Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/20/18

Area Forecast Discussion
National Weather Service Denver/Boulder CO
845 PM MDT Thu Jul 19 2018 .UPDATE... Issued at 832 PM MDT Thu Jul 19 2018 Radar showing multiple boundaries over the northeast plains this evening but too dry and subsident for thunderstorms. The RAP and HRRR do show the surface rh increasing (90-95%) toward 12z Friday. Enough there to warrant the mention of patchy fog primarily north and east of Denver for 2-4 hours. Otherwise, no other updates planned. && .SHORT TERM...(This evening through Friday) Issued at 253 PM MDT Thu Jul 19 2018 Our hot and dry day continues under mostly clear skies. Dewpoints are in the 20s and 30s across the mountains and urban corridor, with 40s and 50s along the South Platte River Valley out to the eastern plains. Fire weather conditions continue to be flirting with warning criteria levels, however not an extended period of time, and are more critical up north where fuels aren`t as dry. Northwesterly winds moving off the mountains will continue to spread southeast across the area. Tonights temperatures will continue to be warmer than normal after today`s near record warm temperatures, and with a surface lee trough and warming at 700 mb. On Friday, even through 700 mb temperatures will be warmer, a low level cooler airmass will push in from the Great Plains. Temperatures will be 3 to 7 degrees cooler over the plains, and up to 4 degrees cooler in the mountains. Moisture will be moving up from the southwest for a return to a chance of afternoon storms over the mountains mainly south of I70. The plains should remain capped, however, some forecast soundings showing areas over the east plains with a weaker cap. Will stick with a dry forecast with the weather pattern in mind of a cooler airmass sliding under warmer temperatures. .LONG TERM...(Friday night through Thursday) Issued at 253 PM MDT Thu Jul 19 2018 An upper level ridge will be the predominant factor leading to continued very warm temperatures Friday and Saturday. Friday evening a short wave trough will dip into northeast Colorado. The GFS and European solutions are indicating potential for evening convection over the Palmer Divide region. Saturday precipitation will become more likely over the higher terrain, spreading onto the plains in the afternoon. For the past couple of days the GFS has continued to forecast high PWs Friday night through the middle of next week. Sunday is expected to bring a cool down as the ridge flattens and with more moisture moving into the region and allowing for cloud cover. This should keep temperatures about 10 degrees F lower than the previous day. Monday through Wednesday cooler, stormy conditions are expected to continue. High PWs with low instability will reduce the chances for severe weather but could lead to a heavy rainfall threat. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 832 PM MDT Thu Jul 19 2018 East/southeast winds at KDEN will switch to east/northeast around 0330z this evening. Could see some gusts to 20 kts as the boundary pushes into the Denver area from the northeast. Still anticipate VFR conditions to prevail through the period. The boundary layer rh over 90 percent however suggests potential for low stratus or fog around 10-14z Friday. Confidence not high enough to include it in the terminals but will need to keep an eye on it. The HRRR keeps most of it north and east of Denver while the RAP has it further east. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Kriederman LONG TERM...Sullivan AVIATION...Cooper
Area Forecast Discussion
National Weather Service Dodge City KS
705 PM CDT Thu Jul 19 2018 ...Updated for aviation discussion... .SHORT TERM...(This evening through Friday) Issued at 1231 PM CDT Thu Jul 19 2018 Scattered storms and heat will continue to be the main forecast points in the short term. A surface low located in southeast Colorado along with a weak frontal boundary in southwest Kansas will be the focus for the potential development of storms late this afternoon into tonight. HRRR and RAP have been fairly consistent showing isolated to widely scattered storms developing after 4pm and moving east to southeast through the forecast area before dying off shortly after sunset. Main risk with these storms will be strong downburst winds given the environment of around 100 degree highs and dewpoints in the mid to upper 60s. CAPE values are forecast to be ~3000 J/kg ahead of the thunderstorm development. It looks like better potential for storm development tonight given the lack of widespread morning convection...however a few isolated thunderstorms from Syracuse to Garden City that developed this morning may provide a more stable airmass for thunderstorm development to overcome. Friday could bring with it similar conditions with more heat through the forecast area as highs in the lower 100s with heat index values around 105 for the counties along the Oklahoma border looking like a good bet. The surface low in eastern Colorado will continue to have a weak frontal boundary in southwest Kansas and with northwest flow another 500-700 mb shortwave will move in late afternoon. Depending on where the boundary sets up more isolated to widely scattered late afternoon storms could develop. A lot will depend on if the CAP can be broken ahead of the boundary so the chance nothing develops is also in the cards. .LONG TERM...(Friday night through Thursday) Issued at 140 PM CDT Thu Jul 19 2018 More chances of spotty storms will continue in the long term as the upper level pattern will continue to stay mainly in northwest flow between an upper level low in the southeast and a ridge in the desert southwest. A 500-700 mb shortwave is forecast to come into western Kansas Saturday afternoon into Saturday night and combining with upslope flow we could once again see isolated to widely scattered thunderstorms develop. Sunday with the ridge moving a little more eastward at this point this should keep us dry through most of the day. Monday the long term models have the hints of a MCS developing in eastern Colorado with a shortwave propagating along the ridge and moving into western Kansas in the overnight. Tuesday through Thursday continue with the upper level flow in a northwest pattern with periodic shortwaves rotating around the ridge in the Rockies providing more chances of isolated to widely scattered storms. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 704 PM CDT Thu Jul 19 2018 Aside from isolated evening t-storms, VFR conditions will presist. With a light pressure gradient, winds will be generally light and less than 10 kts except in vicinity of t-storms through 02z. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 101 70 93 / 20 0 20 10 GCK 68 102 69 94 / 20 10 20 10 EHA 70 104 70 98 / 20 20 20 0 LBL 71 106 71 97 / 20 20 20 0 HYS 70 96 68 91 / 10 0 10 0 P28 73 102 73 94 / 20 0 20 10 && .DDC WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM to 7 PM CDT Friday for KSZ088>090. && $$ SHORT TERM...Tatro LONG TERM...Tatro AVIATION...Finch
National Weather Service Kansas City/Pleasant Hill MO
1059 PM CDT Thu Jul 19 2018 .Discussion... Issued at 311 PM CDT THU JUL 19 2018 Active afternoon across west-central Missouri and eastern Kansas as a strongly unstable airmass interacts with passing midlevel vort maxes and numerous outflow boundaries. EAX radar shows multiple outflow boundaries from ongoing and earlier convection across the immediate KC Metro and points south, with numerous splitting supercells across southern portions of the Metro. In fact, we just received a healthy dose of golf ball sized hail here at the office, with baseball sized hail reported over in Lone Jack. Further to the west, TWX radar showing the next inbound cluster or organized storms moving into the Topeka area which if current movement trends persist, should arrive into the immediate KC Metro by 4 PM. Large hail and damaging winds will be possible with this cluster of storms as well, with latest radar trends suggesting the line of storms is beginning to take on bowing characteristics. If this upstream cluster maintains its intensity, its possible winds in excess of 75 mph will be possible over the KC Metro. Please refer to SPC Mesoscale Discussion #1087 for additional details. And if this were not enough, the region north- central Missouri is also being monitored for another watch as latest SPC mesoanalysis shows a well-defined instability axis extending up into southern Iowa. Southward extent of this activity remains in question, but latest CAMs to include the HRRR suggest isolated activity with increased ascent thanks to incoming shortwave energy in west-northwest flow aloft. By this evening, activity should gradually come to an end as main cold front off to our northwest moves through and eventually stalls south of our region. Between now and then however, the radar will remain active with all severe weather threats possible considering ample buoyancy and increased forcing for ascent as upper shortwave energy approaches. Aforementioned cold front to stall south of our region tonight, with latest models suggesting additional shwr/storm activity possible south of Route 50 through the predawn hours. Hydro concerns should remain low through the overnight as the terminus of the low-level jet is directed away from our region, but radar trends will need to be monitored. By tomorrow, a ridge of high pressure should start extending south into our region from the northern Plains, however models indicate low chance pops along the lingering front during the afternoon and evening hours. Beyond this, high pressure should take hold of the weather pattern with dry and pleasant conditions expected through much of the upcoming weekend as winds remain from the north and northeast. In fact, high temps through the weekend look to be mid to upper 80s, which will feel more than welcomed for many. && .Aviation...(For the 06Z TAFS through 06Z Friday Night) Issued at 1059 PM CDT THU JUL 19 2018 VFR conditions are expected to prevail over the next 24 hours. A few showers may be possible early this morning, but we do not expect them to impact the terminals. Lastly, while it`s not included in the TAF at this time, we may have to amend in a bit of ground fog due to Wednesday`s rain. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...32 Aviation...Cutter
Area Forecast Discussion
National Weather Service Glasgow MT
649 PM MDT Thu Jul 19 2018 .DISCUSSION... Evening update... Going forecast looked good. Made some tweaks to clouds in Phillips County to cover whatever is left of the storms that have been ongoing in southern SK drifting in. POPs looked fine to cover the possibility of them holding together. Avery Previous discussion... Upper ridge over the area tonight has some disturbances moving through. But 500 mb heights don`t really fall, so not all that confident that storms will fire from southern Alberta/SW Sask/NC Montana and move into the NW zones as advertised by the HRRR tonight. Do have slight chance of storms to account for this. Storms over the SW corner of the CWA will dissipate soon as they move away from their elevated heat source (Big Snowy Mountains). Eyes then turn to large closed upper low over British Columbia. EC continues to show more of a split with a piece of upper energy moving into Montana while GFS keeps the system cohesive. Both models do show slight chances of storms Saturday into Sunday, but wind being more of an impact Sunday. GFS stronger with winds than other models, but with models generally too light on cold frontal passages, increased speeds over model consensus. Speeds of 20-30 mph look to be a sure bet with gusts to 35 mph. Thereafter, temperatures for the rest of the period will be 5 to 10 degrees below normal as the upper low deepens as it moves into Manitoba. The cool air mass will extend back to the Canadian Rockies while NW winds will bring that into NE MT. TFJ && .AVIATION... Expected Flight Category: VFR, possible low clouds early Friday morning. Synopsis: Mainly clear skies are expected tonight, but some sub- VFR clouds may blow in from the east late tonight/early Friday morning: however, there is too much uncertainty to include them in the TAFs. Any clouds that do move in should quickly clear off by noon. Winds: Northerly around 10 kts, then becoming variable overnight and diminishing to 5-10 kts. Winds become easterly tomorrow around 10 kts. with higher gusts near GGW. MDA && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Huntsville AL
908 PM CDT Thu Jul 19 2018 .NEAR TERM...(Tonight) Issued at 908 PM CDT Thu Jul 19 2018 The overall forecast is on track. With a loss of daytime heating and a more stable atmosphere, have removed rain chances for the rest of the night. This was based mainly on output from the more recent HRRR and RAP, which have remained consistent in lowering rain chances. The 18Z version of the NAM/GFS were trending that way too. But that being said, future interaction between numerous outflow boundaries spawned by recent convection - cannot totally rule out a stray shower or storm; but those chances should remain on the lower side. Will further evaluate if adding patchy fog will be needed for the late night, mainly in/near areas that received a "wetting" rain earlier today. Parts of NW Alabama (Franklin county) and NE Alabama (Jackson/DeKalb) will be considered for a patchy fog mention per recent MRMS rainfall data. A warmer west to slightly cooler east gradient as was already in place, stayed with that thinking for overnight low temperatures. .SHORT TERM...(Friday through Saturday Night) Issued at 219 PM CDT Thu Jul 19 2018 On Friday, we have gone with a low chance PoP through most of the day, to account for the decaying MCS or MCV (much like today) that may enter the area from our west. There could be some subsidence behind this feature (rain or not) that may squelch afternoon convection. Very warm temperatures (with highs ranging into the low/mid 90s and dewpoints into the mid 70s) will produce apparent temperatures as high as 107 over NW Alabama. As such, have added Lauderdale, Colbert, Franklin and Lawrence counties to a Heat Advisory - valid from Noon to 6 PM on Friday. Then attention turns to the severe weather threat Friday night into Saturday morning. Not much to argue about on the new SPC outlook, other than uncertainty with coverage of storms. There continues to be varied solutions on timing and coverage with this as unseasonably strong NW flow develops and an upper low deepens over the Great Lakes. Multiple clusters of convection, including HP supercells, will likely initiate over the lower OH valley into the Ozarks Friday afternoon. These will rapidly drop southeast feeding off an increasing west-southwest LLJ. As noted yesterday, forecast soundings today continue to indicate a lengthening sharply curved hodograph which yields 1km SRH values of 300+ later Friday evening as these storms drop south-southeast into the region. Obviously, thermodynamics will be favorable for severe convection, including very large hail and damaging winds, and perhaps tornadoes. The main issue is coverage of the cells. The NAM in particular is showing a large gap in coverage of thunderstorms over southern middle TN and north AL Friday night. The GFS seems to point to better coverage of supercells/clusters over western TN, northwest AL and northern MS, with less coverage further east. The previous and current ECMWF have been focusing more on KY and TN into far northeast AL into north GA, with lesser coverage further south and west. In either case, will go with chance to likely PoPs on Friday night into Saturday, favoring our eastern areas on Saturday. Details on Saturday thunderstorms will likely be dictated somewhat by what occurs late Friday night. Will maintain chances with the cold front into Saturday as well, then dry things out by late Saturday evening. .LONG TERM...(Saturday night through Wednesday) Issued at 653 PM CDT Thu Jul 19 2018 There remains a decent amount of uncertainty to start the extended as model differences for timing of precip continue. The overall pattern consists of an upper ridge centered over the desert SW, a trough over the Great Lakes, and a Bermuda high shifting westward slightly. The result is the trough north of the area has no where to go and models indicate it should drop south as a cutoff low. These types of systems are never handled well by models and explains the issues. A few waves rotating around the backside of this cutoff low may be enough for isolated to scattered convection on Sunday with the highest chances closer to the center of the system (NE AL and TN). Then as the core of the system drops south near the area on Monday could start to see more scattered to numerous showers and storms. The system shifts to the S/SW away from the area on Tuesday but upper level flow suggests we might be under a deformation axis and could see another round of scattered to numerous showers and storms. An elongated shear axis remains over the area Wed/Thu and we might see continued showers/storms both days. But with the uncertainty in some of the positioning and just how widespread some of this precip might actually be, have nudged PoPs down below guidance from Tuesday onward. The one thing the system will bring is some relief from the heat as the increased cloud cover and rain chances each day should keep temps in the 80s. Those temps combined with slightly drier air at the surface, and modest lapse rates aloft will result in CAPE values between 1,000 to 1,500 J/kg each day based on latest GFS soundings. Afternoon highs begin to climb back up towards the 90 degree mark Thu/Fri. But again as mentioned above, models have trouble with the cutoff type of systems and uncertainty in the forecast is a bit higher than normal. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 653 PM CDT Thu Jul 19 2018 Surface high pressure to the east of the region will result in VFR flying weather continuing into the late night. Night time cooling and moisture pooling aloft could result in late night MVFR CIGs before daybreak Friday. S-SW winds otherwise will continue on Friday. The period right after this TAF could become very interesting, as some of the mesoscale and longer term models depict thunderstorm complexes moving southward, affecting the terminals Friday evening. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Heat Advisory from noon to 6 PM CDT Friday for ALZ001>004. TN...NONE. && $$ NEAR TERM...RSB SHORT TERM...17/RSB LONG TERM...Stumpf AVIATION...RSB For more information please visit our website at
Area Forecast Discussion
National Weather Service Jacksonville FL
952 PM EDT Thu Jul 19 2018 .UPDATE... Tried to blend the NAM12 and HRRR with the NAM12 indicating the meso-low across southeastern Georgia overnight and the HRRR depiction of convection developing over the Suwannee Valley area and Nature Coast moving inland during the overnight hours. Looking at the radar and satellite imagery can see both happening although the meso-low over Georgia is beginning to wind down a bit. && .AVIATION... Overall looking at a mid deck in the 5-10 kft range at the Florida fields overnight with a low 1-3 kft range deck at KSSI. Tomorrow the convection should begin early with the thunderstorms between 14-20 utc and then with a worked over atmosphere more light rain to showers after 20 utc. Some rain may be heavy with visibility reduced to 1-3sm in storms. && .MARINE... The region will remain between troughing to the northwest and high pressure to the east/southeast through the weekend. The waters will be between high pressure to the east/northeast and a weak low to the West early next week. Rip Currents: Low risk through Friday. && .PRELIMINARY POINT TEMPS/POPS... AMG 74 88 73 92 / 60 70 50 30 SSI 78 87 77 90 / 50 70 60 30 JAX 76 89 74 92 / 40 60 50 40 SGJ 76 88 74 89 / 40 60 50 60 GNV 76 86 74 91 / 50 70 50 60 OCF 75 87 74 89 / 50 70 50 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AM...None. && $$ Sandrik/Kennedy/Cordero
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
914 PM CDT Thu Jul 19 2018 .UPDATE... 913 PM CDT A cluster of storms in northwest Illinois had matured quickly as it moved into Ogle County in north central Illinois early this evening, but has since weakened some. Isolated cores occasionally strengthen, with likely some small hail, and the overall footprint of the storms and associated cold pool likely are producing some 40+ mph gusts in central Ogle County. In addition, rain amounts near an inch in an hour are occurring under these slow-moving and semi-training storms, though antecedent conditions in this area, mainly rural, are not overly wet. These storms are north of the warm front, however the effective air mass is not that far southwest of the CWA per mesoanalysis and 00Z DVN sounding. This along with strong 0-1 and 0-3km shear is likely why these sustained storms have been able to acquire some cold pool development and occasional wind surges. Will need to watch for this behavior, but would think it might be trending less favorable in this northern part of north central Illinois. Further south toward LaSalle and Livingston Counties if any isolated storms were to develop in the gradually increasing forcing/warm advection, they could have a better potential to be strong. It is challenging to say how many more storms will develop south of I-88 for the rest of tonight. There is strengthening ascent ahead of the closed upper low and impinging mid-level jet into the area. Countering that is that some moisture transport over the front is being robbed by very deep convection over the northeast MO/western IL border. The HRRR and its experimental run generally develop little additional convection in the southern two-thirds of the CWA, which could indicate our likely storms including into at least part of the Chicago area overnight are overdone. Suspect these solutions could be somewhat underdone, but middle of the road from current forecast and that solution may be the better route (i.e. scattered storms overnight). Forecast for Friday still looks on track with good coverage of showers and embedded isolated/scattered deeper cores with lightning potential, all forced by the upper vorticity maximum swinging into the area. If there were to be deeper late morning/early afternoon convection in the east/southeast CWA it would have to be watched for a severe weather threat. MTF && .SHORT TERM... 249 PM CDT Through Friday... The line of showers and storms over Western IL is slowly advancing east. There should be sufficient CAPE to keep the line going with embedded thunderstorms. I`m not expecting any severe storms with this line. I kept a chance of scattered showers and storms behind the line as CAPE values should still be supportive of storms and the upper level forcing will be on the increase. PWAT values are 1-1.6 inches so any thunderstorm will produce heavy rain. If storms train over the same area, localized flooding could occur. The upper level and surface low move over southern WI Friday. Forcing aloft should allow scattered showers and thunderstorms throughout the day. There will be dry hours, but I have low confidence in exactly when and where due to the scattered nature of the showers/storms. Increased cloud cover should limit warming, so I lowered high temps into the 70s. JEE && .LONG TERM... 255 PM CDT Friday night through Thursday... A vertically stacked storm system will continue to gradually shift over the region into Sunday. This will generally result in cloudy and seasonably cool temperatures through the weekend, with periods of showers. A couple of thunderstorms will also be possible, especially near Lake Michigan late Saturday and Saturday night. Also, as mentioned in the previous discussion, some funnel clouds will be possible, especially given the proximately to the mid-level circulation. With extensive cloud cover likely, expect cool high temperatures in the 70s to around 80 both Saturday and Sunday. A high risk for swimming is also likely to set up for the weekend for most of the southern Lake Michigan beaches as stout northerly winds over the lake result in high waves. It still appears this upper level system will finally move out of the area early next week. This will likely set up a few dry days with more sun across the area into the middle of next week. Expect temperatures to warm back to around seasonal normals into the mid 80s. KJB && .AVIATION... For the 00Z TAFs... 645 pm...Forecast concerns include thunderstorm chances tonight and Friday...mvfr cigs Friday and possible ifr cigs Friday night. A few showers are possible across the Chicago area terminals for the next hour or so along with an isolated thunderstorm. This activity will continue lifting northeast early this evening. A line of thunderstorms extends from southwest WI into far northwest IL early this evening and while short term guidance has so far not handled this activity well...this is expected to continue to slowly move east/northeast this evening. There remains uncertainty regarding how much more development will occur south of this line and how much will occur/move across the Chicago area terminals later this evening into early Friday morning. Adjusted tempo for thunder a few hours later based on current movement but further timing tweaks can be expected as trends emerge over the next few hours. A lull is then expected around sunrise with additional showers expected to spread into northwest IL by mid morning and the rest of the area by late morning. By this time... the best instability is expected to be south of the terminals. While an isolated thunderstorm will be possible...the potential looks low so no thunder mention during this time period with this forecast. Showers are expected to slowly diminish through Friday afternoon with perhaps much of Friday evening being dry. Brief mvfr cigs will be possible with any thunderstorms tonight but prevailing cigs are expected to remain vfr. Mvfr cigs will begin to move into northwest IL by sunrise and then spread across the rest of the area Friday morning. Possible cigs may drop as low as 1kft at times. Mvfr cigs are then expected into Friday night with ifr cigs possible Friday evening into Saturday morning. An outflow boundary moved across the terminals in the past few hours...briefly shifting winds to the west/southwest. Winds are expected to settle back to south/southeast this evening and then slowly turning southerly overnight and shift west/southwest by mid/late Friday morning. Speeds likely to remain 10kts overnight with gusts 16-20kts developing on Friday. A wind shift to the north is possible Friday evening. Confidence is low that this shift will occur so no mention with this forecast. cms && .MARINE... 321 PM CDT A slow moving storm system is expected to shift over southern Lake Michigan Friday night and then gradually meander over the southern half of the lake through early Sunday. This system is expected to produce hazardous conditions over the lake, especially tonight through early Sunday. Expect southeast winds over the lake (15-25 KT) to develop tonight as the surface low approaches from the west. The winds will then shift northeasterly on Friday over the northern half of the lake and southwesterly over the southern tip of the lake as the low begins to move over central and southern sections of the lake. Finally, winds will likely become north-northeasterly lake-wide for the weekend, with speeds of 25 to 30 kt likely for a period on Saturday. This will likely produce high waves of 5 to 8 feet over southern Lake Michigan, which will likely result in the need for another small craft advisory for the weekend. Winds and waves should subside early next week as the system shifts out of the region. Periods of showers and thunderstorms can also be expected on the lake into the weekend. Waterspouts also appear possible over the southern end of the lake. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Beach Hazards Statement...ILZ006-ILZ014...midnight Friday to 10 AM Friday. IN...None. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...midnight Friday to 10 AM Friday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Marquette MI
750 PM EDT Thu Jul 19 2018 .SHORT TERM...(This evening through Friday) Issued at 414 PM EDT THU JUL 19 2018 WV imagery and RAP analysis indicated a mid/upper and sfc low over sw MN. The leading edge of pcpn with WAA/isentropic ascent ahead of the low was slowly lifting to the ne through wrn WI. Any thunderstorms remained farther south over ern IA, where MUCAPE values were near 1k J/Kg. Otherwise, srly low level flow prevailed through Upper Michigan with sct cu and a few high clouds. Tonight, model trends with fcst moisture advection, isentropic lift, and QPF suggest that the best rain chances/coverage will move into wrn Upper Michigan overnight. However, instability to support tsra will remain south of the area. Pcpn amounts should also remain light, generally at or below 0.10 inch. Friday, as the low slowly moves through srn WI, the heaviest pcpn will continue to remain to the south of Upper Michigan and the highest POPs will remain over the wrn CWA, closest to the stronger 700-300mb qvector conv. Expect enough diurnal heating to boost MLCAPE values into the 500-1000 J/Kg range with potential of isold thunderstorms over the south and east. Highs should climb into the lower 70s near the WI border to around 80 east. .LONG TERM...(Friday night through Thursday) Issued at 347 PM EDT THU JUL 19 2018 Main concerns in the long-term forecast will be the precipitation potential Friday night through the weekend along with the associated cooler than normal temperatures. Friday night through Sunday, Models are showing very similar evolutions of a closed low moving through the Upper Great Lakes through this time period. The models have converged on the upper- level and surface low sliding across WI. This will lead to increasing shower and thunderstorm chances for Friday; however, dwindling instability will keep mainly rain showers and cloud cover in place from Friday night through at least Sunday morning. The increased cloud cover and intermittent precipitation through the weekend, will keep temperatures below normal for this time period, generally in the upper 60s to mid 70s, coolest downwind of the Great Lakes. Doesn`t look like a lot of rain, but the southeast half of the U.P. could see rainfall totals around a quarter to a half inch. That`s good news as those locations have been especially dry over the past couple months. Monday through Thursday, models are depicting a surface low and and upper level trough sliding across Canada. The main impact this would have is perhaps an increase in cloud cover Monday into Tuesday as a weak, moisture starved front slides through the area. Another small chance of rain showers is possible Tuesday night into Wednesday as the aforementioned lows sink a bit farther south across Ontario. This will allow a stronger cold front to slide through the area along with some additional moisture. At this point, with timing and placement similar among the models, will stick with the consensus blend, bringing a few scattered showers for Tuesday night into Wednesday. Temperatures will likely be in the 70s for most locations with a few 80 degree readings possible for inland locations. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 750 PM EDT THU JUL 19 2018 Low pressure system moves across Wisconsin Friday. Winds back from southeasterly this evening to easterly Friday morning and eventually northeasterly late Friday. Rain chances also come with it. Northward extent of any heavier showers remains a bit uncertain but will dictate where low ceilings will end up being an issue. Have kept prevailing ceilings at IWD in low-end MVFR, but upstream obs over central Minnesota and hi-res model consensus support a few hour period of IFR cigs mid-morning Friday so have covered that with a TEMPO. Have kept cigs low-end VFR at CMX and SAW throughout the TAF period as they will be farther removed from the system. Rain should be light enough to prevent any category reductions to vis. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 414 PM EDT THU JUL 19 2018 Expect winds generally 15-20 kts with a few times of gusts over 20 kts through Saturday as a low pressure system slowly crosses the western Great Lakes. High pressure building in Sunday through early next week will result in winds staying mostly 15 kts or less. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...KEC AVIATION...RJC MARINE...JLB
Area Forecast Discussion
National Weather Service Las Vegas NV
600 PM PDT Thu Jul 19 2018 .SYNOPSIS...Moist and unstable air will remain over the region through the end of the week providing fuel for afternoon and evening thunderstorms...especially over the mountains. Next week, a heatwave will be building with very hot temperatures expected and lowering thunderstorm chances. && .UPDATE...The POP/WX grids were updated through 11 PM PDT this evening to reflect the latest trends. A cold pool could be seen on satellite imagery pushing out of southwest Utah into nearby Lincoln and Mohave counties. This will likely lead to isolated to scattered thunderstorms over northeast Clark County this evening. This was the main change to the forecast. Thunderstorm coverage was also increased over Esmeralda and central Nye counties. -Adair && .PREV DISCUSSION... 242 PM PDT Thu Jul 19 2018 .SHORT TERM...Tonight through Saturday. Radar returns as of 2 PM show isolated to scattered deep, moist convection north of Interstate 15. Most storms have developed over terrain and remained anchored. Daytime heating combined with differential heating circulations due to anvil shadowing have allowed strong storms to develop over Nye and Lincoln Counties. HRRR is indicating that storms will develop further eastward into Lincoln County late this afternoon then transition to outflow-dominant and move southwestward toward Clark County this evening. There has decent run-to-run consistency, so PoPs were increased slightly for Las Vegas and northern Clark County. Without a dynamic influence, most convection should wane after sunset, the exception would be convection maintained along outflow. As far as synoptic evolution goes, ridging will continue to move eastward and eventually settle across the Southern Plains by Saturday. As it moves east, southerly flow will increase along the western periphery of the ridge allowing slightly drier air to push northward into the southern Great Basin. This will lead to lowering rain/thunderstorm chances across the forecast area. Rain chances will be limited to higher terrain (Spring and Sierra Mtns.) and Mohave County through Saturday where the best instability, although only moderate, will exist. Temperatures will remain at or just above normal through Saturday. .LONG TERM...Sunday through Thursday. High pressure centered over New Mexico/Texas over the weekend will gradually propagate west early next week. As this happens, temperatures will be on the increase each day. Las Vegas may see 110 as early as Monday, but the more excessive heat will arrive Tuesday and Wednesday as readings will be about 8-10 degrees above normal. This will put places like Las Vegas in the 110-114 degree range, 115- 120 down the Colorado River, and 120-125 in Death Valley. With these readings and little relief expected overnight an Excessive Heat Watch has been issued for much of southern Nevada, southeast California, and northwest Arizona for Tuesday and Wednesday. Moisture is also expected to be rather limited with any thunderstorm chances mainly confined to the higher terrain of central Nevada and the Sierra with only slight chances over the higher terrain of southern Nevada and northwest Arizona Sunday through Thursday. && .AVIATION...For McCarran...Outflow winds from distant thunderstorms could still influence the terminal area this evening, but confidence is low in any direct impacts. Clouds will diminish after sunset. Similar unstable conditions are expected Friday, but confidence is low in a thunderstorm developing within the terminal area. Cloud bases at or above 10k feet. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered to isolated thunderstorms, mainly over the higher terrain across the southern Great Basin and eastern Mojave Desert. Storms will wane this evening. Convection may persist later into the evening across Lincoln, northern Clark, and southern Mohave Counties along outflow boundaries. Outside of thunderstorm influences, southerly winds with speeds of 10-15 knots and gusts to 20 knots should prevail. CIGs at or above 10k feet; CIGs may drop to 5-7 k feet with convection that develops near a terminal. Similar conditions expected Friday, with slightly less thunderstorm coverage. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM/AVIATION...Boothe LONG TERM.............Gorelow For more forecast information...see us on our webpage: or follow us on Facebook and Twitter