Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/27/19


Area Forecast Discussion
National Weather Service Des Moines IA
1001 PM CDT Fri Apr 26 2019 ...Updated for Forecast Trends... .UPDATE... Issued at 1001 PM CDT Fri Apr 26 2019 High resolution models, namely the HRRR and RAP, have been shifting southward with the low pressure this evening. The 00z NAM, which has come in recently, is ever so slightly (less than a county) farther southward. Have tried to blend in some of the RAP into the inherited forecast. Even with the southward shift, the negating factor to adjusting headlines is the time of year and that much of the snow will fall during daylight hours. This often makes it challenging for snow to accumulate on roads, but can occur with high snow rates, which are expected briefly. && .SHORT TERM.../Tonight through Saturday Night/ Issued at 405 PM CDT Fri Apr 26 2019 Active Weather Through Saturday Night Short-wave trough will be kicking off the Rockies with surface Lee Cyclogenesis taking place. This storm system will be moving rather quickly across central/northern Plains into the Upper Midwest. Biggest change in today`s 12z runs have been a southward shift in both the GFS and ECMWF, the NAM track did not change all too much. From a synoptic perspective, this system is looking to be in rather good health for strengthening with plenty of warm-moist air to provide fuel for diabatic processes to allow the surface low to deepen rather quickly. Although the mid-level trough does not dig far south, the PV anomaly associated with it is rather impressive. Large scale lift will not be hard to come by with this system, as by early Saturday morning most of Iowa will be within the left-exit region of 100 knot jet streak at 300mb. Along the warm front, all models are in good agreement that isentropic ascent will be rather strong. In addition, there is no shortage of strong frontogenetical forcing along the temperature gradients with this system. With that being said, precipitation will be very widespread and abundant across the entire forecast area, with the heaviest axis of QPF across northern and northeastern Iowa. With respect to snow, this is where the forecast gets tricky. Temperatures will largely determine the actual snow amounts and snow accumulation that occurs. GFS and ECMWF came in with surface temperatures closer to 40F. The NAM was the cooler model from the 12z runs today. For temperatures on Saturday, have elected to use NAM temperatures and bump them down a few degrees, given strong dynamic cooling likely. If the temperatures are able to cool during the afternoon, then the heavy accumulating snow is likely. Another limiting factor to snowfall could potentially be where the best lifting occurs. As already established, there is no shortage of lift. However, examining model cross section analysis does reveal that the bulk of lift may occur below the DGZ. Model soundings also are not showing the best DGZs from the 12z runs, which could be another concern. So even despite the strong lift, if this does not occur in the DGZ this could certainly limit snowfall amounts across the north. Thus with this low confidence and multiple factors that could reduce snowfall, have opted to stick mainly with a Winter Weather Advisory instead of Warning for the northern counties, with the exception of Worth County which has the best potential to see 6-7 inches of snow within a 12 hour period. The other story with this system will be the winds across most of the state. In the areas with heavy snowfall, wind gusts will be up to about 30 miles per hour, which will present impacts to visibility. However, in southwestern Iowa where the precip will be mostly rain, wind gusts could reach up to 40-45 MPH. This may push Wind Advisory criteria, but for now have held off. A Special Weather Statement will likely be needed for southwest Iowa tomorrow afternoon for gusty winds. For Sunday, high pressure will come in and clear skies just as quick as this storm system came in. Temperatures will be cooler than normal for this time of year. With heavy rainfall from Saturday, flooding may be an issue along some rivers and streams across the forecast area. .LONG TERM.../Sunday Through Friday/ Issued at 405 PM CDT Fri Apr 26 2019 Active pattern stays the course through the long term period, beginning with another shortwave trough quickly passing through the northern Plains Sunday. Upper level QG forcing phases with low level thermal advection to generate widespread rain showers by Sunday evening, continuing into the overnight hours before tapering off early Monday. Precip trends remain on track from previous forecast as models wavered little with their latest runs. QPF amounts look to be on the lighter side for most of the forecast area, but some in southern Iowa may see 0.50"-1" where elevated instability could support some convective activity. Early next week the synoptic pattern transitions to a southwesterly flow regime over the western two-thirds of the CONUS. Several shortwaves propagating through the mean flow look to deliver multiple periods of showers and storms to the state. The first such wave ejects out of the Four Corners on Tuesday/Wednesday and deamplifies as it crosses the central Plains. Heaviest precipitation and convection likely remains along and south of a stationary front draped across OK through MO. Isentropic ascent north of the frontal boundary should generate rainfall over the cwa, highest chances residing across the south. Limited instability north of the front will suppress most potential for severe weather, but can`t rule out some rumbles of thunder in our area. Significant model difference arise past Wendesday which lends to high uncertainty with the forecast. Low chances PoPs remain scattered through the Day 5-7 periods, but is more an artifact of the blends. PoPs should become more focused as models begin to hone in on a common solution. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 657 PM CDT Fri Apr 26 2019 VFR conditions will deteriorate into MVFR as low pressure swings through the region bringing rain showers to the area. Colder air will cause the rain to mix with snow at ALO and change to snow at MCW during Saturday and this will likely bring at least IFR conditions. Strong, gusty winds will also accompany this storm through much of the day before decreasing after 00z Sunday. Restrictions will improve into VFR late in the afternoon over northern and western Iowa. && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 7 AM to 7 PM CDT Saturday for IAZ004>006-015>017-026>028-038-039. Winter Storm Warning from 7 AM to 7 PM CDT Saturday for IAZ007. && $$ UPDATE...Ansorge SHORT TERM...Krull LONG TERM...Martin AVIATION...Ansorge
Area Forecast Discussion
National Weather Service Quad Cities IA IL
946 PM CDT Fri Apr 26 2019 .UPDATE... Issued at 935 PM CDT Fri Apr 26 2019 Have added sprinkles into forecast rest of evening into the early overnight, with first bout of lift attendant to passing weak mid level wave. Lift is fighting dry low levels and mostly evaporating before reaching the surface, but have seen evidence of a trace at a couple of obs out west. Otherwise, with dynamic spring storm system to impact the area tomorrow the Latest NAM is trending a tad slower and further southwest from previous run. However, it`s still clustered with most solutions, which shifted south a bit today. RAP is on the southern edge of the guidance envelope and colder, and would support primarily snow north of Hwy 30 with potential for a bit higher amounts, and possible for changeover to snow further south through I-80 corridor toward late in the day through early evening before system exits. Per vort max trends can`t rule out a bit more change yet in the track of storm system, which if any delta could be of a bit southerly and colder similar to RAP model. With the expectation of a very sharp cutoff from accumulation to nothing, the slightest shift in track will have huge impacts on forecast. Thus, for now we`ve opted to maintain the current watch and let the next shift review the rest of 00z guidance before making any changes. Stay tuned! && .SYNOPSIS... Issued at 250 PM CDT Fri Apr 26 2019 Windy conditions representative of this "warm season" clipper pattern are taking place in the transition from the rapidly progressing areas of strong high and low pressure. Today, northwest winds and dry air are sweeping into the region, with winds of 20 to 30 mph, and a few gusts to around 40. Looking to the west, strong warm advection is already ongoing in Nebraska, in response to the small, but intense upper wave crossing through Idaho and Utah this afternoon. && .SHORT TERM...(This Evening through Saturday Night) ISSUED AT 250 PM CDT Fri Apr 26 2019 A rapid transition to the incoming storm will happen tonight, with the main challenge being snow totals with this storm. There has been a decided shift south today in model guidance, much like often occurs when forecasting a clipper snow system. To be honest, a change in track is still possible yet as this storm arrives. Like a clipper, this is a small system in size and scope, but very intense. All signs point to an extreme frontogenesis event impacting our CWA, especially the north 1/2. A low amount of MUCAPE is likely going to be entrained into this process, allowing for some embedded thunder near and north of the low track, which should move near Highway 34. The amount of rain is challenging, as extreme dynamic lift will wring out every bit of QPF it can while the system moves past. In the north, enough dry air below 700 mb will evaporatively cool the atmosphere aloft for it to change to snow, after the precip develops. This means, after 3 to 4 hours of rain, some areas will change to snow north of the low track. The intensity of lift suggests thundersnow and bursts of heavy snow are possible, leading to a potential that northern areas could reach 5-8"+, THIS IS NOT A CONFIDENT TOTAL! None the less, the potential is there, and with the southern global model shift, a watch seems warranted in the northern counties. If snow is heavy, it will have high impact to trees that are leafing out, as winds will be 30 to 40 mph. Roads are likely going to be slushy, and visibilities poor, thus it`s far from a classic winter impact. Farther south, rain and thunderstorms will continue, with the peak intensity as the low passes by mid afternoon. Winds will rapidly transition to north, and increase to 25 to 35 mph, gusting to 45 for a period of 2 to 4 hours, as the high pressure behind this low will be in place over the CWA, by early Sunday morning! Temperatures will be critical to snow transition, but are forecast to reach the lower 60s south, to near 40 north. That`s likely the 8 AM temperature in the north, with falling readings to the mid 30s by Noon and lower 30s by mid afternoon. As temperatures reach 34, a full transition to snow is expected. Elsewhere, snow will likely occur in a short period through I-80 as the system pulls away. This may lower visibilities, but should not accumulate significantly on anything. Frost/Freeze conditions are expected overnight, and a headline for that is likely going to be issued at a later time. .LONG TERM...(Saturday Night through Friday) ISSUED AT 250 PM CDT Fri Apr 26 2019 An active weather pattern will continue next week with several rounds of rain, possibly heavy, expected. The models have suggested a slight southward shift with the heavy rain. Sunday Assessment...high confidence Quiet, dry and cool conditions will be seen Sunday with below normal temperatures. Sunday night/Monday Assessment...high confidence on another storm system. Low confidence on track and rainfall amounts. The next storm system will impact the Midwest Sunday night into Monday. However, the models continue to disagree on the track the storm system. The difference in track appears to be related to the position of the developing front and the strength of the high from the Great Lakes into the upper Midwest. The ECMWF and FV3 have the front from Kansas into the Ohio Valley with the heaviest rainfall from Missouri into central Illinois. The GFS is slightly north of the ECMWF and FV3 solutions with the front from Kansas into northern Indiana. The heavy rain is along the IA/MO border into northern Illinois. The CMC global is the most ominous as it brings heavy rainfall from southern Iowa to northern Illinois. The model consensus has likely to categorical pops Sunday night with chance to categorical pops on Monday. Monday night on... Monday night through Wednesday Assessment...high confidence on another storm. Low confidence on track and rainfall amounts. The track of this storm system will depend upon where the front is located. The ECMWF keeps the area dry Monday night and Tuesday with rain moving in Tuesday night and Wednesday. The ECMWF has the heaviest rain from the IA/MO border into northern Illinois. The FV3 keeps the area dry Monday night with the next storm system arriving Tuesday and Tuesday night with the heavy rain across Missouri into the southern half of Illinois. The FV3 has Wednesday dry. The CMC global has heavy rain Monday night and Tuesday from Missouri into southern Illinois with very light precipitation Tuesday night and Wednesday. The GFS has Monday night dry with a system moving through on Tuesday with another storm system Tuesday night into Wednesday. The GFS has the heaviest rain from Missouri into northern Illinois on Tuesday and then Missouri into central Illinois Tuesday night and Wednesday. Given all the differences in timing and position of the front/heavy rainfall, the model consensus has slight chance to chance pops across the south third of the area Monday night, chance to likely pops across the entire area Tuesday and Tuesday night, and chance pops on Wednesday. Wednesday night through Friday Assessment...low confidence The models diverge considerably with their respective solutions in regards to the sensible weather. The ECMWF has dry conditions Wednesday night through Friday as a strong Canadian high slowly moves through the Midwest. The GFS has another storm system moving through the Midwest Wednesday night through Thursday night with dry conditions on Friday. The CMC global has mainly dry conditions Wednesday night followed by dry conditions Thursday through Friday. The FV3 has two or three weak systems moving through the Midwest Wednesday night through Friday bringing light precipitation to the area. The model consensus is biased toward the GFS solution and has slight chance to chance pops Wednesday night and Thursday night, chance pops Thursday, and dry conditions on Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) ISSUED AT 655 PM CDT Fri Apr 26 2019 Potent spring clipper system to bring deteriorating conditions in rain/snow and strong winds Saturday. Ceilings... Primarily VFR tonight, but lowering to MVFR and IFR Saturday. Precipitation... Rain changing to snow by midday at DBQ with moderate to heavy snow and several inches of accumulation into early evening. Thundersnow is possible. Mainly rain at CID and MLI, but mixing or changing to a period of snow from mid afternoon into early evening before ending. Predominately rain at BRL, with some dry hours possible late morning and early afternoon. Then showers expected to return in the afternoon which may be accompanied by thunder. Visibility... Generally 2-5SM in the precipitation, with periods of around 1/2SM or less at DBQ in heavy snow. Winds... Becoming strong/gusty from E/SE at 20-30+ kts on Saturday shifting from northeast at 25-40+ kts at northern sites Saturday PM. BRL is likely to see a lighter period of winds for a time in the afternoon with the low passing nearby, but then will become strong from NNW 25-40+ kts by late afternoon. && .HYDROLOGY... Issued at 848 PM CDT Fri Apr 26 2019 Only minor rises of a tenth of a foot or two were made to the Mississippi River crest forecasts this evening. The Mississippi River will remain high or in flood through the Memorial Day Weekend. The Mississippi is rising from Dubuque LD11 down through Burlington. South of Burlington the river will begin rising on Saturday. The crest is currently between La Crosse and Prairie du Chien, Wisconsin. Previous discussion... Issued at 320 PM CDT Fri Apr 26 2019 HOWEVER, the current 7 day Mississippi forecasts do not, repeat, do not take into account predicted snow on Saturday and rainfall from Sunday night through next Thursday. The weather models indicate a narrow band of heavy snow will occur on Saturday from northern Iowa into southern Wisconsin. Runoff from this snowmelt will cause a slightly higher and delayed crest on the Mississippi. The active weather pattern continues well into next week with the potential for several rounds of rain, some of which may be heavy. However, the weather models vary greatly on possible storm tracks and potential rainfall amounts. The high probability of above normal rainfall next week is expected to result in rises on tributary rivers in eastern Iowa and northern Illinois. Looking further out into May, the Climate Prediction Center indicates a 40 percent chance of above normal rainfall through the first 10 days of May along with a slight risk of heavy rainfall. Individuals with interests along the Mississippi River are strongly urged to pay attention to future weather and river forecasts. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...Winter Storm Watch from Saturday afternoon through Saturday evening for Delaware-Dubuque-Jackson. Winter Weather Advisory from 1 PM to 10 PM CDT Saturday for Buchanan. IL...Winter Storm Watch from Saturday afternoon through Saturday evening for Carroll-Jo Daviess-Stephenson. MO...NONE. && $$ UPDATE...05 SYNOPSIS...Ervin SHORT TERM...Ervin LONG TERM...08 AVIATION...05 HYDROLOGY...14/08
Area Forecast Discussion
National Weather Service Lubbock TX
835 PM CDT Fri Apr 26 2019 .UPDATE... Thunderstorms approaching from eastern New Mexico have been gradually weakening over the past 90 minutes, but holding together well enough to spread fair coverage of rain chances across the extreme southwest Texas Panhandle and northwestern South Plains this evening. HRRR runs have been most agressive with forecast coverage though indicate what looks like appropriate weakening. Have trended a little less than HRRR coverage but also expanded isolated thunder coverage a little larger after midnight. Isolated strong wind gusts remain a threat and will add a mention to the overnight Hazardous Weather Outlook. RMcQueen && .PREV DISCUSSION... /issued 557 PM CDT Fri Apr 26 2019/ AVIATION... Breezy south to southwesterly winds will continue this evening into the early morning hours on Saturday. Isolated thunderstorms currently in eastern New Mexico will attempt to make it into the region late tonight or early Saturday morning. However, this activity is not expected to make it to any of the terminals. A cold front will move into the area Saturday afternoon shifting winds to the northwest at KLBB and KPVW and to the northeast at KCDS. PREV DISCUSSION... /issued 351 PM CDT Fri Apr 26 2019/ DISCUSSION... Well, we appear to be heading into a busy weather period. Our immediate question - will we have a repeat of overnight/early morning showers/storms? Storms are once again breaking out over the high terrain of NM this afternoon and slowly pushing eastward. Our upper flow is transitioning from favorable NW to westerly (and weak) flow; however, a LLJ of 30-40 KT is expected to spread south into our FA and strengthen to 45 KT (few pockets of 50 KT) It will veer with time to the SW, so that is not as helpful, though if there are storms, it could mix down and create strong wind gusts at the surface. The main impulse feeding these storms is well to the north, entering the Central Plains tonight. All this to say, there may be just enough energy, moisture and assistance from the LLJ tonight to produce another small round of showers/storms across the FA like last night/this morning. As we head into tomorrow afternoon, we do see about the eastern half of the FA in the marginal risk category for severe thunderstorms. This is a highly conditional situation, in fact, much of our rain this week will be in the conditional category. A front is poised to push through around the eastern two-thirds of the FA tomorrow and stall. Storm initiation is expected along the front near a weak dryline feature, but there are caveats. The first, which is always a concern out here, is moisture. Moisture transport appears to be cutoff early Saturday with the next good surge not coming until Monday. Second, we`ll be capped. There will be plenty of energy, on the order of 1000-1500 J/kg, but if we can`t warm enough to erode the cap, it`ll be of no use. There may be a brief window in the late afternoon to early evening that the cap gets weak enough to overcome, but we`ll have to watch that closely tomorrow. Monday is much like last Monday where we had a front moving through and an upper low off over the Desert SW. Once again, we`ll have to watch to see how far south the front makes it on Monday to determine where the brunt of the storms (possibly severe) will be. Much like last Monday night, storms will move north of the frontal boundary, able to produce locally heavy amounts of rain. As the upper trough approaches and eventually moves by on Tuesday, it will be the track of this feature that determines the highest rainfall amounts. Attm, the current track has those highest amounts moving just to our south, but we aren`t left high and dry either. This is Day 5, so much can change by then. As for highs on Tuesday, models were extremely spread, based on whether we are dry or not. Chose to go cooler on this package as rainfall from the previous day would aid in cooler temps, plus cloud cover should abate the highest temps. Did not, however, go with the coldest temps, as we`ll have to wait until the track of the storm shows itself. Another disturbance approaches Thursday, with a shot at storms, followed by another front, which, you`ve probably guessed by now, appears to be the focal point for another round of storms late Thursday night. An interesting weather period...a challenging one...and one that we must keep a very close eye on. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 05/99
Area Forecast Discussion
National Weather Service Marquette MI
727 PM EDT Fri Apr 26 2019 .SHORT TERM...(This evening through Saturday) Issued at 437 PM EDT FRI APR 26 2019 Water vapor imagery and RAP analysis show a negatively tilted trof extending from northern Ontario to the Carolinas. Shortwave that was over southern Manitoba 24hrs ago is now over the northern Great Lakes. This shortwave has ushered in much colder air on blustery nw winds today. Strongest measured wind gusts so far was at the Munising ASOS at 49 mph at 1900z. Otherwise, gusts have generally been under 40 mph. Low-level moisture, upslope winds and daytime heating helped to generate some -shra across portions of the higher terrain of the nw and n central fcst area earlier today. Some snow was also reported. After rising to around 50F this morning over the e, strong nw winds/caa has dropped temps into the mid 30s to lower 40s. With increasing sunshine toward the MI/WI stateline, temps in that area are currently pushing into the upper 40s. A quiet short term is shaping up after the winds this evening. Low- level winds will reach their max over the next few hrs over the e half of the fcst area. So, before the sfc layer begins to stabilize a bit with the setting sun, there should be higher wind gusts yet to be observed. Per momentum transfer suggested by fcst soundings, gusts should frequently be in the 35-45mph range with the potential of up to 50mph. To the w, winds will be lighter, lightest toward KIWD. Winds will diminish w to e during the evening/overnight. Already by late evening, winds will have dropped off to under 5mph over the far w. Winds may continue to gust to 15-25mph thru the night over the e. A few -shra/-shsn are possible over the e this evening with indication of sharper 850mb troffing pushing down the far eastern part of Lake Superior. As for temps, with light winds and a dry air mass over the w (precipitable water under 0.2 inches), favored the low side of guidance. A few of the traditional interior cold spots may slip blo 20F. Winds will keep temps higher over the e, upper 20s/around 30F. Although a very dry low-level air mass will dominate on Sat, models suggest considerable high cloudiness spreading across the area in association with shortwave tracking e toward the southern Great Lakes. With sun dimmed by high clouds and gradient northerly winds across Lake Superior, it will be a cool day. Expect highs only in the mid 30s/around 40F near Lake Superior to the mid 40s interior w half. .LONG TERM...(Saturday night through Friday) Issued at 431 PM EDT FRI APR 26 2019 Models suggest that a progressive pattern will prevail through the CONUS as a mid level trough over north central Canada slowly drifts southwest into western Canada. Shortwaves moving through the northern Great Lakes will bring pcpn chances to Upper Michigan Monday and again from late Wed into Fri. Temperatures are expected to remain at or below normal through the period. Saturday night into Sunday, Mid level and sfc ridging will continue to dominate the region with dry weather. After a cold start with favorable radiational cooling conditions allowing temps to drop into the lower 20s inland, expect gradual warming as highs rebound into the mid and upper 40s north to the lower 50s south. Sunday night into Monday, A shortwave with moderate to strong 700- 300 qvector conv will bring pcpn through Upper Michigan. Forecast wet-bulb zero heights suggest that much of the pcpn will fall as snow before daytime warming and weak lift move in during the afternoon. With QPF values at least into the 0.20-0.30 range, a few inches of wet snow may accumulate over the west half, mainly on grassy surfaces. Tue, expect dry weather in the wake of the Mon shrtwv as high pressure builds toward the region from the Plains. Wed-Fri, there is lower confidence with the timing/strength of the shrtwv and sfc trough lifting northeast from the plains from Wed into Thu. Although the GFS keeps pcpn south of Upper Michigan, several GEFS members and the ECMWF bring rain into the area from the southwest by late Wed into Wed night. Uncertainty lingers into the end of the week as the GFS/GEFS bring more substantial pcpn, as rain possibly mixed with snow, into the western Great Lakes while the ECMWF is weeks and farther nw with any impacts. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 726 PM EDT FRI APR 26 2019 AS weak high pressure builds into the region, winds will relax with speeds dropping below 10 knots very early on in the forecast, similar to what has already occurred at KIWD. VFR conditions to prevail through the forecast as drier air moves in. Expect increasing mid level clouds for Saturday. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 437 PM EDT FRI APR 26 2019 NW gales of 40-45kt over the e half of Lake Superior will gradually diminish to blo gale force tonight as low pres over southern Ontario lifts ne and pres gradient weakens. Winds have already mostly diminished to under 20kt over western Lake Superior. On Sat, winds should be mostly under 15kt over the w half of Lake Superior while 15-25kt winds are expected over the e half. Winds will mostly be under 15kt on Sun with a high pres ridge over the area, but as the ridge shifts e, winds will begin to increase Sun night and Mon. SE winds will reach 15-25kt over the central and eastern part of the lake on Mon. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Wind Advisory until 8 PM EDT this evening for MIZ005-006-013-014- 085. Wind Advisory until 2 AM EDT Saturday for MIZ007. Lake Superior... Gale Warning until 4 AM EDT Saturday for LSZ251-267. Gale Warning until 2 AM EDT Saturday for LSZ250-266. Gale Warning until 8 PM EDT this evening for LSZ248-249-265. Lake Michigan... Gale Warning until 3 AM EDT Saturday for LMZ248-250. Gale Warning until 1 AM EDT Saturday for LMZ221. && $$ SHORT TERM...Rolfson LONG TERM...JLB AVIATION...RJT MARINE...Rolfson