Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/01/18

Area Forecast Discussion
National Weather Service Dodge City KS
1036 PM CDT Mon Apr 30 2018 ...UPDATE TO SYNOPSIS... .SYNOPSIS... Issued at 1033 PM CDT Mon Apr 30 2018 WV imagery indicates a southwest flow aloft prevailing across the Western High Plains as an upper level trough sinks southward out of the Pacific Northwest into central/southern California. Near the surface, a strong area of low pressure remains anchored across southeast Colorado. && .UPDATE... Issued at 649 PM CDT Mon Apr 30 2018 Updated to lower pops significantly through this evening, but did not eliminate them completely. A strong dryline has established across SW KS this evening, with very strong south winds blowing essentially parallel to the boundary, gusting 40-45 mph. While instability parameters are quite favorable for convection, the lack of surface convergence along the dryline (magnified by a minor capping inversion aloft and cirrostratus limiting insolation) has so far prohibited convection. Over the next couple hours, as the dryline does its typical diurnal retreat westward, increased convergence could still yield an isolated strong/severe thunderstorm as the latest HRRR iterations suggests. Indeed, convective plumes continue to show up on boundaries from time to time. So kept slight chance pops, with a conditional threat for large hail into this evening. Most of us will remain dry, with continued south winds and increasing stratus overnight. && .SHORT TERM...(This evening through Tuesday) Issued at 210 PM CDT Mon Apr 30 2018 Severe thunderstorms possible early tonight across southwest Kansas. This evening will be monitoring convection initiation along the dry line which is forecast from 21z Monday to 00z Tuesday to be located from near Liberal to around Dighton. Warm air still forecast to be in place aloft (near 9C at the 700mb level at 00z Tuesday). Given this warm air aloft am currently favoring keeping thunderstorm development early tonight more widely scattered in nature. However if convection becomes a little more widespread due to some mid level cooling this evening these discreet storms should become more linear over time based on the mean 700mb to 300mb mean flow in relationship to the dryline. The area that remains favorable for the larger hail early tonight will be closer to the Oklahoma border where the hail potential of tennis balls will be possible early tonight. With the improving low level jet these southern storms are then expected to linger longer as they spread east across western and possibly even south central Kansas. Model soundings also indicate cloud bases will be fairly high so based on this and the forecast downdraft cape strong damaging winds will also be an issue. The main event tonight will be focused between 5 pm and 10 pm with the southern most storms possibly lasting through midnight. After midnight the dryline will retreat back to the Colorado border and as a low level jet develops. Model soundings also indicating some low level moisture will begin to surge back westward producing areas of stratus. Based on the increasing clouds and gusty winds continuing overnight will favor keeping temperatures across western Kansas warmer than guidance. On Tuesday the dryline is forecast to move east to near highway 183. West of this dryline it will be another dry and windy day. Conditions once again will be favorable for extreme fire danger levels while along and east of the dryline the chance for severe thunderstorms will once again be possible. The approaching cold front is forecast to be located near the i-70 corridor. Instability and shear late day will once again favor supercell development with severe hail parameters suggesting greater than tennis balls again possible. Strong damaging winds will also be hazard as will the chance for a few isolated tornadoes. At this time based on latest models will place the area more favorable for a few tornadoes being near the triple point in north central Kansas early Tuesday night. .LONG TERM...(Tuesday night through Monday) Issued at 210 PM CDT Mon Apr 30 2018 An upper level trough will cross western Kansas on Thursday as a surface cold front drops south across Kansas and into Oklahoma. This will bring an end to the thunderstorms late week along with some cooler, more seasonal, temperatures returning. Even with this cool down it does not appear the lows late week will fall much cooler than the mid to upper 30s at best in a few location late week. Most areas in western Kansas will likely to see lows mainly in the upper 30s to mid 40s. Warmer temperatures will return this weekend along mainly with dry conditions during the day. This may result in some increasing fire danger levels this weekend but a subtle upper wave combined with warm air advection may give rise to some evening/overnight storms Sunday night. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 524 PM CDT Mon Apr 30 2018 Strong S/SW winds will continue to impact aviation operations through this TAF cycle. South winds continue to gust in the 40-45 kt range early this evening. Once again, south winds will abate some after sunset, but remain elevated and gusty overnight in response to another low level jet. Expect winds to gust 25-30 kts all night long. Included another round of LLWS in the TAFs. Moisture advection continues on these strong south winds, with a consensus of short term models spreading MVFR stratus cigs across the eastern terminals through early Tuesday. Kept stratus minimal at GCK, and kept stratus out of the LBL TAF. Stratus will burn off by 15z Tuesday, followed by more strong S/SW winds. Winds on Tuesday are expected to be a few knots less than we have seen Sunday and Monday. A remote chance of convection near LBL/DDC this evening, and again near HYS Tuesday afternoon. With limited coverage, and very little confidence on impacts at the terminals, kept thunderstorms out of the 00z TAFs for now. && .FIRE WEATHER... Issued at 210 PM CDT Mon Apr 30 2018 Dry and windy conditions can be expected west of a dry line Tuesday afternoon. Models differ some on exact location but generally these models are in good agreement with placing the lower afternoon dew points west of highway 83. Extreme fire weather conditions still look likely in this area Tuesday afternoon. The northern extent will be located just south of a cold front that will be moving into Syracuse to around the Garden City area. Will collaborate with our neighbors and issue either a Fire Watch or Red Flag Warning of portions of extreme southwest Kansas Tuesday afternoon. Later shifts may need to adjust this if needed just in case the dry line ends up a little further east. && .PRELIMINARY POINT TEMPS/POPS... DDC 60 87 55 84 / 20 10 0 20 GCK 55 85 51 82 / 20 0 0 10 EHA 54 85 52 81 / 10 0 0 0 LBL 60 87 53 85 / 10 0 0 10 HYS 62 84 56 79 / 10 20 10 10 P28 64 86 66 85 / 30 20 10 40 && .DDC WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 1 PM to 9 PM CDT Tuesday for KSZ074>076- 084>086. && $$ UPDATE...Turner SYNOPSIS...JJohnson SHORT TERM...Burgert LONG TERM...Burgert AVIATION...Turner FIRE WEATHER...Burgert
Area Forecast Discussion
National Weather Service Duluth MN
1002 PM CDT Mon Apr 30 2018 .UPDATE... Issued at 1002 PM CDT Mon Apr 30 2018 Showers and storms were increasing in coverage and strength this evening, similar to what much of the guidance was forecasting. As of 03Z, showers and a a few storms were occurring form northern Cass County northeast to near Ely. Stronger storms were occurring in west central Minnesota and were moving northeast toward the Brainerd Lakes region. MUCAPE values were 500-1000 J/KG across northern Minnesota with deep layer shear 30 to 40 knots. We expect showers/storms to continue to increase tonight as the low level jet strengthens and a shortwave lifts through the region. There remains a threat for a severe storm tonight, although widespread severe storms are not expected. Hail is the main hazard. We have updated POPs through the evening and will continue to fine tune as storms develop. && .SHORT TERM...(This evening through Tuesday) Issued at 319 PM CDT Mon Apr 30 2018 Chances of showers and thunderstorms will ramp up this evening, mainly over north-central Minnesota as an area of low pressure, currently located over eastern South Dakota, lifts northeastward into the region. Moisture transport will increase as the low approaches due to a strengthening low-level jet, with 850 mb winds increasing to around 35 to 45 knots. MLCAPE will also increase as the low lifts northward due to increased moisture pooling ahead of a cold front that will be draped along the southern flank of the low, with MLCAPE values up to 600 J/kg, per the 30.12z GFS/NAM models. Also, with the low-level jet, shear will strengthen as the system moves through, with 0-6 km bulk shear magnitudes around 40 to 50 knots. The Storm Prediction Center still has a Marginal Risk of severe weather, with isolated chances of large hail being the main threat. The best chances of severe weather in our area should remain over the Brainerd Lakes area where the better instability will be located. Pwat values don`t appear they will be too anomalously high with this event, with values between 1" to 1.3", which is around the 90% of the NAEFS Pwat climatology. The cold front will then move through the region overnight into Tuesday morning, with continued chances of showers and thunderstorms. However, favorable saturation along this cold front appears to be lacking. The high-resolution meso-models are showing very little in the way of precipitation along the boundary, especially the NAMNest, WRF ARW and NMM, and the RAP, with the HRRR being the most bullish with developing precipitation along the cold front. For now, kept some slight chance PoPs over our southern areas to accommodate the HRRR solution, but thinking that little will occur along the cold front. The Storm Prediction Center also removed nearly all of the Day 2 Marginal convective outlook out over northwest Wisconsin with the latest convective outlook suite. Winds will remain gusty from the south Tuesday morning over northwest Wisconsin and adjacent areas of northeast Minnesota, with gusts between 15 to 25 mph possible. Winds will shift more westerly during the day Tuesday with the cold front fropa. .LONG TERM...(Tuesday night through Monday) Issued at 258 PM CDT Mon Apr 30 2018 The extended period will be dominated by a split upper level flow, with the Northland on the northern side of this flow. The northern flow will still be from Pacific origin so expect a mild period, but not necessarily hot. A short wave will be moving through the upper cyclonic flow Tuesday evening and overnight, possibly setting off some showers and storms. Most of the instability will occur Tuesday afternoon, but some residual instability could keep some storms going, especially in northwest WI. Another cold front along with another upper-level short wave trough will pass across the Northland Thursday night. The Northland will be north of the surface low forecast to move over southern Wisconsin while the northern section remains in Canada. Once that system passes east of the Northland, the remainder of the period will be dry until later in the period Sunday and Monday when the northern branch could bring some showers, but with divergent answers in the models, confidence is low. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 647 PM CDT Mon Apr 30 2018 An area of low pressure and frontal boundary extended from Colorado into northwest Ontario this evening. An upper level disturbance will move through the region in southerly flow aloft and a low level jet will strengthen overnight. The front and low will move east through the night into Tuesday. These features will cause showers and thunderstorms to increase in coverage overnight, mainly over western areas. The low level jet will also cause low level wind shear over parts of the area. Later tonight into Tuesday morning, MVFR and possibly some IFR ceilings will develop over much of the Northland. These ceilings will then rise Tuesday afternoon/evening. Shower/storm coverage will diminish but not end late tonight as the upper level support moves off and the low level just shifts further east. && .PRELIMINARY POINT TEMPS/POPS... DLH 53 64 39 61 / 20 20 10 10 INL 44 50 34 58 / 60 60 10 0 BRD 51 61 39 65 / 60 20 10 0 HYR 59 70 43 66 / 10 30 30 10 ASX 49 71 39 63 / 40 20 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ UPDATE...Melde SHORT TERM...JTS LONG TERM...CLC AVIATION...Melde
Area Forecast Discussion
National Weather Service Des Moines IA
1101 PM CDT Mon Apr 30 2018 .UPDATE... Issued at 835 PM CDT Mon Apr 30 2018 Updated to increase precipitation chances late tonight especially across the northern half and into early Tuesday morning based on the latest HRRR and 18z NAM. Trends for activity across SD/NE to move across Iowa late tonight into early Tuesday. Will continue to monitor as the 00Z NAM comes in and may increase from high chance into likely at times. Currently just trended upward into high chance for now. .PREVIOUS UPDATE... Issued at 714 PM CDT Mon Apr 30 2018 Updated to extend the wind advisory for one more hour based on numerous sites still hitting advisory criteria with strong and gusty winds. Bufkit suggests majority of the area will decouple by 8 pm, so did not extend it further at this time. Winds will diminish with sunset, however breezy conditions are still expected through the night. && .SHORT TERM.../Tonight through Tuesday/ Issued at 343 PM CDT Mon Apr 30 2018 Confidence: Medium to High Main concerns remain the wind and increasing thunderstorm threat. Subjective H850 analysis at 12z currently shows narrow ribbon of moisture streaming north into the High Plains/Western Plains with substantial dry line west of the plume over New Mexico and far western Texas. Strong H850 flow will help to direct the moisture plume into eastern Nebraska/South Dakota later tonight. Series of weak impulses will ride north with the larger upper level system from later tonight into Tuesday afternoon...setting the stage for periods of showers and stronger thunderstorms. Tonight will remain breezy but wind advisory will be allowed to expire at 7 pm as winds decouple enough to lessen gusts. None the less...breezy conditions will continue to push milder and moister air into the region through 12z. This will keep overnight lows in the upper 50s to lower 60s over the area tonight. Along with that scattered showers and thunderstorms will move across the region from 06z through 12z and then weaken during the morning hours. By mid to late afternoon an approaching cold front from the northwest will likely be the initial focusing mechanism for increasing shower and thunderstorm activity. The south looks to escape development during the afternoon hours due to lack of forcing and wind shear. By late afternoon storms firing over eastern Nebraska/Northwest Iowa will begin to expand east/southeast with some threat for severe weather continuing into the evening hours as 0-6km bulk shear increases over the south and remainder of the area. The greater severe threat here remains large hail and potentially some wind into the afternoon hours. Highs tomorrow will be highly dependent on cloud cover. With morning cloud cover likely to break up somewhat due to mixing over the south... highs should move into the upper 70s to lower 80s over the south. The greater uncertainty lies over the northwest where the boundary, cloud cover and potential occasional showers/iso thunder is likely to keep temperatures closer to the 70 degree mark. .LONG TERM.../Tuesday night through Monday/ Issued at 343 PM CDT Mon Apr 30 2018 Bottom Line up Front... Strong to severe weather potential and moderate to heavy rainfall hazardous weather threats Tuesday PM through Thursday PM. Uncertainty in overall progression of system leading to low-medium confidence of severe threat. Synoptics... Little change in overall synoptic pattern evolution for this long term fcst period. By 00z Wed, closed upper low/longwave trough over the Intermountain West still digging down through California. Run-to-run consistency still not solid with the overall progression of this system... with long-range models and their members deviating in their level of flatness/amplitude of the trough/low. Long-range models have shown good consistency of propagating trough Iowa Thursday, placing it near the Great Lakes Region by Friday, with high pressure building into the Midwest by this upcoming weekend. Have gone with a general model consensus as confidence lacks to highly favor or rule out individual model outputs. Tuesday PM Through Wed AM... Beginning at 00z Wed, focus will be on ongoing convection across Iowa. Concerns exists with what we will be seeing at that time, convection-wise. A notable, impactful 24-hr shift in location of severe threat here. Yesterday at this time, it appeared a sfc low would trek across northern Minnesota into towards Lake Superior, with its attendant cold front dropping down through northern Iowa during peak heating. Today, that low is faster and further north. Further, its attendant cold front now stalls out across northwestern Iowa and becomes more or less assimilated with the boundary of the surface center ejecting off the longwave trough that is expected to impact SE Nebraska Tuesday PM. Convection will likely wane and become capped by 06z Tue... though precip will likely continue as the LLJ remains placed through Iowa. Wednesday... Wednesday still appears to be the most active of the next 3 days across the DMX CWA. Aforementioned boundary/stationary front will be focus/trigger for convection. It`s location will be key as frontogenetical ascent processes will likely be needed to punch through the 750mb cap. Not enough confidence to pin down precise location of boundary yet as run-to-run variability still remains. Orientation of the boundary is more SW-NE today, whereas yesterday it was more WSW-ENE. At this time, most likely location of the boundary near peak heating seems to be running near Crawford county in western Iowa through Butler county towards northeastern Iowa. Convection window looks to close fairly and notably quickly with loss of daytime heating, so severe weather to wane by 03z Thu, if not sooner. Decent moisture advection processes remain in play through the day Wednesday, so am expecting widespread precipitation, especially in southern Iowa where a reinforcing band of 925mb-850mb moisture flux convergence well-phased with theta-e advection may setup with PWATs nearing 1.5 inches. Thursday... Boundary will sag southward through Iowa during the daytime hours as core of longwave trough/closed upper low begins its eastward push through the Midwest. As with Wednesday, location of boundary during peak heating will be focus for severe weather potential. Another boost of moisture transport into Iowa...mainly confined to SE Iowa looks to occur Thursday afternoon, helping to keep precip going. Impact-wise, southern Iowa can handle a fair amount of rain given their ongoing drought/dry status. Friday Into the Weekend... As mentioned above, the longwave trough finally departs to the east by Friday morning and NW Flow rapidly fills into the state, drying us out heading into the weekend. Pieces of the subsequent thermal ridge building over the intermountain west may eject off into Iowa as long-range models depict a few shortwaves pushing through the Midwest. Ultimately, what this means is there will likely not be a prolonged cool-down during this time period, with persistence being a closer bet than cooler air. && .AVIATION.../For the 06Z TAFS through 06Z Tuesday night/ Issued at 1101 PM CDT Mon Apr 30 2018 Storms moving from SD and NE into IA overnight. Starting to lose their intensity, so have mainly kept VCSH in the TAFS overnight. Chances for storms again into by Tuesday afternoon/evening. Southerly winds through the period. Still strong low level winds aloft with some low level wind shear possible through 12z. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...Beerends SHORT TERM...REV LONG TERM...Kotenberg AVIATION...Beerends
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
837 PM CDT Mon Apr 30 2018 .UPDATE... Updated for evening discussion. && .DISCUSSION... A rather tranquil night is beginning to unfold as temperatures have already fallen off into the 60s. Still looking for some advection fog to affect the far southeastern sections late tonight/toward sunrise Tuesday, but the latest HRRR has backed off some on just how much of a denseness impact there will be. Will keep the limited category in the HWO going overnight in those areas./26/ Prior discussion below: Tonight through Tuesday... Latest RAP analyses and satellite imagery show upper level ridging pushing into the Mississippi Valley region. High pressure was providing sunny skies across the region. Mid afternoon readings were from the upper 70s to the lower 80s. For tonight expect a return of low level moisture across relatively cool ground over our southeastern counties which will cause some fog to develop early Tuesday. Hires guidance shows areas of fog possibly dense developing over the coast early Tuesday and making its way to the Marion County to Forrest County area with patchy fog possible across the northern portions of the Pine Belt area. Expect the fog to lift by midmorning. So for now will put a limited risk of patchy dense fog in the HWO. With that low level return moisture expect some instability for some isolated diurnal thundershowers across the southeast quarter of the region. Do not expect much coverage with the mid level ridge in place. Some of the model soundings showed some capping in place which will favor weaker intensity. With 925 mb temps around 19-21C expect highs from the lower to middle 80s./17/ Tuesday night through Sunday... A strengthening upper-level ridge of high pressure over the central Gulf Coast will dominate our weather through the rest of the work week. This should help to suppress rain chances until the weekend. The strengthening ridge should also suppress cloud cover Wednesday and Thursday, helping to boost Max temps about 5 to 7 degrees above normal for this time of year. Thursday looks to be the warmest day of the week, and although the forecast is for mid to upper 80s, it would not be a surprise if a few sites especially in southeast MS reached the 90 degree mark. The increased warmth will likely continued for at least southeast portions of the area Friday, but increasing cloud cover and influence from an approaching boundary may help to keep temperatures down over northwest portions of the area. Energy from a western CONUS trough is expected to shear out and drag a weak cold front into our area late Friday and into the weekend, with the final upper-level trough expected to pass by Sunday. Models have a few slight disagreements in timing, but overall thinking is for moisture plume to bend across our forecast area and provide moisture for showers and thunderstorms between Friday and Sunday. The threat for any organized severe weather looks to be low at this time, but some storms could become strong with modest instability during the afternoon hours. Gusty winds would be the primary hazard with any stronger storms. /NF/EC/ && .AVIATION... 00Z TAF discussion: VFR conditions will prevail for the most part. However, areas of fog advecting in from the Gulf of Mexico after 01/10Z will reduce flight categories to IFR/LIFR at HBG. Conditions will improve there after 01/13Z. Light winds can be expected overnight, but will increase from the south and southeast at 10 knots with gusts to around 20 knots by afternoon./26/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 54 86 63 86 / 0 14 2 3 Meridian 53 84 60 87 / 0 17 1 3 Vicksburg 57 86 66 86 / 0 11 1 6 Hattiesburg 54 83 61 86 / 3 19 1 2 Natchez 57 85 65 86 / 0 10 4 7 Greenville 56 86 66 86 / 0 7 2 4 Greenwood 55 86 65 86 / 0 8 1 3 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
923 PM CDT Mon Apr 30 2018 .UPDATE... 912 PM CDT Tonight`s forecast remains right on track and no changes planned. Have adjusted tomorrow`s temp/dewpoints. Earlier update lowered the dewpoints, especially eastern CWA as guidance has continued to exhibit a SIGNIFICANT high bias in Tds. The RAP/HRRR have been the only models close to reality. The RAP wasn`t available for the earlier update, but the new RAP has come in with Tds very close to what previous update had, perhaps a bit lower western CWA. Of greater interest is the latest RAP which has 2m temps solidly in the mid 80s across the CWA. The RAP last night was the warmest guidance I saw and was still not warm enough today, so given the parched soil moisture conditions, suspect the RAP 2m temp forecast for Tuesday is likely quite reasonable. Have bumped up high temps tomorrow to the mid 80s and if last night`s performance of the RAP for Monday`s highs is any indication then could even see someone tag 87 or 88 tomorrow, but didn`t get that carried away in the grids. Updated forecast coming momentarily. Updated fire weather discussion will be issued shortly as well. - Izzi && .SHORT TERM... 255 PM CDT Through Tuesday... Critical fire weather conditions continue across much of the CWA this afternoon. South winds have been gusting 20 to 25 mph, and infrequently to 30 mph across the NW CWA, since late morning. Meanwhile, dew points have struggled to rise through the day. RH values across much of the area this afternoon have therefore remained in the 15-20% range, with a few sub-15% values observed. Gusty south winds should ease somewhat through the night, but remain fairly steady at 10-15mph. Expect a mild spring night with lows in the 50s under mostly clear skies. On Tuesday, the area will remain wedged between a low pressure trough across the central Great Plains and high pressure across the SE states. Winds will be higher than today across the area as deeper mixing taps into 35-40kt winds in the 800-850 mb layer. Surface gusts in the afternoon should range from 35mph across the NW CWA and to around 30mph across the SE CWA. Temps will also be a couple degrees warmer than today, with highs in the low 80s across much of the area. Though dew points will rise to around 50F by Tuesday afternoon, elevated wildfire conditions are expected as min RH values reach 30-35%. Some model guidance is trying to bring residual convection from IA into the NW CWA during the afternoon. This convection will be moving into an increasingly unfavorable environment with a strengthening low-level cap. However, cannot rule out that a couple decaying storms will survive this far, so have added slight chance PoPs for generally the NW 3-4 counties. Kluber && .LONG TERM... 255 PM CDT Tuesday night through Monday... A jet max and associated shortwave will shift north of the area Tuesday night, but several fast moving waves will bring periods of showers and thunderstorms to the region. Coverage will be lower initially, but should ramp up during the Wednesday night through early Friday timeframe. The trough-ridge-trough pattern in place across the country, with the lower Great Lakes currently in the ridge portion, will slowly make eastward progress this weak as strong southwest flow pushes into the ridge. As the ridge axis over our area weakens Wednesday, increasing moisture ahead of the deep trough in the west should allow for a little better coverage of convection Wednesday, though we will still feel some of the ridge influence which should likely keep coverage isolated/scattered. It also still looks quite warm in spite of increasing clouds. Coverage should increase Wednesday night into Friday as the western low will eject into the plains Thursday and eventually merge with northern jet stream energy Thursday night. Timing the individual shortwaves will again be a challenge in this pattern. But there does appear a signal of favored times Wednesday night into early Thursday when the low level jet ramps up over the area, and then again Thursday night into early Friday when the main upper trough axis will shift through. Given the slow progression of the deep upper low, the main severe weather threat will still be focused to the west of the Mississippi River. We do get into window were some isolated strong to severe storms remain possible during this period, with locally heavy downpours also a distinct possibility. While excessive rain does not appear to be widespread, model QPF suggests some areas could see up to around 2" of rain by early Friday. Cooler and dry weather will return for the weekend, though certainly not as cool as the start to last weekend. High pressure will dominate, with a cold front on Saturday looking mostly dry, but it will trend our temps closer to normal Saturday and below normal Sunday. KMD && .FIRE WEATHER... 923 PM CDT Have updated temps/dewpoints tomorrow to raise high temps a few degrees. Earlier update lowered dewpoints over eastern CWA, but latest guidance would support slightly lower dewpoints west as well. Latest RH grid derived from the latest T/Td forecast has RH values bottoming out around or just below 25% over the red flag warning area and between 25-30% over rest of the CWA. Given the short term drought-like conditions, felt confident in making these changes to going temps/dewpoints and am concerned that RH could be even lower still. Winds are expected to be considerably stronger Tuesday afternoon and strongly considered expanding the red flag warning west to include the remainder of my CWA, but opted to let midnight shift take another look at things before making any expansion. Given the stronger winds and fuel moisture levels as low as I can recall seeing them in the past 11 years, even marginally higher RH than today could lead to a potentially very dangerous fire wx situation Tuesday afternoon with threat of very difficult to contain fires with potential for explosive growth. - Izzi && .AVIATION... For the 00Z TAFs... Frequency of gustiness should decrease early this evening, though some ocnl gusts are possible this evening at the Chicago terminals. Winds off the deck will increase late this evening with 45-50kt winds around 2k AGL, so going to maintain LLWS in TAFs. Gusty SSW winds are expected again Tuesday with gusts likely topping out between 25-30kt pretty regularly from late morning until early evening. VFR conditions through the TAF cycle. - Izzi && .MARINE... 255 PM CDT Surface high pressure will remain anchored over the southeastern United States for several days, while low pressure organizes in lee of the Rockies. Several waves of low pressure will pass over the northern Great Lakes through early Thursday and maintaining breezy, though sub-gale SW winds. Strongest winds will likely hold at 30 kt over the next few days. Eventually a cold front will setup/stall across the lake on Thursday before shifting south of the lake on Friday. West winds to 20-25 kt early Friday will give way to quieter conditions for the first half of the weekend with high pressure over the lake. KMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Red Flag Warning...ILZ013-ILZ014-ILZ022-ILZ023-ILZ033- ILZ039...noon Tuesday to 7 PM Tuesday. IN...Red Flag Warning...INZ001-INZ002-INZ010-INZ011-INZ019...noon Tuesday to 7 PM Tuesday. LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...9 AM Tuesday to 9 PM Tuesday. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Marquette MI
806 PM EDT Mon Apr 30 2018 .SHORT TERM...(This evening through Tuesday) Issued at 251 PM EDT MON APR 30 2018 The warmest day of the year so far continues with many areas hitting the mid to upper 70s as of this writing (except, of course, the far east where southerly winds off Lake Michigan is providing free air conditioning). High-level debris clouds from convection over Minnesota earlier this morning continues to stream eastward over the U.P. with an apparent MCV and associated light rainfall crossing along the Wisconsin/Michigan border. As the boundary layer continues to deepen and tap into the persistent southwesterly low-level jet, winds have started to gust upwards of 15 to 20 knots across the central and western U.P. which, when combined with dew points in the upper 20s to lower 30s, has led to dangerous fire conditions once again today. While some areas are flirting with red flag criteria, most fuels except for grass are (thankfully) not quite ready to go as passed along from the Michigan DNR. In fact, a small fire was detected in southern Marquette County earlier today but it quickly stopped after burning through the small grassy area. Winds are expected to decrease after sunset as the boundary layer decouples though dew points are expected to increase to mid to upper 30s if not lower 40s area wide. Lows tonight will likely be the "warmest" yet this season, bottoming out in the upper 40s to lower 50s. Such temperatures combined with increased moisture will really put a dent in what is left of the snowpack across the northern tier of counties along Lake Superior. Confidence is not overly high in the potential for additional precipitation this evening. It seems plausible that showers will regenerate across the central and eastern U.P. owing to subtle if not nebulous forcing as hinted by several MCVs passing through western Upper Michigan as of this writing. Such a scenario seems plausible as the aforementioned MCVs interact with increasing convergence along the strengthening low level jet this evening. The latest few runs of the HRRR and RAP show scattered showers redeveloping but vary spatiotemporally. Forecast model soundings indicate a wee bit of CAPE for parcels above the inversion this evening leveraging enough confidence for a clap or two of thunder with the heaviest cores this evening. All in all, have introduced slight chance PoPs area wide from basically now through the overnight hours with slightly higher PoPs from Marquette to Norway eastward after sunset where confidence is highest in coverage tonight. Tuesday looks like another busy day with fire weather and convective potential continuing. Owing to persistent southwesterly flow, dew points are expected to continue rising into the lower to mid 40s by mid-afternoon, and possibly lower fifties by Tuesday evening. Gusty southwest winds of 20-25 kts will also make a return increasing fire danger. However, somewhat moisture conditions are expected to limit the danger compared to yesterday and today. Cloud cover for tomorrow is quite tricky, but the gut feeling is that convective debris off storms expected in Minnesota tonight will spread east and as least partially cover us tomorrow. Even so, temperatures are expected to hit the upper 70s to even lower 80s across much of Upper Michigan. Showers and thunderstorms are then possible Tuesday evening, some of which may be on the strong side. For more details on the convective potential, see the long term discussion below. .LONG TERM...(Tuesday night through Monday) Issued at 315 PM EDT MON APR 30 2018 Late Tue the Upper Great Lakes will be within southwest flow aloft ahead of elongated trough over the western Conus. As one stronger shortwave exits well to the northeast of Lk Superior toward Quebec, another stronger shortwave will be crossing the northern Plains. Cold front well to east of northern Plains wave should be moving into western Upper Michigan to southern Minnesota by late aftn. Temps/dwpnts of 70s/upper 40s-lower 50s will support mlcapes over 750j/kg and perhaps up to around 1000 j/kg. Lift from the front on its own will be weak though but there are indications there could be smaller convectively induced shortwave approaching southern Upper Michigan 21z-24z. The front and instability pooling up over west and south central U.P. (sfc dwpnts maybe as high as 55-58F right ahead of the front) will probably be enough to support isold showers thunderstorms into early Tue evening. Effective shear of 0-6km is forecast over 40 kts so it is possible that an isolated stronger storm could occur over the far west/southwest into Tue evening. WBzero heights 8-10kft indicate storms could produce at least some small hail. If low-level jet was aimed into Upper Michigan instead of focused over WI and lower MI and/or the lead convectively induced shortwave moving into the area Tue aftn/evening is stronger think chances for stronger storms would be greater. Will be something to watch in the near term on Tuesday. With cold front arriving after the onset of the diurnal cooling cycle and then progressing eastward during the cooling cycle on Tue night, shra coverage should tend to be limited as the front crosses Upper Michigan. Could be some rumbles of thunder across much of the area Tue night, but with effective deep layer shear diminishing over central and eastern Upper Michigan, don`t expect any strong storms after the possible risk early Tue evening. Front will continue east across rest of the area Tue night into Wed morning. GFS slowed up with the front and still has lingering isold showers and a possible thunderstorm over south and east even into Wed afternoon. NAM is much quicker, exiting all chances out of the U.P. by Wed aftn while the GEM and ECMWF keep small chances Wed aftn over only scntrl. As is looks now, GFS seems too slow with the fropa and exiting of rain chances. Sfc front settles far enough south and east of Upper Michigan to lead to dry and cooler conditions Wed night and Thu. Coolest temps on Thu near Great Lakes. Could see more 60s over interior west though. Another chance of rain may return Thu night and Fri morning as shortwave and stronger sfc low in southwest flow moves through. Recent trends in models indicated majority of the rain tied to this system staying south and east of Upper Michigan closer to primary sfc front. 12z ECMWF lifts the shortwave farther north though so think the consensus chance pops east half are good for now. Based on track of sfc low, any thunder chances will stay south and east of Upper Michigan. Other than the potential rain, other main issue Fri will be gusty west to northwest winds on the Keweenaw Peninsula and eventually along rest of Lk Superior. Cooler and breezy conditions continue into Sat then slightly warmer on Sun. Depending on where sfc ridge sets up Sat night, probably could see a cold night with sub freezing lows possible inland. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 752 PM EDT MON APR 30 2018 A weak disturbance moving through the upper level ridge has brought some periods of isolated shra to Upper Mi this evening along with some mid-level clouds. However, given very low-level dry conditions, confidence was not high enough to include more than VCSH in the KIWD TAF. LLWS will increase at all TAF sites this evening and overnight as the boundary layer decouples and a southwesterly low-level jet reintensifies across the area. The strongest shear is expected at KSAW. As a trough approaches from the west Tue afternoon, some isolated showers could develop at the western taf sites. Diurnal mixing will allow for gusty ssw winds at or above 20 knots to develop again on Tue mainly at KIWD and KSAW. Expect vfr conditions at all the taf sites through the fcst period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 315 PM EDT MON APR 30 2018 Southerly winds 20-25 knots into the overnight hours across eastern Lake Superior and for Bay of Green Bay and northern Lk Michigan, with 10-15 knots expected elsewhere. Southwest winds of 10-20 knots persist Tue into Tue night before tapering off for much of the rest of the week. Stronger winds will return late Fri into Sat on Lake Superior as west to northwest winds reach 20-30 kts behind a cold front. && .HYDROLOGY... Issued at 315 PM EDT MON APR 30 2018 Ongoing warmup will result in well above normal temps through Tue. Combined with an increase in low-level moisture and breezy conditions, significant snow melt will continue. Additionally, a developing unsettled weather pattern will result in some showers at times, though moderate or heavy rain still appears unlikely at this time. In the end, the potential of minor river flooding will be on the increase the rest of the week in the typical basins prone to spring flooding. Rivers/streams in the Keweenaw will likely be most susceptible. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Borchardt LONG TERM...JLA AVIATION...Voss MARINE...JLA HYDROLOGY...JLA
Area Forecast Discussion
National Weather Service San Francisco Bay Area
501 PM PDT Mon Apr 30 2018 .SYNOPSIS...An upper level trough and weak weather disturbances will impact the region through Tuesday resulting in a slight chance of showers in the hills/mountains. High pressure will then build over the region late in the week to produce a warming and drying trend into the upcoming weekend. && of 01:43 PM PDT Monday...As the HRRR and local WRF suggested, showers have developed over portions of Napa County this afternoon with a decent amount of cumulus clouds. This is all in response to a colder air mass aloft and a weak short-wave disturbance approaching from the northwest. Elsewhere, a mix of sun and clouds persist with temperatures ranging from the upper 50s to middle 60s. Look for showers to diminish this evening by around sunset with overnight temperatures likely to fall into the 40s for most urban locations. Cannot rule out sprinkles or light rain showers over the northwest facing slopes across the Central Coast (similar to this morning) late tonight into early Tuesday morning as the broad mid/upper level trough drops southward across the region. In addition, another short- wave trough/vort max will pass over the region Tuesday afternoon and evening to provide another chance of rain showers, mainly over the hills/mountains of Monterey and San Benito Counties. High pressure is then forecast to build out over the eastern Pacific in wake of the passing mid/upper level trough. By late week, the ridge of high pressure will shift toward the coast and will allow for a warming and drying trend heading into the upcoming weekend. By Thursday, 70s will be more common inland for afternoon temperatures with lower/middle 60s at the coast. Temperatures are then likely to warm into the lower 80s on Friday across the warmer inland locations with upper 60s to lower 70s at the coast. Mild and dry weather appears to persist heading into next week as well with the region dominated by the ridge of high pressure. && .AVIATION...As of 4:40 PM PDT Monday...For 00z Tafs. Despite the lack of a marine layer patchy clouds persist across the region. The only terminals currently being impacted are in the Monterey Bay vicinity. VFR conditions expected across the area tonight with MVFR cigs expected to only scatter out temporarily this evening over Monterey Bay area terminals before returning once again tonight. Moderate confidence overall given the multiple cloud layers. Vicinity of KSFO...VFR conditions will prevail through the forecast period with few to sct clouds decks possible overnight. Gusty westerly winds this afternoon of 15 to 25 kt will ease late tonight into Tuesday morning. Moderate winds expected to ramp up once again Tuesday afternoon. SFO Bridge Approach...Similar to KSFO with possible cigs expected late tonight into Tuesday morning near the San Mateo bridge affecting the approach. Clearing anticipated Tuesday afternoon. Monterey Bay Terminals...Borderline MVFR/VFR cigs persist over area terminals and surrounding areas. Cigs anticipated to scatter out temporarily before returning this evening. MVFR cigs expected overnight. Cigs will scatter out around 18z Tuesday over KSNS while KMRY will once again likely only see partial clearing if at all. Moderate and gusty winds of 15 to 25 kt will gradually ease late tonight to around 10 kt. && of 04:39 PM PDT Monday...A strong pressure gradient over the waters will continue to produce gale force winds, especially over the northern outer waters overnight into Tuesday along with gusty winds along the Big Sur coast. The strong winds will produce fresh and choppy seas with short periods. Winds will gradually ease later Tuesday into Wednesday. Lighter wind and seas are forecast Thursday and Friday as high pressure returns and surface gradients relax. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pigeon Pt to Pt Pinos 0-10 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm GLW...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Mry Bay until 10 PM && $$ PUBLIC FORECAST: RGass AVIATION: CW MARINE: RWW Visit us at Follow us on Facebook, Twitter, and YouTube at: