Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/28/20

Area Forecast Discussion
National Weather Service Gaylord MI
1148 PM EDT Fri Mar 27 2020 .UPDATE... Issued at 939 PM EDT Fri Mar 27 2020 All sorts of unsettled wx to our s and sw, but in our neck of the woods things are quiet...for now. Earlier stratus/fog that bedeviled the Straits and some other coastal locales into late afternoon has been shoved westward by developing east winds. (Though OSC now has a scattered deck at 500ft, so hello Lake Huron. But sat imagery is showing very little low clouds there.) Thin cirrus is presently overhead, thanks to the active wx to our s. Some mid clouds have pushed into central lower MI. Actual precip is found in far southern lower MI, and the south half of WI. Surface low is continuing to spin up in the high plains, and warm/moist advection ahead of it is increasing. Models are in good agreement that we will /not/ see a solid wall of precip push into northern MI overnight. But, it is interesting to see some banded fgen-like radar echoes starting to form over central WI. And it is also interesting to see the Rap and HRRR models push scattered precip as far north as PLN by 12Z. The going forecast is slow to push pops north, in deference to dry low-level air sampled by the 00Z APX sounding (dew pt depressions 10-20C below 850mb). But, stepping back, this is dry but not /very/ dry (and note that surface dew points did not crater particularly hard during our sunny afternoon). So am thinking we need to push chancy pops north to the tip of northern lower MI by morning. Can probably hold back from pushing into parts of ne lower MI (Rogers-APN-Harrisville), as well as eastern upper. Some heavier convective showers (though probably not thunderstorms) could develop as far north by central lower MI by morning. Gladwin Co is the most likely to perhaps see heavier precip rates by morning. && .NEAR TERM...(Through Saturday) Issued at 344 PM EDT Fri Mar 27 2020 ...Showers spread into the region overnight and Saturday... High Impact Weather Potential: Minimal for now. Pattern Synopsis/Forecast: Low amplitude short-wave ridging spans much of the eastern CONUS while surface high pressure extends from eastern Canada down into the Great Lakes. Surface low pressure is across the central-southern Plains with a stalled boundary stretching eastward through the Ohio Valley. Across northern Michigan, quiet/nice conditions now across the region after our stubborn low stratus finally mixed out. That said, there is still a good amount of marine stratus across Lake Michigan and far northern Lake Huron that is skirting some of the coastal locations of the CWA. Surface low pressure will continue to organize/deepen in the central Plains tonight before lifting up through the Midwest on Saturday/Saturday night. This spreads showers up into the region starting overnight. Primary Forecast Concerns: Minimal. Details: First wave of strong warm advection forcing is expected to develop across the lower lakes region tonight along with the first wave of showers just edging up into the southern part of the forecast area overnight into Saturday morning. Initially, there will be quite a wedge of lower level dry air to overcome across northern Michigan through the overnight period. So confidence in getting any substantial precip up into the region is somewhat low through Saturday morning. But, will maintain change to low likely PoPs for the southern parts of the CWA at this juncture. Second stronger surge of moisture/forcing spreads into the region as we go through the day Saturday bringing steady increasing rain chances, particularly during the afternoon hours. Thunderstorm chances eventually enter the picture, but probably not until very late afternoon/evening. && .SHORT TERM...(Saturday night through Monday) Issued at 344 PM EDT Fri Mar 27 2020 High impact weather potential: Chance for thunderstorms Saturday evening/night. Pattern synopsis/forecast: By Saturday evening, vertically stacked low pressure system is expected to be centered across northwest Iowa. Larger scale parent upper-level wave will continue to become negatively titled as it deepens through Saturday night while progressing northeastward across the Great Lakes region. Strong divergence aloft should fairly readily aid in supporting a sub-990 mb sfc cyclone through this time frame before the system`s cold/occluded front is expected to press west to east across the forecast area early Sunday morning. However, wrap around moisture is expected to encompass much of the region on the backside of the departing system through Sunday evening. High pressure returns to the area as early as Sunday night into Monday, ultimately bringing a return to more tranquil conditions. Primary forecast concerns/challenges: Thunderstorm chances Saturday evening/night. Low chance for some gusty winds/hail across southern parts of the forecast area? The primary focus through the forecast period revolves around the Saturday evening/night time frame as a swath of deeper moisture is expected to yield some heavier rain rates and even a few thunderstorms. Despite surface temperatures in the upper 30s and lower 40s, model soundings suggest elevated instability on the order of several hundred J/kg that may support a few rumbles of thunder, primarily across northern lower. Rather impressive veering wind profiles depicted, along with upwards of 50-60 kts of bulk shear may pose a low chance for some hail/gusty winds with any stronger cells able to sustain themselves. This represented well in SPCs Day 2 outlook that paints areas along/south of M-55 in a Marginal Risk for severe storms. By the second half of Saturday night into early Sunday morning, precip chances are expected to diminish from southwest to northeast with the associated frontal passage and deep layer dry air moving in aloft. However, this trend isn`t expected to last long as wrap around moisture arrives from the northwest as early as late morning through much of the afternoon, ultimately renewing shower chances across much of northern Michigan. Some guidance even suggests a bit of lake induced precip continuing into Sunday night; however, very marginal delta Ts and declining deep layer moisture yields little confidence in this solution, and gut feeling is that we`ll have more dry time Sunday night into Monday across the vast majority of the forecast area. High pressure anchored to our north early next week makes its effects felt locally as early as Monday with the expectation of dry weather across the forecast area, despite somewhat cooler temperatures than seen this weekend. Sunday`s highs in the upper 40s to low 50s, falling into the low 40s for most on Monday. .LONG TERM...(Monday night through Friday) Issued at 344 PM EDT Fri Mar 27 2020 High impact weather potential: Minimal for now. Initially tranquil conditions expected across the northern Great Lakes at the start of the period as Saturday-Sunday`s area of low pressure continues to trek eastward. Focus transitions to another well-defined shortwave across the Four Corners region Monday afternoon, which latest trends suggest should safely pass by to our south as it ejects eastward across the southeastern US. Confidence diminishes thereafter in any given solution; however, perhaps the most likely revolves around another system arriving into the Pacific Northwest during the day Tuesday before moving eastward midweek... perhaps increasing precipitation chances locally at times Wednesday- Thursday. Highs through the period are expected to be close to seasonal averages in the mid 40s for many across northern Michigan. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1148 PM EDT Fri Mar 27 2020 Gradually worsening conditions as rain moves in Saturday. Low pressure is advancing out of the high plains, moving ne. This low will move ne-ward, reaching La Crosse WI by late Saturday evening. High and mid clouds will continue to thicken and lower overnight. Some showers could approach the nw lower MI TAF sites late in the overnight. Precip is expected to be somewhat spotty and light until very late on Saturday, when a stronger push of moisture arrives. Still, cigs will lower, and all sites will see MVFR cigs at some point Saturday, though it will wait until very late in the day at APN and PLN. Saturday night, IFR cigs/vsbys arrive, with some potential for LIFR cigs closer to midnight. East to se winds will increase tonight and into Saturday, gusty during the day on Saturday. && .MARINE... Issued at 344 PM EDT Fri Mar 27 2020 Quiet weather anticipated tonight. Low pressure in the Plains will further organize/deepen and lift up through the Midwest Saturday, and the western Great Lakes Saturday night into Sunday. Increasing E/SE flow with this system will likely result in small craft advisories for most nearshore areas Saturday and Saturday night. Winds veer into the southwest then west on Sunday as the system passes through the region. Some gale force gusts are possible on Lake Michigan Sunday and plan to hoist a gale watch accordingly. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...NONE. LM...GALE WATCH from late Saturday night through Sunday evening for LMZ345-346. LS...NONE. && $$ UPDATE...JZ NEAR TERM...BA SHORT TERM...MG LONG TERM...MG AVIATION...JZ MARINE...BA
Area Forecast Discussion
National Weather Service La Crosse WI
1052 PM CDT Fri Mar 27 2020 .SHORT TERM...(This evening through Saturday) Issued at 251 PM CDT Fri Mar 27 2020 At 2 PM, skies were partly to mostly cloudy across the Upper Mississippi River Valley. Temperatures were in the 40s in Clark and Taylor counties in north-central Wisconsin, and in the mid and upper 50s across the remainder of the region. As the 850 mb moisture increases ahead of a shortwave trough ejecting out of the Central Plains late this afternoon and evening, showers will rapidly develop across the Upper Mississippi River Valley. This will occur south of Interstate 90 between 4 PM and 8 PM and across the remainder of the area between 8 PM and 1 AM. Rainfall totals will be up to a quarter of an inch. On Saturday morning, showers and even a few thunderstorms will continue ahead of yet another shortwave trough ejecting out of the Central Plains. There continues to be questions on how much elevated instability will move into the region. Most have very little, but the HRRR and RAP have elevated CAPES in the 500 to 1500 J/kg range. With ample shear aloft, there is a potential of elevated supercells with hail being the primary threat. On Saturday afternoon, the models continue to struggle on whether the thunderstorms will be able to become surface-based or not across northeast Iowa and southwest Wisconsin. Both the HRRR and RAP say that this is a possibility, but many of the other models say no. If we do get into the warm sector, the 0-1 km shear could be in the excess of 40 knots and 0-1 km helicity of 300 to 400. This would provide the potential of supercell tornadoes between 4 PM and 7 PM. Even if they do not become surface based, there will be the threat of hail. Like the past couple of days, there continues to be a marginal risk of excessive rain. Precipitable water values will be in the 1 to 1.25 inch range south of Interstate 90. This is 2 to 3 standard deviations above-normal. .LONG TERM...(Saturday night through Friday) Issued at 251 PM CDT Fri Mar 27 2020 Deep sub-990 mb low pressure will move from north-central Iowa to central Wisconsin Saturday night, with the earlier wave of showers and storms moving off to the northeast in the evening. There could be a few strong storms continuing to move across central Wisconsin early in the evening before moving quickly northeast. We may then get a brief break in the rain for part of Saturday night as the dry slot moves overhead, but wrap-around showers will increase in coverage late overnight and continue throughout Sunday. There may even be a few snow flakes mixing in Sunday morning, but surface temperatures in the mid to upper 30s will make accumulations unlikely. As the low moves away Sunday morning, a tight pressure gradient and large pressure rises (+8 to +10 mb in 6 hours) on the back side of the low will lead to gusty west-northwest winds into the early afternoon. Soundings suggest speeds at the top of the mixed layer of 35-40 knots, and while we may not mix quite that much downward to the surface, gusts of 30 to 40 mph will still be possible during the day, slowly tapering off in the late afternoon and evening as the pressure gradient relaxes. Showers should also diminish by evening as the low moves farther away from the area. Ridging takes over for Monday into Tuesday morning, before a shortwave ejects eastward out of the southern plains Tuesday into Wednesday. This system looks to stay south of our area, and thus the bulk of the precipitation associated with this looks to stay south as well. Deterministic models would suggest Tuesday stays dry, but several GEFS members have light precipitation approaching from the west and this has been carried over into the blend. Details are murky toward the end of the week as several models show differences in temperatures and precip. during this period. Beyond this, there does seem to be a signal for cooler conditions working southward at some point during the weekend. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1052 PM CDT Fri Mar 27 2020 MVFR/IFR conditions expected through the period as a potentarea of low pressure lifts from the Central Plain into the region. Plan on periods of rain overnight through Saturday with even some thunderstorms in the vicinity mainly in the 20-02z time frame. Gusty west-northwest winds will set in after midnight Saturday night, lasting into Sunday along with scattered showers. More detail will be given with the 12z TAF issuance. && .HYDROLOGY... Issued at 251 PM CDT Fri Mar 27 2020 Widespread 0.75" to 1" of rainfall is expected through this weekend, much of it falling Saturday. With already elevated river levels and fairly saturated soils from recent rainfall over the past week, this will lead to additional rises on area rivers and possibly flooding in some spots this weekend into early next week. In addition, heavier rain is expected to fall to the northwest of the forecast area which will lead to continued rises along the Mississippi River through next week. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Boyne LONG TERM...Lee AVIATION...DAS HYDROLOGY...Lee
Area Forecast Discussion
National Weather Service Denver/Boulder CO
918 PM MDT Fri Mar 27 2020 .UPDATE... Issued at 850 PM MDT Fri Mar 27 2020 No significant changes to the forecast package this evening. It appears the heavier showers over Denver area are starting to shift to the east. Although the snow appears to be done in the foothills of Larimer County, light to moderate snow showers continue in Boulder County. Will let the winter weather advisory ride there for now, but it could be cancelled by midnight. No changes regarding the highlights over the northeast plains. Light rain showers or drizzle along and east of a Sterling to Akron line should switch over by midnight once the colder air moves in from the west. Light to moderate snow developing over eastern Weld to just east of Denver. Latest HRRR shows a band of snow through midnight then a short break until 3 am, then the snow cranks up again. Strongest winds should get going around 3 am. No changes to the timing to the blizzard, but the best combination of snow and wind will be after midnight. UPDATE Issued at 526 PM MDT Fri Mar 27 2020 Some thunderstorms developing over eastern Elbert and northern Lincoln counties late this afternoon, so updated to include thunderstorms there until 8 pm. && .SHORT TERM...(This evening through Saturday) Issued at 300 PM MDT Fri Mar 27 2020 Water vapor imagery shows a strong trough moving across the Four Corners region with convective showers developing over the mountains. This trough will strengthen tonight as it moves onto the Central Plains and becomes a closed low. At the surface, a lee cyclone is developing over the Arkansas River Valley in southeastern Colorado. On the north side of the cyclone, upslope flow has kept cool and relatively moist air in place today. Instability over the mountains along with convergent flow is beginning to produce showers across our CWA. These showers will increase in coverage and intensity throughout the rest of the afternoon and evening. Initially, rain will be falling across the plains but a cold front will push southeastward out of Wyoming this evening changing the precipitation over to snow from west to east. The urban corridor will be the first to see snow this evening but it should end rather quickly as northwest, downslope flow dissipates precipitation by the late evening. This is why the urban corridor was left without any advisories since snow amounts and impacts will be much lower than other areas. As the surface cyclone deepens tonight, it will greatly strengthen northwest winds across the eastern plains as moderate to heavy snowfall develops. Models have come into better agreement that areas from the Palmer Divide to northern Washington County will be the focus for heavy snowfall as 4 to 10 inches are possible there. The heavy snow combined with wind gusts up to 55 mph will create blizzard conditions and extremely hazardous travel conditions. A Blizzard Warning was issued from 9pm through noon tomorrow for Washington, Lincoln, and NE Elbert Counties. One of the bigger forecast changes was to increase PoPs and QPF tomorrow morning since the system will be much slower to move out of the region than originally expected. In the mountains, there will be generally light snowfall with the highest amounts north of I-70 were a Winter Weather Advisory is in effect. Strong northwest winds will persist throughout the day tomorrow with clouds decreasing from west to east. A few light snow showers will be possible in the mountains but other areas will remain dry besides the morning snow on the far eastern plains. .LONG TERM...(Saturday night through Friday) Issued at 300 PM MDT Fri Mar 27 2020 Short and medium range models each have the upper level low well east of Colorado by tomorrow evening with weak west to northwest flow aloft over the state. Mountain areas will have a little moisture trapped west of the Continental Divide which will produce some weak snow showers overnight. By Sunday morning, flow aloft will be switching to west and southwesterly, ahead of the next developing upper trough over the southwestern United States. This will bring warmer temperatures back to the area. The next upper trough is expected to be moving over the region Monday with another round of mountain snow showers and plains rain showers Monday afternoon and evening. Warm air will move up over eastern Colorado ahead of the trough, which will keep the showers on the plains in the liquid form. After Monday`s system moves through, moderate to strong westerly flow aloft will dominate through the first half of the week. Some Pacific moisture will be embedded in the flow, causing some orographic snow showers over the mountains. Snowfall amounts in the mountains will be light through the next several days as the trough moves through quickly, and the subsequent westerly flow aloft will not have that much moisture. The plains will be dry for the majority of the week. At the end of next week, the medium range models show the next upper trough arriving. Models have different ideas concerning the magnitude and timing of the arrival of this trough. For the time being, Monday`s trough will be the last significant weather for the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 850 PM MDT Fri Mar 27 2020 Heavy, wet snow may decrease visibilities below a mile mainly between 03-06Z. Snowfall at the Denver airports is expected to be between 2 to 4 inches. Strong gusty winds will also affect the airports with gusts up to 35 knots possible late tonight. Saturday, skies clear out as strong northwest winds persist. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from midnight tonight to noon MDT Saturday for COZ048-050-051. Winter Weather Advisory until 3 AM MDT Saturday for COZ033-035. Winter Weather Advisory until 6 AM MDT Saturday for COZ041-042- 044-045. Blizzard Warning until noon MDT Saturday for COZ046-049. && $$ UPDATE...Cooper SHORT TERM...Danielson LONG TERM...Dankers AVIATION...Cooper
Area Forecast Discussion
National Weather Service Cheyenne WY
723 PM MDT Fri Mar 27 2020 .UPDATE... Issued at 705 PM MDT Fri Mar 27 2020 Most precipitation has shifted south and east, along and east of a Cheyenne-Torrington-Harrison line, though generally light snow showers will continue to the west of this line through tomorrow. This line will not move quickly out of the region however, as the deep surface low moves slowly from the southeast corner of Colorado and shifts northeast through Kansas and finally gets kicked further northeast tomorrow afternoon. In the meantime, still expected quite a bit of snow accumulation overnight along and east of the aforementioned line. At the moment, temperatures are still above freezing across the Panhandle with precipitation falling as rain. Will see a gradual transition to snow in the next few hours. This will lead to several overnight and morning travel hazards as snow accumulates on roads (temperatures and the sun angle were preventing snow accumulations along the roadways earlier today, but that will soon come to an end across the area), becoming slick and snowpacked. We`ll also see reduced visibility across much of the region as patchy fog develops overnight. Additionally, as the surface low deepens and gains strength, winds will increase over the far southeast portion of Wyoming and the southern portion of the Nebraska Panhandle creating areas of blowing snow, that may continue through the day tomorrow, even after the showers taper off. Looking towards warming daytime temperatures to limit driftability as the fresh snowpack crusts over. In this latest update, dropped the Winter Storm Warnings that had been in place over the Snowy and Sierra Mountain Ranges, as only light linger snow showers remain. Also, downgraded the -i80 Summit and South Laramie Foothills to an advisory as the heavier bands shifted east and only 1 to 3 inches of snow accumulation is expected. All other hazards remain in place. && .SHORT TERM...(This evening through Saturday) Issued at 249 PM MDT Fri Mar 27 2020 Lee cyclogenesis has been ongoing this afternoon across southern Colorado slightly farther south than earlier models had been indicating. The low will continue to deepen and push through SE CO into late this afternoon and evening. So far this afternoon, the majority of snowfall has been confined to along the Laramie Range as depicted by current radar imagery and webcams. More widespread lift will move into the region over the next few hours as ongoing cyclogenesis continues increasing coverage of precipitation along the CO/WY border and the Cheyenne Ridge. Recent low-level water vapor imagery trends support this. Recent runs of the HRRR and NAMNEST have had much better agreement with each other than earlier with a bullseye over northeast Laramie County and lower snowfall amounts to the north. Much of the NE Panhandle has started off as rain, but will transition over to snow this evening with the North Platte River Valley staying the warmest and taking the longest to transition to snow limiting accumulation amounts. Changes to headlines include expanding the Winter Weather Advisory to the rest of the NE Panhandle. Widespread 1-2 inches of snowfall is expected tonight with localized spots up to 5 inches along the Pine Ridge and Wildcat Hills. Additionally, models have slowed down the system over the past 24 hours. Therefore, the Winter Weather Advisories for the southern NE Panhandle were extended through 9 AM MDT Saturday. Snow will completely move out of SE portions of the CWA by late Saturday morning. On the backside of the deepening surface low, strong northerly winds will develop over the southern NE Panhandle Saturday morning lasting through the afternoon. Gusts to 40 MPH are likely with a fresh snowpack which could prolong slick road conditions and reduced visibility with blowing snow. However, afternoon temperatures will climb into the low 40s so expecting the fresh snowpack to crust over by midday limiting the driftability of snow. Otherwise, clearing skies expected across the region through the day Saturday. .LONG TERM...(Saturday night through Friday) Issued at 249 PM MDT Fri Mar 27 2020 The GFS & ECMWF both show a rather fast-moving short wave tracking across the Four Corners on Monday/ Tuesday. Widespread precipitation will be possible with this storm system, but gusty westerly winds should keep things fairly dry for the most part. Trending colder mid to late week with a strong cold fropa over the northern and central plains. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 520 PM MDT Fri Mar 27 2020 Wyoming TAFS...VFR at Rawlins. Wind gusts to 30 knots after 15Z Saturday. IFR at Laramie until 06Z, then MVFR until 12Z, then VFR. Wind gusts to 35 knots after 16Z Saturday. IFR at Cheyenne until 13Z, then VFR. Wind gusts to 30 knots after 06Z. Nebraska TAFS...IFR at Chadron and Alliance until 12Z, then MVFR until 16Z, then VFR. Wind gusts to 30 knots after 16Z Saturday. VFR at Scottsbluff until 02Z, with occasional MVFR, then MVFR from 02Z to 04Z, with occasional IFR, then IFR until 13Z, then MVFR until 16Z, then VFR. Wind gusts to 35 knots after 16Z Saturday. VFR at Sidney until 03Z, with occasional MVFR, then IFR until 13Z, then VFR. Wind gusts to 43 knots after 13Z Saturday. && .FIRE WEATHER... Issued at 410 AM MDT Fri Mar 27 2020 No fire weather concerns w/ widespread measurable precipitation & cooler temperatures. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until 5 AM MDT Saturday for WYZ103- 105>108-110-115>118. Winter Weather Advisory until 9 AM MDT Saturday for WYZ119. NE...Winter Weather Advisory until 5 AM MDT Saturday for NEZ002-003- 095-096. Winter Weather Advisory until 9 AM MDT Saturday for NEZ019>021- 054-055. && $$ UPDATE...AB SHORT TERM...MB LONG TERM...CLH AVIATION...RUBIN FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Lincoln IL
901 PM CDT Fri Mar 27 2020 .SYNOPSIS... Issued at 353 PM CDT Fri Mar 27 2020 Periods of showers and thunderstorms will affect central and southeast IL through Saturday evening. There is a risk of severe storms through Saturday along with locally heavy rains, with the greatest potential for severe weather Saturday afternoon and evening. Expect mild temperatures and an increasing temperature trend, reaching the 70s by Saturday afternoon. Dry and seasonably cool weather will return to the area overnight Saturday night and Sunday along with windy conditions. && .UPDATE... Issued at 900 PM CDT Fri Mar 27 2020 Surface analysis shows the warm front is lingering roughly near the I-70 corridor as of mid-evening. High resolution guidance still point toward a scenario where the warm front lifts north and storms develop north of the boundary as it progresses. NAMnest and HRRR are indicating an axis of storm development from SW to NE roughly along I-72 to start, between 04z-06z. Additional development north of a line from Rushville to Bloomington is expected shortly after midnight through late tonight. A corridor of instability (MLCAPE around 1500-2000 J/kg) will support a few vigorous updrafts the rest of the night. That instability is expected to shift north ahead of the warm front overnight, along with surface dewpoints increasing toward the low 60s. The addition of 0-6km bulk shear values of 60-70 kts across the entire area will help a few supercells produce hail, possibly an inch or larger at times. Can`t rule out the possibility of a severe thunderstorm watch for a portion of our CWA toward the 05z time frame. Current forecast database has a decent handle on the forecast, so minor PoP/weather updates were done to match short term convection trends. && .SHORT TERM...(This evening through Saturday) ISSUED AT 353 PM CDT Fri Mar 27 2020 The surface cold front that pushed southward into southern IL overnight has returned northward to around I-70 with very little shower activity in the region early this afternoon, although activity should increase late this afternoon and evening as an additional disturbance approaches, increases warm advection aloft. Hail and locally damaging wind will be the primary severe weather threats in today and tonight`s highly sheared and increasingly unstable environment, however the threat for hail should be higher to the north of the warm front. Batches of showers and thunderstorms, possibly severe, will continue through tonight near the warm front as it lifts toward I-74 by dawn, and into northern IL for the afternoon. At this point, central IL will be well within the warm sector with high temperatures in the mid 70s and dewpoints in the mid 60s. Instability and shear resulting from a potent low pressure system centered over Iowa and tracking toward Wisconsin has prompted the issuance of a moderate risk severe thunderstorm outlook over a large portion of northwest and central IL, with enhanced to slight risk over areas farther southeast. All severe weather hazards including large hail, damaging downburst winds, and tornados will be possible with discrete supercell thunderstorms that form during the daytime, especially afternoon and evening. Favorable areas for these storms to form will be near the warm front, as well as ahead of the approaching cold front in western IL or Eastern IA/northeast MO. Thunderstorm activity should shift eastward across the central IL forecast area during the late afternoon and evening, likely ending as far east as the IN state line by midnight. .SHORT TERM...(This evening through Saturday) ISSUED AT 353 PM CDT Fri Mar 27 2020 The surface cold front that pushed southward into southern IL overnight has returned northward to around I-70 with very little shower activity in the region early this afternoon, although activity should increase late this afternoon and evening as an additional disturbance approaches, increases warm advection aloft. Hail and locally damaging wind will be the primary severe weather threats in today and tonight`s highly sheared and increasingly unstable environment, however the threat for hail should be higher to the north of the warm front. Batches of showers and thunderstorms, possibly severe, will continue through tonight near the warm front as it lifts toward I-74 by dawn, and into northern IL for the afternoon. At this point, central IL will be well within the warm sector with high temperatures in the mid 70s and dewpoints in the mid 60s. Instability and shear resulting from a potent low pressure system centered over Iowa and tracking toward Wisconsin has prompted the issuance of a moderate risk severe thunderstorm outlook over a large portion of northwest and central IL, with enhanced to slight risk over areas farther southeast. All severe weather hazards including large hail, damaging downburst winds, and tornados will be possible with discrete supercell thunderstorms that form during the daytime, especially afternoon and evening. Favorable areas for these storms to form will be near the warm front, as well as ahead of the approaching cold front in western IL or Eastern IA/northeast MO. Thunderstorm activity should shift eastward across the central IL forecast area during the late afternoon and evening, likely ending as far east as the IN state line by midnight. .LONG TERM...(Saturday night through Friday) ISSUED AT 353 PM CDT Fri Mar 27 2020 Following Saturday night`s cold front, strong west winds 20-25 mph with gusts 30-40 mph should develop for Sunday, along with highs reaching only the mid 50s to low 60s. Seasonably cool temperatures with highs in the 50s should continue the remainder of the work week. A southern stream system should pass by largely to the south Tuesday, but bringing a chance for rain, mainly the southern half of Illinois. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 714 PM CDT Fri Mar 27 2020 IFR clouds are lingering ahead of our next period of showers and storms this evening. Isolated VFR ceilings have occurred, but they should be short lived as lower clouds develop in the vicinity of the warm front that will lift north into our CWA tonight. Scattered showers and thunderstorms will be possible through tonight across central IL, along that warm front. The front is expected to reach toward I-74 by 12Z/7 am Sat. Low ceilings below 1k ft along with reduced vsbys with rain showers and some fog will occur at times through tonight, north of the warm front. NE to ENE winds of 8-14 kts to veer SE to SSE tonight as warm front lifts over across central IL. Very strong storms tomorrow later afternoon could produce significant wind damage with large hail possible. Some tornadoes could develop near the terminal sites, mainly after 22z tomorrow toward PIA/SPI, then advancing eastward Saturday evening. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Shimon SYNOPSIS...37 SHORT TERM...37 LONG TERM...37 AVIATION...Shimon
National Weather Service Jackson KY
1105 PM EDT Fri Mar 27 2020 .UPDATE... Issued at 1105 PM EDT FRI MAR 27 2020 The radar trends in the downstream convection keep the better chances of seeing an isolated storm generally in the Bluegrass region. Overall the threat looks low at this point with isolated to widely scattered coverage at best. Otherwise just some adjustments to the deeper valleys were needed as they have decoupled despite the clouds. UPDATE Issued at 831 PM EDT FRI MAR 27 2020 We are seeing broken to overcast skies this evening in the warm sector. We are seeing a upper level wave in Missouri that is expected to push through tonight. This could spark an isolated storm under ample elevated instability, strong mid level lapse rates and strong shear. The HRRR has started to indicate an isolated storm could develop in the recent runs in far northern Kentucky, but this still remains more conditional at this point. Given this will lean toward slowing the PoPs down, but keeping the same general idea of isolated convection. The trends will continued to be watched through the evening. Otherwise this is more of a minor update in terms of the other weather elements. && .SHORT TERM...(This evening through Saturday night) Issued at 312 PM EDT FRI MAR 27 2020 Current conditions across the region features scattered cloud cover with a warm front draped across northern Kentucky and into West Virginia. The scattered cloud cover over eastern Kentucky has lead to some surface heating over the area. Thus some surface temps are creeping into the upper 70s and possibly near 80 in some parts. This has also lead to some impressive dew point depressions across the area with 10 to 15 degree spreads in place. Model soundings have indicated some increasing cap heading into tonight. Thus will keep pops out of the forecast until about 22Z but with a weak wave approaching the area may spark off a few showers or a storm or two but the chances are low here. After this, the chance for pops will be nil through the rest of tonight and into the day on Saturday. In fact a bit of clearing tonight into southeastern KY may lead to a few instances of ridge to valley temperature differences. Still, in this very above normal pattern, lows will only be in the 60s with strong southerly flow. Into the day on Saturday, cloud cover will be on the increase with the approach of the cold front to the west. Thus will see another period of dry conditions as the cap in place will become too strong with the daytime heating and WAA in place. Will expect highs to top 80 in many place tomorrow. By the Saturday night the front will approach the region. With the amount of heating and the lift associated with the approaching front, there will be a concern for winds mainly with any thunderstorm development. Hail will be a possibility as well but wind will be the main threat with a LL jet nearing 40 knots. Moisture will be a concern with the front approach and thus leading to minimal instability but the threat associated with the front will be the main concern. Will time the approach into the area by 03Z to 06Z. Once again wind remains the main threat and prompting SPC to go with a Slight to Marginal Risk of severe weather Saturday night. Conditions right now are looking on the Marginal side with concern to winds and will mention this in the HWO. .LONG TERM...(Sunday through Friday) Issued at 430 PM EDT FRI MAR 27 2020 The period is expected to begin with ridging in portions of the western Atlantic, and upper level low nearing the western Great Lakes, shortwave ridging extending through the high Plains and an trough near the west coast of the Conus. At the surface, a sfc low is expected to be centered over WI to begin the period with a triple point in the Great Lakes and a cold front trailing south into the OH Valley and Appalachians. Current trends point toward the cold front working across East KY at the very start of the period. The upper level and sfc low are expected to move into MI by Sunday evening with the trailing cold front crossing eastern KY early i the period. Showers are expected to accompany the boundary early on Sunday with chances for rain diminishing quickly during the morning. Drier air should move into and across the Commonwealth rather quickly on Sunday in the post frontal dry conveyor belt. This should allow ample solar insolation and mixing down of higher momentum from aloft. This should result in sustained winds in the 10 to 20 mph range with gusts as high as 30 to 35 mph from later in the morning into the afternoon. Opted for more pessimistic dewpoints compared to NBM data due to the expected mixing, hedging toward the lower MAV and MET MOS numbers. Sfc and upper level ridging will gradually build into the region Sunday night and Monday. However, the axis of the upper level ridge will move east of the area by dawn on Tuesday as the next shortwave moving across the Plains near the MS Valley. After dry weather from late Sunday morning into Monday evening, moisture and clouds will increase on isentropic lift ahead of the approaching system on Monday night and showers could occur late. A shortwave trough should move from the Plains/mid south into the OH Valley on Tuesday afternoon and Tuesday night in quasizonal flow. This shortwave trough will depart to the northeast late Tuesday night and Wednesday. Sfc low pressure should track across the OH and TN Valley regions on Tuesday with redevelopment occurring along the eastern seaboard Tuesday evening and Tuesday night. This system will lead to a good chance for showers across the area and a few thunderstorms are possible late Tuesday into Tuesday evening. Another soaking rain should fall from this system. Height rises should follow Wednesday into the day on Thursday as an upper level ridge moves across the southeast and OH Valley. Sfc high pressure will also build into the area during this time. This pattern should result in a drier second half of the week as the next system should not reach the area until next weekend. The airmass should be sufficiently dry that some valley frost could occur on Thursday night with high pressure dominating. If drying occurs quickly enough on Wednesday, patchy valley frost might occur in the west on Wednesday night though confidence in this was not high enough to include that at this time. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 720 PM EDT FRI MAR 27 2020 The cumulus will dissipate through the evening and mostly mid and high level clouds will be left in place. These VFR CIGs will continue through the TAF period. We will see an inversion setup across the region tonight and this will combine with increased low level jet leading to LLWS late tonight into early Saturday morning. The winds will generally remain out of the southwest through the night before we mix out in the late morning and we will see 5 to 10 knots sustained and gusts of 15-20 knots through the afternoon on Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...SHALLENBERGER LONG TERM...JP AVIATION...DJ
Area Forecast Discussion
National Weather Service North Platte NE
631 PM CDT Fri Mar 27 2020 .SHORT TERM...(This evening through Saturday night) Issued at 307 PM CDT Fri Mar 27 2020 The models continue to show a powerful cyclone developing across western Kansas and northeast Colorado late tonight. The storm will lift rapidly northeast through ern Nebraska Saturday and deepen in the process. It appears the storm will pull dry air through ern Wyoming, wrn SD and the Nebraska Panhandle supporting evaporative and near sfc cooling. The NAM even suggests the potential for dynamic and near sfc cooling across ncntl Nebraska. A period of wet snow is in the forecast in that region Saturday afternoon as well as most of western Nebraska. The snow forecast leans on the cooler NAM solution for several inches of wet snow across the higher terrain of western Nebraska. A Winter Weather advisory is in place late tonight and Saturday morning covering parts of western Nebraska. There is little change in the model predicted dynamical forcing for the storm. Strong frontogenesis and the approach of a PV anomaly will fuel a convectively enhanced rain-snow line stretching from southwest to north central Nebraska Saturday. The western Sandhills will be affected tonight and early Saturday morning. Sporadic 1 inch per hour snowfall rates are suggested by the NAM, ARW, NMM models. The GFS, RAP and HRRR are keeping the pcpn mostly rain but these models are known to mix deeply. Our forecast is for a more shallow mixed layer. Ample cold air aloft for snow growth will present itself on the west side of the h700mb low. The wind forecast leans on the guidance blend which is in the middle of the road for wind speeds of 30 to 40 mph. This forecast is close to the 500m AGL winds speeds adjusted downward for friction. The wind gust forecast uses a regression for gusts of 45 to 55 mph. This might be too light considering the 12z HRRR indicated 4 or 5 hours of gusts to around 60 mph and the HRRR was quite correct predicting our last high wind event. The NAMnest also shows a few hours of gusts to near 60 mph affecting parts of wrn and ncntl Nebraska. It is quite possible the region will experience sporadic gusts to 60 mph Saturday. The precipitation and wind will end or subside Saturday evening. .LONG TERM...(Sunday through Friday) Issued at 307 PM CDT Fri Mar 27 2020 Another storm system will move through the central Plains Monday. The h700mb low track suggests the bulk of the rain will fall across nrn KS and srn Nebraska. Likely rain chances are in place across srn Nebraska Monday. This system will exit Monday night. The latest development in the extended forecast is for a closed upper level low to form across srn Canada Tuesday and Wednesday. WPC is holding this low over southwest Canada while the morning runs of the models would suggest the low will drift slowly east through srn Canada throughout next week. The position of the upper low will have a big impact on temperatures as cold air will be colocated beneath the low. Cold fronts will draw this air south, possibly affecting Nebraska. The model consensus is in very good agreement pursuing a warming trend through Tuesday followed by a cold front Wednesday. The warmer GFS ensemble is holding the cold front north of Nebraska while the ECM and GFS are cooling highs into the 40s Wednesday and beyond. The forecast uses a blended approach for highs in the 50s. The rain forecast Wednesday and beyond is basically dry except for isolated chances with the front Tuesday night and Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 631 PM CDT Fri Mar 27 2020 A strong springtime storm will present multiple aviation weather hazards to western and north central Nebraska through Saturday, including low cigs, reduced visby, and strong winds. Moisture overspreads the region tonight, mainly in the form of rain, as cigs drop into IFR (for terminals not already in it). Rain mixes with and switches to snow overnight, then transitions back during the day. Meanwhile, northerly winds strengthen through the forecast period with peak gusts near 40 kts early afternoon. && .HYDROLOGY... Issued at 303 PM CDT Fri Mar 27 2020 North Central Nebraska is under a Flood Watch late tonight through Saturday afternoon. There is little change in the model solution which suggest 1 to 1 and 1/2 inches of rainfall. Most of this rain will fall during the day Saturday potentially causing overland flooding across the Sandhills, flooding of small creeks and mainstem flooding on the Elkhorn river. The Elkhorn river near Atkinson is near action stage from a previous storm. && .LBF WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 1 AM CDT /midnight MDT/ to 1 PM CDT /noon MDT/ Saturday for NEZ004-022>024-035-036-056>058-069-094. Flood Watch from 1 AM CDT Saturday through Saturday evening for NEZ006>010-026>029-038. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively HYDROLOGY...CDC
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
940 PM CDT Fri Mar 27 2020 .UPDATE... 940 PM CDT No big changes to forecast tonight. Broad zone of warm air advection continues over a large portion of the Midwest this evening. Already seeing areas of showers and some isolated thunderstorms developing across portions of IA, MO, and IL. The more robust convective development at this time is underway over central Missouri. This is closer to the greater instability observed on the 00z KSGF sounding where some fairly impressive lapse rates were sampled along with better moisture. Already seeing a broad low level nocturnal wind maximum developing over the MS Valley which will help advect the deeper moisture and instability northward tonight. The strengthening theta-e advection should also promote increasing coverage of convection overnight. Short range CAMS agree and current forecast of ramping up POPs overnight looks good. Given the moderate instability and strong effective shear with steepening lapse rates, potential for elevated supercells overnight with attendant large hail threat look reasonable. The 00z model guidance suite is in the process of rolling in, oncoming shift will take a look at the full suite of data to access the severe threat for Saturday. - Izzi && .SHORT TERM... 238 PM CDT Through tonight... A period of active weather will commence this evening and a powerful upper level jet takes aim at the region. Warm advection continues to ramp up in the southwest flow ascending the warm front, which at the surface is still through central Missouri to St Louis then on east through the Ohio Valley. Plentiful impulses exist in the flow which will lead to continued/increased shower coverage in waves tonight. There is some limited, though elevated instability well north of the warm front such that some thunder is expected south of I-80 but severe weather is not anticipated in the afternoon hours. The instability axis will shift northward tonight, though the surface warm front really should not make it into the area for most of the overnight hours. Still, RAP indicates some 500-1000 J/Kg of elevated instability will nose farther into the area tonight. As the low level jet gets cranking a bit more late this evening and overnight, expect a further expansion of showers and thunderstorms. These pose mainly a risk for severe hail given the strength of the shear in the hail growth region. These would be favored south of I- 80, as GFS/EC are much more limited in the degree of instability farther north. Still a few rumbles of thunder are possible area wide. PWAT values will also increase significantly tonight. Training storms to not appear all that favorable, and storms will be moving somewhat quickly. So in spite of some favorable regeneration of storms near the front in the Kankakee and Iroquois River basins, the flash flood risk does not appear high enough to warrant a flash flood watch. Still, some periods of locally heavy rain in this corridor is possible with localized ponding of water favored as the soils are a little more damp than usual this time of the year. Meanwhile, the cool marine airmass and the warm moist air to the southwest continue to clash close to the lake. Clouds and fog continue near Lake Michigan, especially on the Illinois side. Fog will continue to be a concern right along the shoreline. Anticipate fog may become more of a concern overnight in between waves of precipitation as onshore flow continues while dewpoints continue to creep up. Some showers and storms will linger in the morning, but we could be in between waves for a time as the morning progresses. KMD Saturday afternoon and evening... Concerns are increasing that a significant severe weather event will occur for portions of northern Illinois late Saturday afternoon into mid-evening, with the potential for tornadic supercells. A slightly negatively tilted trough axis rounding a strong mid-level over the central Great Plains Saturday morning will shift northeast across northern IL late Saturday afternoon into the evening. A surface low associated with the mid-level low will drift northeast from northwest/far north-central Kansas Saturday morning to near Omaha by early evening. Surface theta-e progs indicate a warm front will extend eastward from the low across far northern Missouri to along roughly the I-72 corridor in Illinois at daybreak Saturday. The front will drift north through early afternoon as the low begins to occlude over southeast Nebraska. The occluded triple point will shift ENE from roughly near Des Moines mid-afternoon to near Clinton by 00z, then tracking to around or just north of Chicago by 03Z. Dynamics are rather impressive with this system, highlighted by the nose of a 150kt upper jet and 100kt mid-level jet shifting into northern Illinois during the afternoon. The impressive wind profile extends down to the surface, producing deep layer shear values on the order of 80-90kts, 0-3km shear of 40-50kts, and 0-1km shear of 30-40kts. A narrow ribbon of MLCAPE in excess of 1000 j/kg just ahead of the cold front is expected where rapid erosion of CIN will be underway in response to the incoming jets and trough. This sets the stage for a potentially significant severe weather event for at least a portion of the area. Deep layer shear vectors nearly perpendicular to the cold front support discrete supercell structures. With the surface low only slowly moving ENE across Iowa, surface winds will remain backed in the vicinity of the triple point, especially west of the I-39 corridor. Resultant 0-1km SRH values in this area will be 200-300 m2/s2, with rather curved low-level hodographs present in forecast soundings. Combined with LCL heights around 500m or potentially lower, there is an increased risk of tornadic supercells. Fixed layer STP values in excess of 5 and previously mentioned parameters support the potential for significant tornadoes with any well- established supercells. The greatest risk for this potential is roughly south of I-88, particularly in the western CWA from Lee to La Salle to Livingston counties. North of I-88, any sustained elevated supercell will be capable of large hail given favorable mid-level lapse rates of 7-8C/km. A couple caveats exist, as is usually the case with any severe weather set-up. First, the longevity of elevated convection north of the warm front and its impacts on the northward movement of the warm front remain somewhat unclear. However, with the strong dynamics in place, a late afternoon northward surge in the warm front is expected. Second, substantial MLCIN will be present in the warm sector and as a decent amount of cloud cover reduces diurnal warming. But again, the potent jets combined with the cold front should rapidly remove inhibition, resulting in convection remaining confined to the cold front. Lastly, if enough low-level destabilization/warming does not occur, shear may be too high to maintain/develop significant updrafts. The window of greatest concern is 5-10pm, earliest west and latest east. Timing for the Chicago metro is roughly 7-9pm for the west suburbs and 8-10pm for the remainder of the metro and Chicago. Kluber && .LONG TERM... 238 PM CDT Sunday through Friday... As the center of the strong synoptic system pushes off to the east, winds will continue to be strong on the back side of the low on Sunday. Combined with a strong isallobaric response and strong low level jet winds mixing down to the surface, could see wind gusts to 45+ mph, possibly higher at times based on the past few ECMWF runs. Depending on the exact track of the surface low, winds turn westerly by Sunday morning. Winds gradually diminish though the day on Sunday, although gusts could still be as high as 30-40 mph late Sunday afternoon. Rain showers may also linger though the day on Sunday as precip wraps around the low. High temperatures for the day will likely occur in the morning hours for most areas with temperatures expected to decrease through the remainder of the day, lows Monday morning will drop into the upper 30s. Beyond Sunday, as the lead trough shifts east, a secondary trough and an associated developing surface low is expected to translate east across the central plains and southern Ohio Valley early next week. It is still several days out, but current trends keep much of this activity primarily to our south, but it isnt out of the question that our far southern counties could see some precipitation on Tuesday. Onshore flow is expected through Wednesday which will keep temps cooler for areas along Lake Michigan. Considerable model variability exists beyond Tuesday. Models are struggling to handle what happens behind the secondary trough moving through with respect to the split upper jet pattern and an interesting retrograding low over Canada. It is worth noting that the 12Z GFS has come more into alignment with the 00Z Euro suggesting ridging will build in over across the eastern CONUS into the latter part of next week. Petr && .AVIATION... For the 00Z TAFs... 630 PM CDT The primary aviation concerns through the next 24 to 36 hours are: * Development of low-level stratus deck and fog overnight lasting through much of Saturday * Potential for several rounds of thunderstorms with hail and gusty winds * Strong southwesterly winds and eventually westerly winds at the end of the TAF period. A busy aviation period is expected with multiple potential. impacts. Ceilings and visibilities: While the low-level stratus deck that has plagued ORD/MDW/GYY/DPA has shown signs of eroding over the past hour, persistent easterly flow off Lake Michgian and an influx of low- level moisture from the south will lead to a redevelopment within a few hours of the start of the TAF period, spreading to all terminals by midnight. Dense fog development is also possible with visibility drops below 1 mile. The soupy conditions will last overnight through much of Saturday as the terminals remain on the north side of a northward-surging warm front. As easterly winds increase modestly after noon Saturday in response to an increasing surface pressure gradient, modest improvement to conditions is possible but confidence is low. Ceiling and visibility conditions will finally improve toward the very end if not just after the TAF period as the warm front lifts northward, and in the wake of an eastward- surging cold front. Several rounds of thunderstorms: Showers are increasing in coverage at press time in response to increasing low-level warm air advection. Thunder chances appear low for the first portion of the TAF period as the instability axis is well south of the terminals, though lightning has been noted recently near RFD. A more substantial push of showery activity is expected after midnight within which thunderstorms are possible. At this point, it seems the best chance for thunderstorms will be south of the terminals but opted to maintain the inherited PROB30 group at all TAF sites for now. Any thunderstorm overnight will have the potential to produce small hail. A lull in activity is possible from roughly daybreak through mid-afternoon Saturday, but with continued low-level warm air advection, would not be surprised to see activity fester with a continued small hail threat. Confidence is high that a band of thunderstorms will sweep through the terminals Saturday evening, though confidence is low on exact timing. At this point, it seems they will pass through toward the very end if not just after the 24 hour TAF period and in the last 6 hours of the TAF period at MDW/ORD. Note that any thunderstorm Saturday evening may produce damaging hail and strong winds. Gusty winds at end of the TAF period: In the wake of the cold front, strong southwesterly to westerly gradient winds are expected at all TAF sites, with the strongest winds after daybreak Sunday (and indeed after the TAF period). Wind gusts may exceed 40 kts. While the strongest winds will occur after the 24-30 hr TAF period, felt it would be prudent to mention continued aviation impacts beyond the explicit forecast. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Dense Fog Advisory...Wilmette Harbor to Michigan City IN until 10 AM Saturday. Small Craft Advisory...LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...1 PM Saturday to 4 AM Sunday. Gale Watch...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM Sunday to 10 PM Sunday. Small Craft Advisory...LMZ740...7 AM Saturday to 4 AM Sunday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
918 PM CDT Fri Mar 27 2020 .UPDATE... Issued at 915 PM CDT Fri Mar 27 2020 Strong to severe storms have developed over central Missouri along the quasi-stationary front. Latest objective analysis is showing that the MUCAPES have increased into the 1000-2000+ J/kg range with deep layer shear of 70-80KTS. This latest development is occurring as a 35kt low level jet has intersected the front. Expect these storms to continue to develop and move quickly northeast across central and east central Missouri into southwest Illinois. RAP mass fields and CAMS still support thunderstorms becoming more numerous late this evening into the overnight across northeast Missouri into west central Illinois as the front begins to lift north. Still expect the rain to decrease in areal extent late tonight as the low level jet veers. Britt && .SHORT TERM... (Through Late Saturday Night) Issued at 455 PM CDT Fri Mar 27 2020 Quasi-stationary has moved very little today and was located roughly along I-70 late this afternoon. Latest objective analysis was showing MLCAPES of 1000-2000 J/kg with deep layer shear values of 70kts. Forecast from the RAP are depicting that these values will develop across central and east central Missouri as well as southwest Illinois by early evening. Severe thunderstorms have developed over southwest Missouri in this unstable airmass. The CAMS have been fairly consistent today in developing thunderstorms along the front by early-mid evening. This will occur as the RAP is showing a 35 kt low level jet intersecting the front. Given the amount of shear/instability available in addition to the 700-500mb lapse rates in the 7-8C/km range, expect the primary threat to be large hail, with damaging winds and a tornado or two also possible in the vicinity of the front. These storms will spread across northeast Missouri and west central Illinois overnight before chances decrease by 12Z as the low level jet veers. A few storms tonight may also produce locally heavy rainfall, particularly where any storms can train. Focus then switches to tomorrow when an upper low moves across the Plains which will bring large scale ascent to Missouri and Illinois during the afternoon and early evening. It will also cause an attendant front to move east across the CWA during the late afternoon and evening. Forecast MLCAPES ahead of the front will be around 2000 J/kg with deep layer shear around 80kts which be favorable for supercells. Greatest threat will be over northeast Missouri and west central Illinois which will be closest to the retreating warm front and CAMS is showing the most discrete cells, particularly given the orientation of the deep shear vector to the front. Will continue to message all severe hazards tomorrow afternoon and early evening. Will continue to mention that straight line wind gusts outside of thunderstorms will be in the 35-45 mph range given the tight pressure gradient associated with the deep surface low that will move from the Plains into the Upper Midwest. Winds will continue to be breezy Saturday night into Sunday. Temperatures will remain above normal through Saturday night. Expect the warm front to move north of the area on Saturday, so with sun during the afternoon, still expect highs in the mid 70s- low 80s. Britt .LONG TERM... (Sunday through Next Friday) Issued at 455 PM CDT Fri Mar 27 2020 Sunday into Monday continues to look mainly dry as both the GEFS and EPS show a upper ridge/surface high moving across the area. The next chance for showers will be on Monday into Tuesday as a upper trough moves out of the western CONUS and across Missouri and Illinois. Britt && .AVIATION... (For the 00z TAFs through 00z Saturday Evening) Issued at 641 PM CDT Fri Mar 27 2020 Showers and thunderstorms are expected to continue to develop across the area this evening into the overnight hours. This activity is expected to affect all of the terminals mid-late evening, with showers persisting into the overnight hours. These showers and storms will bring MVFR/possible IFR conditions with possible hail and wind gusts over 35KTS. Storms will move out of the area after 12Z with low chances for showers and possible MVFR conditions through 18Z. There will be another chance of thunderstorms ahead of a cold front on Saturday afternoon. Winds will gust to 30KTS ahead of this front on Saturday afternoon. SPECIFICS FOR KSTL: Thunderstorms are expected to develop at or near the terminal by 01Z and persist through 06Z with lesser chances between 06-12Z. The strongest storms may produce hail and wind gusts in excess of 35KTS. Mainly dry and VFR conditions are expected tomorrow morning, though there is another chance of thunderstorms after 21Z on Saturday. Wind gusts will be near 30KTS on Saturday afternoon. Dry and VFR conditions are expected after 00Z. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
740 PM EDT Fri Mar 27 2020 .SHORT TERM...(This evening through Saturday) Issued at 342 PM EDT FRI MAR 27 2020 Light southerly winds under high pressure have given us a warm and mostly clear day across the UP. The exception has been this morning`s fog in the central UP, caused by moist lower levels capped by an inversion. As temps warmed up in the late morning/early afternoon, the inversion broke, allowing for more dry and warm air to mix down. This broke the fog and cleared the skies. On Lake Michigan and on the Bay of Green Bay, advisory level fog has advected in from the southeast, slowly enveloping the nearshore zones. For the remainder of the afternoon into the evening, high pressure will continue to dominate the region. Positive tilted trough exiting the Rockies will transition into a slightly negative closed low moving across the central Plains toward the Upper Midwest. As the accompanying surface low approaches, light southerly flow will back easterly tonight, advecting more fog into the Bay of Green Bay and Lake Michigan nearshore zones. The light winds and high dewpoints relative to surface temps, capped by an inversion will once again create some patchy fog across the central CWA. In terms of timing of precip arriving in the CWA Saturday, the NAM has been notably earlier then other deterministic models today, but the extended RAP started picking up on it this as well. For the moment, have chance PoPs beginning during the mid-late morning, becoming likely in the afternoon. Upper-level dynamics with isentropic lift should be enough to pop out about an inch of liquid for this event but mainly after this forecast period. .LONG TERM...(Saturday night through Friday) Issued at 430 PM EDT FRI MAR 27 2020 Models suggest that pattern amplification taking place this weekend will continue through much of next week. The trough over the western CONUS will shift through the Rockies into the Plains as a ridge builds over the southeast. As a result, a vigorous shortwave/closed low and associated sfc low is expected to lift from the central Plains into the western Great Lakes bringing a period of widespread moderate to possibly heavy pcpn into Upper Michigan late Sat into Sat night with some lingering wraparound pcpn into Sun for west and north central sections of the U.P. By next week, a split flow pattern is expected bringing mild and mainly dry weather into the region as the heavier pcpn remains to the south with the stronger southern stream shortwave and sfc low. Beginning Sat night, strong 700-300 mb q-vector convergence, upper diffluence and 290k-300k isentropic ascent ahead of the Plains storm system lifting northeast into the region will support widespread moderate to possibly heavy pcpn spreading across Upper Michigan Sat evening. Still some differences noted with the 12Z deterministic model runs...with the ECMWF/NAM/Canadian farther nw than the GFS although the GFS appears to be trending farther west on this latest run. Based on the SREF ensemble mean and a blend of the 12z ECMWF/NAM/CMC would expect the sfc low to track along or just west of a Menominee-Escanaba-Newberry line. This likely scenario will push enough warm air into the area for mainly rain through most of Saturday night across much of the U.P. Forecast soundings suggest that the rain may change to snow late Sat night over the west. Sun, even though the heaviest pcpn will have moved off to the north and east with the exiting system, cold conveyor moisture wrapping around in a moist northerly cyclonic low level flow could support the potential for several inches of wet snow into the west, especially from IWD to the Porcupine Mtns where orographic enhancement would be strongest. Eventually enough cold air will filter into the rest of the Upper Michigan for a rain/snow mix that could bring additional light accumulations of wet snow over the higher terrain of northwest and north central Upper Mi. Rainfall and overall pcpn QPF amounts to around an inch along with melting snow will result in some ponding of water in low lying areas and rises on streams and rivers into Sun and perhaps even Mon. Mon-Fri, mid level and sfc ridging is expected to build into the area Mon bringing a general drying/warming trend into the middle of next week. The CMC and ECMWF do hint at some pieces of shortwave energy lingering across the area Mon-Tue from the weakened storm system to the east, although it remains to be seen if these features will be able to initiate any isolated showers. Although model spread increases significantly by Thu-Fri, trends suggest that a mid-level trough and associated inverted sfc trough will approach the area with increasing chances for pcpn (especially by Fri), mainly in the form of rain. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 740 PM EDT FRI MAR 27 2020 VFR ceilings and visibilities continue this evening, there is the potential for fog development beyond that which is occurring along the Lake Michigan shores this evening. Southerly winds at KSAW will advect that low level moisture toward that TAF site this evening before winds slacken later on and and a NE flow slowly develops. The NE upslope flow also is good for fog development, and with plenty of antecedent moisture around from today`s snowmelt, fog is a given at KSAW. The timing and reduction to visibilities and ceilings is resulting an a very tricky forecast for KSAW in the short term. Expecting IFR conditions there for a time overnight, mainly for visibilities. Elsewhere, the cloud cover thickens overnight, with ceilings gradually lowering through the day. MVFR ceilings expected at all three sites by late in the forecast, but can not discount IFR cigs at KSAW as rain approaches and weak NE flow increases slightly. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 342 PM EDT FRI MAR 27 2020 Light winds today under high pressure will give way tomorrow to a vigorous low pressure moving into the Upper Great Lakes. Winds will shift easterly this evening, increasing during the afternoon and becoming predominately NE. The low is progged to transit through the Upper Peninsula Sunday, shifting the axis of higher winds from the eastern half into the central lake by afternoon, and then into the east half by Sunday evening. NE gales are anticipated in the western half beginning Saturday evening and then northern gale force gusts will be possible Sunday night in the eastern half. Sustained northerly winds above 20kts in the eastern half of the Lake will linger into mid-afternoon Monday. Beyond Monday afternoon, winds should be light. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 7 PM EDT /6 PM CDT/ Saturday to 11 AM EDT /10 AM CDT/ Sunday for LSZ162. Gale Warning from 2 AM to 2 PM EDT Sunday for LSZ263-264. Lake Michigan... Dense Fog Advisory until 11 AM EDT Saturday for LMZ221-248-250. && $$ SHORT TERM...JP LONG TERM...Voss AVIATION...RJT MARINE...JP
Area Forecast Discussion
National Weather Service Shreveport LA
1050 PM CDT Fri Mar 27 2020 .AVIATION... For the ArkLaTex S/SSE winds 5-10KT with ocnl gust will persist in advance of a deep upper trough and eventual fropa this wknd. VFR will go MVFR 09-15Z. S10-20KT with KTYR 1st up seeing the ra/-tsra by 12Z for a few hrs as S shifts to SW and W by 18Z. Other sites will have similar 3-6 hr window with push to the E mid/late a.m. as system progresses. KGGG/KTXK will shift 15Z and KSHV/KLFK at 18Z. Thunder ongoing for our KELD/KMLU sites 21Z/00Z respectively. SFC winds shifting w/ dry line and the fropa will be dry and pass overnight. /24/ && .PREV DISCUSSION... /issued 1013 PM CDT Fri Mar 27 2020/ UPDATE... To add a slight chance for showers in our NW corner before 06Z. SHORT TERM... Hearty range of 70s this evening with few gusts with still good South winds 5-10 mph. The evening will remain quiet areawide, but a few more showers may brush into Red River and McCurtain counties before midnight. We have seen on good cell NW of our area earlier and that has become an area of light showers draping into SE OK at this time. Amounts will be light if at all. Now after midnight little change on timing anticipated. The new NAM is still the slowest solution at 00Z. The HRRR for its time frame shows a few showers in central LA by around 09Z and we have a slight pop here too. /24/ PREV DISCUSSION... /issued 331 PM CDT Fri Mar 27 2020/ SHORT TERM.../Tonight through Saturday night/ Another day of dry conditions and above normal temperatures as upper ridging continues to expand into our region, with the center of the ridge still parked over the Gulf of Mexico. By tonight, the upper ridge will start to shift eastward as the center of the high in the gulf moves east. However, another near record warm night is expected. Low-level southerly flow will push low clouds into the region after midnight, limiting radiational cooling, as temps will only fall into the mid to upper 60s. At the same time, an upper trough in the Great Basin Region will push eastward into Colorado and will start to strengthen and close off as it moves into the Central Plains by Saturday morning, dragging a cold front with it towards our region. The front will move into our northwestern zones by Saturday morning. Scattered convection should develop ahead of the front, likely just east of Interstate 35 in Oklahoma and Texas Saturday morning, then increase in intensity and coverage as they move into our forecast area on Saturday. Deep layer shear well over 50 kts and CAPE values of 1000-1500 J/kg will support a threat for a few severe thunderstorms, particularly Saturday afternoon over Southern Arkansas and Northern Louisiana. Wind shear will be largely unidirectional, which suggests primarily a damaging wind threat. Given the recent rainfall and wet soils, any training or heavy rainfall could result in an isolated flash flood threat. Most of the convection should be out of the area late Saturday evening/Sunday morning, as the cold front pushes east of the region. Noticeably cooler and drier conditions will move into the region as temperatures by Sunday morning will be in the upper 40s and lower 50s. /20/ LONG TERM....LONG TERM.../Sunday through Friday/ By Sunday morning near sunrise, expect a strong short wave trough centered over WI to continue moving E into the New England area through late Sunday. The line of decaying TSTMS on the backside of the trough exits NE LA into MS through Sunday morning. The next short wave trough then moves into the Central Plains states by Monday afternoon with strong warm air advection developing across OK, AR, E TX, and LA. This trough then proceeds to deepen and become negatively tilted through Tuesday. Expect a line of TSTMS, some likely severe, to develop by late Monday afternoon and then exit NE LA and SE AR by late Tuesday morning. Fortunately, the system does not tarry and moves quickly enough to avoid excessive rainfall issues. With these two shortwave trough passages, expect the early season subtropical ridge that recently and currently provided our balmy March temperatures to retrograde W into Mexico and weaken. Expect temperatures to accordingly to return to near normal for late March and early April, that is highs in the lower 70s and overnight lows in the lower to mid 50s. /VIII/ && .PRELIMINARY POINT TEMPS/POPS... SHV 69 78 51 75 / 10 80 10 0 MLU 69 85 55 77 / 10 60 70 10 DEQ 66 75 47 73 / 20 60 0 0 TXK 68 76 49 72 / 20 70 0 0 ELD 68 79 50 74 / 10 80 30 0 TYR 68 75 49 74 / 20 70 0 0 GGG 68 76 49 74 / 20 70 0 0 LFK 70 79 52 78 / 20 80 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/20/08
Area Forecast Discussion
National Weather Service Tulsa OK
855 PM CDT Fri Mar 27 2020 ...UPDATE... .DISCUSSION... The biggest short term forecast change was to increase PoPs across southeast Oklahoma through the overnight hours. Shower and isolated storm activity currently in the area should continue off an on through a good chunk of the night. There continues to be uncertainty in storm coverage this evening and even more so since storms developed over northeast Oklahoma this afternoon which may play a factor in limiting storm development tonight. The latest HRRR runs have hinted at really little development over northeast Oklahoma with only shower and occasional storm activity over southeast Oklahoma and northwest Arkansas. The 18Z NAMNest however shows a couple clusters of potentially strong to severe storms over mainly northeast Oklahoma. The latest upper air guidance is suggesting that northeast Oklahoma may be within the favorable left exit region of an incoming jet streak which would indicate more favorability for synoptic lift. A little lower in the atmospheric column shows deep moisture extending from the surface (surface dew points currently in the mid 60s with even a few upper 60s along the Red River) to 850mb which will continue to be advected into the region through the night via modest southerly winds. Mid level lapse rates should be more than sufficient to support the potential of large hail, but hail size is not expected to be to the degree we saw earlier today. Shear is also expected to increase through the night as the low level jet kicks in leading to high Bulk Shear and high SRH values. Instability should also be sufficient with over 1000J/kg of MUCAPE expected with some locations closer to 2000J/kg. So given a storm in this environment, it is entirely possible severe weather will occur but the question is if storms will get going given the atmosphere across northeast Oklahoma potentially being worked over from earlier storms. At the moment, leaning toward the NAM Nest solution with isolated to scattered storms across eastern Oklahoma and northwest Arkansas with a couple of those storms possibly being severe given a mostly favorable scenario. The primary threat being large hail with a secondary threat for damaging wind gusts. Given that these storms will likely be elevated, a tornado threat is not expected. A couple of storms may also be possible over southeast Oklahoma though the strong/severe threat is considerably lower. The best chances for storms still appears to be over northeast Oklahoma at this time. The best guess as to timing of any strong to severe storms appears to be between 1AM and 5AM tonight. After 5AM, storms should begin to weaken and will continue to slide to the east until exiting northwest Arkansas by late morning tomorrow. So with all that said, other than the addition of higher PoPs across southeast Oklahoma, the forecast remains largely on track. Snider && .PRELIMINARY POINT TEMPS/POPS... TUL 65 73 46 72 / 40 10 0 0 FSM 67 76 46 71 / 40 40 0 0 MLC 64 73 46 72 / 40 20 0 0 BVO 63 72 43 70 / 50 10 0 0 FYV 64 73 45 68 / 40 40 0 0 BYV 66 74 45 67 / 40 50 0 0 MKO 66 72 45 69 / 40 20 0 0 MIO 66 73 44 68 / 40 20 0 0 F10 64 73 45 71 / 40 10 0 0 HHW 66 73 47 72 / 30 30 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...21