Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/13/17


Area Forecast Discussion
National Weather Service Northern Indiana
713 PM EDT Thu Oct 12 2017 .SYNOPSIS... Issued at 306 PM EDT Thu Oct 12 2017 Cloudy skies are expected to continue through tonight into early Friday. Skies will become partly sunny on Friday and it will be warmer with highs in the upper 60s to low 70s. Showers and perhaps even a few thunderstorms will move into far northwest Indiana and Michigan late Friday night into Saturday, and into the remainder of the forecast area Saturday night into Sunday morning. Highs on Saturday will be unseasonably warm into the mid to upper 70s. Cooler and drier air will filter into the region later Sunday into early next week. && .SHORT TERM...(This Evening through Friday) Issued at 306 PM EDT Thu Oct 12 2017 Strong subsidence inversion under shortwave ridge has locked in moist near surface layer. Depth of this moist layer per latest AMDAR soundings 1-2 km deep suggesting extensive low stratus deck will remain in place into tonight. A weak sfc trough draped from sw OH wnw to central IL will lift north through the area later tonight into Friday morning. Could see some patchy fog/drizzle in advance and along this feature as it moves through, though coverage should be limited with most locations remaining dry. Warm advection and expected mix out of low clouds in wake of weak trough (from sw to ne) in the morning/early afternoon should afford a warmer Friday as low-mid level flow veers more southerly. && .LONG TERM...(Friday Night through Thursday) Issued at 306 PM EDT Thu Oct 12 2017 A relatively potent shortwave trough is still on track to work west to east across the US this weekend in progressive pattern, with the associated deepening sfc cyclone taking a Central Plains to Northern Great Lakes track by Saturday night/Sunday morning per latest model consensus. Excellent moisture return/convergence within downstream LLJ core will likely allow shower/embedded thunder coverage to blossom from Iowa east-northeast into the lower-central Great Lakes by later Friday night-Saturday. This strengthening baroclinic zone will be the focus for higher PoPs during this time into our nw IN and sw Lower MI zones, while ne IN/nw OH remains dry and unseasonable mild within a well mixed warm sector. Rainfall totals in excess of a half inch will be possible in sw Lower MI, with higher amounts just north from the IL/WI border into central Lower MI. Trailing cold front will work through later Saturday night/Sunday morning with additional shower chances. Transient/brief shot of cooler/drier/seasonable air then follows into early next week as high pressure builds in wake of trough. && .AVIATION...(For the 00Z TAFS through 00Z Friday Evening) Issued at 704 PM EDT Thu Oct 12 2017 Have maintained MVFR cigs/vsbys into Fri morning with uncertainty on impacts of lingering low level moisture. Cigs heights have been slowly edging up, higher than previously forecasted. Therefore somewhat optimistic for only minor changes in cigs/vsbys but not enough to send to IFR at this time. Will monitor trends for amendments. Skies should slowly start to clear from SW to NE with both sites seeing VFR conditions hopefully by late Fri morning into the afternoon hours as moisture is finally mixed out. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Steinwedel SHORT TERM...Steinwedel LONG TERM...Steinwedel AVIATION...Fisher Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PDT Thu Oct 12 2017 .SYNOPSIS... Onshore flow and an upper level trough will bring areas of low clouds west of the mountains tonight and Friday morning, but otherwise the weather will be fair. Offshore flow will develop Saturday and continue into Sunday and likely bring a moderate Santa Ana Wind to parts of the Inland Empire and adjacent mountains and inland Orange County. Temperatures will increase over the weekend. Gradual cooling will occur the middle of next week as a Pacific trough of low pressure approaches. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Skies were sunny over the region with some cooling versus Wednesday, mostly in the upper 60s and 70s west of the mountains and in the 80s to near 90 in the lower deserts. The marine inversion base, based on aircraft soundings, was around 2200 ft MSL, and this should lower overnight. A broad trough covers most of the western half of the US with an axis moving through So-Cal this afternoon. This resulted in today being the coolest day of this week with temps slightly below seasonal normals. Some height rises should result in the lower marine inversion tonight, but WRF cross-sections show enough humidity below the inversion for some stratus, but with less valley penetration than last night. Temps will increase some on Friday, generally around 5 deg F. The trough will shift east Saturday as surface high pressure builds in the Great Basin. Offshore flow will develop late Saturday morning as the colder air mass makes it to the San Bernardino County Mountains, with an inversion level possible near the mountain crests. 12Z NAM was fairly vigorous with the offshore flow as was the 00Z NAM, though 06Z NAM, plus GFS and ECMWF runs were weaker and having the main temp gradient farther northeast closer to Nevada. Local WRF runs depend on the model used for boundary conditions, but NAM-based runs show gust potential around 55 MPH while GFS-based runs are more like 35 MPH. Current thinking is around 50 MPH. Both NAM and GFS have strong MSLP gradients from northern Utah to San Diego, up to 20 MB, though with best gradients in southern Nevada. Timing of strongest winds would be late morning and early afternoon Saturday and then again late Saturday night/early Sunday morning. Profile is much less favorable for NE winds in San Diego County versus farther north. The one thing the models are more consistent with is that very low humidities will occur, possibly as low as around 5 percent Sunday in the Inland Empire. Winds will decrease by Monday when the upper ridge axis is overhead. Parts of the Inland Empire will have highs in the lower to mid 90s Sunday and Monday (a few 90 deg F temps Saturday). Troughing from the east Pacific will bring a cooling trend starting around Tuesday, and the return to onshore flow will bring at least some stratus west of the mountains. Some of the model solutions have a closed low on the south side of the trough and even light precip for our area Wednesday/Wednesday night. If the models continue to have this in the next few runs, it will be needed to be added to the forecast, but closed lows usually do not verify well 6 days in advance. && .AVIATION... 122000Z...Coast/Valleys...SKC and light westerly sea breezes will prevail through 02Z Friday. After 02Z, low clouds will begin to reform near the coast then slowly push inland overnight. A return of BKN low clouds with initial bases around 2,000 ft MSL is expected at the coastal TAF sites between 03Z and 09Z. Ceilings should fall to around 1,200 ft MSL by 12Z Friday. Low clouds are not expected at KONT. Areas of reduced visibility, 2 SM or less, will occur near higher coastal terrain overnight. Coastal TAF sites should clear around 16Z Friday, leaving SKC for all Friday afternoon. Forecast confidence is moderate. Mountains and Deserts...SKC, unrestricted visibility and light winds will persist through 00Z Saturday. && .MARINE... No hazardous marine weather is expected through Tuesday. && .FIRE WEATHER... Another Santa Ana wind pattern is expected to occur Saturday through Sunday as surface high pressure builds in the Great Basin area. The winds with this event do not appear to be as strong as the Santa Ana winds that were experienced this past Monday. However, relative humidities will be very low (5-10 percent for areas away from the coast) with very little overnight humidity recovery Saturday night and even Sunday night. Thus, with the gusty northeast winds (gusts of 30-40 mph and locally 50+ mph possible) and very dry conditions, critical fire weather conditions will be likely over and southwest of the San Bernardino County Mountains and possibly the Santa Ana Mountains and Orange county foothills. A Fire Weather Watch has been issued from 10 AM Saturday through noon Sunday for these areas. && .SKYWARN... Skywarn activation is not needed. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...Maxwell AVIATION/MARINE...Albright