Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/09/19

Area Forecast Discussion
National Weather Service Denver/Boulder CO
804 PM MDT Mon Jul 8 2019 .UPDATE... Issued at 710 PM MDT Mon Jul 8 2019 The strongest thunderstorms from earlier this afternoon have weaken while pushing eastward out of the area this evening. Therefore, have allowed the Severe Thunderstorm Watch to expire early for all of the far eastern counties. Expanded coverage of pops for a few extra hours across the foothills and Urban Corridor locations due to the last batch of scattered showers moving off the higher terrain. Water vapor channel starting to show much drier air aloft edging into the state from southwest and will expect showers to diminish through 04z. Otherwise, current forecast is on track. && .SHORT TERM...(This evening through Tuesday) Issued at 303 PM MDT Mon Jul 8 2019 Scattered thunderstorms have been developing on the plains over the last couple hours with a combination of showers and outflow boundaries currently being depicted in the radar data. Some storms on the plains will be strong enough to produce hail and/or damaging winds for the next couple hours. Shower activity extends back into the mountains as far west as KRIL and as far south as KALS. This line defines the back edge of the short wave trough that we have been tracking. As the trough continues in northeastward track, shower activity is expected to continue developing ahead of it. The HRRR shows that the majority of shower activity will be finished by 8 PM MDT with only isolated, weaker showers after that. Thunderstorms on the eastern plains will tap into better moisture and be strong to severe for the next couple hours. Forecast will show thunderstorms through the early evening and then rapid clearing by midnight. For Tuesday, drier westerly flow will prevail, leading to a rare summer day with no afternoon convection over the forecast area. Skies will be mostly sunny with temperatures warmer than today. .LONG TERM...(Tuesday night through Monday) Issued at 303 PM MDT Mon Jul 8 2019 For Tuesday night into Wednesday, a closed low will be to the North over North Dakota with the trough extending into portions of eastern Wyoming and Nebraska. A boundary bringing slightly cooler air and increasing stability will push into the northern plains by the evening hours on Tuesday helping to cap convection for Wednesday and decrease highs slightly into the lower to mid 80s. The only exceptions would be the higher elevations where there would be enough moisture to help diurnal heating spark some isolated convection by the late afternoon hours. Some models are more excited about these storms than others so will keep pops in the slight chance area for now. By late Wednesday into Thursday, the 596 DM ridge will continue to build over the desert SW cutting off moisture for much of the state. Models show some moisture making it under the ridge in the mid- levels on Thursday. The focus for isolated storms will mainly be over the higher terrain with just a slight chance across the Palmer Divide given increased NE flow from a circulation over the southern foothills. Storms will mainly produce light rain with some gusty winds. Temperatures will rebound slightly with highs across the plains in the lower 90s with 70s in the mountains. For the latter half of the week, the ridge remains in place over the region with an increasing plume of moisture from the desert SW. Precipitable water (PW) values will increase starting Saturday with GFS putting over an inch across the eastern plains through Sunday. Storm coverage is expected to increase through the weekend. Friday will be more isolated over the higher terrain and Park county with Saturday having more widespread scattered storms into the evening hours. Models show CAPE values increasing Saturday with values from 500 to just over 1500 j/kg over the far NE plains. Steering flow will be decent between 12 and 18 kts with deep layer shear just between 20 and 25 kts. PW values will be around 0.90 inches by Saturday evening. These storms could produce moderate to heavy rain and gusty winds. Similar story for Sunday with slightly lower confidence on storms making it onto the plains. Models are showing increased warming in the mid-levels over portions of the plains with increasing upper level zonal flow. Storms could have a hard time surviving as the move east off the higher terrain. If they are able to survive, the main hazards will be gusty winds with DCAPE values near 1500 j/kg. Highs over the weekend will reach back into the lower 90s with 70s expected in the high country. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 710 PM MDT Mon Jul 8 2019 The greater coverage of showers and thunderstorm from earlier this afternoon have pushed well east of the terminals. Clearing skies should be the rule through the evening and overnight hours. Drier westerly flow aloft will then bring mostly clear skies and unlimited visibilities through Tuesday afternoon. Winds will return to drainage southerlies this evening and then be light and westerly through tomorrow. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Fredin SHORT TERM...Dankers LONG TERM...Bowen AVIATION...Fredin
Area Forecast Discussion
National Weather Service Billings MT
834 PM MDT Mon Jul 8 2019 .UPDATE... Severe convection and heavy rain continue to shift east this evening. Have extended the Severe Thunderstorm Watch til 11 pm for Custer, Fallon, Powder River and Carter Counties. Activity has weakened to the west and have cancelled Rosebud, Treasure, Big Horn and Sheridan Counties. JKL && .SHORT TERM...valid for Tdy and Tue... Potential exists for severe thunderstorms and flash flooding this evening. BE PREPARED! Convection already developing over the Beartooth Absarokas at 1140 am. Latest mesoanalysis shows capping across our lower elevations, but since this morning`s activity we`ve had a few hours of sun which is helping to destabilize our air mass. We are already seeing temps in the 70s, with dew points mainly in the 50s, except low 60s in our far east. Recent HRRR runs show convection initiating in our southwest at 19-20z, but this is too late given what we are seeing now. Water vapor imagery shows a seasonally strong shortwave lifting thru the great basin, and this will provide plenty of large scale ascent for today`s convection. Ingredients are all coming together for a risk of both severe storms (mainly hail/wind) and flash flooding (pwats over an inch) this afternoon and evening. CAMs show a couple rounds of storms moving thru, and this seems reasonable given the ascent. Moisture will be greatest east of Yellowstone County, an area that has seen significant rainfall over the past several days. Storms will be moving, but any heavy rain (or multiple rounds of heavy rain) on top of saturated soil could produce flash flooding. The potential for severe weather will last til around midnight in our far east. For Billings, 3-9 pm seems to be the prime time. Cooler air will surge in tonight behind a cold front, and the upper trof axis will finally shift east early tomorrow. We will see hints of a trowal as the low deepens to our northeast, and looks like a good chance of showers even in the morning on Tuesday. Low will pull away later in the day but with enough diurnal instability under the NW flow aloft to keep scattered showers going thru the afternoon and early evening. Freezing levels will be quite a bit lower under the upper trof, the GFS shows wet bulb zero heights around 7kft agl, so expect small hail with any modest thunderstorm that develops. Tuesday high temps will be only in the low-mid 70s. After a relatively chilly night, upper level ridge will build in for drier and warmer conditions on Wednesday. We should see highs get closer to normal and in the 80s. JKL .LONG TERM...valid for Wed...Thu...Fri...Sat...Sun... Upper ridge over the area on Thursday gets flattened with a shortwave moving through the region. Some late day showers and thunderstorms are possible over western areas. Ridging builds back over the region Friday and through much of the weekend, with moisture and energy advecting into the area, undercutting the ridge. Showers and thunderstorms look possible most afternoons/evenings in this monsoonal pattern. High temperatures look to range from the middle to upper 80s most days, with low temperatures mainly in the 50s. STP && .AVIATION... Potential exists for severe thunderstorms east of KBIL through the evening, with large hail, strong winds and very heavy rain possible. Storms will produce a brief period of MVFR or lower flight conditions. To the west, showers with a few embedded thunderstorms will produce local MVFR, and mountains will be occasionally obscured. More showers w/ scattered thunderstorms can be expected on Tuesday, along with breezy NW winds. Small hail is possible with any storm, along with localized MVFR conditions. Mountains will be frequently obscured. NW winds will gust from 20-30 kts across the east, including KMLS and KBHK. JKL && .PRELIMINARY POINT TEMP/POPS... Tdy Tue Wed Thu Fri Sat Sun ------------------------------------------------------- BIL 080 056/073 054/085 062/087 061/085 062/089 063/091 +/T 96/T 20/B 02/T 21/U 11/B 21/U LVM 075 049/074 047/084 055/086 055/085 055/087 057/088 9/T 85/T 00/B 12/T 22/T 22/T 23/T HDN 080 056/072 052/085 059/086 060/084 061/089 062/091 8/T 96/T 20/B 01/U 11/B 11/B 20/U MLS 084 058/070 051/081 059/087 060/084 061/088 063/090 4/T +8/T 30/U 00/U 11/U 21/U 21/U 4BQ 082 057/071 050/081 059/087 060/084 061/087 062/090 4/T +8/T 30/U 01/U 12/T 22/T 21/U BHK 083 057/068 049/078 057/085 059/082 060/086 061/088 4/T +9/T 50/U 01/U 11/U 21/U 21/U SHR 081 052/072 047/085 057/088 057/084 057/087 059/091 7/T 96/T 20/U 02/T 24/T 33/T 31/U && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Flash Flood Watch in effect until 6 AM MDT Tuesday FOR ZONES 30>33-36>38-57-58. Severe Thunderstorm Watch 499 in effect until 11 PM MDT this evening FOR ZONES 32-33-36-37. WY...None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
651 PM MDT Mon Jul 8 2019 .UPDATE... Issued at 649 PM MDT Mon Jul 8 2019 The Severe Thunderstorm Watch for the southern Nebraska Panhandle has been canceled. The line of thunderstorms has moved out of our area, and the severe threat has diminished for the day. UPDATE Issued at 334 PM MDT Mon Jul 8 2019 A Severe Thunderstorm Watch is now in effect for counties in the southern Nebraska Panhandle including Scotts Bluff, Banner, Morrill, Kimball, and Cheyenne Counties until 10 PM tonight. A line of thunderstorms is moving out of eastern Wyoming and into western Nebraska. The main threats with this line of storms are wind gusts up to 70 MPH and hail up to 2 inches in diameter. Heavy rainfall is also possible. && .SHORT TERM...(This evening through Tuesday) Issued at 220 PM MDT Mon Jul 8 2019 Forecast concerns in the short term deal with severe thunderstorm chances/locations both today and Tuesday. Currently...Cold front lays across east central Wyoming this afternoon from a surface low over northwestern South Dakota. Mid 60 dewpoints in the Panhandle with 64 being reported at Alliance...63 at Sidney and 65 at Chadron. Water vapor imagery showing an upper level disturbance moving into the central Colorado/Wyoming state line at this time. 250mb jet around 50-55kts moving into the area with this shortwave. Thunderstorms are beginning to develop along the Laramie Range...moving very slowly to the east. Seeing outflow boundaries emanating from these storms along the I-80 corridor. With the slow storm expect erratic storm motions. Latest SPC Mesoanalysis showing best instability over the Panhandle this afternoon. By mid afternoon...looking at surface based CAPE values on the order of 4000 J/KG out near Bridgeport. Not a whole lot of shear out there with light low level winds. Effective Bulk Shear around 20kts down near the southern Panhandle. So not really looking at extremely large hail. Better severe hazards may be heavy rain today. Latest HRRR shows on its simulated radar forecast for storms to slowly shift east into the Panhandle through 01Z. Given storms we have received the past several days...did not want to go with no severe storms this afternoon. Do expect severe storms to be on the low end though this afternoon. For Tuesday...Showing a surface boundary pushing southeast out of north central Wyoming Tuesday afternoon with upper level trough moving through late afternoon. Will need to watch the timing on this front/shortwave as SPC does have a Slight Risk area for the northern Panhandle. .LONG TERM...(Tuesday night through Monday) Issued at 220 PM MDT Mon Jul 8 2019 Drier and warmer period for Wednesday through Friday as upper level ridge builds into the area from the south. Could see some fire weather issues as afternoon humidity falls below 15 percent each day...expanding east each day. Fortunately...fuels are still reported as chances for fire starts are small. One final thing for the weekend...backdoor cold front set to move back into the area Friday afternoon/evening from the north. So looks like storms returning for the weekend. For way out there...GFS and ECMWF beginning to show the onset of the monsoon with a Four Corners high setting up and qpf developing over northern Mexico. This qpf makes it up into northern Colorado by mid week next week. Just on time for Frontier Days. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 513 PM MDT Mon Jul 8 2019 Latest radar loop was showing a line of thunderstorms stretching from Alliance to Sidney. This line should exit the area by 01z or so. Gusty west winds have been following this line due to good subsidence in the stratiform region. Meanwhile, more isolated convection was moving through Carbon county. This convection may produce some gusty winds, but this convection should die off after sunset. Meanwhile, wind speeds are expected to be quite gusty && .FIRE WEATHER... Issued at 220 PM MDT Mon Jul 8 2019 Scattered to numerous showers and thunderstorms this afternoon...mainly along and south of the Interstate 80 Corridor. One more day of wetting rains mainly east of the Laramie Range for Tuesday. High pressure then builds into the area for Wednesday with very dry air. Afternoon humidity becoming critical each day through Friday...especially along and west of the Laramie Range. Overnight humidity recoveries poor Thursday and Friday mornings. Gusty west winds to 30 mph possible...could lead to areas of critical fire weather. Fortunately...fuels are still being reported as not fire weather concerns should be minimal. Unsettled weather returns to southeast Wyoming and Nebraska Panhandle by the weekend with increasing chances for wetting rains. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...CW SHORT TERM...GCC LONG TERM...GCC AVIATION...REC FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Wichita KS
650 PM CDT Mon Jul 8 2019 .SHORT TERM...(This evening through Thursday night) Issued at 314 PM CDT Mon Jul 8 2019 Tonight: Anticipate ongoing high precipitation storms will dwindle this evening with loss of heating. Still appears probable that storms rolling off High Plains will move into central KS sometime around or just after midnight, given favorable upper support. Anticipate storms will hold together overnight given the upper diffluent and departing jet streak. The unknown is the southern extent of the storms towards daybreak, which would be further removed from upper support, but into a more moisture rich environment. Quick peek at 1800 UTC SPC HRRR looks to be in the ballpark both the rest of this afternoon and tonight. Tuesday: Think some showers/storms will probably be ongoing in the morning across Flint Hills and into southeast KS. It is possible precipitation might end in the morning, but thinking middle level warm air advection and MCV would keep it festering. It is not inconceivable that precipitation could linger/expand back across central KS in the morning with middle level warm air advection. With additional heating in the afternoon and plenty of moisture, think storms will either develop or increase in the afternoon, aided by outflow from morning storms. Tues night-Thursday: Front will likely push through sometime Tuesday night or Wednesday, with a fair amount of slop on timing between various models. Odds likely favor slower arrival if storms are less organized Tuesday night. Kept small chances going in southeast KS Tuesday night ahead of front. Drier air supposedly filters in during the day Wednesday. Still not entirely convinced that Wednesday will be completely dry - thinking slower frontal passage is more likely, but consensus dictated a dry forecast on Wednesday. Expansive surface high pressure will cover the area later Wednesday through Thursday. .LONG TERM...(Friday through Monday) Issued at 314 PM CDT Mon Jul 8 2019 Weak return flow develops on Friday, with a slow increase in low level moisture. Rising upper heights also signals an increase in temperatures. There is an outside chance of isolated storms Sunday afternoon in southeast KS and then again Monday, but chances were too low to include at this point. Of note, ECMWF still shows remnants of tropical system approaching area late Monday. -Howerton && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 644 PM CDT Mon Jul 8 2019 Main forecast concern will be storm chances tonight. Storms that developed late this afternoon have pushed north and convection over southeast KS is slowly pushing southeast. Next chance for storms will come as the activity over the High Plains works east tonight. Current thinking is that areas generally north of Highway 50 will have the best chance to be affected generally around or shortly after 06z, with strong winds being the main threat. This activity should also push outflow south, which should temporary flip winds around to the northeast. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 72 93 74 92 / 20 10 10 10 Hutchinson 71 93 72 91 / 30 10 10 10 Newton 71 92 72 90 / 30 20 10 10 ElDorado 72 91 73 90 / 20 20 20 10 Winfield-KWLD 72 91 73 92 / 20 10 20 10 Russell 66 94 68 89 / 70 10 10 0 Great Bend 67 93 69 90 / 50 10 10 0 Salina 70 93 71 90 / 60 20 10 10 McPherson 70 92 71 90 / 40 20 10 10 Coffeyville 73 91 74 94 / 40 20 30 10 Chanute 72 90 74 92 / 30 30 20 10 Iola 72 90 74 92 / 30 30 20 10 Parsons-KPPF 73 90 74 93 / 30 20 20 10 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...PJH LONG TERM...PJH AVIATION...RBL
Area Forecast Discussion
National Weather Service Key West FL
1039 PM EDT Mon Jul 8 2019 .DISCUSSION... Temperatures this evening are already near forecast overnight lows, but they shouldn`t fall much more as light south to southwest winds have developed and will persist overnight. Boca Chica is the warm spot of the Keys recording 85 degrees at 10 PM, with Big Pine Key the cool spot clocking in at 79 degrees. Mid 70`s dew points are found all across the Keys and coastal waters. Radar returns have dropped off substantially this evening, with a very distinct dry area aloft (800-550 mb) on the evening sounding. This area is capped off by an impressive inversion around 500 mb, where there is very little adiabatic cooling for a depth of about 4000 ft. These features are in good agreement with the lack of convection that we are seeing. Upper-level cloud cover is still plentiful, with northerlies near the jet stream level continuing to transport thunderstorm exhaust from our north over the region. Concerning the forecast, the primary change from the afternoon package was to lower PoPs for much of the overnight period. Short term high resolution CAMs are in great agreement with MOS guidance in continuing this lull in precipitation until the early morning hours. As the atmosphere recovers from earlier convection, we are still in a prime area of upper-level support as lobes of vorticity pivot around the area of troughiness wedged between ridges to our east and west. Southwesterly transport of moisture in the low- levels will be the main catalyst to prime the atmosphere for new convective initiation. The HRRR paints a picture of localized convergence across the island chain sparking the development of scattered showers and eventually thunderstorms after dawn. The rest of the forecast is on track. && .MARINE... Light to gentle south to southwest breezes can be expected across the coastal waters of the Florida Keys tonight. Although formation of a tropical system is becoming increasingly likely in the northeastern Gulf of Mexico later this week, the Keys will remain on the periphery with no significant impacts other than increased chances for showers and thunderstorms. && .AVIATION... A cyclonic low-level envelope is in place across Florida, with the apex extending south of the Upper Keys. Long duration satellite and radar loops reveal storm motion in line with the cyclonic envelope. This evening`s KKEY 00Z RAOB sampled a distinct drop in TPW compared to 12 hours ago. Of particular note, extremely dry air near 700 mb, corroborated by composite 700-500 LPW satellite products. Moisture recovering south to southwesterly BL winds should develop overnight and showers are included in the vicinity of both terminals after 10Z. Statistical guidance once again agrees with our assessment of thunder chances after 15Z. Prepare for spells of MVFR CIGS/IFR VIS and convective wind gusts near 20 knots. Similar to today, a distinct stable/dry period is expected after the storms. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...WLC Aviation/Nowcasts....CLR Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service North Platte NE
642 PM CDT Mon Jul 8 2019 .SHORT TERM...(This evening through Tuesday night) Issued at 118 PM CDT Mon Jul 8 2019 MCV is tracking northeast across southwest and south central Nebraska this afternoon. Lift enhanced by the MCV is helping to regenerate thunderstorm development across southwest Nebraska. In addition to the MCV, large scale ascent is overspreading the area as an upper trough approaches from the west. Storms should continue to develop near the MCV late this afternoon and evening, with additional thunderstorms forming across the western High Plains as the upper trough approaches. PWATS are quite high, ranging from 1.3 to 1.5 inches across the region. Heavy rainfall can be expected with the thunderstorm activity this evening. There is a lesser threat for severe storms with weak shear and mid-level lapse rates around 6.5 C/km likely limiting the potential. The main severe threat would be from strong outflow winds. The area most prone to see heavy rainfall will be across portions of southwest Nebraska, where storms will be most persistent due to the remnant MCV. The upper trough tracks eastward across the Central and Northern Plains Tuesday. This will result in a surface low developing across North Dakota. A cold front will develop southwest from the low and track into northwest Nebraska during the late afternoon hours. Isolated thunderstorm development is possible along the front. CAPE looks less than previous days but overall shear is stronger. Appears that even though coverage will be isolated, shear supports the potential for a supercell, and 12Z HRRR supports this scenario and tracks a strong cell across Sheridan into Cherry county. Otherwise expect a warm up ahead of the front...with highs nearing 90 across portions of southwest Nebraska. Mid to upper 80s can be expected elsewhere. .LONG TERM...(Wednesday through Monday) Issued at 118 PM CDT Mon Jul 8 2019 Warmer and drier weather is expected by the middle and end of the work week. The GEFS and ECMWF build upper level ridging into the four corners region and much of the Central and Southern Plains. This will spread a warm layer aloft across the region which will limit rain chances. The upper ridge will flatten just a bit Friday night into the weekend, which will allow for a couple of weak disturbances to migrate eastward across the area on the northern periphery of the ridge. Isolated to scattered thunderstorm chances will return as a result. Above normal temperatures are expected with highs climbing into the lower 90s Thursday into the weekend. Climate Prediction Center is forecasting above normal temperatures and below normal precipitation for both the 6 to 10 and 8 to 14 day outlook - a first for this Summer. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 637 PM CDT Mon Jul 8 2019 Scattered thunderstorms this evening into the overnight across western, southwest and north central Nebraska. Thunderstorms should move out of the forecast area after 2am continuing into central and eastern Nebraska. Skies should clear tomorrow morning with VFR conditions. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Taylor LONG TERM...Taylor AVIATION...Gomez
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
540 PM CDT Mon Jul 8 2019 .SHORT TERM... 241 PM CDT Through Tuesday... There are no significant concerns in the forecast through Tuesday afternoon. Main item of note continues to be lingering haze from wildfire smoke. HRRR experimental smoke fields show decreasing concentration this evening into the overnight, so will carry definite haze mention through mid evening. Area web cams indicate that most visibility is 6+ miles in the haze, though possibly locally around 4-5 miles. Suspect that the 2-3 mile visibility being reported as of 2pm hour at DuPage Airport (DPA), Aurora Airport (ARR) and Schaumburg Airport (06C) is overdone considering FAA observers carrying 10 mile visibility at ORD and MDW. Winds will be light easterly to calm/variable tonight, and with dew points mixing out this afternoon along with clear skies tonight, expecting lows in the upper 50s to lower 60s outside of Chicago tonight (locally mid 50s near WI state line). Mid 60s will be the rule in/near downtown Chicago. On Tuesday, we`ll start to lose influence of departing surface high pressure, as winds turn southeast/south-southeast synoptically. Gradient will certainly remain weak enough for a lake breeze to form and push inland, much farther so into Illinois than northwest Indiana due to southeast synoptic component. Warming thermal profiles will support highs in the 84-88 range, including northwest Indiana near the lake prior to lake breeze passage. The Illinois shore will top out in the mid to upper 70s. There will be increasing high cloud cover through the afternoon. Regarding humidity on Tuesday, lingering dry air aloft and mixing into this should support dew points topping out in upper 50s-low 60s northeast IL and NW IN. With higher Td not far away to our south, increasing southerly flow should increase dew points into mid to upper 60s well inland in Illinois, making it a bit more uncomfortable there during the afternoon. Castro && .LONG TERM... 312 PM CDT Tuesday night and Wednesday... A shortwave trough is projected to eject northeastward out ahead of a larger mid-level trough that will move into the upper Great Plains on Tuesday. This shortwave trough should have enough forcing associated with it to generate convection over portions of Iowa and Missouri on Tuesday night that should slowly decay overnight into Wednesday morning as it works its way eastward into a stabilized environment across northern Illinois. Depending on how much this initial period of clouds/showers influences the atmospheric conditions near the surface, a threat of severe weather may exist later in the day. In the wake of this shortwave trough, a cold front associated a surface low working its way across Lake Superior will pass through the CWA sometime late Wednesday afternoon/early Wednesday evening. Surface heating throughout the day is expected to destabilize the boundary layer in the thermal ridge out ahead of the cold front with temperatures expected to rise into the low 90s and heat indices possibly breaching the 100 degree threshold. This heating will lead to large CAPE values, possibly in excess of 3000 J/kg in some areas. This large amount of instability, coupled with pre-frontal moisture advection and effective bulk shear values approaching 40 kts will create an environment that will be conditionally favorable for severe storms with large hail and damaging winds to fire up along the aforementioned cold front in the late afternoon/early evening. However, some uncertainty remains with the location and timing of the development of the initial convection, as models disagree over the timing of the frontal passage and the amount of influence the earlier convection will have. While most models are supportive of storm formation over southern Wisconsin and northern Illinois in the late afternoon/early evening, some guidance suggests that the cold front may pass through earlier in the afternoon, preventing the atmosphere from destabilizing enough in time for storms to develop over northern Illinois, instead favoring storm initiation over northern Indiana. In addition, the main core of forcing for ascent looks to remain displaced immediately to our north. However, hodographs suggest that any initial storms that develop may initially be discrete and supercellular before clustering and becoming more linear over time. The main window for a severe potential seems to be during the late afternoon into the early-evening hours on Wednesday. Ogorek Wednesday night through Monday... A noticeably drier and somewhat cooler airmass will descend upon the region Wednesday evening and into Thursday in the wake of evening storms and the attendant cold front. Thursday is shaping up to be a pretty fantastic day featuring high temperatures either side of 80 degrees with dewpoints which will probably mix out into the upper 50s and lower 60s. Combined with a slight northwest breeze (which will likely turn out of the north or northeast in the afternoon near the lakeshore), can`t do much better in the middle of July. As the spine of a surface ridge builds across the region on Friday, moisture will begin to creep upwards once again, however, with dewpoints in the upper 60s and lower 70s looking like they`ll return through the afternoon hours. The heat and humidity will only build from there into the weekend, with afternoon heat indices looking like they`ll once again make a run into the mid and upper 90s across much of the region. The core of the subtropical high will begin to build northward Friday and through the weekend, settling across the Four Corners region and into the Central Great Plains. As this occurs, we`ll be located at the southern terminus of stronger northwesterly flow aloft. Global model guidance hints at an initial mid-level perturbation possibly drifting towards the region either late Friday night or into Saturday afternoon. The presence of strengthening 500 mb flow (40-45 kts), steepening mid-level lapse rates at the edge of an expanding EML plume, and increasing moisture in the 700-500 mb layer supports some potential for elevated convection. This might occur across portions of northern Iowa or southern Minnesota late Friday night and into Saturday morning at the nose of a strengthening low-level jet. Should storms develop, there`s a non-zero potential this activity could congeal into a complex and press into our northern zones into Saturday afternoon. Obviously a low confidence forecast, but opted to throw in some low storm chances mainly near and north of I-80 to account for this potential. We`ll remain in a pattern supportive for showers and storms into Sunday, although confidence in this remains too low to warrant any explicit precipitation mention at this juncture. Carlaw && .AVIATION... For the 00Z TAFs... Only forecast points of interest during this 00Z TAF cycle are: - Possible smoke impacts on visibility tonight and early Tuesday morning - Likely lake breeze passage at ORD and MDW Tuesday afternoon High pressure is centered over Michigan early this evening and trapped within this light low to mid-level flow is smoke originating from central Canadian fires. This smoke has provided a milky white appearance to the sky as far south as the I-80 corridor in Illinois, and has resulted in a few northern Illinois sites reporting 2-5 SM visibility. ORD and MDW have not been two of those sites but it is possible tonight if some of this smoke settles below the developing inversion. Also outlying airports such as DPA and RFD that are reporting 3-5 SM already as of 23Z could drop solidly into IFR visibility tonight if indeed the smoke does settle lower. For Tuesday, southeast winds will gradually increase, at times possibly near due south, topping out near 10 kt. A lake breeze will develop and there is medium-high confidence in this easterly wind shift reaching ORD and MDW. Timing of this shift in the current TAF has medium confidence. MTF && .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...Updated Aviation
National Weather Service Saint Louis MO
1019 PM CDT Mon Jul 8 2019 .SHORT TERM... (Through Late Tuesday Afternoon) Issued at 942 PM CDT Mon Jul 8 2019 Quiet weather is occurring across the CWA with isolated thunderstorms staying near the stationary front over far southern Missouri into eastern Kansas. Will maintain a dry forecast until late tonight when latest RAP runs continue to show weak low level moisture convergence over central Missouri which supports going isolated thunderstorms. Going low forecasts look good. Britt .LONG TERM... (Wednesday through Next Monday) Issued at 330 PM CDT Mon Jul 8 2019 The greatest weather impacts and threat potential resides on Wednesday and there continues to be a fair amount of uncertainty in some of the specifics, especially with regards to heat. The concern is that clouds and/or ongoing showers and thunderstorms on Wednesday morning could hamper heating. Basically kept close to the previous forecast for both heat and thunderstorm chances. The upper level trof currently in the Pacific Northwest will migrate eastward through the upper-mid MS Valley and into the Great Lakes on Wednesday into Wednesday evening sending a cold front and accompanying pre-frontal trof through the area on Wednesday afternoon and evening. Summer heat and humidity will be back provide the morning cloud/precipitation scenario is at a minimum. Afternoon temperatures in the upper 80s and lower 90s will contribute to SBCAPE of 4000-5000 j/kg and little CIN. The advancing boundaries should be able to initiate scattered thunderstorms, with deep layer shear in the 20-30 kt range favoring multicell modes. The combo of shear and instability would suggest a few severe storms would be possible per the latest SPC day3 outlooks with damaging winds and large hail the primary threat. We are still anticipating heat index values of 100-105 across portions of east central MO and southwest IL centered on metro St. Louis, and ultimately a heat advisory may be necessary. It still looks like we finally see a respite from the heat and especially humidity in the wake of the front on Thursday-Friday with northwest flow aloft and controlling surface high pressure. However model consensus shows that by the weekend an upper high/ridge will build and elongate from the southern Rockies eastward into the MS Valley bringing a return of the heat and eventually humidity. Glass && .AVIATION... (For the 06z TAFs through 06z Tuesday Night) Issued at 1013 PM CDT Mon Jul 8 2019 Dry and VFR conditions are expected to continue through late tonight before a isolated thunderstorms move into central Missouri which will affect KCOU. The chance of thunderstorms will spread east and increase during the morning affecting KUIN and the St. Louis area terminals by 18Z. The chance of thunderstorms will continue at all of the terminals through 00Z with MVFR/possible IFR ceilings and visibilities. Scattered thunderstorms will then be confined to parts of central and northeast Missouri as well as west central Illinois including COU and UIN after 00Z. SPECIFICS FOR KSTL: Mainly dry and VFR conditions are expected through 18Z Tuesday. The chance of thunderstorms will continue until 00Z with MVFR/possible IFR ceilings and visibilities. Winds will remain light through the period. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
753 PM EDT Mon Jul 8 2019 .SHORT TERM...(This evening through Tuesday) Issued at 235 PM EDT MON JUL 8 2019 Per RAP analysis, broad surface high pressure centered over the Upper Great Lakes has been nearly stationary. Satellite imagery continues to show a broad area of elevated smoke, thicker over the south-central than elsewhere. Diurnal cumulus has developed this afternoon in Gogebic and Ontonagon Counties where the smoke has generally cleared. The HRRR-smoke runs today have consistently indicated more low level smoke over the east half, and this is supported by reduced visibility to 5-8SM at KSAW and KERY at times this afternoon. However, reduced visibility has also been reported at KCMX, in Baraga County and at KIMT as well, so perhaps the model is underdoing low level smoke over the central and west. Regardless, afternoon temperatures have risen into the 75-83 degree range inland, lowest south-central where the smoke layer is thickest. Lakeside locations remain in the upper 60s. As high pressure slowly moves off to the east, surface low pressure crossing North Dakota will bring a slight increase to gradient southerlies and southwesterlies at low to mid levels over Upper Michigan. This should aid in dispersing the smoke, and as such it is expected to gradually thin out from west to east overnight into Tuesday. Lows will fall into the 50s for most, with some lower 60s far west and a cold spot or two inland falling to around 49. Some smaller concentrations of smoke are likely to still be floating around tomorrow but will not be as ubiquitous or have as much of an affect on temperatures. Early indications are that it will remain thicker over the east and perhaps wrap around to the far west as well, but given the HRRR-smoke didn`t have the best handle on it today, have opted to hold off on adding smoke to the forecast after 12Z tomorrow. With more modest southerly flow, highs should easily reach the 80s except for in locations near Lake Michigan and a few spots right along the shores of Lake Superior like Grand Marais and Copper Harbor. Clouds should begin to move in from the west during the evening hours, but we are expected to remain dry though this forecast period. .LONG TERM...(Tuesday night through Monday) Issued at 326 PM EDT MON JUL 8 2019 The long-term starts with an amplifying upper-level short wave over the Northern Plains and WAA out ahead of it over the Upper Great Lakes. Models depict enough moisture convergence and isentropic lift with the warm front for showers Tuesday night, mainly across the west and perhaps making it to the central U.P. by Wednesday morning. The NAM shows just enough elevated CAPE that there could be a rumble of thunder with these showers, but most of the destabilization is behind the front so have kept capped thunder chances at slight for now. The main story this week will be the potential for strong to severe thunderstorms on Wednesday as the aforementioned short wave moves closer. As far as potential severe wx setups go in this part of the country, the model solutions over the past two days have been remarkably consistent. The GFS, NAM, EC, etc. all march the short wave currently over the Pac NW eastward across the northern tier of the U.S. tonight and tomorrow, to be overhead late Wednesday. Out ahead of the associated cold front, warm moist southerly flow allows modeled surface based CAPE values to rise to as high as 4000 J/kg. Even with surface dew points probably overdone by a few degrees, and assuming a bit more mixing, still looking at MLCAPE AOA 2000 J/kg and MLLCLs < 1000 m. Seasonally strong mid-level flow through this short wave means effective shear of anywhere from 35 to as high as 50 knots, which given the aforementioned buoyancy, would support supercells along the cold front. Any limiting factors? Yes, plenty. Given lack of a well-defined EML in most (but not all) model solutions over the past couple of days, and thus mid-level lapse rates that are a not-so-impressive 5.5 to 6.5 K/km, think severe hail will be less of a concern than severe wind gusts - though that is not to say the most robust storms couldn`t still support a few isolated instances of severe hail. Timing is also a factor. The front looks to race across Upper Michigan from west to east in as little as 9 hours, so a difference of just a couple hours in FROPA timing could force it through too quickly before diurnal instability builds, or too late after it has already waned. Also, southerly surface flow off Lake Michigan will stabilize the low levels over the east, forcing storms to go elevated there and thus reducing the severe weather risk. Could also end up with too much cloud debris from morning showers and not realize all of the instability that`s modeled. To summarize... Wednesday looks like the best severe weather setup we`ve seen in our area so far this year (though that`s not saying much), but it`s not without its caveats. For now, the best advice is simply to continue watching. One last note, given fat CAPE profiles and seasonally fast storm motions, do not expect flash flooding to be a concern except perhaps in very isolated pockets. Now for the rest of the long-term... Thursday looks cool and comfortable behind the cold front with 850 mb temps dropping to about 10 C and thus highs should stay in the upper 70s inland and in the 60s along Lake Superior given NW surface flow. With cooler air aloft, should mix down enough wind for 20-30 mph gusts Thursday both on land and on the water. WAA returns Friday and 850 temps quickly climb back to 15-17 C, so will likely see highs back in the mid to upper 80s away from Superior Friday. Models also bring another short wave/cold front through and show enough shear/instability for another round of thunderstorms, though obviously this is less certain simply given how far out in time it is. Given right now this looks like an overall weaker system, the amount of cooling behind the front looks less than what`s expected Thursday. Therefore, looks like we stay in the 80s for the weekend (inland). Though still far out, fairly good model consensus right now that next week will be hot. With 850 temps climbing to 20-22 C (gross!) could see highs near 90 with enough sunshine, or at least 80s and high humidity. Hey, at least it`s not fire weather. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 753 PM EDT MON JUL 8 2019 Although high pres will be drifting e away from the area tonight and Tue, a dry air mass will linger, allowing for VFR conditions at KIWD/KCMX/KSAW thru this fcst period. Only exception will be smoke from Canadian wildfires that mixed down sufficiently to lead to some vis restriction today. An MVFR vis may continue at KSAW this evening. Otherwise, the elevated smoke layer will gradually thin out over the next 24hrs. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 235 PM EDT MON JUL 8 2019 Winds under 20 knots are expected to prevail through Tuesday as high pressure moves overhead. There is a chance for a brief period of 20- 25 knot winds Tuesday night over the central lake. A cold front will pass through on Wednesday night and winds may increase to 25 knots behind it over all zones except 162 and 263. Expect these elevated winds to persist into Thursday. Through the end of the week into early parts of next weekend, winds will again remain below 20 knots. Some fog is also a good bet Wednesday given the warmer moister air moving in and showers moving across the lake, but exactly where and how dense is still uncertain. Whatever does form Wednesday should dissipate by midday Thursday given the amount of wind behind the cold front. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...KCW LONG TERM...RJC AVIATION...Rolfson MARINE...KCW/RJC
Area Forecast Discussion
National Weather Service Pueblo CO
336 PM MDT Mon Jul 8 2019 .SHORT TERM...(This evening through Tuesday) Issued at 336 PM MDT Mon Jul 8 2019 Currently...Shortwave in the southwest flow aloft was tracking across the state, tapping into the available moisture for isolated convection across the forecast area. Temps have warmed into the 70s for the high valleys as of 3 pm, and into the 80s to lower 90s for the plains. Tonight and Tomorrow...Latest HRRR model runs have a fairly decent handle on current convection, and indicate that activity will persist along the I-25 corridor until around 6 pm, then quickly exit across the eastern plains between 8 and 9 pm. This is due to the upper shortwave exiting the region, then as the upper trough crosses the northern Rockies flow aloft becomes westerly. This westerly flow will dry out the forecast area overnight through tomorrow, making for mostly clear skies overnight and plenty of sun tomorrow. The Marginal area for severe weather is still in place across the far eastern plains, and with higher available precipitable water amounts across the east, storms developing over or moving into Kiowa, Bent and Prowers Counties will still need to be watched closely through the early evening. Clearing skies tonight will allow temps to drop into the upper 30s to mid 40s for the high valleys, and 50s to near 60F for the plains. Max temps tomorrow will heat up into the 80s for the high valleys, and upper 80s to mid 90s for the plains. Moore .LONG TERM...(Tuesday night through Monday) Issued at 336 PM MDT Mon Jul 8 2019 Initially, basically dry meteorological conditions are expected from Tuesday evening into early Wednesday afternoon as supported by projected Interstate 25 precipitable water values dropping form over 1 inch today(Monday) to under 0.70 inches in combination with healthy upper ridging building over southern Colorado during this time-frame. In addition, cooler maximum temperatures are expected Wednesday afternoon in the wake of a dry northerly surface surge moving across eastern locations Tuesday night. Upper ridging is then expected to remain anchored over southern Colorado and northern New Mexico from later Wednesday into next Monday, allowing near to above seasonal early to mid July temperatures to prevail over the CWA during the period. In addition, increased projected precipitable water values from Wednesday afternoon into Friday and especially from this weekend into possibly next Monday in combination with the diurnal heating cycle and passing generally weak upper disturbances will allow for increasing precipitation chances, favoring this weekend into possibly next Monday(where an elevated potential for locally heavy rainfall and associated primarily recent burn scar flash flood risks may occur if recent trends continue). Finally, latest longer range forecast model soundings and computer simulations continue to signal that generally low-grade gradient winds should be noted over the majority of the CWA during the balance of the longer term. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 336 PM MDT Mon Jul 8 2019 VFR conditions expected across much of the forecast area over the next 24 hrs, including the three main TAF sites of KCOS, KPUB and KALS. Showers and storms have developed across the forecast area this afternoon and may affect TAF sites through 00z this eve, with all activity forecast to exit the plains between 02z-03z. Conditions may become MVFR to at times IFR under heavier showers and storms. Clearing skies then tonight, with mostly clear conditions overnight and tomorrow morning. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$