Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/17/19

Area Forecast Discussion
National Weather Service Bismarck ND
935 PM CDT Tue Apr 16 2019 .UPDATE... Issued at 931 PM CDT Tue Apr 16 2019 No big changes with this update. Forcing will increase across central North Dakota late this evening into early Wed morning as a mid level wave moves towards the ND/MT border, and as a sfc trough now over eastern Montana pushes east. Forcing will also be enhanced farther east as upper level jet dynamics (right entrance region) moves east from my southwest into the central. UPDATE Issued at 631 PM CDT Tue Apr 16 2019 Area of light to moderate rain showers continues over the southwest and far south central, slowly developing to the east and slightly north. Rain encountering a dry low level atmosphere across portions of the south central so there is a delay in the rainfall some locations, including here at Bismarck. T/Td spread decreasing the past couple of hours so should see rain picking up for these locations over the next few hours as we saturate better. Overall the forecast for this evening/overnight remains in good shape, with the only edits delaying the onset of showers a tad. Thunderstorms over far northeast Wyoming/far southeast Montana transitioning to showers as they move north and encounter more stable air so will keep thunder out of the forecast. && .SHORT TERM...(This evening through Wednesday night) Issued at 355 PM CDT Tue Apr 16 2019 Through the rest of today and into tonight, we will transition from near zonal to southwest flow aloft as a low amplitude shortwave trough approaches from the west. Ahead of this wave, temperatures have warmed quickly through the early part of the day as some sites in the southwest and south central observed 3-hour surface temperature changes of 15 to 25 degrees late this morning. At the surface, an inverted surface trough is extending north into eastern Montana from a developing low over eastern Wyoming. This trough will be the focus of showers and a few isolated thunderstorms through Wednesday. 20 UTC RAP mesoanalysis shows that very steep low-level lapse rates have developed along and north of the precipitation/cloud shield currently spreading across the southwest. In these areas mid-level lapse rates are fairly meager but will steepen at least modestly as the wave continues to approach, bringing with it colder temperatures aloft. The latest HRRR and RAP iterations show these favorable lapse rate areas may begin to slightly overlap late this afternoon and through the overnight, suggesting an arc of potential MUCAPE in the range of 100 to 200 J/kg along the leading edge of the precipitation. While rain showers appear to be the primary convective activity as precip chances spread north and east, a few rumbles of thunder can`t be ruled out with some elevated instability floating around, but confidence is not high enough to include mention in the forecast yet. The leading wave passes quickly to our east by early Wednesday afternoon and another wave rides down an amplifying ridge to our west, providing the focus for widely scattered showers and isolated thunderstorms during the afternoon and evening. Instability will once again be meager (~250 to 500 J/kg MUCAPE) but appears to be a bit more favorable for thunder. With the setting sun and loss of daytime heating, showers and thunderstorms will likely diminish rather quickly Wednesday night. .LONG TERM...(Thursday through Tuesday) Issued at 355 PM CDT Tue Apr 16 2019 As the upper-level ridge continues to move into the state behind the departing trough, there is a chance for showers and thunderstorms Thursday during the day associated with a low-level convergence zone. 300-400 J/kg of CAPE is possible, and combined with daytime heating could be enough for some brief thunderstorms in central ND. As this clears out, an upper-level ridge will develop and bring a surge of warm temperatures. Current highs on Friday are in the low 70s, but these are on the low end of the ECM MOS guidance. Left them where they are for now, but we`ve been chasing high temperatures the past few days so these could be bumped up a few degrees if the multi-model blends do not raise them in the next few runs. A cold front is forecast to move through on Saturday, with the main forecast struggle being timing. The 12Z GFS has it moving through central ND around 15Z, while 12Z Euro is closer to 18z. As these details are ironed out, a better picture of the sensible weather fields should come into focus. Behind the front, cooler and drier conditions are expected for the remainder of the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 631 PM CDT Tue Apr 16 2019 Rain will continue for KDIK and develop into KBIS this evening, then eventually other terminals tonight. Decreasing ceilings as well, to MVFR/IFR and MVFR visibility tonight. Improving conditions after 18Z Wednesday for all but KJMS. Isolated thunderstorms will then be possible late Wed aft/Wed evening over western North Dakota (KISN-KDIK). && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...NH SHORT TERM...ZH LONG TERM...MJ AVIATION...NH
Area Forecast Discussion
National Weather Service Cheyenne WY
526 PM MDT Tue Apr 16 2019 .SHORT TERM...(This evening through Thursday) Issued at 330 PM MDT Tue Apr 16 2019 Scattered thunderstorms are beginning to develop across southeast Wyoming and will continue to do so this afternoon. These storms will move into the Nebraska Panhandle early this evening and will last until about 06Z Wednesday. High resolution guidance shows thunderstorms initiating east of the Laramie Range where RAP analysis CAPE of around 500 J/kg exists near a weak frontal boundary and 0-6 km bulk shear around 40 kts. These storms will bring slightly heavier rainfall amounts than the storms the past few days, however they should still remain sub-severe. Isolated showers have developed west of the Laramie Range and will continue through Wednesday morning while light snow showers are possible above 8000 feet in the Snowy and Sierra Madres. Strong winds are in-store Wednesday behind the cold front as Tuesday`s disturbance pushes east. Sustained winds out of the northwest will reach 25 MPH, especially in the Nebraska Panhandle. Besides light snow showers in the mountains, most of the area should see sky`s clearing Wednesday as an upper level ridge builds in bringing drier and warmer conditions through week`s end. .LONG TERM...(Friday through Tuesday) Issued at 258 PM MDT Tue Apr 16 2019 Friday...Rather impressive ridging aloft moves over Wyoming, producing a dry and quite mild end to the workweek with 700 mb temperatures near 6 Celsius yielding maximum temperatures from the 60s to middle 70s. Saturday...Another mild day expected as the flow aloft turns west southwest with the ridge flattening. With adequate low and mid level moisture, we may see some showers over and near the Snowy, Sierra Madre and Northern Laramie Ranges in the afternoon. Sunday...The next potent shortwave trough aloft approaches from Utah and with a cold frontal passage and adequate moisture, we expect cooler and cloudy conditions with scattered showers. Monday...The cooler and unsettled weather pattern continues with a trough aloft over our counties and adequate low and mid level moisture along with low level upslope east and southeast winds producing a chance of showers. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 524 PM MDT Tue Apr 16 2019 VFR to MVFR conditions are expected at all terminals this period. A cold front sliding down from the Northwest will trigger scattered showers and storms this afternoon and evening. SCT to BKN mid decks will develop overnight and this morning with MVFR CIGS. Visibility should remain high but patchy fog cannot be ruled out. MVFR to VFR conditions are expected for more terminals tomorrow. && .FIRE WEATHER... Issued at 330 AM MDT Tue Apr 16 2019 Unsettled weather to continue through the early part of this week as low pressure remains over the area. Will see chances for wetting rains and mountain snow tonight into Wednesday morning as low pressure tracks across the area. Drier weather for Thursday through Saturday with afternoon humidity falling to the low 20 percent range. Another cold front Saturday afternoon/evening will bring increasing chances for wetting rains and mountain snow. weather issues are minimal. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MB LONG TERM...RUBIN AVIATION...AL FIRE WEATHER...GCC
National Weather Service Sioux Falls SD
655 PM CDT Tue Apr 16 2019 .SHORT TERM...(This Evening through Wednesday) Issued at 410 PM CDT Tue Apr 16 2019 Primary concern the next 24 h is the thunderstorm chances. All models agree on the overall set up later tonight. Strong warm air and moisture advection around 1 km AGL will result in an increasingly unstable atmosphere - especially along and east of I-29. An weak upper wave will move north later tonight in an area where 1 km moisture convergence will be greatest. HRRR, RAP, NAM and GFS model soundings all show that initially there is a fairly strong cap around 700 mb but this cap is gradually eroded after 06Z as the unstable layer and area of convergence move northward. The model differences and largest uncertainty is where and when convection will develop later tonight as well as how widespread convection will be. One consistent message is that around 06Z near KSUX there is ~1000 J/kg MUCAPE but CIN of 50-100. At KFSD around 11Z there is similar MUCAPE but < 10 J/kg CIN. While we cannot rule out convection at KSUX the most likely area for development is in the vicinity of I-90 from far eastern SD into southern Minnesota. Bulk shear is only 20-25 kts so expect elevated multicellular convection. However, the initial updrafts may be strong enough to support up to dime size hail late tonight. As more updrafts develop north of I-90, the instability will decrease and storms should produce primarily rain Wednesday morning as they move north toward Highway 14. Expect additional development of showers on the southern side of the precipitation shield. This will keep rain over much of southwestern Minnesota and portions of east central South Dakota much of the morning and this is where we have categorical PoPs. The region from Sioux Falls to Spencer Iowa seems to be where new showers will be developing at least through midmorning before shifting north. Farther south toward YKN and SUX, while showers cannot be ruled out with continued instability, a capping inversion is likely to result in little precipitation in the morning. On Wednesday afternoon, the surface low will move eastward from the Missouri River into north central Iowa. It will remain unstable ahead of the cold front. The southern jet streak will move northward in the afternoon with enhanced divergence aloft in the exit region. This is expected to result in convection developing by early afternoon along the boundary. The GFS, ECMWF, RAP and HRRR have pushed this front east more rapidly with the initial cells developing near Highway 71 or even farther east. Did extend likely PoPs along Hwy 71 during the early afternoon for this convection with only chance PoPs around KSUX and KFSD. Convection will be east of the area by late afternoon and the persistent rain is expected to be north and east of the area by evening. West of I-29, the chances of precipitation are less. There is less instability and weaker advection. The northern stream jet streak is expected to move northeast into North Dakota. This leaves little forcing for ascent in south central South Dakota and there is likely to be little or no rain. North of I-90, around KHON and KMDS, there will be better forcing for ascent but instability is still very limited. So while rain is more likely - especially in the morning - it will be fairly light. The highest QPF, up to 0.75", is expected in southwestern Minnesota where there is expected to be a few thunderstorms and more persistent rainfall. Rainfall decreases going going farther west and south into South Dakota and Iowa. .LONG TERM...(Wednesday Night through Tuesday) Issued at 410 PM CDT Tue Apr 16 2019 The primary concern in the long term is the low chance for rain Thursday and then warm up for Saturday. Any precipitation is expected to end by late evening on Wednesday. Another jet streak and associated wave will move south out of Canada Thursday. With cool air aloft, a few afternoon and evening showers are possible west of I-29. These showers should quickly dissipate after sunset. Then a ridge will build across the area for Thursday and Friday. Friday looks to be a near or just above normal - in the 60s to around 70. Saturday looks to be the warmest day of the year so far. A thermal ridge will develop just ahead of a cold front which will move through during the afternoon and evening. With 925 mb temperature around +20C, this would mix well into the 70s. In fact with brown vegetation and enhanced mixing near the front, fairly deep mixing is possible with a few places approaching or even exceeding 80 degrees. After the cold front goes through normal April weather will return with highs in the 50s and 60s. There will also be a small chance for rain on Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 643 PM CDT Tue Apr 16 2019 Difficult aviation forecast warm air advection and weak wave later tonight leading to scattered convection. Best chances for thunderstorms mainly looks to be between 06-18Z Wednesday. Could see some lower ceilings develop as convection/boundary move through the area. MVFR to IFR ceilings will linger through the daylight hours on Wednesday, with gusty winds possible. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...Schumacher LONG TERM...Schumacher AVIATION...BT
Area Forecast Discussion
National Weather Service Goodland KS
606 PM MDT Tue Apr 16 2019 .UPDATE... Issued at 530 PM MDT Tue Apr 16 2019 Increased rainfall chances for the northwest and northern part of the forecast area for tonight as an upper level short wave trough moves through. All near term models are showing a group or two of thunderstorms initiating over East Central Colorado and moving northeast this evening. RAP has been trending the area of elevated CAPE/lift to the southern group of storms. Current radar is beginning to show storms already. As these thunderstorms move northeast into the forecast area ahead of the upper level short wave trough, the low level jet also moves up from the south bringing moisture advection with it and higher shear/helicity. DCAPE is quite low north of the stalled weak frontal boundary along the southeast border of the forecast area, so severe wind gusts are not much of a concern. However, the enhanced helicity/low level shear, presence of a weak boundary near the western border of Kit Carson/Yuma counties, and potential absence of an inversion raise the concern for tornadic potential. Model soundings show the inversion being erased by mid evening. This could be in response to the storm activity moving through. A tornado has occurred due to the wet-bulb effect removing the inversion after midnight, but this was behind a line of training thunderstorms. Not sure if this will be one of those events since the storm activity will not be as long lasting as the event referenced, and this evening will likely be a cluster of storms, not distinct supercells following each other. Main threats will be large hail up to ping pong balls. Confidence of this occurring is on the low side, however the environmental support of this is not out of the question given the large hail parameter values and the amount of effective shear to work with. && .SHORT TERM...(This evening through Wednesday) Issued at 217 PM MDT Tue Apr 16 2019 As of 300 PM CDT, 2 PM MDT, skies across the Tri-State Region are partly cloudy to mostly clear, depending on your location and the position of the cirrus. Temperatures have climbed into the upper 60s to low 70s for many locations where clouds have cleared. Winds are southeast at 5 to 15 mph with some gusts up to 20 mph observed earlier. At the surface, a low pressure continues to deepen in far southeast Colorado. Aloft, a short wave trough is moving across northern New Mexico into southern Colorado. For the rest of today into this evening, am anticipating some thunderstorms to develop over Colorado, spreading into the forecast area. Overall, the environment isn`t terribly favorable for storms. For example, there is a decent cap over portions of the area, mainly south of the interstate. However, there is also a stalled frontal boundary in the same area which provides a localized boost in moisture and therefore instability. Further north, the forcing is stronger but the atmosphere isn`t as moist, thus limiting instability. Based on the latest forecast guidance, there should be a couple areas of thunderstorms. The first area will form on the Palmer divide, spreading northeast across NE Colorado and extreme southwest Nebraska. The second area looks to form in east central Colorado. This area will struggle with initial development due to a poor environment. However, as these storms approach the stalled front and better instability, we should see an uptick in coverage and intensity, most likely around Logan and Gove Counties in NW Kansas. As the storms spread northeast, they may be come strong with gusty winds and small hail as the primary threats. This is not an event that is one to worry about too much but it does pose the risk of a strong storm or two. For tonight, the low pressure moves northeast, exiting the region after midnight. North winds return behind the low and precipitation will diminish. Depending on where the stalled is, there may be some low stratus. During the early morning hours Wednesday, a cold front will move through. Behind the front, expect cooler weather and gusty northwest winds. Winds should gradually climb through the day with peak winds observed by mid-afternoon. No precipitation should be expected as all the instability will be south of the area. In addition, subsidence will spread in behind the departing low pressure. Am unsure on dust potential as wind speeds aren`t terribly high but it is always something to keep in mind, especially with it being somewhat drier lately. .LONG TERM...(Thursday through Tuesday) Issued at 151 PM MDT Tue Apr 16 2019 An upper trough pushes east of the region on Thursday, placing the region under northwest flow aloft as a ridge builds across the western half of the country. Dry conditions are anticipated along with gusty north to northwest winds on the backside of the low associated with this passing system. Gusts of 40 to 50 mph will be possible in the afternoon before declining in the evening. Following this disturbance, ridging progresses east, leading to warm and dry weather Friday and Saturday. A trough and cold front move into the High Plains Saturday night, breaking down the ridge and generating chances for light rain showers Saturday night through Sunday. Some spotty chances linger into Monday and Tuesday as a series of shortwaves pass through the westerly flow. Temperatures fluctuate throughout the long term period, starting with a warming trend Thursday (low 60s), Friday (70s), and Saturday (near 80 degrees). A cold front drops highs into the upper 50s/low 60s on Sunday, followed by another warming trend with highs back near 70 degrees on Tuesday. Low temperatures range mainly in the 30s and 40s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 530 PM MDT Tue Apr 16 2019 VFR conditions forecast for the TAFs. Main issue with these TAFs will be when/if the thunderstorms move near the sites. Am expecting thunderstorms to develop in the next hour or so over Eastern Colorado and move northeast. Two groups of storms may end up forming, one moving over Yuma County and nearby counties, the other southern group moving through KOEL and KHLC. At this time KGLD should be between these two groups, so confidence of thunderstorms moving in the vicinity of KGLD is not quite to moderate yet, so have left a mention out of the TAF. Timeframe for thunderstorms would be 3-5z for KGLD. As the two groups of thunderstorms move northeast, they may merge together or the northern group may expand east. Either way, confidence of thunderstorms in the vicinity of KMCK is moderate so added a mention to the TAF. In addition, there may be MVFR ceilings for the site behind the storms before the cold front move through (cold front passage around 12z). && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...RRH LONG TERM...JBH AVIATION...JTL
Area Forecast Discussion
National Weather Service Northern Indiana
639 PM EDT Tue Apr 16 2019 .SYNOPSIS... Issued at 632 PM EDT Tue Apr 16 2019 A warm front will provide a focus for shower chances overnight into Wednesday morning along and north of Route 30. Dry and mild otherwise with lows tonight ranging between the upper 40s and mid 50s. Highs on Wednesday will range between the mid 60s and mid 70s. Better chances for showers and thunderstorms arrives late Wednesday night into Thursday evening. Heavy rain and strong thunderstorms will be possible on Thursday. Chances for showers will linger into Saturday before drier air moves in and sunshine returns for Easter Sunday with mild temperatures. && .SHORT TERM...(This Evening through Wednesday) Issued at 351 PM EDT Tue Apr 16 2019 Warm front has pushed well north into MI allowing for mostly sunny skies and temps well into the 60s and eventually even 70 in a few spots. Challenges in the short term remains how far south this boundary will return tonight and shower/thunderstorms chances that may accompany it. NAM and to lesser extent HRRR both show a weak sfc reflection across central Lake Michigan, which is confirmed on surface observations, leading to some model preference shift to these 2. That being said all models force the front back south to at least the I 80/90 corridor with HRRR and NAM to between the US 30 and 24 corridors. Isentropic lift does increase tonight along the boundary with 30 kt or so low level jet settling in. Plenty of elevated instability takes shape along the front with Showalters 0 to -3 C. Low levels will still be quite dry which will likely limit coverage as well. Pulling it all together, looks like slight chance to chance pops still warranted with a rumble of thunder possible with anything that can manage to develop. Previous grids had the general idea already but did confine any pops till after 3Z and possibly well after 6Z. Warm front will attempt to work back north again on Wednesday but how far NE it makes it will be a challenge again with large difference in temps possible SW to NE with highs well into the 70s SW and maybe struggling to reach 60 far NE. Rain chances will end during the morning. && .LONG TERM...(Wednesday Night through Tuesday) Issued at 351 PM EDT Tue Apr 16 2019 No significant changes to long term as copious amounts of moisture (by mid April) standards will advect in on Thursday in advance of deep upper level trough now onshore in the western US. As noted in previous discussion not only will moisture from the Gulf of Mexico arrive but also Pacific moisture that has been caught up in the trough. PWATs will increase towards 1.5 inches to bring pockets of moderate to heavy rain mainly Thursday. QPF amounts are still on the lower side but think models will catch up with most locations seeing 1 to maybe 2 inches of rain. ESF already in place to handle these concerns. As for severe threat, something still to be monitored depending on amount of clearing and instability as well as timing/location of low and upper level jet maxes. With trough likely to slow down, precip will linger into Friday although thunder chances will end by overnight Thursday. Friday will be a raw day with highs only in the 40s to maybe lower 50s. Quick rebound though with highs back into the 50s and 60s into the weekend and next week as the next system takes aim for the start of the work week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 632 PM EDT Tue Apr 16 2019 VFR/dry conditions through this evening. A frontal boundary will dip south through KSBN at or shortly after issuance, and stall near KFWA later tonight into tomorrow morning. A few showers may develop near this feature later tonight into Wednesday morning, though chances/coverage remain too low for a shower mention at this time. Post-frontal saturation/cooling may support a trend toward high MVFR cigs at KSBN by later tonight and Wednesday morning. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Steinwedel SHORT TERM...Fisher LONG TERM...Fisher AVIATION...Steinwedel Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service North Platte NE
626 PM CDT Tue Apr 16 2019 .SHORT TERM...(This evening through Wednesday night) Issued at 328 PM CDT Tue Apr 16 2019 Two discrete areas of rainfall are in place tonight and Wednesday. The models are showing a disturbance moving off the cntl Rockies late this afternoon which should lift through swrn and ncntl Nebraska tonight and Wednesday. A second candidate area of rain forms off the low level jet tonight and lifts northeast through scntl Nebraska tonight and Wednesday morning. The two areas of rain will compete for moisture and it is possible the srn rain area will dominate. The rain forecast uses a model blend of the RAP, HRRR, GFS, NAM and HRRR plus the model blend and the previous forecast. Thunderstorm chances appear speculative as the SREF maintains less than a 15 percent chance and the RAP and NAM models show very little elevated instability. The low level jet is aimed at southeast Nebraska and this shunts the significant instability mostly south and east of swrn Nebraska. The temperature forecast uses a model blend tonight and Wednesday. The guidance blend is in place for Wednesday night. Bias correction was added to all temperature forecasts. The guidance blend is in place for winds. H850mb winds of 30 to 40 kts should support winds of 20 to 25 mph Wednesday with gusts to around 35 mph. .LONG TERM...(Thursday through Tuesday) Issued at 328 PM CDT Tue Apr 16 2019 A high amplitude ridge will build across the western US on Thursday as a upper level trough moves through the central US. This trough will enhance the chance for some light rain across the central Nebraska region on Thursday evening. For now, not anticipating any severe weather, but that can certainly change over the next day or two. Stay tuned to later forecasts for more detailed information. Beyond Thursday night, surface high pressure will build into the area with dry conditions returning. Temperatures will also continue to slowly climb through Saturday as warm air advection surges into the high plains. Highs on Saturday will be in the 70s across the entire forecast area with locations south of I-80 possibly rising into the low 80s. Rain returns on Sunday as a stronger mid-level wave develops off the Rockies and pushes eastward. Rain only lasts into Sunday night as high pressure quickly builds back by Monday morning. Temperatures return to near normal (low 60s) for the beginning of next week as colder air rushes in behind the departing disturbance. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 625 PM CDT Tue Apr 16 2019 VFR is generally expected throughout wrn and ncntl Nebraska tonight. Scattered showers and isolated thunderstorms across northeast Colorado will move northeast and mainly affect southwest into eastern portions of north central Nebraska from 02z-12z tonight. By morning, easterly winds across ncntl Nebraska are expected to produce widespread MVFR cigs as low as 1000 ft agl near and east of Valentine through Broken Bow which will hang around during the morning. There is still a chance of showers Wednesday morning across eastern portions of north central Nebraska. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...Kulik AVIATION...Roberg
Area Forecast Discussion
National Weather Service Marquette MI
758 PM EDT Tue Apr 16 2019 .SHORT TERM...(This evening through Wednesday) Issued at 412 PM EDT TUE APR 16 2019 WV imagery and RAP analysis indicated a mid/upper level trough over the western CONUS with ridging from the southeast into the Northern Plains resulting in wnw flow through the Great Lakes. At the surface, weak ridging extended through the northern Great Lakes into MN bringing light winds and mostly sunny conditions. Tonight, favorable radational cooling conditions under mostly clear skies will allow teps to drop into the lower 40s inland. However, an increase in southerly downslope flow over the west near Lake Superior should keep temps into the upper 30s. Wednesday, a shortwave trough lifting from the Central Plains to nw WI and a deepening sfc low to se MN will bring increased WAA and moisture advection toward Upper Michigan. 293k-305 isentrpoic ascent from the mid afternoon into the evening should be strong enough overcome dry se flow at the lower levels. However, model trends have been toward a later arrival of the pcpn. .LONG TERM...(Wednesday night through Tuesday) Issued at 425 PM EDT TUE APR 16 2019 Active storm track, featuring significant pcpn producing systems, that developed across the CONUS last week under a progression of shortwaves dropping se off the ne Pacific will continue this week. The third shortwave trof in the series is currently over the far western CONUS. It will reach the Mississippi Valley Thu/Fri and then slowly shift across the eastern CONUS thru the weekend. While widespread rainfall will occur across the fcst area with this system, the last 24hrs of model runs have fortunately trended downward with pcpn amounts. This downward trend is due to the trof closing off a mid-level low well se of here over the southern Appalachians early this weekend as opposed to farther n over the Ohio Valley over even southern Great Lakes as suggested by previous days model runs. Result is a shorter duration rainfall for Upper MI. Still, with widespread rainfall falling somewhere in the range of 0.5 to 1.25 inches Wed-Thu along with plenty of snow on the ground yet to melt, there will be increased concerns for minor river and stream flooding, beginning Thu and continuing thru next week under continued snow melt. See the lastest Hydrologic Outlook issued this aftn for more info on the potential of flooding. The next trof will reach the western CONUS late this week. It now appears that the flow across the CONUS next week will be more progressive and more split than it appeared yesterday. With the Upper Lakes falling under a more progressive/lower amplitude northern stream, the potential of any additional widespread significant pcpn next week has diminished significantly. The trof arriving over the western CONUS late week will shift across the area early next week, providing a chc of some light pcpn. Drier weather should following into the midweek period. As for temps, brisk northerly winds/diminishing rain on Thu will lead to cool conditions/blo normal temps. Temps will rebound Fri/Sat, rising above normal under dry weather. Many locations away from lake moderation will see high temps on Sat into the 60s, maybe well into the 60s. The more progressive regime next week may end up bringing the next front across the area on Sun. Temps on Sun will depend on the timing of this front. If slow, Sun will be another day well into the 60s. If the front is faster which is the trend, Sun will be cooler than Sat, especially so near Lake Superior. Temps will be back close to normal early next week. The main period of pcpn associated with the trof shifting e to the Mississippi Valley Thu into Fri will occur Wed aftn into Wed evening. This pcpn will be driven by fairly strong isentropic ascent in advance of lead shortwave energy lifting up across the Upper Lakes in the sw flow ahead of the trof as it moves out over the western Plains. Bulk of the rainfall will occur Wed aftn through Wed night, though pcpn will be diminishing sw to ne overnight Wed night. With general rainfall amounts of 0.5 to 1.25 inches, expect rises on streams and faster responding rivers Wed night/Thu. Some ponding of water in low-lying areas and poor drainage areas may occur as as well. With a little instability aloft, up to a couple hundred j/kg spreading across the s central and eastern fcst area, not out of the question that there could be a few rumbles of thunder s central/e. There is still a small potential that the rain could switch over to sloppy snow over the high terrain of the nw fcst area. NAM is most supportive of cooling the column just enough for a switch over to snow. Will be something to monitor. For now, will carry a rain fcst. Most of the rainfall will be done by Thu morning with departure of the isentropic ascent and arrival of some mid-level drying. However, with the mid-level trof axis still to the w to provide some forcing, expect some lingering -ra/-dz, especially where northerly wind leads to upsloping across the w and n. With a brisk wind off Lake Superior, it will be chilly across the w and n with temps only in the 30s to around 40F. Lingering -ra/-dz will gradually end from w to e Thu night, followed by clearing skies into Fri. Deep, dry air mass on Fri will support sunny skies or clearing to sunny skies where any clouds still linger to start the day. Temps will respond by rebounding into the 50s, except near Lake Superior. Stronger gradient flow across Lake Superior into the eastern fcst area will keep temps no higher than around 40F near the lake over the e. Although there will be some increase in mid/high clouds w, abundant sunshine will be the rule e on Sat. Warming will continue with highs into the 60s w. Will be cooler e, especially near the Great Lakes with a wind component off the water. 12z models have continued to trend faster with the flow progression early next week. As a result, it appears the next shortwave will push a cold front across the area on Sun. There won`t be much moisture avbl, so pcpn chc will be limited as the front crosses the area. As mentioned above, high temps on Sun will be highly dependent on timing of the front. Cooler (temps close to normal) and dry weather should follow Mon/Tue as high pres builds se into the northern Great Lakes. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 754 PM EDT TUE APR 16 2019 With ridging and dry air persisting, expect VFR conditions through this evening along with light winds. Overnight, radiational cooling along with light southeast winds could bring some fog into KSAW with MVFR and possibly IFR vsby. Confidence in the lower end of vsby is lower. Expect thickening mid clouds on Wednesday with rain developing by early evening at IWD and SAW as a low pressure system moves to southeast Minnesota and an associated warm front lifts across Wisconsin and lower Michigan. Plan on conditions deteriorating to IFR or lower in periods of rain and fog at all sites Wednesday evening into Wednesday night as the low pressure system lifts tracks toward northern lower Michigan. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 412 PM EDT TUE APR 16 2019 Light winds of less than 15 knots are expected through Wednesday morning. As low pressure approaches the region, NE winds will increase from 15 to 25 knots late Wednesday to 25 to 30 knots Wednesday night then become N and subside to around 20 knots Thursday morning. These winds persist through Friday morning then calm back below 15 knots for the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Rolfson AVIATION...JLA MARINE...JLB
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday) Issued at 340 PM CDT Tue Apr 16 2019 A severe weather threat remains on the docket for Wednesday afternoon, with large hail, damaging winds, and heavy rainfall the main threats. Several forecast challenges lead up to the severe weather event for Wednesday afternoon. The first couple of hurdles that need to be jumped are with respect to cloud cover, precipitation chances, and temperatures. Lower-tropospheric moisture gradually streams northward on a broad southerly fetch through Wednesday afternoon. Increasing 300K isentropic lift and theta-e advection under a strong EML may lead to the development of a thin stratus/stratocumulus deck tonight. The early signs of this cloud deck have been noted in satellite/surface observations in Oklahoma and the GFS/RAP support these clouds advecting into the forecast area overnight. There is some discrepancy in the thickness of the cloud shield, with the RAP depicting a very thin deck as opposed to the habitually over-saturated NAM solution. For the going forecast, have trended closer to the RAP in the timing, height, and behavior of the clouds. The first hurdle overcome, we now turn to precipitation chances for tonight. The aforementioned EML and shallow nature of the stratus will substantially limit the threat for precipitation and have trended drier in the going forecast. There are some signals in the RAP bufr soundings of a weakening in the inhibition closer to the lifting surface boundary/warm front along the Nebraska border and have maintained the mention of a stray shower or thunderstorm in this area. Earlier CAM runs were quite bullish in the areal extend of their PoP and QPF fields, but a closer inspection of these fields, in combination with forecast soundings, points towards more convective feedback noise driving these values than realistic meteorological solutions. The synoptic models trended back on PoPs 12 hours ago and only now are the HRRR/RAP likewise backing off on these chances. Did keep some mention of sprinkles in the forecast along and north of I-70 to account for any stray, shallow showers that manage to generate along the best forcing axis attendant with a passing H500 wave, but these should have minimal impacts on the sensible weather. Highs for Wednesday will depend on how quickly the low clouds mix out, but given the thin nature of the clouds, am expecting that clearing should take place by mid to late morning with a rapid warming trend into the afternoon. Increased highs into the low 80s in agreement with the GFS/EC/CMC guidance given the strong warm nose in place and ample mixing ahead of the approaching front. We finally turn our attention to Wednesday afternoon`s severe weather threat. The overall timing, coverage, and mode forecast has varied little from previous updates. With the northern and southern stream waves remaining slightly out of phase until Wednesday night, the threat for the best severe weather appears tied to the subtropical low over TX and OK. Across the forecast area, southwesterly synoptic flow will feature a large line- normal component relative to the orientation of the cold front and rapid upscale growth into line segments and clusters is expected shortly after convective initiation in the mid to late afternoon hours along and east of a line from Abilene to Marysville. Forecast hodographs also feature multiple inflection points and loops that would not favor discrete cells. These storms will move in a northeasterly fashion with the entire system shifting eastward into the evening. MLCAPE values of 1500-2000 J/kg and deep shear of 30 to 40 kts would support any robust updrafts that manage to become sustained. Large hail--possibly up to 2 inches in diameter--and strong winds would be the main threat. Any line segments that roll up the surface boundary could become oriented into a favorable QLCS tornado alignment, but with 0-3 km shear values of only 15 kts, it will take a large mesoscale augmentation of the pattern to realize this potential. The heavy rain threat would likely manifest itself after 00Z and is covered in the long- term discussion below. .LONG TERM...(Wednesday night through Tuesday) Issued at 340 PM CDT Tue Apr 16 2019 Storms persist Wednesday night across east-central Kansas, with temperatures briefly cooling down before rebounding by the weekend. Convective coverage along the surface to H850 boundary should be widespread throughout Wednesday night owing to strong forcing for ascent and unidirectional, boundary-parallel storm-relative flow. The near-surface front advances slowly, but steadily, southeastward during the night and should clear the forecast area around sunrise Thursday. There is some concern that a flash flood threat may develop, mainly along and southeast of the Kansas Turnpike, during the overnight hours as multiple waves of convection ride up and along the lower tropospheric baroclinic zone. Model progs depict strong low-level moisture convergence and H925-700 mixing ratios of nearly 10 g/kg. PWATS of 1.25"+ are well above the 90th percentile of values observed on the TOP/SGF RAOB for this time of year, possibly even approaching the daily max value of around 1.4". Thankfully, the pattern has been dry going into this event and flooding potential may hinge more on rainfall rates than amounts (at least initially). Multiple convective resolving and parameterizing solutions print 1 to 2+ inches of storm-total QPF over the southeastern forecast area and given the meteorological setup, these solutions are within the realm of possibilities. Thursday looks to be blustery and cooler with highs topping out in the low 60s and northwesterly winds of 10 to 15 kts--with steep low-level lapse rates mixing down gusts of 25 to 30 kts. The surface cyclone and attendant deformation zone should reach the Great Lakes region Thursday afternoon, therefore the chance for any showers Thursday afternoon will be dependent on the degree of solar insolation and differential CAA during the peak heating hours. With this latest update, have removed most of the precipitation chances across all but the far northwestern forecast area during the afternoon where deeper convective processes could be realized. Large scale subsidence should lead to quiet weather for Friday and Saturday with the surface ridge axis passing through Friday afternoon. As WAA ensues, highs rebound back into the upper 60s on Friday and mid-70s for Saturday under mostly clear to clear skies. The next chance for precipitation comes late in the weekend as a series of subtle upper-tropospheric shortwaves propagate around the periphery of a western North America longwave trough. These waves will interact with a surface baroclinic zone meandering southward through the region, but it is too soon to pin down the exact timing of this precipitation. Early next week does look to feature cooler temperatures behind this surface trough, but given the subtleties in this pattern and inconsistent inter- and intra-model continuity, confidence is low in this forecast. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 627 PM CDT Tue Apr 16 2019 VFR conditions continue until late overnight. Toward early morning, MVFR CIGS should move into the area. Expect any overnight showers to remain well north of the terminals. Winds should stay brisk from the south with even a few gusts into the late night. Therefore, have removed LLWS mention as the trend with model guidance was also supportive of stronger surface flow and overall winds aloft a little weaker than previous forecasts. Therefore, currently thinking that LLWS would be see a very small window of time and be marginal if it does pan out. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Skow LONG TERM...Skow AVIATION...Drake