through 06 UTC to hasten cyclogenesis with northern wave moisture orphaned along with further whittling away of warm Tw layer aloft. This will allow transition back to rain/snow mix through the evening hours. Later tonight as primary mid level shortwave moves eastward into the Lower Great Lakes, lagged moisture depth to remove ice nucleation with precipitation potentially ending as brief period of light freezing rain/drizzle. Notable downtrend on prior enhanced shortwave cusp over northern IL/Quad Cities region indicative of these trends as well. Overall light qpf/high evening/early night pops wending west to east with only low/dwindling pops beyond 06 UTC east of I-69. Dry conditions Monday along with lack of strong cold air advection and at least partial midday/afternoon insolation to allow surface temps to embark on moderation trend. && .LONG TERM...(Monday Night through Sunday) Issued at 405 PM EST Sun Nov 12 2017 Good agreement with respect to continued moderation with high belted partial ejection of northeast Pacific system into Ontario/western Upper Great Lakes by midweek. Strong height falls centroid in excess of 100 m/12 hrs along with low level jetlet moving from northern MO eastward through central IL/central IN along with higher pool of mid level lapse rates sufficient for a slight chance mention of thunderstorms. With respect to early weekend system, model blends and signals continue to point at warm/convective system, though varying degree of timing and strength. At some point thunder may need mentioned with this system as well, but for now with many variables/lower confidence with defer for now and continue to assess with time. && .AVIATION...(For the 00Z TAFS through 00Z Monday Evening) Issued at 615 PM EST Sun Nov 12 2017 The discussion for the 18Z TAFs suggested deteriorating conditions are likely for the overnight hours. The latest data supports this thinking and thus our 00Z TAFs introduce a period of IFR conditions. Satellite and radar imagery depicts the back edge of precipitation moving over SBN at this hour. Behind this, observations show ceilings falling to IFR conditions; something guidance is a bit slow on. This area of IFR ceilings ends near Madison, WI, at this time. Therefore, we are led to believe MVFR conditions can return early Monday morning at SBN. FWA will face precipitation for the next several hours before the back edge of precipitation lifts out. A few snowflakes can mix in with rain, but we expect rain to be the dominant precipitation type. At the time of this writing, FWA is reporting a temperature of 35F. By the time this activity exits, we have a forecast temperature of 34F. Then, we expect IFR conditions to unfold for a time. At FWA, we played the 12Z forecast ceilings a bit conservative, but there are some solutions that suggest ceilings could be VFR. At this time, we will pass this off to the next team to monitor. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ UPDATE...Fisher SYNOPSIS...Murphy/Fisher SHORT TERM...Murphy LONG TERM...Murphy AVIATION...Brown Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
932 PM CST Sun Nov 12 2017 .UPDATE... 932 PM CST The main concern tonight is the threat of dense fog development overnight into Monday morning. At the moment skies remain cloudy across the area. However, the back edge of the cloud cover is now beginning to approach north central IL around Rockford. Expect this area of decreasing clouds to continue towards the Chicago region by around 1 am. Surface high pressure is expected to build over the area overnight, and the associated light winds should allow temperatures to drop into the upper 20s. Given the ample low-level moisture from todays rain and snow, it appears likely that once the cloud cover clears dense fog will develop overnight across north central IL. For this reason, I plan to issue a dense fog advisory for north central IL through Monday morning. If the fog develops farther west and south, this advisory may need to be expanded later. Some minor glazing may also occur with this dense fog tonight as temperatures drop into the upper 20s. As a result, this could result in some slippery conditions early Monday morning. The fog should dissipate by midday. KJB && .SHORT TERM... 117 PM CST Through Monday... Precipitation will exit to the east this afternoon as our compact and fairly potent upper wave continues into the Ohio valley. Biggest question for the night is how quickly clouds will clear. We are seeing a steady erosion of the lower clouds which linger behind the higher precipitation-producing cloud shield. Light winds with the high moving in and some recent precip may result in a little fog. RAP does suggest a gradual thinning of the cloud shield which may slow some at night, so will continue the general clearing trend. Monday looks like one of our nicer days of the week after a gray, cold, and damp weekend. High pressure across the upper midwest will become centered across northeast Illinois by Monday mid to morning before shifting to the eastern Great Lakes region. This should result in sunshine, light winds, and warmer though still seasonally cool temperatures. Highs will reach the lower to mid 40s. As the high shifts east Monday afternoon, some increase in higher clouds is expected. KMD && .LONG TERM... 211 PM CST Monday night through Sunday... High pressure expected to still be in place at the start of the period, but will shift east Monday night into Tuesday. Southerly flow/WAA will support continued warming trend with highs in the upper 40s expected Tuesday. However, sky cover will increase during the day Tuesday ahead of the next system to affect the region. Next chance of precip arrives Tuesday night into Wednesday with the approach of a deeper trough and surface trough/front. All rain expected, and with increasing WAA and instability, slight chance thunder wording still seems reasonable. Some slight and brief cooling expected behind this system but once again only brief, as WAA ramps back up in advance of the next system. This system looks to arrive late in the work week into the early part of the weekend. There are still some timing and placement differences with this anticipated system, however, wet conditions appearing likely for most locations within the CWA during this time. Confidence with overall thunder trends still low. However, did add slight chance thunder mention Thursday night into Friday. It`s conceivable that at least a narrow moisture/instability axis could be in place ahead of the strong/dynamic system, with thunder a definite possibility. Will need to monitor the possibility for more robust development somewhere in the region, given the potential strength of the system. Anticipate colder air to move in behind this system into next weekend. Rodriguez && .AVIATION... For the 00Z TAFs... 530 pm...Main forecast concerns are cigs/vis/drizzle this evening and then fog again Monday morning. Cigs have continued to lower into ifr for many locations late this afternoon with visibilities also lowering into ifr west of the Chicago terminals. This area of lower cigs/vis will slowly work its way southeast over the next few hours. Ifr cigs will slowly lift into mvfr later this evening and scatter out as the back edge of the cloud cover...currently from eastern WI to eastern IA... moves across the area. Some patchy drizzle will also be possible with the ifr cigs this evening. Once skies clear...temps will likely drop to the dewpoints and then continue falling by morning with fog developing...mainly west of the Chicago terminals. Its possible some dense fog may develop over northwest IL including rfd but confidence is low. Trends will need to be monitored for fog potential further east for Monday morning. Northwest winds 6-9kts this evening will slowly diminish overnight and turn more westerly Monday morning and then shift southerly Monday afternoon...but speeds well under 10kts as high pressure moves across the region. cms && .MARINE... 211 PM CST With a relaxed gradient in place, relatively lighter winds have been in place today. Expect this overall trend to continue into Monday with the arrival of high pressure. This will change going into the middle part of the week as winds turn southerly and increase ahead of the next system to affect the region. The strongest southerly winds during this time expected to be Tuesday night. Expect winds to mainly stay at or below 30 kt, however, will need to monitor the possibility for at least a small window of gales. Winds diminish after this system departs, but will once again see an increase by late in the work week. Still some likely variability with the forecast in the coming days, but at this time, guidance indicating the possibility for higher end gales. Rodriguez && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ 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 Twin Cities/Chanhassen MN
533 PM CST Sun Nov 12 2017 .Updated for 00Z Aviation Discussion... Issued at 522 PM CST Sun Nov 12 2017 && .SHORT TERM...(This evening through Monday) Issued at 300 PM CST Sun Nov 12 2017 As surface ridging builds in from the west, we have been slowly eroding away the clouds. Question for this evening with these clouds is where does the west edge set up. The HRRR had been showing the west edge setting up from Mille Lacs to the west of Eau Claire through the night, but current satellite trends would support these clouds getting east of the MPX area, meaning mainly clear skies for us tonight. That may sound great, but with the surface ridge axis overhead and dewpoints this afternoon in the upper 20s, we will have to watch for the threat of seeing fog/low stratus develop tonight across eastern MN into western WI. Though skies will be clear, lows should not get too carried away tonight for a couple of reasons. For one, dewpoints currently in the mid/upper 20s will help keep lows from falling much below the mid 20s, while return flow will be getting going tonight in western MN, where temperatures will likely start rising before sunrise. Monday, no precip is expected, though a weak short wave passing in zonal flow will result in a mostly cloudy day thanks to its associated mid/upper clouds. As the high moving through tonight moves into the Great Lakes, increasing southeast winds through the day will help push highs back up into the upper 30s in northwest WI to near 50 out in southwest MN, which is pretty close to normal for the time of year. .LONG TERM...(Monday night through Sunday) Issued at 300 PM CST Sun Nov 12 2017 Not much has changed in the general thinking for the extended, with systems passing through Tuesday evening and again Friday/Friday night. Tuesday will be the warmest day before the cold front comes through, with a brief cool down Wednesday before getting back into WAA Thursday. System for the end of the week looks to deepen significantly into a "Gales of November" type system for the Great Lakes this weekend, but locally looks to bring mainly rain on Friday, followed by strong northwest winds Friday night into Saturday. We will see a quick cool down behind this system for next weekend, but temperatures look to moderate again as we head toward Thanksgiving. Though our warmest day, Tuesday won`t exactly be the nicest day of the week. Both the GFS and NAM support dense low stratus the entire day, while even through Tuesday night they lack moisture above about 5k feet, which means any precip we see starting late Monday night and lasting through the fronts passage would be in the form of drizzle. Greatest moisture feed and threat for drizzle/light rain still looks to be found across eastern MN into WI, which is where highest PoPs continue, especially Tuesday night, when we will finally get a little added lift from shortwave coming across the northern Plains that will be catching up to the front as it is heading out the east end of the MPX area. Tuesday still looks to very well be the Twin Cities last chance this month at cracking 50, though if we do it, it will be based purely on advection, with overcast conditions expected all day. Blended current SuperBlend with going forecast to pull a degree or two off our highs for Tuesday, though still be warmer than blended guidance. For the end of the end of week system, models agree on a general idea for large scale evolution, but still differ significantly on timing of one of those features. Where there is good agreement is that we will see a northern stream wave go off to our northwest on Thursday night, which will help push a front into the upper Midwest. Where differences lie in timing is with a much stronger southern stream wave that will ride up along this boundary from the central Plains into the Great Lakes. Our precip chances look to be tied to the developing baroclinic leaf on the northwest side of the southern stream wave. The ECMWF is a good 12 hours behind the GFS with this wave. With either solution we look to get precip, especially from south central MN up toward northern WI, but it`s a question of does it come Friday morning/afternoon (GFS) or Friday night (ECMWF). Though timing differences exist, both solutions show it being warm enough to where the majority of precip we see will be rain. Only change made to the SuperBlend was to boost winds for the whole Thursday through Saturday period. Saturday looks to have the greatest wind potential with strong CAA. It`s not out of the question that we see gusts Saturday between 40 and 50 mph before an approaching high finally knocks winds down for Sunday. As we get on to the backside of the low, we will see a quick hit of cold air, with h85 temps dropping to around -15c Saturday into Sunday, but with zonal flow/flat ridging building back in for next week, we will quickly see temps moderate back near to a little above normal as we work into the week of Thanksgiving. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 522 PM CST Sun Nov 12 2017 VFR conditions tonight with clear skies, light winds, and the potential for some MVFR/IFR fog north of I-94. High clouds will move across the region on Monday with southeast winds. Deeper low level moisture will develop Monday night into Tuesday. KMSP... VFR conditions throughout. There is a chance for fog but at this time did not include it in the TAF. Could see MVFR ceilings develop Monday night. /OUTLOOK FOR KMSP/ Tue...IFR/MVFR cigs. Chc -dz. Wind S 5-10 kts. Wed...Chc MVFR. Wind NW 15G20 kts. Thu...VFR with MVFR/-RASN possible late. Wind SE 10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...MPG LONG TERM...MPG AVIATION...JRB
Area Forecast Discussion
National Weather Service Paducah KY
807 PM CST Sun Nov 12 2017 .UPDATE... Issued at 807 PM CST Sun Nov 12 2017 With mounting evidence that we will keep overcast skies over the entire region into at least Monday morning, have done a major overhaul to the sky grids and in concert have increased temperatures through the night. Some modest cold advection will continue, but looking upstream it will be difficult to get anything lower than the upper 30s even into the I-64 corridor. Not sure what to do with the clouds Monday, but for now will just show gradual clearing after 15Z. Was hopeful that the 925mb RH forecast from the RAP would pan out, with its rapid clearing over most of the region beginning around midnight. The latest RAP forecast holds onto the low clouds through the night over the eastern third of the area, but still has the rapid clearing over the rest of the area. Will not be surprised if this still pans out for most of the area, but those satellite trends are difficult to discount at this point. && .SHORT TERM...(Tonight through Tuesday night) Issued at 301 PM CST Sun Nov 12 2017 A weak cold front/surface wind shift was well on its way across the PAH forecast area this afternoon as a mid level trof axis approached from the northwest. Lingering pcpn has ended in the east. Some breaks in the clouds may occur for a few hours this afternoon, mainly over parts of southeastern MO/western KY, but should fill back in as the aforementioned trof creates a bit of lift. Generally light surface winds should be out of the north to northwest everywhere by around nightfall. As northwesterly flow aloft and high surface pressure move into our region overnight, a general reduction in cloudiness is expected to begin. Mon and Mon night will be mostly clear and relatively cool, followed by a modest warming trend for Tue/Tue night. Tue night, another low-amplitude mid level shortwave is progged by the models to move through the Dakotas and upper Midwest, dragging a cold front eastward toward the PAH forecast area. As a result, winds will gradually gain a more southerly component Tue/Tue night. Clouds are forecast to increase from west to east Tue night, with an accompanying increase in PoPs for showers after midnight for most of the region. At this time, indications are that instability will not be enough for lightning activity before 12Z. .LONG TERM...(Wednesday through Sunday) Issued at 301 PM CST Sun Nov 12 2017 Confidence in the Wednesday forecast remains fairly high. The models are in good agreement moving a front through during the day, with categorical PoPs for showers maintained, along with a continued slight chance of thunder. The instability is weak, and difficult to find until lifting parcels from h8 and especially h750. Mid level lapse rates aren`t too bad either. The chances will end quickly by early evening, with mainly dry weather Wednesday night through Thursday morning. Left a token slight chance in along the TN/AR border so we don`t discount the GFS completely. However the last few runs of the ECMWF/CMC are definitely trending dry all areas. In the afternoon, will maintain a low chance PoP over SEMO, probably not much until dark as again, the ECMWF/CMC are slower to push the warm front and associated moisture and lift back northeast into the area. Thursday night, will gradually spread the chance of showers northeast across the CWFA, with the front pushing northeast into the area. Same timing and confidence problems exist for the Friday through early Saturday time frame. The 12z ECMWF and UKMET have slowed down even more, suggesting the front may not move through until early Saturday. This would leave Friday and early Friday night warm sector, with lower PoPs in the wake of the warm front. The GFS remains slightly faster though it slowed as well, as does the CMC (not as fast). We have seen the EC/UKMET solutions slow down too much in the past only to speed back up with time. Think a middle ground approach remains the way to go, with just a trend slower. Therefore once again, the ridiculous categorical blend PoPs here and there are simply not appropriate for a low confidence forecast that could shift 6-12 hours either way Day 6 and beyond, until we get closer to the event. Therefore just high chance PoPs again Friday. Went low end likely Friday evening, mainly to collaborate without being too far off with other offices. Then we taper off PoPs after midnight Friday night. Saturday through Sunday remain dry and cooler in the wake of the front. If the slower solutions hold, Saturday morning may be in question (not dry). The ensemble mean solutions from the NAEFS, GEFS and ECENS all support not slowing down as much as the latest 12z EC/CMC models. Temperatures will be highly tied to how events unfold. So low confidence call here as well. Went close to persistence and MOS to minimize the sway. We may be looking at strong convection with the Friday/Friday night system. Still an awful lot of question marks at this point. && .AVIATION... Issued at 510 PM CST Sun Nov 12 2017 Post frontal stratus will move from VFR to MVFR through the evening for KCGI and KPAH, clearing after 06z Monday. A similar situation will occur at KEVV and KOWB, but have much lower confidence of clearing during the rest of the forecast period. At this time, numerical models indicate that there is significant moisture (greater than 90 percent) in the first 1500 feet agl for each of the TAF sites. Given the lowered pressure deficits and mixing in the layer, there is some potential that a low MVFR cloud deck could persist for all of the WFO PAH TAF sites through Monday. Do not have high confidence after 08z for cloud forecast. Will monitor trends during the evening, especially for KEVV and KOWB. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...DB LONG TERM...CN AVIATION...Smith