Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/17/23

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Wednesday Night) Issued at 243 PM CDT Tue May 16 2023 We continue to watch the progression of upper level smoke drifting south-southwest into the CWA. RAP-Smoke Vertically Integrated output has this handled pretty well when aligning it with current satellite data. Trend remains in bringing this area of smoke further south and west through the CWA into the evening hours, then an eastward drift and eventually out of the area through the day Wednesday. Will then have to keep an eye on the near-surface smoke potential Wednesday night with the frontal passage, which the RAP model keeps bringing across the CWA. Aside from the smoke, the Wednesday night frontal passage is the other forecast highlight. Timing remains similar to previous model runs, with the front moving into north central SD after 21Z and placement near MBG at 00Z. It appears the front will clear the whole CWA by 12Z Thursday. Coverage of showers looks to be scattered to perhaps numerous (in spots) along the front. Still not too excited about the severe potential, but cannot rule out a few strong to perhaps marginally severe storms with gusts over 50 mph across central SD. Best instability with MLCAPE on the order of 1000-1500 J/KG sets up along/ahead of the front late Wednesday afternoon over central SD, but quickly wanes with the loss of daytime heating, with very limited instability further east across the CWA as the night progresses. Shear values are lacking as well. So, seems there`s a late afternoon/early evening threat for a few strong to perhaps severe across central SD, but with the loss of daytime heating, don`t expect that threat to translate too much farther to the east. .LONG TERM...(Thursday through Tuesday) Issued at 243 PM CDT Tue May 16 2023 Northwest flow shortwave moves across the area early in the extended with a cold front moving rapidly out of the CWA. Showers will be moving southeast associated with this feature...however with a colder airmass, post frontal showers and weak thunderstorms are possible according to BUFKIT profiles which is the reason for most of the POPs here. Loss of daytime heating will reduce coverage of showers/thundershowers and a 1024mb high sinks into the western Dakotas Friday morning. Gradient winds east river should keep us mixed, though 850mb fall as low as -2C in far northeast South Dakota/western Minnesota, so even with mixing temperatures could still fall well into the 30s. Mixing should keep any frost from forming it will take ground temps at/below freezing to see any damage. Out in far northwestern counties, a bit better scenario for radiative cooling thanks to the high placement, for frost. Either way, its going to be close for some places. A general warming trend follows thereafter. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 631 PM CDT Tue May 16 2023 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast through the TAF period. A layer of smoke aloft will remain over the region tonight. It`s possible some of this wildfire smoke may get ducted down to/near the ground late in the day on Wednesday in the wake of a cold front forecast to sweep southeast across the forecast area. For the moment, some shower/VCTS has been introduced into the KMBG TAF way out at the very end of the TAF valid period. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...TMT LONG TERM...Connelly AVIATION...Dorn
Area Forecast Discussion
National Weather Service La Crosse WI
617 PM CDT Tue May 16 2023 .DISCUSSION...(This evening through Tuesday) Issued at 227 PM CDT Tue May 16 2023 Key Messages: - Wildfire smoke to linger over the area into Wednesday. - Next chance for rain comes in Thursday afternoon and lingers into Friday. Limited CAPE and shear to work with with extremely low severe probabilities. Tonight - Wednesday... Visible satellite shows an area of smoke from some Canadian wildfires has worked south across the Upper Midwest and over the local area. Looking at the vertical integrated smoke fields from the RAP suggest this smoke might thin out a little overnight before thickening up again during the day Wednesday. Some potential that a little bit of the smoke could get mixed down to the surface this evening behind the weak cold front that is working across the area. Thursday... The next chance for rain is centered on Thursday afternoon and night as a cold front sweeps across the region. The upper level low over the central Canadian Rockies is expected to drop southeast across the Upper Midwest and Great Lakes Thursday afternoon into Friday. Still some differences between the models on how far south the upper level low is expected to get before turning more to the east to track across the Great Lakes. However, all the models show that this system will have a positive tilt to it placing the best pv advection and forcing on the poleward side of the system. In addition, the flow south of the upper level low looks to be zonal and not off the Gulf of Mexico, the moisture return ahead of the low looks to be very limited. This is expected to result in limited CAPE being available for the system to work with. The NBM shows maybe around 500 J/kg of SB CAPE Thursday afternoon with the NAM very similar with the ML CAPE. With the positive tilt, the deep layer shear will be mainly behind the front with maybe up to 30 knots in the 0-3 km layer available to work with. This looks to be enough to support some general thunder but not anticipating any severe storms to occur, which is in agreement with current SPC day 3 outlook and Colorado State machine learning forecast. Friday into the weekend... Depending on how fast the upper level low departs the region, there is a small chance that some showers could linger into Friday, mainly for parts of Wisconsin. After that, the upcoming weekend looks to be dry with seasonable temperatures expected to top out in the 70s. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 630 PM CDT Tue May 16 2023 VFRs expected at both TAF sites (KRST & KLSE) for the 17.00-24Z TAF period. Biggest concern is wildfire smoke, advecting south through much of the period. High resolution models and cross sections keep PM2.5 particles elevated 10k feet west of the Rockies, and well above that locally. Smoke (FU) becomes more of a forecast concern and question through Thursday as a subsequent upper level trough may drive higher concentrations down the Upper Mississippi River Valley. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...04 AVIATION...JAR
National Weather Service Bismarck ND
1017 PM CDT Tue May 16 2023 .UPDATE... Issued at 1006 PM CDT Tue May 16 2023 Thunderstorms and showers continue to move across eastern Montana. A cold front continues to move across Saskatchewan into eastern Montana. Light and variable winds will continue across the state as smoke continues to move across eastern North Dakota and could settle due to the subsidence from surface high pressure. No updates needed at this time. UPDATE Issued at 633 PM CDT Tue May 16 2023 A cold front continues to approach the region from western Saskatchewan. Satellite imagery shows some diurnal cumulus across eastern Montana moving into western North Dakota, but with the loss of day time heating clouds should diminish. Smoke from the wildfires in Alberta continues to stream in from the North covering the Red River Valley, some of the smoke has trickled into south central North Dakota. Luckily there has been no visibility reductions from smoke. Tonight surface high pressure could move some of the smoke closer to the surface across eastern North Dakota ahead of the frontal passage. Precipitation is still forecast ahead of the cold front tomorrow. Adjusted the clouds grids match current conditions. && .SHORT TERM...(This Evening through Wednesday night) Issued at 237 PM CDT Tue May 16 2023 For the remainder of this afternoon and evening, elevated smoke will continue creating hazy skies across much of the state. The thickest of this smoke looks to remain over the eastern half of the state. Otherwise, expect dry conditions with highs reaching the upper 70s to low 80s. For the remainder of the period, upper low pressure will dig down towards southern Canada. Associated broad surface low pressure and cold frontal boundary will approach the state form the northwest late tonight through the day Wednesday. As a result, there could be a few showers in the north late tonight. As the frontal boundary continues crossing the forecast area from northwest to southeast, expect shower coverage to expand with a few thunderstorms likely to develop during the day Wednesday. Post frontal breezy northwest winds are also expected. Moderate instability looks to accompany the fropa. However, the RAP suggests somewhat limited shear with up to 30 kts of 0 to 6 km bulk shear. Although, this is a bit higher than was progged earlier today. Model forecast soundings also suggest a skinny CAPE profile, which is more supportive of pulsing thunderstorms than longer lasting storms. At this point in time, the Marginal risk remains just south of the border. However, wouldn`t be surprised to see a few strong storms develop Wednesday afternoon, potentially with a severe storm or two. These stronger to potentially severe storms look most likely to impact the south central part of the state. One last note is that as the cold frontal boundary passes through, the RAPSmoke model suggests smoke will be brought down to the surface. This may result in visibility reductions to six miles or less at times during the day Wednesday. However, these reductions are likely to be relatively brief as smoke should become elevated once again behind the front. Elevated smoke looks likely to persist through the remainder of the period. .LONG TERM...(Thursday through Tuesday) Issued at 237 PM CDT Tue May 16 2023 Starting the extended period, a west CONUS ridge will be in place with an upper low skating over far eastern North Dakota and northern Minnesota. Shortwave energy off the low may produce a few showers over the north and east during the day Thursday. As the low moves out, the pattern will remain relatively stale through most of the weekend as the west CONUS ridge remains in place and northwestern flow aloft persists. The result being mostly dry conditions with average temperatures Friday, as well as mostly dry conditions and above average temperatures for the weekend. At the surface, high pressure looks to slide down from Canada and through the Dakotas Thursday night through Friday night. With the high likely centered somewhere over western North Dakota Friday morning, expect temperatures to tank. At this point in time, the expectation is the temperatures will approach freezing, but generally remain above freezing. That said, areas of frost are possible over much of western ND Friday morning. Highs Thursday are expected to be mostly in the upper 50s to lower 60s. By this weekend and through the remainder of the period, highs look mostly to be in the 70s to low 80s. Lows are expected to drop into the 30s for most of the area Friday morning. .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1236 PM CDT Tue May 16 2023 VFR ceilings and visibility are generally expected through the period, although skies may appear hazy at times from elevated smoke. A cold frontal boundary passing through the state from northwest to southeast tonight through Wednesday morning may produce occasional showers and possibly a thunderstorm, along with gusty northwest winds. Per usual, reduced ceilings and visibility are possible with any shower or thunderstorm that passes through. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon) Issued at 1236 PM CDT Tue May 16 2023 VFR ceilings and visibility are generally expected through the period, although skies may appear hazy at times from elevated smoke. A cold frontal boundary passing through the state from northwest to southeast tonight through Wednesday morning may produce occasional showers and possibly a thunderstorm, along with gusty northwest winds. Per usual, reduced ceilings and visibility are possible with any shower or thunderstorm that passes through. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Johnson SHORT TERM...Telken LONG TERM...Telken AVIATION...Johnson
Area Forecast Discussion
National Weather Service Boston/Norton MA
935 PM EDT Tue May 16 2023 .SYNOPSIS... A cold front will move across the region overnight, however very little rainfall will accompany it. Wednesday will cooler, but still dry and breezy. Sub-freezing temperatures are expected Wednesday night. Clear skies and dry weather continues into the rest of the workweek, with mild days and cooler nights. Expect unsettled weather for the weekend, with near normal temperatures. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 9:30 PM Update... As anticipated, visibilities have begun to drop across the immediate south coast, Cape, and Islands where dewpoint depressions have dropped below 3F. Fog formation will peak over the next couple of hours, but with the cold front already near the MA/NH and MA/VT border, will dissipate quickly after 04-06Z as winds shift to the north; drying out the column. Dewpoints are rather high, at least compared to what they will be post frontal, across SE MA, mainly in the upper 40s to mid 50s. Surface temps are too warm away from the coast for any fog formation, but did bring dewpoints in line with current observations. 700 pm update... The cold front is currently working its way through central VT and NH. Latest hi-res model guidance has the showers currently associated with the cold front drying up before reaching our region. Winds this evening will briefly drop off after sunset as the boundary layer decouples, but will pick up again as the front passes through the region. Some fog is possible overnight for the Cape and Islands due to the warm SW winds moving over the cold waters. Confidence is low on fog formation, as models tend to struggle with shallow moisutre scenarios and the approaching cold front. 430 pm update... Overall no big changes to the expectation for the weather overnight. Looking at a cold front to push southward late this evening and overnight. Moisture ahead of and with that front is really lacking, with precipitable water values of about 3/4", and very dry atmosphere below 8000ft or so. Hard to get a lot of rain with that setup. Blended in the latest models, which brought down the PoPs we had in place. Looking for at most a 25% chance of precipitation across NE MA -- 10% or less elsewhere. For most of us, the only clue to the frontal passage will be a period of mid level clouds and a wind shift to the northwest. Front should be pushing south of the region before dawn. Guidance suggests the development of some low clouds and perhaps some light fog across the waters south of Cape Cod with some low level moisture pooling. Not totally confident in this aspect, but did add it in to the forecast. Stuck with a blend for low temperatures, so basically low 40s NW to near 50 SE. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... 430 pm update... Colder air filters in behind the front, with 850mb temperatures down to -2C to +2C by the afternoon. With plenty of sunshine and dry air (precipitable water values 1/4"), we expect another day of deep boundary layer mixing -- upwards of 7000-8000ft (roughly 750mb). So mixing that -2C to +2C air down to the surface suggests maximum temperatures in the mid 50s to low 60s (with the warmest across the south). The mixing will also bring down the 20-25kt winds that will exist several thousand feet above ground, so another day with gusty at times winds. Super dry, so no PoPs. Even clouds will be limited, but we may see some shallow cumulus develop at the top of that mixed layer. These conditions also set the stage for another fire weather day. More on that in the fire weather section. Per the RAP smoke model, the smoke aloft from the Alberta wildfires we`ve seen recently will actually push mostly south of the region, so perhaps a return to deeper blue skies? With clear skies and very dry air, and some continued weak cold air advection, tomorrow night is expected to be rather cold, especially for this time of the year. BUFKIT soundings show 10kts of wind continue all night just a few hundred feet above the surface, so it won`t be a perfect setup for radiational cooling. That said, it will be close enough. Normally cold spots will be, well, cold. Sub-freezing temperatures are likely across western MA, and more localized in the rest of the region. In areas of eastern MA where we have more sandy soils, those locations that typically radiate/cool off quick when in these situations will probably do that again. I`m talking about you Norwood, Taunton, Plymouth and even Martha`s Vineyard. Statistical MOS guidance typically is better than raw model outputs, so as prior shifts have done, I leaned on MOS as well. Given the expected temperatures, have raised a Freeze Watch for far western MA. Quite possible that spots outside of the watch area will drop down to 30-32F as well. If that happens, it`s for perhaps an hour, and that should not result in any real issues. Plants around here are built for this. With the very dry air, frost is actually probably going to be hard to find as well. Maybe a spot here or there. Left it out of the forecast. Once the sun starts to rise, temperatures will quickly rise as well, so the cold threat is a small window. && .LONG TERM /THURSDAY THROUGH TUESDAY/... 430 pm update... * Continued dry weather Thursday/Friday * Precipitation possible over the weekend a 500 mb short wave ridge accompanied by a 1020mb surface high will move over Southern New England on Thursday. With a weakening pressure gradient due to the high pressure center moving overhead, winds will be lighter then earlier this week. Fire weather may still be a concern on thursday with the dry air mass over head, dew points will still be in the low 20s and RH near or below 20%. between the cold start Thursday morning and 850mb temps only between 0C-2C, high temps on Thursday afternoon will be near normal in the upper 60s except near the coasts where highs will struggle to hit 60F if a sea breeze develops. Another cold night is expected Thursday night with clear skies and calm winds. Used the lower end of guidance for lows Thursday night due to the good radiational cooling expected. The upper level pattern begins to change on Friday as an upper level trough begins to eject out of the great lakes. The forcing from that trough wont arrive until friday night or Saturday. Friday will remain dry with increasing high level cloud cover. Winds will likely be gusty out the south on Friday as the pressure gradient tightens between the departing high and approaching low to the NW. The southerly winds likely help boost highs into the low 70s. Our next chance at measurable precipitation looks to start Saturday morning. GFS and Euro models are starting to come in more agreement with a surface low traveling up the coast and the main trough arriving from the great lakes. Current ensembles give most the region a 60% chance for one tenth of an inch of rain, but less then 30% chance for a half an inch of rain. Dry air quickly works its way back in behind the system for Saturday night into Sunday which should bring an end to the rain showers. Decreasing clouds sunday will allow high temps to warm into the mid to upper 70s. An upper level ridge begins to build over the SE U.S Monday bringing us back to clear and dry conditions with highs in the mid 70s. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. High confidence interior terminals Low confidence for Cape and Island terminals Tonight, main weather feature will be a cold frontal passage between 03-10z (north to south). It`s a dry front, so main features will be a band of mid- level clouds at 5000-10,000 ft. Could be a very light shower (probably more like sprinkles), especially across NE MA, but probability is so low that have kept mention of any -SHRA out of the BOS TAF. Much of the guidance suggests the development of some stratus and perhaps some light fog across Marthas Vineyard and Nantucket after 04z, so have included it for the ACK TAF. Confidence in this specific aspect. Any IFR/MVFR conditions that do form will quickly come to an end with the passage of the cold front (somewhere 07-10z at ACK). Tomorrow, another day with VFR. Surface N/NW winds should again become gusty from the morning through mid-afternoon, with gusts 20-30kt. KBOS Terminal... High confidence. Small probability (less than 25%) that BOS experiences a brief -SHRA with and just after frontal passage (04-05z), but not high enough to include in the TAF. Remaining gusty after frontal passage overnight. KBDL Terminal...High confidence in TAF. Frontal passage will shift winds NW overnight between 04-05Z. Winds will remain gusty overnight after frontal passage. Outlook /Thursday through Sunday/... Friday: VFR. Breezy. Friday Night: VFR. Breezy. Slight chance SHRA. Saturday through Saturday Night: VFR. Breezy. Chance SHRA. Sunday: VFR. Chance SHRA. Sunday Night: VFR. Slight chance SHRA. Monday: Breezy. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 430 pm update... Overall High Confidence. Pockets of fog are possible across the southern marine zones for a brief period late this evening and early overnight before winds switch to the NW/N behind a mainly dry cold frontal passage. Marginal SCA conditions this evening into the overnight hours will diminish. Post cold front conditions should still remain below SCA thresholds, with winds gusting 18-23kt and wave heights 2 to 4 feet, especially in the outer waters. At this point have held off in issuing any small craft advisories. Winds and seas diminish even more so late Wednesday and Wednesday night. Outlook /Thursday through Sunday/... Friday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Friday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. Saturday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers. Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Sunday Night through Monday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. && .FIRE WEATHER... 430 pm update... Maintaining the red flag warning for today that goes until about sundown, and then expires. Not a lot of RH recovery overnight, and tomorrow all the weather criteria are supportive of another round of red flag criteria. Projecting lowest RH values down around 20% and gusty winds pushing 25mph throughout the day. Of course the fuel moistures aren`t improving between today and tomorrow either. We have coordinated with fire partners and WFOs ALY and OKX about tomorrow and the expectation is that we will shift the watch for tomorrow up to a warning, but after we get through today. && .CLIMATE... Record Low Temperatures Thursday, May 18th BOS: 37F (2002) PVD: 35F (1983) BDL: 31F (1984) ORH: 33F (2002) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Red Flag Warning from 8 AM to 8 PM EDT Wednesday for CTZ002>004. MA...Red Flag Warning from 8 AM to 8 PM EDT Wednesday for MAZ002>021-026. Freeze Watch from late Wednesday night through Thursday morning for MAZ002-003-008>010. RI...Red Flag Warning from 8 AM to 8 PM EDT Wednesday for RIZ001>007. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ231>235-237. Small Craft Advisory until 2 AM EDT Wednesday for ANZ250. Small Craft Advisory until 8 AM EDT Wednesday for ANZ254>256. && $$ SYNOPSIS...KP/Nash NEAR TERM...Frank/KP/KS/Nash SHORT TERM...Nash LONG TERM...KP AVIATION...Frank/KP/Nash MARINE...KP/Nash FIRE WEATHER... CLIMATE...
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
559 PM MDT Tue May 16 2023 .UPDATE... Issued at 545 PM MDT Tue May 16 2023 Updated 00z aviation discussion can be found below. Main forecast remains on track this evening with isolated to scattered showers and a few thunderstorms. Thunderstorms could briefly be strong to severe with pea to nickel sized hail and upwards of 40 to 60 mph winds, plus lightning. Did have a few reports of pea to penny sized hail with the strongest of storms so far this afternoon. Marginal parameters of only near 1000 J/KG MLCAPE and little to now effective bulk shear will not be conducive for more then an isolated risk of pulse strong to very briefly severe storms through early evening. Risk will decrease post sunset as stability increases with lingering showers occurring through mid to late evening before all activity ceases by midnight. Another round of afternoon showers and storms is expected tomorrow with another marginal risk outlooked for the NE Panhandle per SPC. && .SHORT TERM...(This evening through Thursday night) Issued at 300 PM MDT Tue May 16 2023 The current short term weather analysis depicts a shortwave disturbance slowly propagating southward over northwest Nebraska as of 20Z, per GOES satellite WV imagery. Taking a look at the SPC mesoanalysis for our sector, steep low-level lapse rates from 0-3km are 8-10 degrees C/km for our cwa as of 20Z, with a 50 knot jet streak positioned over a similar area as well. Wind shear is on the weak side, with less than 25 knots of effective bulk shear. However, the moisture does look appreciable as dew points of the upper 40s to middle 50s remain present for the Interstate 25 corridor into the Nebraska Panhandle. All that being said, thundershowers have become present early this afternoon thanks in part to the atmospheric setup localized to the Front Range and Laramie Range toward portions of the Central Plains. This is co- located with the SPC Day 1 Marginal severe Model guidance shows this trend continuing through the early evening hours, with some of the convection becoming potentially severe. The highest likelihood of any single- cell thunderstorms transitioning to potentially supercell thunderstorms are pinpointed to be in the Nebraska Panhandle where moisture, lapse rates, and atmospheric dynamics are the most favorable through sunset. Convection will likely continue to initialize in southeast WY, but is likely to be short- lived in duration. The main hazards will be isolated strong wind gusts up to 60mph with the strongest convective thunderstorms, and hail up to 1 inch in diameter. Isolated to scattered rain showers will be present across the remainder of the cwa. Model soundings depict inverted-V profiles between 21Z-3Z today/this evening, thus gusty winds with even weak rain showers could become present. Overnight, there will be weak winds across portions of cwa, with moisture and the coolest nighttime temperatures located across the North Platte River Valley from Torrington to north of Sidney. Other low- lying valley areas in the Nebraska Panhandle area will be favored for patchy fog. Hi-res guidance from the HRRR and NamNest depict another area near Chadron and Alliance seeing potentially patchy, dense fog from the overnight hours through approximately 14Z. We will need to monitor this in the event a Dense Fog headline may be prudent. Wednesday will be more of the same as another opportunity for widespread rain showers and thunderstorms become present by the afternoon. The one difference maker will be that the atmospheric forcing dynamics will become more organized due to an approaching cold front. Lapse rates, surface moisture, and forcing will be confined to the I-25 corridor towards the NE Panhandle after 18Z Wednesday. SPC Day 2 has a Marginal Risk for severe thunderstorms being possible in the NE Panhandle. Based off the latest model data, this lines up nicely with what our thoughts are internally regarding the potential for isolated strong winds up to 60+mph and large hail. Highest confidence remains with the wind gusts due to model soundings depicting inverted-V profiles, especially the NE Panhandle. DCAPE values between 700-1000 J/kg, and MUCAPE between 500-1500 J/kg on model soundings east of I-25 should suffice more organize convection. Niobrara and Sioux County have the strongest signal for MUCAPE being above 1000 J/kg between 18Z-0Z Wednesday afternoon. Thunderstorm activity should begin to wind down shortly after sunset from west to east. Any organized convection is anticipated to push toward the central Plains between 0Z-6Z Thursday. Much cooler temperatures are forecast for Thursday as the cold front will have passed through the majority of our cwa, and cloudy conditions persist for the region. Daytime highs will be on the order of 10-15 degrees cooler, topping out in the 50s and 60s, instead of the 70s to low 80s for the high plains. Showers and isolated thundershowers will slowly push from north to south by the late afternoon and evening hours. Cooler temperatures in the higher terrain will remain present. Seasonal overnight lows can be expected for most of the cwa, as the upper 30s to lower 40s occur thanks to widespread clouds. A few snow flurries in the highest elevations may remain overnight as cloud cover persists coupled with the colder overnight lows. .LONG TERM...(Friday through Tuesday) Issued at 300 PM MDT Tue May 16 2023 The models are in pretty good agreement in showing the upper level ridge building over the region through the weekend. This will provide mild and dry conditions to the region. The coolest day will be on Friday as Canadian high pressure builds into the area. This should tend to suppress the majority of the convection southward into Colorado on Friday, but one cannot rule out a few isolated showers over the Snowy and Sierra Madre mountains on Friday. Although, confidence is not high in this scenario. Saturday should end up being a very nice day with afternoon highs climbing back into the 70s with mostly sunny skies. The WPC clusters are showing some signs of this upper level ridge beginning to flatten out on Sunday in response to the upper level closed low moving into the Pacific northwest. The ECMWF tends to keep this closed low mainly over the Pacific northwest on Sunday through Tuesday while the GEM/GFS and NAEFS Ensembles has this closed system a little further east over the northern Rockies. Either way it looks like our Precipitable Water values will be on the increase early next week as the southerly flow advects more moisture into the region. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 545 PM MDT Tue May 16 2023 Main aviation concerns next 24 hours will be the ongoing isolated to scattered TSRA/SHRA across SE WY, overnight lower ceilings/fog in the North Platte River Valley near KBFF, and another round of scattered TSRA/SHRA after 19-20Z Wednesday. TSRA/SHRA ongoing in proximity to KCYS as of 00Z with additional activity north and west. Carrying VCTS or VCSH for WY sites through 03-04Z with activity ending thereafter. NE Panhandle sites currently more clear of SHRA/TSRA but some isolated activity could occur near KBFF through 03Z. Fog/low ceilings of IFR/LIFR could occur at KBFF similar to this morning but signal is slightly less. HRRR hints at very localized drops of visibility due to fog. Have trended KBFF this direction from 09-14Z. Another round of TSRA/SHRA likely Wednesday afternoon with VCTS/VCSH mentioned for all sites post 20Z. TSRA/SHRA could temporarily drop visibility down to 2-3SM under stronger rain cores along with localized turbulence. Storm tops Wednesday to near 350/400. && .FIRE WEATHER... Issued at 300 PM MDT Tue May 16 2023 Recent precipitation and the seasonal green-up has resulted in the majority of fuels remaining below elevated to critical thresholds. Minimum humidity values of 25 to 35 percent will be present this afternoon and Wednesday afternoon. Isolated to scattered rain showers have the potential to bring wetting rains greater than 0.10 inches this afternoon through Wednesday evening. Gusty and erratic winds are possible with some of the thunderstorms during that time. && .HYDROLOGY... Issued at 300 PM MDT Tue May 16 2023 The Little Snake River basin will continue to see water levels rise through the week in response to warming temperatures and copious snow melt taking place. This will also cause rises on the North Platte River basin especially near Encampments and Saratoga. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...JSA SHORT TERM...BW LONG TERM...REC AVIATION...JSA FIRE WEATHER...BW HYDROLOGY...REC
Area Forecast Discussion
National Weather Service Duluth MN
858 PM CDT Tue May 16 2023 .DISCUSSION...(This evening through Monday) Issued at 351 PM CDT Tue May 16 2023 Summary: Wildfire smoke from Canada and near-critical fire weather conditions remain the primary forecast concern today into tomorrow. Frost will also be possible along parts of the WI South Shore tonight as temps drop to around 34 degrees. A cold front entering the region tomorrow night into Thursday will bring widespread showers with embedded thunderstorms. Following the front, scattered showers will be possible on Friday before high pressure brings sunny skies on Saturday. With the exception of Friday, temps will remain warm across the vast majority of the CWA. The primary near-term forecast concerns are near-critical fire weather conditions and wildfire smoke from Canada entering the CWA. A dry cold front propagating through the CWA this afternoon has resulted in decreased smoke aloft, reflected in satellite obs this afternoon. The HRRR smoke model continues to handle this event poorly, showing no vertically integrated smoke over the CWA. Fortunately, both the RAP and Canadian smoke models continue to perform well with this event. The near surface smoke model from the RAP shows minimal sfc smoke tomorrow, which should limit air quality concerns. However, the CWA is expected to see another day of hazy skies as the RAP shows a high concentration of vertically integrated smoke aloft. Capped sky cover at 50 percent CWA-wide for tomorrow, since sunlight is likely to filter through smoke aloft, similar to today. Conditions for the day tomorrow will be following the trend of the past few days, with dry conditions and warm temps. Preceding the warm temps will be low temps that may produce frost along portions of the South Shore in WI. Issued a Frost Advisory this afternoon for Douglas, Bayfield, and Ashland counties due to the potential for temps as low as 34 degrees tonight. Minimum relative humidity dropping to or below 25 percent across the Arrowhead and in the pine barrens of Douglas and Bayfield Counties will very likely lead to near- critical fire weather conditions. South winds of 10 to 15 MPH and gusts to around 20 MPH in the MN Arrowhead also increase fire weather concerns for tomorrow. A change in the dry pattern comes Wednesday night into Thursday as a trough that is currently traversing a large ridge to our west arrives into the region. This trough will result in a low pressure center moving through Manitoba and Ontario tomorrow night through Thursday. An attendant cold front will be sweeping through the CWA over the same time period, with widespread rain expected through the day Thursday. A few embedded thunderstorms may be possible as the cold fropa occurs on Thursday given favorable 0-6km bulk shear of 30-40 knots. However, the thermodynamic environment will be marginal at best on Thursday. Model soundings show weak lapse rates and model MUCAPE is only up to a few hundred J/kg in the CWA. Therefore, severe weather is not anticipated on Thursday as this front moves through. Following the cold front on Thursday, cyclonic flow combined with cool air aloft will likely lead to scattered diurnal showers on Friday. High pressure will be regaining control of the pattern on Saturday, leading to a pleasant day with sunny skies and warm temps in the 70s. Several global ensemble members for QPF show that showers may be possible Saturday night into Sunday along a cold front for portions of the CWA. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 620 PM CDT Tue May 16 2023 VFR conditions are expected through this TAF period. Easterly winds this evening shift southeasterly by early Wednesday morning and then southerly into the midday hours tomorrow. Lofted smoke could return again Wednesday and is represented by the SCT100 in place at some terminals. If smoke makes it to the ground, then future issuances may need a limited vis restriction. && .MARINE... Issued at 855 PM CDT Tue May 16 2023 Winds and waves will subside tonight as the pressure gradient relaxes. Another northeast winds of 10 to 20 knots and gusts of 15 to 25 knots are possible Wednesday afternoon, mainly at the head of the lake. These conditions may prompt Small Craft Advisories to be needed from Silver Bay to Duluth for tomorrow afternoon. A stronger cold front will move eastward across the region on Thursday, bringing a period of stronger winds, light rain, and possibly a few thunderstorms. && .PRELIMINARY POINT TEMPS/POPS... DLH 37 62 46 66 / 0 0 20 90 INL 43 75 50 62 / 0 10 50 70 BRD 45 76 56 68 / 0 0 30 80 HYR 36 70 50 73 / 0 0 10 80 ASX 33 64 48 70 / 0 0 10 80 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Frost Advisory from 2 AM to 7 AM CDT Wednesday for WIZ001>003. MN...None. LS...None. && $$ DISCUSSION...Unruh AVIATION...NLY MARINE...NLY
Area Forecast Discussion
National Weather Service Quad Cities IA IL
656 PM CDT Tue May 16 2023 ...AVIATION UPDATE... .SYNOPSIS... Issued at 216 PM CDT Tue May 16 2023 A mix of sun and clouds was seen over all of eastern Iowa, northwest Illinois and far northeast Missouri early this afternoon. Surface analysis showed an area of high pressure centered over central Nebraska and Kansas, with ridging extending over the Midwest. Meanwhile, a backdoor cold front was in place from north central Minnesota eastward across the Great Lakes into northern Ontario. && .SHORT TERM...(This evening through Wednesday) Issued at 216 PM CDT Tue May 16 2023 [Key Messages] 1) Backdoor cold front arrives tonight with winds shifting to the east 2) Smoke from Canadian wildfires arrives tonight and persists through tomorrow [Discussion] The primary weather concern in the short term period is the arrival of the aforementioned backdoor cold front from the north tonight. Not expecting any precipitation with its passage as lift and moisture levels with the front are weak. Weak CAA accompanying the front, with winds gusting around 20 MPH at times tonight, will help lower temperatures into the low to mid 40s mainly for areas in northwest Illinois and far northeast Iowa. Elsewhere, temperatures in the 50s are expected. For tomorrow, with east winds persisting, highs are expected to range from the upper 60s (northwest Illinois) to near 80 (northeast Missouri). The next concern will be the arrival of smoke from Canadian wildfires, which looks to build into the area with the arrival of the cold front tonight. The RAP remains the model of choice with this package given its larger domain, with the HRRR continuing to struggle with overall coverage and timing. Vertically integrated smoke calculations show the bulk of higher smoke concentrations arriving across the area Wednesday afternoon, persisting into the early portions of the long term period. Thankfully, much of this will remain aloft with little to mix it down to the surface. The only exception may be with the frontal passage tonight, as vertical mixing temporarily increases along it. Otherwise, expect a milky haze appearance with the sky and a nice sunset! .LONG TERM...(Wednesday night through Tuesday) Issued at 216 PM CDT Tue May 16 2023 [Key Messages] 1) Wildfire smoke persists through Thursday 2) Chance of showers/storms Thursday night through Friday 3) Dry and warm through the weekend [Discussion] Wednesday night and Thursday... Dry weather is expected for this period with clouds on the increase ahead of our next weather maker approaching from the west. Wildfire smoke will also be in place aloft, but will start to get shunted east with the arrival of stronger winds aloft. Increasing southerly flow and WAA will help afternoon highs climb into the upper 70s to mid 80s. Thursday night and Friday... Positively tilted shortwave and surface front will move into the area to start the period, with enough lift and moisture in place to lead to an increasing threat of showers and storms. Bulk of precipitation will fall during the overnight hours, but some guidance tries to hold on to POPs through much of Friday morning into midday (GFS). Will be holding on to the NBM which favors precipitation chances mainly from the 00z-12z period Friday. With little in the way of vertical shear, low instability, conditional lapse rates aloft and timing of the front arrival during the night, the overall severe weather risk is low at this time. Friday night on... Dry weather will be the rule for this period as strong high pressure builds across the Midwest and Great Lakes. Expect temperatures near normal for the weekend, with a trend back above normal next week once surface flow shifts back to the south. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 656 PM CDT Tue May 16 2023 VFR conditions are expected through the period with no sig wx impacts to aviation expected. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Speck SHORT TERM...Speck LONG TERM...Speck AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Glasgow MT
200 PM MDT Tue May 16 2023 .DISCUSSION... Going forecast was in good shape but humidity has been a bit higher than anticipated and has begun to generate cumulus (eastern zones) and isolated thunderstorms over central Montana. HRRR and SREF models suggesting a bump up in pops through tonight as a result but with little shear, storms will not be severe. Gusty winds are possible if they collapse however, so added that wording. Otherwise, issued a Lake Wind Advisory for Wednesday afternoon as a wind gust to 30 mph has about a 50-70% chance. TFJ MORNING DISCUSSION: Synoptic Setup: Hot high pressure from the desert southwest has worked its way up into a ridge that runs north into the Pacific Northwest and British Columbia. To the northeast a large trough has positioned itself over the eastern half of the Hudson with roughly northwest flow residing between these two large features from Yukon through Alberta and into northeast Montana. Within this flow are several meso to sub-synoptic ridges and troughs which will lead to a bit of an unsettled pattern. Today: A sub synoptic ridge will will move through the territory keeping conditions warm with highs int he 80s and clear skies. Tonight through Wednesday: As the ridge exits early in the evening a meso trough will smash a cold front into the area behind it before midnight, flipping light winds to gusty ones out of the northwest. Hit-and-miss showers and thunderstorms are expected to accompany the frontal passage with them developing over the central Montana mountains in the afternoon and getting pulled along the front once it arrives. Shear profiles suggest that this will be just general thunder with no severe elements. With the hit-&-miss nature and high bases evaporating rain before it hits ground most locations will see very little if any QPF with a few hundredths being the higher totals. Wednesday night into Friday: Cooler stable high pressure will settle into the region at the surface generating light winds, clear to partly cloudy skies and highs in the 60s and 70s. Friday night into Sunday: Ridge to the west will become thin yet gain more prominence over eastern Montana. Being thin, there are higher chances for meso-scale disturbance with extra moisture breaking through and generate isolated showers and thunderstorms, but the prominence means that temps will start to rise back into the 80s for highs. Monday onward: Ensembles begin to break down and go out of phase with the destruction of the ridge across the region. A few runs are suggesting a southwest flow pattern with maybe some severe weather, but disagreements in the members are too heavy to bring any confidence to that possible forecast. GAH && .AVIATION... UPDATED: 2200Z FLIGHT CAT RANGE: VFR DISCUSSION: A cold front moving through the area this evening will bring a wind shift along with scattered convective rain showers and a few THUNDERSTORMS. Chance for showers at any given terminal is only about 40%, so will be using Prob30s to handle it for now. This shower activity will begin impacting KGGW around 03Z and transitioning from northwest to southeast across the rest of the terminals overnight. Nocturnal showers will be mostly high based around 8 to 10 kft and should clear the area by about 15Z Wednesday morning. WIND: Light (less than 10 kts) southwest and west early evening, then becoming northwest behind a cold front late this evening and accelerating to 15 to 25 kts Wednesday morning. GAH/TFJ && .GLASGOW WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory from noon to 7 PM MDT Wednesday For Fort Peck Lake for Central and Southeast Phillips...Central and Southern Valley...Garfield...McCone...Petroleum. && $$
National Weather Service Hastings NE
611 PM CDT Tue May 16 2023 ...AVIATION UPDATE... .DISCUSSION...(This evening through Tuesday) Issued at 325 PM CDT Tue May 16 2023 Key Messages: *Warmer tomorrow with a chance for thunderstorms late tomorrow evening. *Cold front Thursday with continued thunderstorm chances. *Dry and mild Friday and Saturday and then warming through early next week. The stratus deck has continued to erode to the southeast today and only a little scattered cumulus remains on satellite this afternoon across southeastern portions of the area. Winds are light with high pressure at the sfc and we are still on track to top out in the 70s today, quite a bit warmer than yesterday. Clear skies will continue tonight with light and variable winds and lows in the 40s to near 50. There could be the potential for a little bit of fog to form towards dawn but models don`t seem too keen on this potential, so have not included it in the forecast at this time. Warmer still on Wednesday with highs in the 80s and continued light winds that will shift to being out of the south which will help us to warm. Some thunderstorms are expected to develop with a sfc trof moving east later in the evening hours but should weaken some as they move towards the area. Have delayed the onset of PoPs as models have slowed down the progression and the onset of precipitation for the western portions of the area. A cold front comes through on Thursday and reinvigorates thunderstorm chances during the day and particularly the afternoon hours. Some of these storms could be on the strong side, with around 500-1,000 J/kg of MUCAPE but severe storms are unlikely as bulk shear is rather weak and limited. There is also the potential for northern most portions of the area to be affected by a little near surface smoke Thursday late morning and into the afternoon according to the RAP Smoke model, from the wild fires up in Canada. This might bear some watching in the coming days, even with the potential for thunderstorms in the area (which might negate the smoke). Cooler temps on Friday as a drier pattern sets in for the weekend and into early next week. Highs will be in the 60s and 70s with breezy winds Friday afternoon. Ridging aloft will build over the Western CONUS and will help keep us dry and warming into the weekend and early next week. Highs on Saturday will be in the 70s, and back into the 80s on Sunday and Monday. There is a small chance for a few isolated storms to pop up across the far southwestern portions of the area Sunday afternoon, but a vast majority of the area will likely remain dry. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 607 PM CDT Tue May 16 2023 VFR conditions are expected through the TAF period. A few cirrus clouds may be present this evening, but skies should be clear the remainder of the period. Winds will be light and variable (6 kts or less) through Wednesday morning. Winds will become southerly at around 7 or 8 kts Wednesday afternoon into Wednesday evening. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Shawkey AVIATION...Hickford
Area Forecast Discussion
National Weather Service Grand Junction CO
605 PM MDT Tue May 16 2023 .SHORT TERM...(Tonight through Wednesday night) Issued at 300 PM MDT Tue May 16 2023 Showers and storms began to fire between 11 am and noon as expected across the higher terrain. The HRRR seemed to verify pretty well with convective initiation with the northern areas seeing the best activity and coverage. However, storm coverage is much less than the previous couple days and storms are struggling to survive as they drift off the terrain, appearing pulse like and producing some outflow winds as outflow boundaries are evident on radar through the lower elevations. It makes sense that the eastern Uintas into northwest Colorado is the hot bed for the better activity as the upper level jet support remains to the north over Wyoming, so they are in closer proximity to this added source of lift. Our CWA remains under this westerly flow as a ridge of high pressure is overhead and allowing this moisture to be trapped underneath and recycled. Precipitable water values will remain in the 0.5 to 0.6 inch range on average today and tomorrow as the pattern largely remains unchanged. The main threat with storms today is gusty outflow winds and lightning. We could see some brief locally heavy rain and small hail with a few of the stronger storms but this appears short-lived and isolated at best. For Wednesday, the jet remains along the northern Colorado and Wyoming border, with zonal flow continuing under high pressure. Storms will favor the high terrain, developing in the afternoon like today, with storms having a tough time surviving into the lower elevations. Changes in the pattern and coverage appear Thursday and beyond...more on that in the Long Term section. But for the time being, today and Wednesday will be less coverage and activity than later in the week. Temperatures as a result will be warmer with highs 5 to 10 degrees above normal with partly to mostly sunny skies in the valleys and building cumulus and storm activity favoring the high terrain in the afternoons. Storm activity should end around sunset both days with the loss of daytime heating and limited forcing to help sustain activity. .LONG TERM...(Thursday through Tuesday) Issued at 300 PM MDT Tue May 16 2023 In general, Rex-Blocking pattern persists for much of the long term period along the Western US, maintaining fairly consistent weather for the region: unsettled and warm. Thursday brings an uptick in storm coverage, as well as intensity, as a short wave rotates around the base of closed low displaced to the northeast. The trailing end of its trough axis carries along a weak upper level jet and swath of positive vorticity as the whole system swings across the Central Rockies. Jet dynamics and PVA will aid as a lifting mechanism, though, orographics typically suffice in this department. Other key components include, moisture and instability. In terms of available moisture, PWAT levels will continue to range from 150 to 200 percent of normal, which translates to precipitable water values of 0.5 to 0.6 inches across the board. NamNest data trickling in support elevated SBCAPE by Thursday afternoon, as well, which would support the longevity of thunderstorms...rather than cells dissipating as soon as they drift on higher terrain. Main concerns with storms on Thursday include periods of heavy rain, small hail, lightning and gusty outflow winds. Basins still filled with a heavy snowpack are expected to see an acceleration of snowmelt due to rain on snow, IF cells materialize. Still some uncertainty there, with regard to where and how much rain falls. However, there is potential for rivers rising due to increased runoff from warm, spring temperatures as well. The blocking pattern shifts east on Friday into the weekend, which will shunt moisture content to the southern half of the CWA. Storm development will favor the moist side of the zonal line, therefore, expect higher coverage for afternoon convection south of the I-70 corridor. The next low pressure system that`s projected to nose into the PacNW will likely break down the Rex-Block. However uncertainty grows with the variance between deterministic guidance beyond Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 543 PM MDT Tue May 16 2023 Showers and storms will continue to dissipate this evening but not before throwing out some gusty outflow winds. This could impact TAF sites mainly along and north of I-70 over the next few hours. Otherwise VFR conditions will persist over the next 24 hours. && .HYDROLOGY... Issued at 300 PM MDT Tue May 16 2023 Forecast hydrographs continue to show elevated river and stream flows/stage through Friday. Areas across the north, namely the Yampa River Basin, are exceeding Flood Stage and even Moderate Flooding in some areas. River flood products will continue, at least, into the weekend to cover forecast peaks within the next 10 days. River levels and flooding potential will depend on temperatures and precipitation during this period, so there remains some uncertainty in the river forecasts in that regard. Increased cloud coverage could suppress temperatures and thus reduce snowmelt/runoff. In contrast, heavy rainfall over a specific basin would increase snowmelt and runoff... Despite uncertainty, if located in the warning or advisory areas, please stay vigilant to changes in the river, as conditions and hazards may change minute by minute. Water is already running with high levels and fast currents along most main stems, including the Yampa, Colorado, Green, Gunnison and Dolores Rivers. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDA LONG TERM...ERW AVIATION...TGJT HYDROLOGY...ERW
Area Forecast Discussion
National Weather Service Green Bay WI
939 PM CDT Tue May 16 2023 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Wednesday Issued at 219 PM CDT Tue May 16 2023 A cold front will continue making its way through central and east-central Wisconsin this afternoon, turning winds to a north to northeasterly direction. Satellite imagery shows a layer of smoke in the atmosphere above 12,000 feet from the wildfires in Canada. The cold front is expected to push through the rest of the region dry given the dry atmosphere and likely some influence from the smoke above the surface filtering out some of the incoming solar radiation. Skies are expected to clear overnight with subsidence behind the cold front as the RAP Vertically Integrated Smoke product indicates the smoke will push south with the cold front. Overnight lows are expected to tumble into the 30s with some patchy frost possible in central and north-central Wisconsin. Given the brief period of cold temperatures tonight will not issue any frost/freeze headlines for tonight. A surface high will build in from the northeast Wednesday morning, then push off to the east during the afternoon. Although skies will start out mostly sunny, the RAP Vertically Integrated Smoke product indicated the smoke from the west will advect back into the region Wednesday morning and linger across the area through at least the afternoon hours. Therefore, some filtered sunshine is once again expected on Wednesday from the wildfires. The combination of filtered sunshine and southeasterly winds will keep temperatures cooler than today. Highs on Wednesday are expected to only rise into the 60s with the warmest temperatures across north-central and central Wisconsin away from the Great Lakes. Further east temperatures near the lake will be limited to the 50s. .LONG TERM...Wednesday Night Through Tuesday Issued at 219 PM CDT Tue May 16 2023 Through most of the long term forecast the pattern features broad ridging over the west coast leading to northwest flow across central and northeast Wisconsin. This will result in a couple mid- level shortwaves/sfc fronts impacting the area and temperatures generally near to slightly below normal. The forecast starts out dry Wednesday night, and then the first shortwave/sfc cold front will move through Thursday or Thursday night. Starting out with a very dry airmass in place, so expect it will take a while for saturation to occur and rain to begin, and models seem to be latching onto the later start time. Therefore, this will bring about some elevated fire weather potential on Thursday afternoon ahead of the cold front. Forecasting minimum RHs approaching 25 to 30 percent in far northern Wisconsin, high temps in the 70s, and south winds gusting up to 30 mph. The later arrival will also mean less instability to work with, but there is still some, so kept a chance of thunderstorms as well. Severe weather in not likely, with max CAPE values of 300 to 700 J/kg. After the front moves through, cooler temps will settle in with highs on Friday only in the middle 50s to middle 60s. Models still vary on how quickly the shortwave departs, with the ECMWF and Canadian keeping it around through Saturday morning. Similar to the previous forecast, kept chance PoPs through Friday night and then dry for the rest of Saturday as high pressure builds in. Another weak shortwave and coinciding sfc front moving through on Sunday, but time sections show a very dry atmosphere, so not expecting much, if any, precip. West coast ridging starts to migrate east and flatten late this weekend and early next week. This will result in a change to southerly low-level flow and somewhat warmer temperatures early next week. && .AVIATION...for 06Z TAF Issuance Issued at 938 PM CDT Tue May 16 2023 VFR conditions are expected through at least Wednesday night. An elevated smoke layer from forest fires in northern Canada may return to the area Wednesday, but should not affect surface weather conditions. && .FIRE WEATHER... Issued at 219 PM CDT Tue May 16 2023 Low humidities between 15 and 25 percent are expected on Wednesday afternoon across north-central and far northeast WI, though high temperatures will be cooler into the low and middle 60s and winds will remain light in the 5 to 10 mph range. This will bring elevated fire weather conditions across this area during the day on Wednesday. Elevated fire weather conditions are also possible on Thursday as temperatures will be warmer in the low to middle 70s with gusty winds. However, RH values will be higher in the 25 to 30 range due to rain potential in the afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM.....Kurimski LONG TERM......KLJ AVIATION.......RDM FIRE WEATHER...Kurimski
Area Forecast Discussion
National Weather Service Grand Rapids MI
730 PM EDT Tue May 16 2023 LATEST UPDATE... Aviation .DISCUSSION...(This evening through next Tuesday) Issued at 207 PM EDT Tue May 16 2023 - Dry cold frontal passage through late afternoon The cold front up around Cadillac was dropping steadily southward. Most of the clouds with this front were up around 10k ft. Conditions below were dry. This front is not forecasted to pick up any additional moisture. Thus as the front drops southward through the CWA, no precipitation is forecast. This is how we currently have the forecast and no changes are anticipated. - Some Frost Possible Up North Tonight The atmosphere behind this cold front will be cooler and continued dry. Skies will remain mostly clear. The wind however is forecast to remain up through the night. Ensemble wind gust forecast from Big Rapids shows mean gust values of 10 to 15 knots through the night. The main reason for the winds tonight is because the surface high pressure system will be building in and we remain in the pressure gradient. Generally this limits the frost potential. Thus we are leaning away from a Frost/Freeze headline at this time. - An increased potential for Frost/Freeze headlines Wednesday night The pressure gradient weakens in the afternoon...which sets the stage for the winds to go light early in the evening. It will be a dry air mass in good radiational cooling looks likely. High temperatures will also be lower Wednesday as compared to today`s we will get off to an early start for unseasonably cool overnight low`s. Ensemble min temperature values look colder than tonight`s values, especially for inland locations like Lansing and Mount Pleasant. We will feature temperatures dropping into the 30`s for inland locations. - Potential for some showers Friday into Friday night The most recent run of the models generally show a closed mid level low in central/northern WI 18z Friday, heading east. The main lift and moisture depth here in MI is progged to come through Friday. Mid level lapse rates do steepen up but not enough to warrant a risk for thunder throughout the CWA. Ensemble mean values are mostly a third of an inch or less with some spread. Bufkit overviews from the NAM show a 6 to 8 hr period of deeper moisture and lift for KGRR Friday morning with the GFS fairly similar. This is when we will feature the highest POPs. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 730 PM EDT Tue May 16 2023 We currently have a frontal system dropping down through the terminals this evening. The only thing this front has is a wind shift from WNW to N and some mid clouds with it. In addition, a band of smoke from the Canadian Wildfires is progressing through the area to the south. The mid clouds will clear out toward or just after midnight for the southern terminals, and winds at all locations will become from the NE. Skies will be mostly clear on Wed, but we are expecting more smoke to move in around 25k ft agl. We have left a bkn250 layer in the forecast for Wed to account for this. Winds will remain from the NE at most of the sites. KMKG will see their wind become from the NW as the lake breeze kicks in around 18z. && .MARINE... Issued at 207 PM EDT Tue May 16 2023 We will maintain the small craft advisory for the north zones this evening. The cold front was dropping through these zones and wind gusts have been on the increase. A buoy off of Ludington had gusts in the 15 to 20 knot range over the past couple hours. The HRRR and NAMNST suggest these sites will make a run at gale force late this afternoon. Looking upstream we have not seen gale force winds so for now we will keep the small craft advisory going. && .FIRE WEATHER... Issued at 207 PM EDT Tue May 16 2023 Conditions were around Red Flag criteria at this time. We will maintain the current headline. Looking at Thursday, the atmosphere will be very dry given its Canadian origin. High temperatures may struggle to reach 75 degrees and the winds may fall a little short but it is forecast to be close to Red Flag criteria. We will need to monitor trends concerning Thursdays Red Flag potential. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Red Flag Warning until 8 PM EDT this evening for MIZ038>040- 044>046-051-052-057>059. LM...Small Craft Advisory until midnight EDT tonight for LMZ848-849. && $$ DISCUSSION...MJS AVIATION...NJJ FIRE WEATHER...MJS MARINE...MJS
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1102 PM CDT Tue May 16 2023 .SYNOPSIS... Issued at 1101 PM CDT Tue May 16 2023 High pressure will keep much of the cloud cover at bay through Wednesday. However, the sky will be muted by a thick layer of smoke aloft, which will drop into the area overnight and linger through mid week. Temperatures will be close to mid May normals, with humidity levels on the comfortable side through Thursday morning. && .UPDATE... Issued at 812 PM CDT Tue May 16 2023 Backdoor cold front (moving southwest) was located from just west of Rockford back into northern Indiana at 8 pm. This is forecast to reach the I-74 corridor between 1-2 am, and into the central CWA by sunrise. Behind the front, northeast winds will briefly gust 10-20 mph, and temperatures will drop several degrees. Expect lows at 50-55F from north to south. Skies will be mainly clear with some cirrus and the leading edge of the upper level smoke layer currently over northern IL, tracking south into central IL after midnight per RAP vertically integrated smoke product. This will likely not be visible until around sunrise. 25 && .SHORT TERM... (Through Thursday) Issued at 236 PM CDT Tue May 16 2023 Main challenge in this part of the forecast is with sky cover. Most of the steadier rain has moved into Indiana, though a few showers linger further west with a weak upper wave currently located near I-55. This should exit over the next few hours, and will go with a dry forecast by early evening, continuing through Thursday afternoon. Latest satellite analysis shows a thick layer of smoke extending from Manitoba into eastern South Dakota, then eastward to southern Ontario. PIREP`s from this area show visibility being impacted as low as 3,000 feet off the ground, though surface observations are not showing much in the way of a ground impact. The HRRR is not handling this smoke at all, likely due to the source region (Alberta) being outside the domain, but the RAP`s larger domain appears to have a good handle on it. Initial ribbon of dense smoke (the east-west band approaching Madison WI this hour) should be close to I-74 toward late evening and I-70 shortly after sunrise. Tail end of the projection shows a much larger area of smoke will descend across the upper Mississippi Valley Wednesday morning, and extrapolation would bring it into central Illinois toward midday. With high pressure only slowly drifting across the Great Lakes, the smoke would not exit too quickly. Thus, minimum sky cover grids will generally be set to the 35-40% range through Thursday, despite not much of an actual cloud cover between late this evening and Thursday morning. The other feature of note is a backdoor cold front/pneumonia front that will be pushing southwest from the Lake Michigan region by early evening. While the wind shift with it should reach I-74 shortly after midnight and Springfield toward sunrise, the actual "pneumonia" feature of the front (defined as a 1-hour temperature drop around 16F or greater) would fizzle out before reaching this far south. Temperatures don`t drop off too dramatically, but typical mid-May lows in the lower 50s will be widespread in our area tonight. With more of the easterly flow prevailing due to the high to our northeast, lows Wednesday light are likely to dip into the upper 40s east of a Peoria-Mattoon line. Geelhart && .LONG TERM... (Thursday Night through Next Tuesday) Issued at 236 PM CDT Tue May 16 2023 Through the weekend, the longer range models are in decent agreement with upper ridging across the western U.S., keeping the Midwest in more of a northwest flow. An upper low currently over northern Saskatchewan will drop into northern Minnesota by Thursday evening, before swinging east across the Great Lakes Friday and early Saturday. The GFS is a little more progressive with this system and its associated front and rain chances, while the international models linger the rain a bit longer into Friday night. Overall, not a lot of moisture influx into this system and instability is not too high, so impacts should not be great. A weaker wave moving through the upper Mississippi Valley on Sunday is expected to come through dry. Heading into early next week, the ridge is expected to begin building eastward across the CONUS, though the GFS flattens it out with an upper low that the international models otherwise linger over the Pacific Northwest. Consequently, it has more of a south/southwest flow and scattered showers/storms by Tuesday. Will go with the drier solution at this point Geelhart && .AVIATION... (For the 06z TAFs through 06z Wednesday Night) Issued at 1102 PM CDT Tue May 16 2023 VFR skies and winds near/under 10 kt through Wednesday evening as high pressure builds across the Great Lakes. A backdoor cold front will shift winds northeast overnight, and remain northeast through Wednesday. 25 && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$ WFO ILX
Area Forecast Discussion
National Weather Service Indianapolis IN
1014 PM EDT Tue May 16 2023 .Forecast Update... Issued at 1014 PM EDT Tue May 16 2023 Little to no change to the forecast with this evening`s update. Latest surface analysis shows clearing skies across the region with a moisture starved front pushing in from the north. The main impacts from this front will be switching light winds around to the north/northeast tonight and tomorrow. This northerly flow pattern aloft will advect in haze/smoke in the upper levels from wildfires in Central Canada. With mainly sunny skies expected, hazy conditions may occur at times during the day. Not expecting any impacts from the smoke other than the potential for a colorful sunset. Despite cooler air advecting in aloft as well, surface temperatures will likely reach the 70s given abundant sunshine. Upper level smoke may potentially keep highs a degree or two cooler than guidance, but overall do not think the smoke will have a meaningful impact on surface conditions. && .Short Term...(Through Wednesday) Issued at 105 PM EDT Tue May 16 2023 Somewhat complex pattern is over the region now. One midlevel perturbation is moving through today and it has origins from an old MCV/midlevel low that evolved from convection two diurnal cycles ago along the Texas gulf coast. Its ascent coupled with deep moisture plume has resulted in widespread rain across southern portions of the area and intermittent/patchy light rain across the north. This is now exiting with its most intense convection forming on the southern flank over Kentucky where instability is greatest. Meanwhile, another weak perturbation over northeast Missouri is enhancing rain shower coverage over Illinois and until this clears the area late this afternoon, at least light showers should persist. There has been a decreasing trend, so much of this may be nonmeasurable/sprinkles as it moves through central Indiana mid- late afternoon. Deepening eastern trough will nudge drier continental/cP air mass into Indiana this evening ending rain chances, and resulting in decreasing clouds. Despite weak cold advection, temperatures tomorrow will be warmer than the previous couple of days since more radiative component will be present under clear skies. There could be some haze by late in the day based on HRRR smoke model. This is originating from wildfires in the boreal forest region of Alberta and Saskatchewan. Low level trajectories should take this southward into the northern Plains, but upper level flow is more directed over our region. Its unknown how noticeable this will be at this time, but it may at least enhance sunsets visually with color due to light scattering from smoke particles. && .Long Term...(Wednesday night through Tuesday) Issued at 105 PM EDT Tue May 16 2023 Some haze/smoke from Canadian wild fires may be observed Thursday per HRRR smoke model, and eventually cirrus will move in on the downstream end of high-level moisture plume preceding the next system. Temperatures should peak Friday (warmest of the week) due to strengthening warm advection regime, despite increasing mid- high clouds. There remains about a 9-12 hour timing difference with the next closed mid-upper low and attendant cold front late Friday into early Saturday. GEFS-weighted clusters are still quicker than the EPS- weighted clusters. So, we`re still unable to narrow a specific ~6- hour window of greatest precipitation chances/intensity, and will continue a fairly broad-brush approach of precipitation chances between Friday afternoon and Friday night. These patterns of split flow and embedded closed lows are notoriously difficult for models especially at this time range. We will refine timing over the next few days. What we can say now is the overall way in which synoptic-scale forcing interacts with the warm sector, a frontal band of showers and thunderstorms is the most likely outcome. Again, there is about a 6-hour window for the bulk of the precipitation. Furthermore, some lightning may accompany this but instability should be tempered by the track of the low and higher-latitude path of steeper midlevel lapse rates. Deep moisture and nearly moist adiabatic profiles are indicated for our area. Thus, the risk of severe convection currently appears low. Post-frontal air mass should be slightly cooler (but near seasonal normals) and less humid into early next week. We will be in northwesterly flow aloft albeit modest at this latitude. One more shortwave trough may pass with some clouds but dry continental air mass should preclude precipitation. Temperatures warm above normal toward the middle of next week as medium-range ensemble guidance shows mean troughing in the east deamplifying and positive midlevel height anomalies across the higher latitudes of the U.S. and Canada increasing substantially. Early indications are that this quiescent synoptic pattern will carry into the Day 8-14 period with generally near or above normal temperatures and below average precipitation. && .Aviation...(00Z TAF Issuance) Issued at 734 PM EDT Tue May 16 2023 Impacts: * Isolated showers ending, VFR conditions expected through the period * Light winds under 10 kts, periods of variable winds * Hazy skies tomorrow from Canadian wildfire smoke Discussion: Latest satellite and radar imagery shows rain and clouds from earlier finally pushing off to the east. Scattered high clouds will linger through the rest of the evening before clearing out later tonight. Weak front pushing in from the north will switch winds from west to northerly overnight, but speeds should remain under 10 kts. Subsidence and dry air associated with high pressure tomorrow should keep VFR conditions through the rest of the period. Satelitte imagery does show smoke from wildfires in Canada being transported south over the region tomorrow from northerly upper level flow. While no impacts will be seen at the surface, it will make skies hazy at times tomorrow. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ Update...CM Short Term...BRB Long Term...BRB Aviation...CM
Area Forecast Discussion
National Weather Service Northern Indiana
613 PM EDT Tue May 16 2023 .SYNOPSIS... Issued at 243 PM EDT Tue May 16 2023 Dry weather will prevail through Thursday night with clear to partly obscured skies as a result of smoke from Canadian wildfires. Seasonable temperatures can be expected through the rest of the work week aside from Wednesday, which is cooler as a result of this evening`s cold front. Our next chance for rain is Friday with a few thunderstorms also possible. && .SHORT TERM...(This Evening through Wednesday) Issued at 243 PM EDT Tue May 16 2023 A strung out area of vorticity from the Ohio Valley into the Middle Mississippi Valley coincident with a thermal gradient in the Ohio Valley serves as a path that the low pressure system that brought rain to our area travels along. It will continue to travel to the east this afternoon allowing drier air to sink in from the north and for clouds to dissipate. Meanwhile in Canada, an upper low pressure system slowly sinks south and an area of vorticity pinwheels south around the upper low`s periphery. As the area of vorticity dives southward, it pushes a boundary southward along Lake Michigan. Cold air is able to come in tonight behind the boundary and will allow for a cooler Wednesday with minimal cloud cover as a result. However, smoke from Canada is expected to filter into the area in some capacity likely limiting Lows tonight will be slightly cooler than last nights, but still in the low 40s to low 50s. Highs Wednesday will only be in the mid 60s to low 70s. Height rises on Wednesday also signal the arrival of surface high pressure, which brings dry weather through Thursday, but again we`ll have the smoky haze around as long as the RAP smoke model is correct. && .LONG TERM...(Thursday through Tuesday) Issued at 243 PM EDT Tue May 16 2023 With high pressure now to the east of the forecast area, temperatures will be able to warm back to around normal, in the low 70s, for Thursday. Continued dry air will provide plenty of sunshine for the forecast area. In fact, even without adjusting model dew points for expected low level lapse rates, MinRH values are already falling below 25 percent. This is as 30 degree dew points pair with temperatures rising into the low 70s. However, 10hr fuels still appear rather wet at greater than 10 percent and sustained winds, and gusts for that matter, remain below 20 mph. These conditions will need to be watched going forward for possible elevated fire danger. For Friday, Thursday`s mid level ridging will be overtaken by an upper level low pressure system arriving from Central Canada. A cold front still looks too fast on the GFS when compared to the ECMWF/NAM consensus. Depending on the arrival of the cold front, there`s a chance highs in the upper 70s might be too warm for two to three tiers of counties southeast from Lake MI, but low to mid 70s appear more reasonable there. Again, this will depend on the timing of the cold front through the area, and therefore, the amount of instability that can be generated, but could see some showers/thunderstorms form with the most likely area of their formation being south of US-24. Instability being modeled at this juncture doesn`t appear very strong so the chance for severe weather appears low Friday afternoon. The aforementioned upper low passes by the area on Saturday allowing for cooler temperatures and a drier airmass. Therefore, have removed Saturday`s precipitation chance. It`ll be warmer ahead of a frontal boundary arriving around evening time, but without a clear moisture connection, expect a dry frontal passage. The beginning of the next work week also looks dry as high pressure follows the aforementioned frontal passage. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 613 PM EDT Tue May 16 2023 A cold front will drop through from the north this evening with winds veering to the east-northeast overnight into Wednesday. A very dry airmass will ensure dry/VFR conditions through the TAF cycle and beyond otherwise. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...Roller SHORT TERM...Roller LONG TERM...Roller AVIATION...Steinwedel Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
623 PM CDT Tue May 16 2023 .SHORT TERM... Issued at 215 PM CDT Tue May 16 2023 Through Wednesday night... The much advertised lake enhanced cold front is racing south across Lake Michigan early this afternoon. Temperatures ahead of the front are warming into the mid to upper 70s already early this afternoon with the anticipation that some places even reach the lower 80s. The forecast for the cold front arrival time remains unchanged from the morning update with the expectation that it reaches far northeast Illinois between 4-5pm, Chicago between 5-6pm, and northwest IN and the outer IL suburbs 6-7pm. Cannot rule out a slightly earlier arrival. Regardless, the message remains the same, if planning to spend time outdoors later this afternoon into the evening be sure to take a jacket along with in anticipation of a 15-20+ degree drop and gusty winds to 20-30 mph in the immediate wake of the cold frontal passage! Lows tonight dip into the lower-mid 40s north of I-88 and upper 40s to near 50 south. The weather looks quiet tonight through Wednesday night as surface high pressure becomes established over Lake Superior. This will result in continued easterly flow through the day. Accordingly lake cooled air will keep high temperatures mid 50s along the shore and lower 60s across the Chicago metro. Areas further inland may still manage to warm into the lower to mid 70s. Last item worth discussing is the smoke layer aloft drifting southeast from Alberta wild fires. A thin ribbon of smoke is expected to drift south out of Wisconsin over the area this evening. Depending on how quickly it gets here it may result in a pink tint to the sun as it is setting. This ribbon continues south of the area overnight. Looking at the RAP Vertically Integrated Smoke product a broader area of smoke aloft is forecast to move back into the area tomorrow morning/early afternoon that persists the next couple of days and resulting in a milky/hazy appearance to the sky. Always tricky to account for this in the sky cover grids. While not ideal, for now have increased vales to 45 percent so that the forecast reads "partly cloudy" during those periods. Petr && .LONG TERM... Issued at 300 PM CDT Tue May 16 2023 Thursday through Tuesday... Key Forecast Message: * Showers with a limited threat of thunderstorms Thursday night- Friday ahead of the next cold front * Upper level smoke from wildfires in Alberta likely persisting through Thursday A primarily quiet west-northwest flow aloft pattern will be in place through early next work week. The exception to this and main period of interest will be associated with a potent mid-upper low and its associated cold front embedded in a weak surface trough. Thursday and much of if not the entire evening will be dry, with maybe a few showers sneaking into the far northwest CWA toward midnight. If the upper level smoke isn`t too thick on Thursday, highs are pegged to reach the mid to upper 70s inland, warmest far west/southwest, and 60s Illinois shore due to southeast winds and an afternoon lake breeze backing winds more easterly. The strongest forcing with the mid-upper low will lag the front Thursday night into Friday and focus just to our north. That said, frontal convergence near and maybe even just behind the front and upper level jet support will team up with a ribbon of higher column moisture to produce fairly widespread shower coverage. There is variance in the guidance in the exact frontal timing, with an overall slightly faster frontal approach and passage noted in the past 24 hours or so. If the fastest timing verifies, showers should end northwest to southeast mid day through mid Friday afternoon. Regarding thunder chances, weak mid-level lapse rates and progged meager elevated instability should keep lightning instances isolated/sporadic at best if not entirely preclude lightning. Low but relatively better chances may include the overnight Thursday night period in parts of northern IL and then near/southeast of I-55 Friday afternoon depending on the cold frontal timing. Following forecast highs in the 70s ahead of the front on Friday, there will be a healthy cool-down behind it, but not nearly the magnitude and quickness of this (Tuesday) evening`s lake enhanced front. Forecast lows are in the upper 40s-lower 50s Friday night- early Saturday. A series of high pressure systems will bring quiet weather in aforementioned west-northwest flow aloft. Temperatures will be near to slightly perhaps slightly below normal Saturday, coolest lakeside, warming back above normal Sunday ahead of another strong lake breeze (could be another lake enhanced front in this setup). The pattern will repeat itself on Monday and Tuesday. Beyond current day 7 (next Tuesday) may be next opportunity for rain, though all in all, not yet seeing signs of a change to an active/stormy pattern. Castro && .AVIATION... For the 00Z TAFs... Northeasterly winds will gust 20-25 kt for the first few hours of the TAF period behind a lake-enhanced cold front before decreasing in magnitude by 03Z. Thereafter, east-northeasterly winds of 10-15kt will prevail through the TAF period. Per experimental RAP-SMOKE guidance, extensive wildfire spoke trapped above FL250 appears on track to stream over the terminals tomorrow. So, opted to introduce SCT250 at all terminals for an expectation for opaqueness in the sky tomorrow. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...IL nearshore waters until 7 AM Wednesday. Small Craft Advisory...IN nearshore waters until 7 AM Wednesday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Marquette MI
645 PM EDT Tue May 16 2023 .SHORT TERM...(This afternoon and tonight) Issued at 130 PM EDT TUE MAY 16 2023 Cold front dropped south through the region today, kicking off a period of cloud cover near Lake Superior and gusty winds CWA-wide. A majority of sites observed winds gusting above 20mph while temperatures cooled from north to south. By publishing this, most of the northern half of Upper Michigan was in the 40s or 50s, while the south half was still in the 60s. Dry air building in behind the front has helped scour out cloud cover save for some patches in the interior west and north-central. As we progress through the remainder of the afternoon and overnight, cloud cover will mix out and winds will weaken, going light and variable across a majority of the forecast area. The drier airmass will allow for a colder night then last, and most areas in the interior are expected to dip into the low 30s or high 20s. Together, this should support patches or areas of frost. .LONG TERM...(Wednesday through Tuesday) Issued at 447 PM EDT TUE MAY 16 2023 Slightly below normal temperatures and near normal precipitation is forecast for the extended period. Precipitation chances are focused in the late Thursday (west) into early Saturday period (east) as an area of low pressure tracks across the region. A cold front on Sunday could bring a few showers, but the bigger story is another very dry ridge moving across the area. Regarding fire wx potential, Thursday seems to have the worst combination of elevated winds and low RHs. Starting with Wednesday, dry surface ridging results in light winds and mostly sunny skies that should result in RHs dipping below 20% in spots. RAP guidance shows a plume of smoke tracking into our area Wednesday morning that could limit high temps or at least make it feel more comfortable. A ~35 knot southwesterly low level jet tracks across the area Thursday morning (west) and Thursday evening (east). This should result in gusty winds ramping up as the sun comes up Thursday morning resulting in some low level mixing. Think this good mixing and dryness should continue until the cold front and precip arrives. The strongest winds appear to be across the east (gusts to 30 kts) during the afternoon and evening hours when RH values below 30% lead to bonafide Elevated Fire Wx Conditions. Nighttime recovery is also questionable ahead of the frontal boundary since southerly flow should keep the boundary layer well-mixed. I tried to keep RHs low until the FroPa occurs to reflect this. Showers and perhaps a few rumbles of thunder are expected along and immediately behind the FroPa. The 12z 3km NAM brings the front into IWD shortly after 18Z, CMX around 21Z, and MQT/IMT just before midnight, and the far eastern UP around sunrise on Friday. Currently forecast PoPs probably move east a bit too fast, but I felt fire wx concerns were more worthy of my time investment. Precip chances ramp up again as the cold core upper level low Friday into Friday night, but there should be a few hours of drying between these two features. Ensemble means have total QPF amounts around 1/2 inch across the western 2/3rds with lighter amounts across the east. A cold front Sunday morning scours out any remaining moisture as a much drier air mass associated with a 1025+ mb ridge moves into the region. This drier air mass is likely to bring renewed fire wx concerns. Fortunately winds appear mostly light, but there are some higher winds on Sunday as the ridge builds and perhaps on Tuesday as the high shifts away from the area. The lowest RHs should be on Monday when the ridge is centered over our area with light winds and afternoon lake breeze development. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 645 PM EDT TUE MAY 16 2023 A dry airmass moving into the region will support clear skies at all terminals with VFR conditions in this TAF period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 447 PM EDT TUE MAY 16 2023 Northerly winds are currently around 20 to 25 knots across southern Lake Superior this afternoon, then fall below 20 knots this early this evening. With ridging over the Upper Great Lakes Wednesday, wind gusts remain below 20 knots until the afternoon across the far western lake as a low pressure approaches. Easterly gusts around 20 knots Wednesday afternoon veer southerly Wednesday night and increase to around 20 to 25 knots over the north central lake as a low level jet passes over the lake. Thursday, southerly gusts around 20 to 30 knots are expected, with some higher gusts possible across eastern Lake Superior during the evening immediately ahead of the cold front. Behind the front Friday, winds generally out of the northwest continue to gust to around 20 knots. There is some forecast uncertainty into the weekend but a period of lighter winds is favored as high pressure slowly builds in Friday night. WSW gusts increase again to around 25 kts on Saturday ahead of another cold front expected Sunday morning. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JTP LONG TERM...EK AVIATION...07 MARINE...EK
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 309 PM CDT Tue May 16 2023 Key Messages: - Next shower and thunderstorm chances Wednesday night into Thursday night. - Dry Friday through Monday with highs near to slightly above normal. Tonight and Wednesday: Relatively quiet weather conditions are expected for the next 24-36 hours as a low-level ridge axis progressively weakens over the mid-MO Valley. A plume of mid/upper-level smoke originating from wildfires over western Canada is spreading south through the northern Plains and upper-MS Valley this afternoon with the smoke moving into our area tonight into Wednesday. RAP and HRRR forecasts suggest that the majority of smoke will remain suspended aloft, though some potential will exist for reduced air quality and minor visibility reductions at the surface. Otherwise, expect slightly warmer conditions Wednesday with highs in the lower to mid 80s. Wednesday night into Thursday night: A mid/upper-level low will progress from Saskatchewan and Manitoba into the upper Great Lakes during this time period with an associated surface cold front moving south through the mid-MO Valley Thursday. Height falls/dynamic forcing for ascent attendant to the upper-air system coupled with low-level convergence/uplift along the front are expected to foster widely scattered to scattered showers and thunderstorms along and ahead of the front. No severe weather is expected with rainfall amounts of less than 0.25" at most locations. Highs Thursday will be modulated by clouds and areas of rain with readings generally in the mid 70s to lower 80s. Friday through Monday: A slightly cooler air mass will move into the region Friday on the backside of Thursday`s cold front with highs in the upper 60s to low 70s. Developing south winds Saturday will draw warmer air into the region with highs bouncing back into the mid to upper 70s. By Sunday, model differences exist in the strengthen of a midlevel trough from Hudson Bay into the Great Lakes, and the effect of that feature on the surface pattern. The deterministic ECMWF depicts the lowest midlevel height field, which in turn drives a surface cold front into the mid-MO Valley, which in turn would bring a chance of rain to the area. The deterministic GFS and Canadian models suggest the midlevel trough will be weaker with no frontal intrusion, and reduced precipitation chances. The GFS/Canadian model solutions are supported by the NBM, so we will not include any precipitation chances. Highs Sunday will be in the upper 70s to low 80s. Similar conditions are expected Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 532 PM CDT Tue May 16 2023 VFR conditions expected through the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Mead AVIATION...DEE
Area Forecast Discussion
National Weather Service Pocatello ID
227 PM MDT Tue May 16 2023 .SHORT TERM...Tonight through Fri afternoon. Showers and thunderstorms just in the last hour have developed on weather radar, mostly in the northeast corner of the forecast area so far. This should continue into the early evening, then some morning showers are possible in the central Idaho mountains on Wed, if the HRRR is to be believed. There is some moisture available, but good instability does not occur until Wed afternoon. And this applies not just to the central Idaho mountains, but all over the forecast area, with increased available moisture and continued good shear. At this time, do not expect any severe conditions on Wed afternoon/evening. The pattern creating this weather is very slow in changing with showers and thunderstorms continuing at least through Thu evening. The low finally exits to the east on Fri, with stronger warming developing under a high-amplitude ridge, with temperatures over the weekend warming in populated areas to above/around 80 degrees even in places as far north as Rexburg. On Friday, the thunderstorm threat falls off, but the heating does not eliminate the threat totally; the central Idaho mountains and the southeast highlands have a slight chance level of threat. Wind outside of thunderstorms shouldn`t amount to much. Yesterday, for Thu an organized trough was producing moderate wind in the Snake River plain. This is not the case with the morning guidance run, so will need to keep an eye on if this is a permanent change. Messick .LONG TERM...Friday night through next Tuesday. Ensemble means and cluster analysis data remain in good agreement showing upper ridging dominating the local weather scene Friday night into Sunday. As a result, we continue to anticipate the warmest temperatures of the next week to occur this weekend, with daytime highs reaching the 80s at lower elevations and 60s/70s at all but the highest mountain elevations (where temps will top out in the 50s). Sunday should be the warmest day, and probabilities of exceeding 90F remain in the 40- 60 percent range across portions of the Lower Snake Plain and Eastern Magic Valley. Probabilities of exceeding 80F in the Wood River and Big Lost River Valleys are running between 50-80% from roughly Ketchum and Mackay south. Overnight lows will also be well above normal, remaining above freezing across the vast majority of the area, excluding only the typical high-elevation coldest spots. Of course with this building warmth through the weekend, flooding will continue to ramp up for areas still dealing with snowmelt (more on that in the Hydrology section below). While coverage/chances of showers and thunderstorms will decrease this weekend under the upper ridge, they won`t shut off entirely. Remnant moisture trapped under the ridge appears sufficient to team with diurnal heating over the higher terrain to support some afternoon/evening convection. Heading into early next week, considerable uncertainty exists with the evolution of an upper low over the PacNW/southern BC. H5 cluster analysis shows a roughly 60%/40% split on a more progressive system pushing east through the Northern Rockies vs. a closed low spinning over the PacNW for several days, ejecting shortwaves across the area in a southwest flow aloft. The former scenario would support a stronger cold frontal push and more consolidated precip event early in the week, followed by moderated cooling and at least a brief dry period. The latter would support continued warmer conditions and daily shower/thunderstorm chances downstream of the low. This latter scenario (warmer/wetter) could further exacerbate flood concerns next week, and thus we`ll be keeping a close eye on this pattern evolution in the days ahead. KB && .AVIATION...Expecting less -TSRA activity with less available moisture, although instability is quite good. It is the reason why gusty wind is expected this afternoon and evening. Some late night and morning -SHRA are possible over the mountainous regions, including KSUN and KDIJ. By Wed afternoon, moisture levels in the atmosphere are up and the low overhead produce another round of -SHRA/-TSRA in the afternoon and evening. This has the potential to be stronger with more rain, but it should not produce significant CIG or VSBY impacts at the airdromes. Chief hazard will be lightning and shifting wind. Messick && .HYDROLOGY...With the gradual warming trend continuing, so do the flood concerns from snowmelt across the area. The main changes today were to upgrade the Flood Watch for the Henry`s Fork near Rexburg to a Flood Warning, as flood stage is expected to be reached Wednesday morning. In addition, an Areal Flood Warning was issued for much of Bear Lake County, replacing the Areal Flood Advisory, as local Emergency Management reports the flooding has escalated along the Thomas Fork near the WY border and also in many canyons emerging from the Bear River Range in western portions of the county. Otherwise, the going suite of flood headlines remain unchanged. The Big Wood River at Hailey is now expected to reach moderate flood stage earlier (Thursday) than previously forecast. The latest forecasts have delayed the Big Lost at Howell Ranch reaching flood stage by a couple of days (now Saturday), so have maintained the Flood Watch there. Antelope Creek remains just under flood stage. Per coordination with local Emergency Management, will hold off on issuing a Flood Warning for now, but anticipate needing one in the next day or two as flood stage is reached. Camas Creek has dropped over the past 24 hours, with no impacts of note there. The continued warmth into the weekend will drive further rises on rivers and streams still being fed by snowmelt. No noteworthy cool downs are currently anticipated over the next week, so look for the runoff to continue to drive high flows. KB && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$