Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/19/23

National Weather Service Albany NY
1022 PM EDT Tue Apr 18 2023 .SYNOPSIS... An upper low will continue to bring isolated to scattered showers through tonight. Some snow may mix in at times across the higher elevations north and west of the Capital Region. Below normal temperatures and brisk conditions are expected on Wednesday with sunshine mixing with clouds. High pressure builds in from the south Wednesday night into Thursday with a moderating trend of temperatures back above normal prior to the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 1022 PM EDT...Large upper level low remains situated north of the region over Quebec. Cyclonic flow around this feature continues to provide widespread stratus and stratocu clouds over the region. There have been a few breaks at times, but satellite imagery continues to show most areas are fairly overcast at this time. Cold advection is ongoing and the cloud shield will remain over our region through the night. The cyclonic flow, aided by some moisture off the eastern Great Lakes, has been allowing for some spotty light showers. Many of these have been drying up as they head eastward, but some rain will be possible at times. The highest terrain may be some wet snowflakes as well, with any accumulation limited to just an inch or less at the highest terrain. Based on radar imagery and 3km HRRR guidance, the best chance for showers may wind up being the first half of the overnight hours. Lows tonight in the 30s with 20s in the higher terrain. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Upper low exits through SE Canada and as upper heights begin to rise, some weak warm advection begins. Clouds will gradually decrease from SW to NE through the day and west to northwest winds will become gusty during the afternoon. High temperatures Wednesday will depend on the timing of the clearing since any sunshine along with the gusty winds would help temperatures to warm to the higher side of guidance levels. Highs in the 50s with 40s in higher terrain, could be well into the 50s in areas that see enough afternoon sunshine. Small upper impulse tracks through our region Wednesday night as flat upper ridging begins to build into our region. A tightening of the boundary layer thermal gradient with a little bit of enhances warm advection could support a few showers into the Schoharie Valley and eastern Catskills, and some intervals of cloud cover over the rest of the region. Stronger upper ridging into our region Thursday along with more rapidly warming boundary layer temperatures. A mix of clouds and sun with light winds and highs in the 60s with some 50s higher terrain. Continued upper ridging and warming through Friday before the leading edge of deeper moisture and some weak boundary layer convergence ahead of increasing boundary layer winds supports some mixed clouds and isolated to scattered showers late Friday afternoon into evening. Highs Friday in the 80s with some 70s in higher terrain. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Complex evolution of a closed upper low that forms in the western Great Lakes and very slowly builds east as an upper block in eastern Canada makes for highly amplified and slow moving upper flow in eastern North America Saturday through Monday. Increasing chances for showers as upper energy within the circulation of the upper low builds gradually east and strong south to southeast boundary layer flow brings moisture advection and warm advection, supporting the increasing chances for showers. There could be isolated thunder and locally heavy rain with the slow eastward movement of the axis of deeper moisture ahead of the thermal gradient at the leading edge of cold advection. The cold front and cold advection look to be times for Sunday or beyond and there are some disagreements in sources of guidance/ensembles as to the timing of the exit of the cold front. Including showers likely Saturday and Sunday. Highs Saturday in the 70s with some 60s higher terrain. Highs Sunday in the 60s with 50s higher terrain. There are hints that the upper energy weakens as it tracks through our region and moisture dissipates as the low level thermal gradient weakens as does cold advection. Still lingering weak upper energy could support more clouds than sun and scattered showers Monday into Tuesday. Highs Monday and Tuesday in the 50s with some 40s higher terrain. Potential drying into Wednesday with highs in the 50s to lower 60s. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Through 00z/Thu...An upper-level low will continue to swing across the region through Wednesday. VFR stratus continues across the TAF sites with some light precipitation mainly from around Albany and points north and west. Cannot rule out a shower or two through this evening at KALB/KPSF/KGFL, then shower chances will be fairly low overnight and through the day Wednesday. Cannot rule out brief MVFR cigs and/or vsbys in any showers this evening but any reductions should be very short lived, if they even occur. Due to this uncertainty, will maintain VFR conditions and monitor trends this evening if any amendments are needed. Some breaks in the clouds are expected on Wednesday. Wind will remain west to southwesterly tonight between 5-10 kt, then increase from the west to west-northwest on Wednesday at 10-15 kt with gusts 20-25 kt. Outlook... Wednesday Night: No Operational Impact. NO SIG WX. Thursday: No Operational Impact. NO SIG WX. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: Moderate Operational Impact. Chance of SHRA. Saturday: Moderate Operational Impact. Breezy. Chance of SHRA. Saturday Night: High Operational Impact. Breezy. Likely SHRA. Sunday: High Operational Impact. Breezy. Likely SHRA. && .FIRE WEATHER... Wind gusts 25 to 30 mph expected Wednesday afternoon... An upper low will continue to bring isolated to scattered showers through tonight. Some snow may mix in at times across the higher elevations north and west of the Capital Region. Below normal temperatures and brisk conditions are expected on Wednesday with sunshine mixing with clouds. High pressure builds in from the south Wednesday night into Thursday with a moderating trend of temperatures back above normal prior to the weekend. RH values will be above 70 percent tonight and drop to 30 to 45 percent Wednesday afternoon. RH values rise again above 70 percent Wednesday night and dry out to 35 to 45 percent Thursday afternoon. Winds will be west to northwest at 15 mph tonight, then increase to 15 to 20 mph Wednesday morning and afternoon with gusts 25 to 30 mph. Winds diminish to 15 mph or less Wednesday night. Winds become west to southwest Thursday at 15 mph or less. && .HYDROLOGY... Flood Warning for the Schroon River at Riverbank remains in effect as it continues to hover in the minor flood stage in response to snowmelt and some rain yesterday. It is expected to remain in minor flood stage over at least the next couple of days. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...NAS NEAR TERM...Frugis/NAS SHORT TERM...NAS LONG TERM...NAS AVIATION...Rathbun FIRE WEATHER... HYDROLOGY...
Area Forecast Discussion
National Weather Service Denver/Boulder CO
800 PM MDT Tue Apr 18 2023 .UPDATE... Issued at 750 PM MDT Tue Apr 18 2023 Cross-sections show moisture will increase late tonight into Wed morning over the nrn mtns. In addition QG fields show developing ascent as well. Thus should see an increase in snow shower activity late tonight into Wed morning across the nrn mtns. At lower elevations there has been some virga this evening over the plains with brief gusty winds up to 50 mph. Also satellite shows some blowing dust across srn Lincoln county so have mentioned that in the fcst for this evening. && .SHORT TERM...(This evening through Wednesday) Issued at 200 PM MDT Tue Apr 18 2023 Core of stronger winds aloft ahead of the ejecting shortwave in the Northern Rockies is currently working into the state, and will push across the Front Range and adjacent plains late this afternoon and evening. We`ll see gusty winds continue in most areas into early evening, although the classic shear zone (in southwest flow events) that stretches from the western suburbs of Denver to the northeast into Weld and Morgan Counties will be slow to succumb. Meanwhile, there was increasing convection over northwest Colorado which will be pushing slowly east/northeast into the northern tier of mountains through this evening. Later tonight into Wednesday morning, weak Q-G lift but a band of stronger mid level frontogenesis arrives. This would support a round of decent snow for the high country, despite the relatively limited moisture. The moisture will hold back accumulations, but we will have high PoPs and snow amounts of 1-6" in mountain areas through Wednesday. Lots of spread there, but that`s typical spring-time in the Colorado high country. By early to mid afternoon Wednesday, we`ll see at least scattered showers spread onto the plains. That will be aided by the F-gen, weak QG, and even some shallow anticyclonic upslope flow on the plains. That upslope develops and slowly deepens behind tonight`s cold front. We don`t see the amount of erosion of this shallow cold pool offered up by the HRRR and RAP as these models typically overmix, and thus we`ll likely maintain an east to northeast component in areas north of I-70 tomorrow. Temperatures will be warm enough for mostly rain in lower elevations (below 6000 feet), but can`t rule out a few snowflakes in a couple spots by very late in the afternoon as the column cools thanks to precipitation and latent heat of melting. .LONG TERM...(Wednesday night through Tuesday) Issued at 250 PM MDT Tue Apr 18 2023 The axis of a shortwave trough will be moving across our forecast area Wednesday evening. This will combine with the factors mentioned above (frontogenesis, weak QG ascent, shallow upslope flow) to create a few bands of precipitation mainly across the eastern plains along I-70. During the evening, the precipitation may transition from mostly rain to mostly snow as colder air behind a cold front along with the loss of daytime heating will help this transition. Considering temperatures earlier in the day will be in the 50s, most of the snow will melt on contact. However, some of the stronger bands of snow may be able to have snowfall rates that overcome the melting for a brief period of time such that about an inch of snow accumulates on the grassy/elevated surfaces. Snow is not expected to accumulate on pavement so travel conditions will be ok. Across the mountains and foothills, the precipitation will fall as all snow Wednesday night but there will be a lack of moisture aloft so snowfall amounts will be rather light. A broad trough will begin to stall over the Northern Plains on Thursday with very cold air aloft over Colorado. 500 mb temperatures will be as cold as -30C and 700 mb temperatures will be as cold as -10C. Assuming some sun will make it to the surface during the day on Thursday, there will be very steep lapse rates that develop up to 9.5 C/km. Convective showers, mainly over the higher terrain, will develop in the afternoon. The western slopes of the mountains may see another couple inches of snow accumulation. Across the plains, there will likely be scattered rain/snow showers. These likely won`t amount to much at the surface. Otherwise, high temperatures will be well below normal with highs in the mid 40s across the plains. Friday will be somewhat similar to Thursday with cool temperatures. A jet streak will move across our area with the left exit region providing lift during the day. There will again be scattered snow showers in the mountains with rain/snow showers across the plains. The NBM was quite excited about strong winds across the northeast plains on Friday afternoon. It is possible that gusts reach 50 mph especially in the usually windy spots like Akron. Northwesterly flow will persist into the day on Saturday. Models are coming into agreement that a very slight shortwave trough will move across our forecast area with increased mid level moisture. This will keep the snow showers going in the mountains with a few making it onto the adjacent plains. Temperatures will modify slightly. Ridging over the western US will develop on Sunday and Monday. This will allow for temperatures to warm to seasonal normals. The ridge aloft should provide enough subsidence that precipitation doesn`t form but a couple isolated showers can`t be ruled out. Ensembles are showing a strong signal for precipitation across our entire CWA during the late Tuesday into Wednesday period of next week. We don`t know many details about this period but it has the potential for higher end precipitation amounts. Most of the ensembles are too warm for snow across the plains though. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 529 PM MDT Tue Apr 18 2023 Winds will remain gusty from the southwest up to 35 mph through 02z but then should decrease. Overnight, winds will gradually shift to more northwest by 06z and then to the east northeast by 09z. Winds will then become southeast by 11z. On Wednesday will keep winds more easterly by 18z and then northeast by 21z. Ceilings will drop down to 7000 ft by 21z with with a chance of rain showers. && .FIRE WEATHER... Issued at 200 PM MDT Tue Apr 18 2023 Red Flag conditions are developing this afternoon and will become more widespread through late afternoon/early evening. We`ve opted to extend the Red Flag another hour (until 8 pm) due to arrival of mid level wind field max late this afternoon and early evening which will keep winds blowing stronger, later. We may even need another hour or so near the Palmer Divide/southern Foothills where humidity recovery will be slower due to gusty winds/mixing, so will continue to monitor. Eventually humidity recovery will be better with cooling temperatures and weakening winds overnight. On Wednesday, we`ll be approaching critical Red Flag levels in South Park and the foothills of far southern Jefferson/Douglas Counties. However, humidity should stay a few percentage points above 15%, and clouds will increase in the afternoon keeping conditions shy of Warning criteria. && .BOU WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM MDT this evening for COZ214-216- 238>251. && $$ UPDATE...RPK SHORT TERM...Barjenbruch LONG TERM...Danielson AVIATION...RPK FIRE WEATHER...Barjenbruch
Area Forecast Discussion...CORRECTED
National Weather Service Quad Cities IA IL
652 PM CDT Tue Apr 18 2023 ...00Z AVIATION UPDATE... .SYNOPSIS... Issued at 222 PM CDT Tue Apr 18 2023 Latest sfc analysis was indicating a quasi-stationary front draped from west-to-east acrs KS and central MO, while high pressure occupied the upper MS RVR Valley. Despite ample sunshine, weak sfc wind/mixing regime hindering afternoon temp warm up some. Aloft,an omega type upper ridge was pressing eastward acrs the MO and MS RVR Valleys while a short wave trof was seen on water vapor imagery shearing acrs the central to northern Rockies. && .SHORT TERM...(This evening through Wednesday) Issued at 222 PM CDT Tue Apr 18 2023 Tonight...Fair early evening, before an increasing south to southwesterly H85 MB jet of 30-40 KTS cranks up and produces an elevated convergent THTA-e feed wing pushing north acrs the area. With increasing mid layer MUCAPES and 6.5+ lapse rates aloft, this process should fuel a sctrd band of high based showers and a few thunderstorms after 10-11 pm or so. These same processes already perculating some activity acrs MO into southern IL this afternoon. This as we get on the other side of the upper ridge lobe and southwesterly steering flow with a lead vort max sprawls in acrs the region from the west. Some of this initial activity may produce small hail an brief passing downpours, before lifting out of the northern cwa after 4 am. The main front to the south will look to try and retreat into the southern CWA toward dawn. Ongoing LLJ converging on an elevated boundary and remnants of the earlier precip activity with a stronger approaching vort max, may spark a new cluster of showers/storms before 12z acrs central into eastern IA. This new 2nd round of elevated convection will then look to push eastward acrs the CWA into mid Wed morning above substantial lower level inversion. Wednesday...Will have to walk the above mentioned cluster of showers/storms acrs the CWA thru at least late morning. Looking at a higher mid layer CAPE/lapse rate plume with 25-40 KT effective storm layer shear, some concern that the morning activity may have a better chance to produce larger hail near severe criteria than the overnight activity. If the warm front can make it far enough north, a gradient riding storm may also be capable of some enhanced wind gusts. But hopefully they stay elevated north of the main boundary with just a hail and locally heavy downpour threat as PWATs increase to 1 to 1.2 inches. After the morning activity clears, much of the afternoon may then be precip free. Challenging high temp fcst depending on extent of warm front retreat and convective debris clear off or sustenance. Could be a large gradient from the low 60s in the far north/Hwy 20, to the mid an upper 70s in the far south. Breezy as well south of the main warm front with any clearing and mixing. ..12.. .LONG TERM...(Wednesday night through Tuesday) Issued at 222 PM CDT Tue Apr 18 2023 Key Messages: 1. Showers and thunderstorms, possibly severe, Wednesday night and again Thursday afternoon 2. Near or below freezing low temperatures Friday Night through Monday morning Wednesday night and Thursday, showers and thunderstorms will be seen across the area as a warm front pushes north through the area late Wednesday and then a cold front sweeps across the area on Thursday morning into the afternoon. Overall not much change to the previous forecast. SPC has maintained the Slight risk for severe storms in the west and northwest portions of our CWA for Wednesday night with a Marginal risk elsewhere. The main threat will be large hail with wind gusts near 60 MPH as a secondary threat as storms bleed into the area from central Iowa mainly in a weakening phase, but can`t rule out some stronger cells especially in the evening. The showers and storms, mainly sub-severe, will progress east with the cold front Thursday morning. Some CAMs are showing a resurgence or strengthening of storms again near and more-so east of the MS River in the early afternoon hours Thursday. This will be quick to move out of the CWA. SPC has a Marginal risk for severe storms for areas along and east of a line from Geneseo to Sterling. With the rain and cold front, temperatures were nudged down a bit with upper 50s west and upper 60s east. Winds ahead of the front on Thursday will be quite gusty out of the south, with gusts of 30 to 40 MPH. Friday through Monday, generally dry conditions are expected as a sprawling high pressure builds in from Canada. Much colder temperatures will be common, with overnight lows in the upper 20s to mid 30s. Each night portions or all of the area may need freeze headlines. Saturday, highs will only be in the 40s. Highs Monday and Tuesday will get back into the 50s to low 60s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 645 PM CDT Tue Apr 18 2023 VFR conditions are expected for much if not all of the evening. A lifting warm front overnight and Wednesday will bring a couple of chances for showers and storms (the first 05z-09z from south to north across the terminals, and the second chance 13z-16z mainly at CID/DBQ). This was handled with either prevailing or VCSH/VCTS mention. CIGs will lower into MVFR to lower VFR on Wednesday, with a chance for IFR at DBQ. LLWS mention was retained for later tonight (07z-13z), despite latest CONSShort guidance backing off on potential, as NAM and HRRR soundings do show an uptick in winds to around 40 kts in the 1000-1500ft layer from S/SE. Surface winds will become occasionally gusty at 10-20+ kts from E to S/SE later tonight and Wednesday. && .HYDROLOGY... Issued at 222 PM CDT Tue Apr 18 2023 The 2023 Spring Snowmelt Flood will continue to work its way down the main stem Mississippi River over the next couple of weeks. This morning, re-issued warnings to increase the forecast flood category to Major flooding for Dubuque Railroad Bridge, Camanche, and Rock Island. Elsewhere from Dubuque to Burlington, the 7-day forecasts have maintained the Moderate flood categories. Additional rises are expected beyond the 7-day forecast. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...12 SHORT TERM...12 LONG TERM...14 AVIATION...McClure HYDROLOGY...14
National Weather Service Hastings NE
556 PM CDT Tue Apr 18 2023 ...Aviation Update... .DISCUSSION...(This evening through Tuesday) Issued at 302 PM CDT Tue Apr 18 2023 Key Messages: * Strong to severe thunderstorms possible this evening/tonight mainly between 6 PM and 1 AM with large hail and damaging winds the primary severe weather threat. * Showers and thunderstorms are again possible Wednesday evening into Wednesday night with a slight threat for severe storms mainly across our far southeastern zones. * Near critical to critical fire weather conditions expected most days across portions of the outlook area through Friday. See fire weather section below. * Hard freeze expected all areas Saturday and Sunday morning. This Evening And Tonight... The SPC has issued a Marginal Risk for severe thunderstorms for this evening into tonight. The main forecast concern has centered around how quickly the moisture can return northward today as dew points started out the day in the 20s. At 3 PM dewpoints across the forecast area were generally still in the lower 40s. We have some forecast models such as the 12Z and 18Z NAM that nose 60 degree dewpoints into our southern Kansas zones with a strong low level jet late this evening. There is good agreement between forecast models (18Z HRRR, NAM, NAM NEST, and 12Z GFS) that we will see convective initiation prior to sunset (5-8 PM) over our southwestern forecast area. These thunderstorms will then track northeast through the evening hours and may be enhanced by strengthening low level jet after dark along with additional thunderstorm formation as the low level jet ramps up. MLCAPE values around 1500 J/KG along with deep layer shear values of 40-50 KTS and steep lapse rates will support vigorous updrafts and the potential for severe wind and hail. The wind threat will be greatest early on with the inverted V soundings and steepest lapse rates early. The storms should become more elevated with time after sunset with primarily a hail threat late. Could certainly see the possibility for needing several severe thunderstorm warnings this evening. Wednesday... Cooler with northerly winds behind the front. The 18Z NAM seems too far northwest with the precipitation as the front pushes back to the northwest during the afternoon hours allowing for significant precipitation as far northwest as the Tri-Cities. Am not buying heavy precipitation that far northwest or the surface front pushing that far back to the northwest. The 18Z HRRR solution seems more realistic with most of the strong to severe thunderstorms south of our forecast area closer to a more southerly cold front location. I would sure love to receive the 18Z NAM precipitation here in the Tri-Cities, but is seems unlikely that the front will return that far northwest. There is still some uncertainty here, but I would not get your hopes up for big rain across our forecast area Wednesday evening. Our rain chances are probably on the highs side. Wherever the front is there will be a threat for severe thunderstorms and that could clip our southeastern most zones Wednesday evening. Thursday and Friday... Breezy northwest winds on Thursday and down right windy on Friday will lead to at least near critical fire danger with the RH being somewhat marginal. See fire weather section below. Temperatures will be falling as cold air swings south behind a large northern plains upper level low. Saturday and Sunday... Overall a cool weekend in a northwesterly flow regime with morning lows expected to be in the 20s, which may lead to some problems for area trees that have flowered early or for tender garden plants that were planted during our recent warm spell. Sunday should be the better day with lighter winds and temperatures finally starting to rebound. Monday and Tuesday... Next storm system approaches and then enters the plains and will bring at least some chance for rainfall, but too far out for much certainty at this point. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 546 PM CDT Tue Apr 18 2023 Scattered thunderstorms moving out of KS may affect the GRI vicinity this evening. LLWS is expected into early Wednesday morning when winds turn to the northwest. Northwest winds gradually decrease through the mid to late afternoon Wednesday. && .FIRE WEATHER... Issued at 302 PM CDT Tue Apr 18 2023 Wednesday...The RH values should be very low in the teens by afternoon, but the wind will be decreasing through the afternoon hours and thus am not expecting the need for a fire weather headline given the decreasing winds. Thursday and Friday... The winds pick up out of the northwest especially on Friday, but the RH values will be a bit higher due to cooler temperatures. Even so, we could approach near critical or critical fire weather conditions mainly across southwestern zones. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Wesely AVIATION...Mangels FIRE WEATHER...Wesely
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Tue Apr 18 2023 .SHORT TERM...(Through Tonight) Issued at 418 PM EDT TUE APR 18 2023 The closed low over southern Quebec as noted on RAP analysis and water vapor imagery is progged by models to continue to lift east- northeast through Quebec tonight as ridging and associated subsidence from the Plains builds in behind it into the Upper Great Lakes. As a result, lingering clouds, gusty northwest winds to 25-30 mph and isolated -shsn over the mainly the east half will quickly dissipate or diminish later this evening/early evening resulting in dry conditions and a clearing trend into tonight. Given the expected dry conditions, the forecast focus will be on min temps tonight as building high pressure will result in winds weakening or going near calm under clear skies and the recent snow from yesterday into tonight will aid radiational cooling tonight. Subsequently, went on the lower end of model guidance with min temps tonight. Expect readings to get into the lower to mid teens over the interior west with mostly 20s readings elsewhere. Gut feeling is readings could go lower than this so evening shift may need to keep an eye on temp trends and adjust mins accordingly. .LONG TERM...(Wednesday through Monday) Issued at 325 AM EDT TUE APR 18 2023 Moving into the middle part of the this week, expect temps to return to around normal for this time of year, with highs generally getting into the 40s to some low 50s in spots. In addition, a strong, vertically-stacked lower pressure system is expected to set up over the Northern Plains around the US/Canada border beginning Wednesday. This low looks to push its warm front over us sometime Wednesday, bringing in our next chance for precipitation into the afternoon. With the frontal passage, expect to see mainly rainfall, although there may be a wintry mix of snow, sleet, and freezing rain early. However, with quite a bit of dry air at lower levels, very little by way of any precipitation should be reaching the ground before Wednesday afternoon, so accumulating snow/ice is not a particular concern. This initial round of precip, while dropping only around a quarter to perhaps a half inch of rain, may slow the descent of river levels across the UP. There may be a quick break in the precip Wednesday night as a shortwave low lifting from the Central PLains moves towards the area. However, if the precip continues, expect it to be light rain save for maybe a transition to freezing rain over the Michigamme Highlands. Don`t expect much of a break in the precip if we do get one, however, as the vertically stacked low over the Northern Plains pushes the deepening shortwave low over the area Thursday. With the passage of this shortwave low, expect only rainfall, with a few thunderstorms being possible. We may need to keep an eye on some flooding concerns Thursday into Friday as ensemble guidance is showing PWATs flirting with the 90th percentile to modeled climatology, not to mention the high river levels and the wet soils still remaining across the area; some minor flash flooding may even be a concern under the strongest thunderstorms. The area that would be of most concern is the western UP, where the heaviest liquid amounts fell over the past several days. Many of the GFS and Euro ensembles also show a swath of heavier QPF over the western half of the UP Wednesday through Thursday. The low over the Northern Plains begins to phase with the deepening shortwave low as it moves over the Upper Midwest and Lake Superior late in the workweek. This in turn, could bring a dry slot over us late Thursday night and a brief break in precipitation. However, some lake-effect snow could be seen on the backside of the phasing lows late Friday as cooler NW flow develops over the area. Colder than normal temps and possibly some weak lake-effect/upslope snow looks to continue over the N snow belts into this upcoming weekend. Temperatures start to increase again early next week and dry weather returns as the sprawling low slowly meanders E/NE into Ontario. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 743 PM EDT TUE APR 18 2023 VFR will prevail thru the night at IWD/CMX/SAW, though there may be bkn MVFR cigs at 3000ft for the next couple of hrs at SAW. Winds will become light at all terminals as high pres ridge passes. On Wed, a warm front to the s may generate pcpn as far n as portions of Upper MI. This pcpn may reach IWD early aftn and SAW late aftn. While CMX/SAW will remain VFR on Wed, cigs should fall to MVFR at IWD by late aftn. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 418 PM EDT TUE APR 18 2023 Any lingering nw gale gusts should dissipate over the eastern shores of Lake Superior early this evening as the low over Quebec continues to push eastward. Wind gusts should die down briefly to 20 knots or less later tonight as a high pressure ridge moves over the Upper Great Lakes. This brief lull in the winds will come to an end late Wednesday morning. Easterly winds of around 20 to 30 knots develop over the western lake by Wednesday afternoon as the warm front of vertically- stacked low pressure begins to move into the region; a few gale- force gusts up to 35 knots are possible near the MN shoreline. As a deepening shortwave low over the Central Plains lifts towards Lake Superior Wednesday night and Thursday, expect ENE winds to begin picking up over the rest of the lake; gales of 35 to 45 knots are expected Thursday into Thursday evening across the western half and north central portion of the lake and Gale Watches have been posted for that time period, and up to 35 knots in the eastern half. As this low lifts through Lake Superior Thursday night, expect the winds to die-down and turn slightly NW`rly behind the low; NW winds of 20 to 25 knots are expected over the lake by Friday. Another low pressure lifting through the Lower Midwest into southern Ontario Saturday should result in 20 to 30 knot N`rly winds late Saturday into Sunday. North gales to 35 knots can`t be completely ruled out over the east half of the lake during this period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Watch from late Wednesday night through late Thursday night for LSZ162-263. Gale Watch from Thursday morning through late Thursday night for LSZ243-244-266-267. Gale Watch from Thursday morning through Friday morning for LSZ264. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...LC AVIATION...Rolfson MARINE...Voss
Area Forecast Discussion
National Weather Service San Francisco Bay Area
402 PM PDT Tue Apr 18 2023 .SYNOPSIS...Below normal temperatures on Tuesday give way to a gradual warming trend through the end of the week. Drier conditions remain in place, including into the extended forecast. && of 01:40 PM PDT Tuesday...As the last two showers over the ocean began to fizzle out, confidence was high enough to switch the radar back to "clear air" mode. The HRRR still has the chance for a last push of scattered showers Tuesday afternoon, mainly over the waters, but with the possibility of it moving over the Sonoma coastline. But given how clear the skies are over the northern waters currently, there is low confidence in it transpiring. And should it happen, there is high confidence for it only being light rain with minimal accumulations. While the cold front is long gone and traveling over Southern California, northwest flow prevails over the Bay Area and the Central Coast, with a cooler air mass in place. Temperatures at the time this discussion was posted are running one to two degrees warmer than what they were just 24 hours previously on Monday. Despite that "warmth", the remain in the upper 60s. And considering the mid-to-upper 60s is normal for the area this time of year, it still remains cooler than what we would expect. With skies continuing to clear, that will allow for more radiational cooling overnight for another morning of chilly temperatures. Interior sheltered valleys have the chance to drop into the upper 30s Wednesday morning. While widespread temperatures at or below 35 degrees Fahrenheit is not expected, there is the risk of patchy frost in certain areas. Considering there was no major change in models compared to previous runs, and the lack of widespread areal coverage, no Frost Advisory was issued. However, for those with sensitive plants in interior areas, taking precautions against tomorrow morning`s temperatures would not be the worst idea either. By Wednesday afternoon, ensemble members are showing agreement in strengthening ridging for 500 mb heights to grow through out the end of the week. Wednesday will still be at or below seasonal norms, whereas the main warming will become apparent on Thursday afternoon with Friday and Saturday being the warmest of the week. With 850 mb temperatures increasing to at least 10 degrees Celsius, mid-to-upper 70 degrees Fahrenheit is certainly in play for interior areas with the chance for even some low 80s. With the higher pressure in place, there is no precipitation in the forecast through the weekend. The weather pattern looks to change at the start of next week. Ensemble members are showing another upper level trough to develop at 500 mb west of British Columbia Sunday afternoon, which will translate to weakening high pressure around the Bay Area with more zonal flow aloft. This will allow so cooler air to slip in. While it is not a strong cooling trend, there is a chance for a few numbers to drop back below seasonal norms. But it won`t last long. The way ensembles are looking for late next week, it could have high pressure grow once again for a return of warmer temperatures. As it stands, the trough early next week does not have much moisture with it and limited instability. Add that to the chance for high pressure at the end of next week and it translates into no precipitation in the current forecast. && of 4:00 PM PDT Tuesday...For the 00Z TAFs. Generally VFR through the TAF period. Light winds overnight becoming locally breezy through the coastal gaps (AKA SFO) late tomorrow afternoon. Low probability for a ceiling at/around KMRY tonight with the greatest odds between ~07-12Z. VFR expected all areas for tomorrow. Vicinity of KSFO...VFR. Light winds overnight becoming onshore and breezy tomorrow afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Generally VFR. Small potential (~20 percent) for a ceiling at KMRY late tonight. Light E-SE drainage winds overnight. Onshore winds developing tomorrow afternoon. && of 08:28 AM PDT Tuesday...Breezy to gusty northwesterly winds continuing through late week, with hazardous seas through Tuesday, seas temporally subsiding during midweek then increasing late week. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Mry Bay 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...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm && $$ PUBLIC FORECAST: DK AVIATION: SPM MARINE: Canepa Visit us at Follow us on Facebook, Twitter, and YouTube at:
Forecast Discussion:

This afternoon, a mid level ridge is moving east of the area with several shortwave troughs noted aloft over the northwestern quadrant of the US. A surface ridge axis stretches from central Canada southward toward a large surface high over the southeastern US. Dew points have been increasing and are approaching 50 degrees within southerly low level flow today. With the moisture advection, a dryline will set up in western Kansas this evening. A few of the CAMs have been consistent in the development of isolated storms ahead of the dryline this evening. Storms that form are expected to move northeast toward north-central Kansas. At 00Z, the environment in north-central Kansas will consist of high LCL`s and substantial SBCIN, but steep mid level lapse rates and around 1000 J/kg of elevated CAPE. There does appear to be ample cloud layer shear, especially as a 60+ kt LLJ develops into tonight. Thus, any storms that are able to develop will pose a risk for large hail and damaging winds. Focus then shifts to a more widespread threat for severe thunderstorms tomorrow (Wednesday) evening and night. By tomorrow afternoon, a cold front will be draped across north-central KS as low pressure deepens in southwest Kansas. A dryline will extend from the low southward through OK and TX. Destabilization of the atmosphere will occur as temps warm and dew points reach the low 60s in eastern KS. MLCAPE is likely to exceed 2000 J/kg near and south of I-70. Thunderstorm initiation ahead of the cold front is possible by 23Z or 00Z (6 PM or 7 PM). Effective inflow shear initially does not look overly strong, however, and enhancement in shear and an enlargement in hodographs is expected as a LLJ develops during the evening. All modes of severe weather will be possible with large hail and damaging winds being the main hazards. A few tornadoes could also occur given shear parameters. Coverage of storms is likely to increase into the overnight period as the jet strengthens with storms growing upscale into a line segment. Damaging wind and hail will remain possible into the night. Thunderstorms should exit to the east Thursday morning. Elevated fire danger could again occur Thursday afternoon in central and north-central KS, where less rain is expected this week. RH values fall to near 20 percent in that area with gusty west- northwest winds Thursday afternoon. Less than ideal weather for burning is also expected Friday and early this weekend with gusty winds and low afternoon RH continuing. A cool Canadian based air mass then looks to settle into the area late this week and during this upcoming weekend. With that, high temperatures are expected to be in the 50s Friday and Saturday with overnight lows dropping to near freezing Friday night and possibly in the 20s Saturday night. For reference, average temperatures right now in Topeka are 45 degrees for the low and 68 degrees for the high. Temperatures will then gradually warm each day into early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 544 PM CDT Tue Apr 18 2023 This evening`s convection should remain north and west of the terminals given large MLCIN over northeast KS and the dry line remaining well west of the terminals. Strong winds overnight and into Wednesday are forecast. Winds around 3KFT are expected to increase to around 60KT. A strong pressure gradient is expected to prevent the boundary layer from decoupling and turbulent mixing is likely to limit wind shear. So will not include wind shear in the forecast, but anyone flying overnight is likely in store for a bumpy ride. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 3 AM CDT Wednesday for KSZ008-009-020>022- 034>038-054. && $$ UPDATE...Wolters DISCUSSION...Teefey AVIATION...Wolters