Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/07/21

National Weather Service Albany NY
1045 PM EDT Mon Sep 6 2021 .SYNOPSIS... High pressure will bring generally fair weather, and near seasonable temperatures tonight through Tuesday night. A strong frontal system will approach from the west later Wednesday, bringing showers and thunderstorms Wednesday afternoon and night, with some locally heavy downpours possible. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 10:30 PM EDT, winds continue to weaken tonight which should allow the boundary layer to decouple over the coming hours. Temperatures have cooled down a bit quicker than the forecast showed so we adjusted temperatures downward a few degrees to account for the latest trends. A few isolated showers associated with a pressure trough and the incoming upper level disturbance/cold pool are moving off Lake Ontario and through the Adirondacks. These showers/sprinkles are weakening and will likely diminish before reaching our western Mohawk Valley or southern Adirondack areas. The high res NAM seems too aggressive in allowing showers to extend far inland into our area but the HRRR seems more reasonable so we leaned closer to that drier solution. Given some sprinkles tracking towards far southern Herkimer County off Lake Ontario, we introduced some slight chance POPs there which lined with BGM but otherwise, maintained a dry forecast. Patchy fog should then develop mainly after 06 UTC in prone valley areas as the temperatures close in on the dew points which will be in the low 50s. Since we did not rain in the evening like we did yesterday and winds will be elevated for the first half of the night, fog should not become as dense or widespread as last night. Thus, we limited it to valley areas. Still expecting overnight lows to turn chilly and based on current trends, we decreased our lows a few degrees and we now forecast lows to reach into the low 50s with upper 40s in the southern Adirondacks and southerns Greens. Previous discussion... Tuesday...Heights continue to rise aloft, and we will end up under the axis of an amplifying upper-level ridge tomorrow afternoon. This will help keep tranquil weather for our region during the day tomorrow. Meanwhile, the surface high will slide to our southeast during the day, which will result in northwesterly winds and cold air advection early in the day switching to southwesterly winds and warm air advection tomorrow afternoon. After a cool start to the day, high temperatures will recover to the mid and upper 70s for valley locations, although higher elevations will only have highs in the 60s. Tuesday Night...Looking aloft, the upper-level ridge axis will depart to our east as an impressive closed upper low digs south from Ontario towards the Great Lakes Tuesday night. A surface low is expected to develop in response to the upper low and track north of the Great Lakes. As this low deepens to 992 mb by Wednesday morning, it will drag a strong cold front towards our region. Therefore, even though the best upper forcing (cyclonic vorticity advection, height falls) will remain to our west through much of the nigh, a few showers will be possible towards daybreak for our far northwestern areas ahead of the approaching front. In the lower the surface high slides further to the east, warm air advection into the region continues, with a warm front expected to lift through the region overnight. Behind this warm front, advection of higher theta e air into the region will continue, with PWAT values rising to around 1.2-1.3" by Wednesday morning. The combination of warm air advection, higher dewpoints, and more cloud cover than the previous night will result in warmer overnight lows, with mid 50s expected in the high terrain and upper 50s to around 60 for valley locations. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... A cold front will slowly approach from the west later Wednesday into Wednesday night. Strong south/southwest flow will develop, especially within the mid and upper levels of the atmosphere. As the front tracks east, it should tend to slow down a bit, especially as ridging off the New England coast potentially builds a bit stronger, while Hurricane Larry tracks into the northwest Atlantic Ocean. PWAT`s are forecast to increase to 1.5-1.75 inches across eastern New York/western New England, and with winds becoming nearly parallel through a deep portion of the troposphere, the potential for training showers/thunderstorms with locally heavy rainfall exists for late Wednesday afternoon into at least the first half of Wednesday night. The best chance for heavier downpours currently appears to be the region from the northeast Catskills, Capital Region into southern VT, however this could change. There could be some embedded thunderstorms as well, although the coverage of stronger thunderstorms will be modulated by timing of frontal passage, which may not occur until after sunset in some areas. However, mid level wind fields will be strong, with H500 winds of 40-50 KT, so strong wind gusts could occur within any bowing line segments. Even outside convection, some strong south winds may occur ahead of the front, perhaps gusting 25-35 mph within some north/south oriented valleys, including portions of the Hudson River Valley close to the Capital Region. As for temperatures, some morning breaks of sun and warm temps aloft should allow max temps to reach 75-80 in most valley areas, with upper 60s to lower 70s across higher elevations. Lows Wednesday night mainly in the mid 50s to lower 60s. && .LONG TERM /THURSDAY THROUGH MONDAY/... A mostly quiescent weather pattern can be anticipated during the long-term forecast period. The large-scale upper level pattern during this period will still undergo a transition from a more amplified (warm West U.S. vs. a cooler East U.S.) configuration to start the period to a more zonal/semi-zonal setup later on in the extended. This transition will contribute to some of the uncertainty in the weather pattern later in the extended. The weather pattern will remain progressive too through the extended. As far as temperatures, we`re expecting to see a cooler than normal bias in anomalies with things feeling more Autumn-like over the region during this period. We start off the long-term period Thursday with eastern New York and western New England on the backside (cold-side) of a pretty potent storm system that will be centered well off to our north near the Hudson Bay and it`s associated cold front to our east just off the coast of New England. Cooler and drier conditions will be in place as cold air advection (CAA) ensues. Thermodynamics between Lake Ontario and the air just above it plus several mid-upper level impulses overhead associated with an upper level trough/broad- cyclonic flow aloft will be supportive of some lake-enhanced rain showers over parts of the area as backing winds out of the west flows downwind of Lake Ontario. Additionally, there could also be areas of orographic enhancement during the diurnal peak hours on Thursday. Lake-enhanced and any diurnal-orographically driven rain showers should wane during the evening/nighttime hours due to the loss of energy from the sunlight and westerly winds subsiding. On Friday, a broad 1016 hpa surface high pressure system is progged to build into the region from the west-southwest. This will effectively result in dry and tranquil conditions returning to the ALY forecast area. Expect a mostly sunny to partly cloudy day with areas south of Albany seeing the clearer conditions due to its proximity to the aforementioned high pressure system building in. On Saturday, expect a sunny to mostly sunny day as the high pressure system gets a firmer grip over the region with the center of the 1020 hpa high over the Mid-Atlantic states into the Carolinas. For Sunday, forecast models are advertising a powerhouse storm system that`s currently forecast to track from the Northern Plains/Upper Midwest Region northeastward into Ontario and eventually Quebec. It`s uncertain this far out as to how much influence weatherwise this storm system will have over our area. Current thinking is that clouds will increase during the day on Sunday especially over our northwestern zones (Herkimer and Hamilton Counties). Most areas at this point will remain dry with the exception of Herkimer and Hamilton Counties. Will have to continue to monitor trends on how much extent and thus influence this storm system will have on the area. For now, have just low-grade PoPs for areas northwest of Albany with the 30% PoPs over Herkimer and Hamilton Counties. Dry and tranquil conditions return to the area to start the new workweek, should we have any precipitation over the area on Sunday. The passage of a cold front associated with the aforementioned storm system will result in cooler, more Fall-like temperatures on Monday. With the exception of Sunday, high temperatures will hover in the lower 70s along the river valleys (60s and even some upper 50s in the higher elevations). On Sunday, high temperatures will top out in the mid 70s along the river valleys (60s higher elevations). Overnight low temperatures during this period will be mostly in the 50s (40s higher elevations) with the exception of Sunday night where lows are progged to be in the upper 50s to lower 60s along the river valleys (mid 50s higher elevations). && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... VFR conditions in place this evening will continue through at least 06 UTC. Then, radiational cooling and calming winds should allow patchy fog to develop, mainly at GFL and PSF. This could result in IFR visibilities and ceilings. Since winds will be a bit elevated through the first half of the night and we did not experience rain this evening, we kept ALB and POU VFR where there is low confidence that fog will develop. Any fog should lift by 13 - 14 UTC. Some guidance hints that the fog will lift into a stratocumulus deck resulting in MVFR ceilings at GFL and PSF but due to low confidence, we did not include this potential. Otherwise, VFR conditions are expected through the rest of the TAF cycle with daytime heating resulting in diurnal fair weather cumulus clouds. Westerly winds this evening ranging 5 to 9kts should gradually decrease this evening, becoming light to calm after midnight. Then, once we reach peak heating tomorrow morning by 14 - 15 UTC, westerly winds should increase towards 5 - 8 kts. Outlook... Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: High Operational Impact. Breezy. Definite SHRA...TSRA. Wednesday Night: High Operational Impact. Definite SHRA...TSRA. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: No Operational Impact. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... High pressure will bring generally fair weather, and near seasonable temperatures tonight through Tuesday night. A strong frontal system will approach from the west later Wednesday, bringing showers and thunderstorms Wednesday afternoon and night, with some locally heavy downpours possible. RH values will increase to 90-100 percent tonight with areas of dew formation likely. RH should drop to 45-55 percent Tuesday afternoon. Gusty west to northwest winds of 15-25 mph should diminish to less than 5 mph after midnight, then become west to southwest at 5-15 mph on Tuesday. && .HYDROLOGY... Mainly dry conditions are expected tonight through Tuesday night. More showers and thunderstorms are possible for Wednesday afternoon and night. Thunderstorms could produce locally heavy rain, resulting in ponding of water on roadways and standing water in low lying areas. However, river flooding is not expected at this time. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...KL NEAR TERM...Main/Speciale SHORT TERM...KL LONG TERM...Evbuoma AVIATION...Speciale FIRE WEATHER...KL/NAS HYDROLOGY...KL/NAS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
854 PM MDT Mon Sep 6 2021 .UPDATE... Issued at 853 PM MDT Mon Sep 6 2021 Only some cirrus clouds were tracking south into the forecast area this evening. Otherwise a very dry and mild airmass remained in place. Surface analysis showed a couple surges moving south across Wyoming and Montana, the first which is weakening. The main front should arrive by/shortly after daybreak resulting in about 8-9 degrees of cooling (but still above normal temperatures) across northeast Colorado Tuesday. Satellite imagery from earlier this evening showed a plume of smoke shifting this way behind the front, so we do expect an increase for tomorrow and will mention areas of smoke in the forecast. && .SHORT TERM...(This evening through Tuesday) Issued at 220 PM MDT Mon Sep 6 2021 The strong upper level high will remain over the Great Basin and only shift slightly eastward through Tuesday. Weak northwest flow around the high will continue to bring warm and dry conditions to the Central Rockies. It will be a cool night in the low lying areas again due to the dry airmass and light winds. An upper level trough will pass well north of Colorado and over the Northern Plains. A weak cold front associated with this system will push south through Colorado tonight and bring slightly cooler temperatures for Tuesday. Highs across northeast Colorado will be about 4-7F cooler than today. This will put highs in the mid to upper 80s. Looking at satellite and the HRRR model, appears smoke will increase over the region tonight and Tuesday. This may limited afternoon heating by a couple of degrees. .LONG TERM...(Tuesday night through Monday) Issued at 220 PM MDT Mon Sep 6 2021 Hot and dry is the main headline for the period. There is good consensus among ensemble and deterministic guidance that an upper level ridge slowly progresses eastward over the region through the week. This will promote unseasonably warm temperatures and dry conditions. The mentioned conditions will increase fire weather concerns; however, winds may likely keep us below criteria for red flag headlines. An upper level ridge will dominate the pattern for much of this week. Weds., the main axis remains to the west and gradually moves eastward. This will support below normal moisture and unseasonably warm temperatures. Temperatures trend warmer into Thurs. marked by a bump in 700mb temperatures. There is increasing potential for the Denver area to break records Thurs/Fri (94/93) with highs forecasted to be in the mid to upper 90s. Slightly cooler temperatures expected for the weekend in the low 90s at the lower elevations and 70s over the higher elevations. In regards to moisture this week, relative humidities drop into the teens in many areas through Fri. increasing fire weather concerns. Weaker winds will help keep conditions below red flag criteria. Ensemble guidance shows the jet max to stay north of the region which will limit high wind potential. Fri/Sat afternoon may warrant monitoring as ensemble guidance has members with gusts above 20 mph over parts of North Park, but confidence is not high at this time. Deterministic guidance continues to show potential for the passage of a few embedded shortwave troughs in the NW flow aloft this weekend. Details still remain uncertain with differing solutions, but general consensus exhibits them to be fairly weak. A signal for gradual moisture return combined with weak QG forcing for ascent will bring back chances for afternoon showers and thunderstorms Sat/Sun over the higher terrain. Limited instability and average precipitable water amounts should keep coverage scattered. May see increased winds over the higher terrain Monday with increased WNW flow aloft. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 853 PM MDT Mon Sep 6 2021 Winds should transition to light southwesterlies around 5-10 knots overnight, and then turn northerly around daybreak Tuesday with passage of a weak front. Smoke will likely increase behind the front, with limited slant range visibility for the Denver area TAF sites limiting visual approaches. We`ll go with P6SM but some smoke (FU) in the TAFs to account for that. && .HYDROLOGY... Issued at 220 PM MDT Mon Sep 6 2021 Hot and dry conditions will limit flash flood potential for much of the week. Moisture gradually increases over the weekend resulting in scattered showers and thunderstorms over the higher terrain. Instability appears to be limited and precipitable water values are closer to average which will keep flash flood potential low. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Barjenbruch SHORT TERM...Meier LONG TERM...Mensch AVIATION...Barjenbruch HYDROLOGY...Mensch
Area Forecast Discussion
National Weather Service Des Moines IA
629 PM CDT Mon Sep 6 2021 .DISCUSSION.../Tonight through Monday/ Issued at 200 PM CDT Mon Sep 6 2021 Main Points: - Breezy tomorrow behind passing cold front - Cool mornings mid-week - Dry through majority of forecast period Not much has changed with the forecast since the overnight shift. A shortwave trough sweeps across the northern Plains into the Great Lakes region over the next 24 hours, which will drag a cold front through the area Tuesday. Convection tries to fire along the boundary, however models squash any initiation attempts due to lack of instability and displacement of the strongest kinematic lift to our north and east. CAA and a relatively tight pressure gradient leads to breezy northwest winds in the wake of the frontal passage. Pressure rises relax a bit into the afternoon hours, but winds of 25 kts or so near the top of a well-mixed boundary layer should keep surface winds somewhat elevated through the day. Cooler air settles into the region as lows Wednesday and Thursday morning possibly dip into the 40s in some areas, 50s elsewhere. Also of of note is the HRRR smoke output suggests a plume of wildfire smoke aloft overspreading the state late today into tonight. Not expecting any impacts near surface or to highs tomorrow as changing winds aloft scour out the smoke before the peak heating hours. Deep north/northwesterly trajectories on the eastern periphery of a western conus ridge pushes the cold front well south toward the Gulf region. This essentially cuts off our area from any appreciable moisture for a while. Pattern becomes a bit more active toward the weekend into early next as a series of shortwaves begin to break down the western ridge, particularly Friday night into Saturday as models bring a shortwave through the northern Plains. Considerable timing/amplitude differences exist in the latest deterministic model runs. GFS/EC/ECENS still favor a dry solution with all precip displaced to our north, while the GEFS output is more split on precip chances for the state. Favored the dry NBM forecast for now given the scant moisture availability and fairly progressive flow. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 629 PM CDT Mon Sep 6 2021 VFR conditions are forecast through the period, with few clouds and no precipitation or obscurations expected. LLWS of 35-40 KT is expected during the overnight/early morning hours, but will diminish as surface winds increase after sunrise Tuesday. A front will then sweep from northwest to southeast across the area from late Tuesday morning into the early afternoon, with winds shifting from SW to NW as the front passes and becoming brisk and gusty during the afternoon hours. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...Martin AVIATION...Lee
Area Forecast Discussion
National Weather Service Grand Forks ND
928 PM CDT Mon Sep 6 2021 .UPDATE... Issued at 928 PM CDT Mon Sep 6 2021 Storms have finally started to strengthen along and behind the cold front pushing into eastern and southern regions of the CWA. The strongest storms have been along the surface front in Beltrami county, where storms have taken off in 1000 J/kg of MUCAPE and very strong effective bulk shear. Storms further west behind the front across central portions of the CWA have also strengthened as the main shortwave rotates into the area. CAMs have the strongest cells moving quickly east of our CWA during the next few hours, and that seems reasonable given the quick movement of the shortwave and cold front. Still could see an isolated elevated storm producing some hail through midnight. UPDATE Issued at 650 PM CDT Mon Sep 6 2021 Will continue to monitor for any thunderstorm development in northwestern MN as the shortwave comes in and encounters elevated instability. HRRR and some of the other CAMs have been showing some stronger cells developing around 01 or 02Z, and there is still some MUCAPE over 1000 J/kg and plenty of shear to work with, so not ruling out a few isolated strong to severe storms just yet. Kept POPs pretty close to what we had going. Some decent showers along the 700mb frontogensis zone in our northern counties, so some spots are finally seeing a bit of rain reaching the ground instead of just virga. && .SHORT TERM...(This evening through Tuesday night) Issued at 337 PM CDT Mon Sep 6 2021 Isolated severe thunderstorms remain possible this evening with better chances possibly shifting southeast along/southeast of the Highway 2 corridor. Showers are beginning to spread into northeast ND as the shortwave digs southeast into Manitoba. Tds are finally increasing more and mid level lapse rates are supporting increasing elevated instability into the 500-1000 J/KG range in our south. Winds are already shifting to the northwest in the northern Devils Lake Basin and axis of better instability will also likely flatten towards the eastward over the next 3hrs and then slide southeast (based on current RAP). This lowers confidence in strong/severe updrafts further north, but does still allow for window for severe near the convergence zone along the prefrontal trough axis. The last 4 runs of the HRRR and latest SSCRAM probabilities favor stronger initiation near this region near and southeast of Hwy 2 mainly in MN in the 8-10PM period. 12Z HREF was already showing this shift east-southeast with UH track probabilities of at least 35 m2/s2 in our far east during that window. Good forcing, high shear (35-55kt effective progged by RAP), and elevated CAPE near 1500 J/KG should be in place amd supportive of isolated severe potential. Hail to 1" continues to be a threat due to steep mid level lapse rates, and wind may not be as much of a threat due to DCAPE values being progged to remain under 1000 J/KG. High bases and strong shear do still rain some isolated severe wind potential especially if storms cluster and track orthogonal to stronger 0-3km shear vectors (hard to anticipate at this time). Any lingering showers/storms are timed to exit our east around midnight tonight, and CAA then overspread our CWA through Tuesday. Cyclonic flow and cold pool aloft could support a few showers or weak thunderstorms near Lake of the Woods during peak heating Tuesday otherwise dry conditions and only diurnal CU development would be anticipated elsewhere. Unidirectional flow and increasing pressure gradient will support windy conditions. Max winds within the mixed layer at this time are in the 30-35kt range so while windy current guidance isn`t as favorable for potential advisory gusts. Highs should be lower by 10F compared to today due to CAA and mostly locations should remain the low to mid 70s. Lows Tuesday night should be near seasonal averages around 50. .LONG TERM...(Wednesday through Monday) Issued at 337 PM CDT Mon Sep 6 2021 The chance for hazardous weather is low within the long term period. Synoptics starting the period feature a large, anomalous anticyclone parked over the Four Corners region with upper troughing moving through southeast CAN. This places the area firmly under northwest flow aloft into Thu. Late in the work week, one or two shortwave troughs travel over the crest of the anticyclone, flattening the upper ridge in the West. Temperatures will be near to above average with highs in the 60s to 80s, and lows in the 40s and 50s. Despite a very dry air mass (dew pts into the mid-upper 30s) moves into ND around Wed, chance for frost looks low at this time with influence of the departing upper trough keeping winds elevated and driest air shunted to the western Dakotas. As the ridge starts to flatten towards Thu-Sat, warm temps bottled underneath the anticyclone attempt to break east into the Great Plains. Best chance for exceeding 80 F spreads into FA as noted by NBM probabilities greater than 40% spreading into eastern ND, the Red River Valley, and west-central MN during this timeframe. The flattening ridge as a result of one or two shortwave trough passage/s also increases chances for showers and thunderstorms between Thu-Sat, although progressive and flat nature of the shortwave and general lack of confidence in assoc surface features lessens confidence in timing and coverage at this time. A general lack of better moisture looks to prevent possibility for heavy rainfall, with ENS, CME, and GEFS all showing less than a 10% chance of advecting PWATs at least 1.5 inches anywhere near the FA. Strong to severe storms are not favored at this time as well, again owing to the lack of suggested better low level moisture despite sufficient shear likely to be present with the shortwave and some signal for weak instability to briefly approach the Dakotas and Minnesota. Getting beyond Sat, ensemble consensus continues to flatten the Western ridge promoting more zonal flow over much of the northern tier of the CONUS. Zonal flow typically favors progressive shortwave trough/ridge passages which will continue low chance PoPs and near normal temps. Confidence in details finer than this is lacking as timing and amplitude of such features remain outside of the predictability horizon. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 650 PM CDT Mon Sep 6 2021 Convection and winds will be the main aviation concerns with all ceilings VFR and no restrictions to vis. There could be an isolated thunderstorm developing over northwestern MN in the next few hours that could get close to KBJI, but uncertainty still too high for more than VCTS mention. Other sites will just see some light showers. Winds have already shifted to the north for all but KBJI and KFAR, and the front coming in will cause the remaining airports to shift north before 06Z. Some gusts above 15 kts this evening, but should be settling down later tonight. Winds will pick back up out of the northwest tomorrow, with some locations gusting close to 30 kts in the afternoon. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...JR SHORT TERM...DJR LONG TERM...CJ AVIATION...JR
National Weather Service Hastings NE
712 PM CDT Mon Sep 6 2021 ...AVIATION UPDATE... .DISCUSSION...(This evening through Monday) Issued at 315 PM CDT Mon Sep 6 2021 Quiet weather continues this afternoon with clear skies across the region. Today may very well be the warmest day of the week with temps on track to reach into the lower 90s most places, with a few mid 90s across Kansas. Winds are fairly steady out of the south at around 10 kts. Late overnight tonight a dry cold front will push through the area, swinging winds around to the north. This front will also make for rather breezy and cooler conditions tomorrow. Highs tomorrow are expected to be around 10 degrees cooler than today, with south central Nebraska highs around 80 and north central Kansas highs around 85. Winds will also pick up quite a bit with sustained speeds around 15-20 kts and gusts around 25-30 kts at times. The prominent and dominating feature of the forecast is the large upper level high pressure over the western CONUS. This high will keep us in northwest flow aloft till the weekend. This is not great news for smoke haze in the upper levels, with the HRRR Smoke already indicating an increase in upper level smoke for tomorrow (and likely the rest of the week as well). The high will then slowly meander southeast to be centered over the Four Corners region by Thursday. This shift will bring warmer temperatures to the midlevels and subsequently at the surface. Temperatures are expected to warm on Thursday and Friday, with Friday`s highs possibly rivaling today`s. Thursday could also be a sneaky breezy day (if you believe the NAM) as the sfc pressure gradient tightens and we sit wedged between a lee trof to the west and high pressure to the east and southeast. Heading into this weekend a series of shortwaves aloft work to flatten out the high as it continues to move east and transitions us to more zonal flow aloft. Saturday morning another cold front moves through attached to a low centered over the northern Great Lakes. Currently there are some minor discrepancies between the GFS and the EC during the extended periods. One of these is the strength of the front on Saturday morning, where the GFS shows a stronger front, but both models keep things dry. Currently in the official forecast temps come down only a few degrees (still maintaining mid to upper 80s in NE and lower 90s in KS). Another discrepancy is with Sunday morning. The EC shows a minor embedded shortwave moving through and bringing a quick round of morning showers to northern portions of the CWA. The GFS on the other hand keeps things dry Sunday morning. Right now the official forecast is dry for the entire 7 days, but this will bear watching for changes in the weekend forecast in particular. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 704 PM CDT Mon Sep 6 2021 Significant weather: Brief LLWS with strong frontal passage First 6 hours: VFR with S-SSW wind 5-10kt. Confidence: High. Rest of the period: VFR. Main concern will be timing/effects of cold front passage at the terminals. Winds will veer to SW by about 09Z, and continue veering to NW w/ passage of cold front in the 11Z-13Z time frame. Immediately along/behind the front, and before mixing depth increases, could see a brief 1-2 hr period of LLWS around 13-14Z. Models are in good agreement showing 40-45kt around 1K ft AGL while boundary layer remains shallow and sfc winds are largely less than 15kt. Expect to mix into this layer by around 15Z, resulting in gusty sfc winds that will last through early-mid aftn. Expect a gradual decr mid to late Tue aftn. Confidence: frontal timing - high, LLWS - medium. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Shawkey AVIATION...Thies
Area Forecast Discussion
National Weather Service Goodland KS
504 PM MDT Mon Sep 6 2021 .SHORT TERM...(This evening through Wednesday Morning) Issued at 151 PM MDT Mon Sep 6 2021 The forecast period begins with northwesterly flow over the area with an amplifying ridge over the western CONUS. A dryline is setup across the CWA with elevated to near critical fire conditions behind. RH values less than 15% are currently being located along and west of Highway 83 in Kansas. Winds have remained light throughout the day (less than 10 knots) mitigating the overall fire weather risk somewhat. Weather wise not much is occurring due to the subsidence caused by the high pressure, as not even diurnal cumulus have been able to form thus far. Temperatures as of 1pm have already warmed into the upper 80s to mid 90s with a few hours remaining of peak heating, the current high temperature forecast remains on track of widespread 90s. The HRRR Near Surface smoke has been showing some elevated areas of smoke moving south down the eastern periphery of the ridge causing the potential for haze to occur through the afternoon and into tomorrow morning, some visibility restrictions are possible especially towards sunrise. Overnight lows for tonight are forecasted in the mid 50s across east Colorado to the mid 60s across eastern portion of the forecast area. A cold front moves through the CWA Tuesday morning as a stronger system occludes over the Great Lakes. As the front moves through winds will switch out of the north with gusty winds along and behind the front, some wind gusts may approach 30-35 mph. Fire weather is again possible due to the wind however, with RH`s not as low as today but in the low 20s. Breezy to gusty winds will persist through the afternoon before waning during the evening. Afternoon highs wont be as warm as temperatures will remain in the 80s. Mainly clear skies are expected for Tuesday night with the entire area in the 50s; some locales across east Colorado may even fall into the 40s for a brief period of time. .LONG TERM...(Wednesday through Monday) Issued at 157 PM MDT Mon Sep 6 2021 The primary concern in the long term period is the potential for near critical fire weather conditions and blowing dust resulting from a prolonged period of hot and dry conditions combined with breezy winds. A large high pressure area aloft moves across the 4-corners region on Wednesday night and Thursday and into the southern Rockies and southern high plains on Friday and Saturday as several short wave troughs move through the westerly flow tracking along the U.S./Canadian border. With the somewhat chaotic pattern moving across the northern tier of states, model solutions are showing a wide variety of timing and location differences with the individual short waves embedded in the flow. Suffice to say the bulk of the dynamics associated with the embedded waves remain north of the central high plains region through the weekend and into the beginning of next week. The consistencies that have remained are the slightly warmer than average temperatures on Wednesday that warm to well above average with highs in the lower to middle 90s on Thursday and the middle to upper 90s on Friday ahead of a cold front that moves across the forecast area early Saturday morning along with one of the stronger short wave troughs aloft moving east of the Rockies and across the northern High Plains. Hot and dry conditions on Thursday and Friday will produce near critical fire weather conditions across mainly the western sections of the forecast area along and west of KS Highway 27. Afternoon minimum relative humidity values across this area will be in the middle teens or lower. Wind speeds are not expected to be over 25 mph at this time, which would keep the area from reaching critical fire weather thresholds. This will, however, bear watching over the next few days as it will be close. The cold front moving across the area early Saturday following several days of hot and dry conditions will bring the potential for blowing dust as wind speeds increase immediately along and behind the front that could continue through mid-day on Saturday. Models are not currently advertising windy conditions, but expect this to change over the next couple of days. Even with the increase in winds with the front, critical fire weather conditions are not expected to be met on Saturday as relative humidity values will not exceed critical thresholds due to high temperatures being slightly cooler with readings in the upper 80s to lower 90s. Temperatures will rise into the lower to middle 90s with an increase in the potential to meet near critical fire weather conditions as afternoon minimum relative humidity values venture back into the teens. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 504 PM MDT Mon Sep 6 2021 Mainly VFR conditions expected for both terminals. Smoke aloft could create hazy conditions that could lower visibility to around 5sm at times from 08z-14z Tuesday for KGLD, and 11z-13z Tuesday for KMCK. Boundary pushing thru the region will see southerly flow currently over the area, to become northerly. Winds for KGLD, southeast to southwest 10-20kts from 00z-08z Tuesday, then northwest around 10kts. By 14z, north-northeast 15-30kts becoming northeast 10-15kts by 21z. Winds for KMCK, light/variable thru 11z Tuesday, then north 10-15kts. Gusts up to 30kts from 13z-23z. By 23z, northeast around 10kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...TT LONG TERM...LOCKHART AVIATION...JN
Area Forecast Discussion
National Weather Service Gray ME
1043 PM EDT Mon Sep 6 2021 .SYNOPSIS... High pressure and fair weather build in Tuesday, lasting into Wednesday with temperatures warming into the upper 70s and low 80s by Wednesday. A slow moving cold front will approach Wednesday afternoon bringing increasing chances of showers with a chance of thunder late Wednesday through Thursday. Hurricane Larry will pass well offshore this week but building long-period swells are expected, which may result in increased rip currents. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1040 PM Update...No forecast changes at this time. Other than some mountain clouds the rest of the region is clear, cool, and dry and will continue that way overnight. 720 PM Update...Have updated the forecast mainly to clear out the mention of thunder most everywhere. One last batch of weakening convective showers currently near MWN will gradually dissipate as they move eastward over the next hour or two. Thereafter, the forecast area will be rain-free. Previously... Update... Have updated the forecast based on current conditions and latest mesoscale models. Deep convection will exit east of our forecast area over the next hour with just isolated convection remaining to the west. Latest HRRR does have some precipitation crossing into northern New Hampshire from Vermont over the next couple of hours so have upped pops for that region. Otherwise, just minor tweaks to the near term portion of the forecast. Prev Disc... A trough of low pressure will exit to our east this evening with the latest HRRR showing the precipitation shifting east of our forecast area after 23Z. Will continue to include enhanced wording for the possibility of gusty winds and hail in a few of the strong storms. Drier air will filter into the Maine and New Hampshire as winds switch to a westerly direction tonight. However, there may sufficient low level moisture to allow for patchy late night fog mainly in northern and western New Hampshire. Temperatures will bottom out in the 50s in all areas tonight. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... High pressure will build towards the East Coast on Tuesday bringing dry conditions to the region. A west to northwest flow will allow for mostly sunny conditions downwind of the mountains due to downsloping. A few more clouds will linger in the mountains during the day. Temperatures will climb through the 70s for afternoon high temperatures. Mostly clear and cool conditions are expected Tuesday night. There may be some late night clouds arriving over western New Hampshire towards morning as the next front system approaches from the west. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... With low pressure becoming vertically stacked between James Bay and the UP of Michigan, the associated cold front will move through the region Wednesday through Thursday. Out ahead, warm and moist air will advect into the region. Highs Wed should reach the mid to upper 70s, with southern locations bumping into the 80s. Overall, guidance continues to agree on general onset of precip late Wed afternoon, with rain and thunder continuing overnight. As previously alluded to, the speed of departure of the front remains more uncertain. Showers will likely be continuing for far eastern areas come Thursday afternoon. Additional forcing may arrive along the coastal plain with the formation of low pres amid the boundary into Thurs evening and overnight. This would keep rain showers in the forecast for another night, finally exiting Fri morning. This area of lift comes as a strengthening upper jet entrance region begins moving north with the longwave trough trending negative from a neutral tilt. Current forecast aligns with the ECMWF and GEM showing this feature; a right entrance region w/ divergence aloft conducive to increased precip intensity and coverage. The quicker GFS suppresses this idea as the region falls below the less favorable sinking motion of the left entrance. The trough moving off the coast into Friday will also be responsible for guiding Larry in the open Atlantic. As dry conditions work into the area for much of the weekend, long period swell and increased wave heights will impact the coast with possible erosion and threat of rip currents. Temperatures will trend to around normal through the period with daytime highs in the 70s and overnight lows in the 50s, with some 40s in the higher terrain. Another upper low will progress south of James Bay by early next week which could bring more showers to the region. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Short Term...VFR conditions will prevail with clearing skies. There may be some late night patchy fog in the northern valleys as well as the Connecticut River valley. VFR conditions expected Tuesday and Tuesday night. Long Term...VFR conditions will prevail Wed afternoon, with brief MVFR possible around showers/thunder in NH terminals. Ceilings will lower to IFR overnight with continuing rain and breezy southerly winds. West wind shift occurs Thurs afternoon with IFR improving to MVFR Thursday evening. VFR Friday. && .MARINE... Short Term...Low pressure centered to the north crosses the waters today, pushing a cold front with potentially gusty showers or storms into this evening. Conditions are not expected to reach SCA thresholds, however gusts to 25+ kts are possible with showers/storms this evening. Winds turn westerly behind the system tomorrow as high pressure crosses the East Coast. Long Term...An SCA will likely be needed beginning Wed afternoon for increasing southerly winds as well as wave heights overnight. Wave heights will continue to run about 5 to 6 ft Thurs and Thurs night, increasing 5 to 9 ft Friday with increasing long period swell from Larry. Waves and swell will begin to decrease into the weekend. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
912 PM CDT Mon Sep 6 2021 .UPDATE... 912 PM CDT The forecast message for the rest of tonight and into a windy Tuesday looks on track. Have added some more detail on the specific timing for storms into the forecast for Tuesday, which looks like a 1-2 hour duration in places that experience storms. The best chances look to be along and southeast of a line from O-Hare through Pontiac. The old frontal boundary remains draped near the far southern CWA edge this evening, with a few clouds lingering along it but all showers having faded or pushed southeast. This front is starting to creep northward in Iowa and should do the same overnight in our area with no fanfare. The inversion that has set-up though will be a factor in how quickly the wind gusts come up Tuesday. Looking at forecast soundings from the RAP and HRRR and assuming high clouds are not thick in the morning, it seems by 10-11 A.M. that enough warming will have occurred that tapping into 35 mph gusts is likely and by 12-1 P.M. some 40 mph gusts are probable. Highs in the mid-upper 80s look good, supported by early September climatology of 22-23C 925mb temperatures and 19C 850mb temperatures. Synoptic scale forcing and frontal timing in guidance solutions remain in good agreement to support the cold front moving through the CWA during the afternoon and clearing the southeast area sometime during the early evening. For the Chicago area, the 2-5 p.m. window seems the most likely for developing storms. Coverage should be higher on the front the further east along it due to greater convergence, so that`s why the eastern CWA is most favored with higher PoPs and the potential for gustier storms. As for the outlook on some strong to possibly scattered severe storms along the convective broken line, that continues to look supported by incoming guidance trends, including lapse rates, wind fields, and convection-allowing model output convective gusts (spotty 45+ mph in the Lower Great Lakes region). MTF && .SHORT TERM... 220 PM CDT Through Tuesday night... The primary weather concern continues to focus on the threat of severe thunderstorms Tuesday afternoon through very early evening as a cold front shifts into northern IL. Gusty southwest winds of 35 to 40 mph are also expected Tuesday prior to the arrival of the front during the afternoon. Surface low pressure will develop and deepen into southwestern parts of Ontario tonight in response to an amplifying mid-level impulse and a ~115 kt upper jet streak over the Northern Plains and Upper Midwest. This low is likely to deepen to around 995 mb on Tuesday as it approaches the north central shores of Lake Superior. Its associated cold front will then be driven southward across northern IL and northwestern Indiana Tuesday afternoon through early evening. Southwesterly winds will become gusty up to 35 to 40 mph during the morning into the afternoon in advance of this approaching cold front as the surface gradient strengthens across the region. Warmer temperatures into the middle to upper 80s will accompany these gusty southwest winds Tuesday afternoon just ahead of the approaching cold front. While a lingering surface ridge of high pressure over the Gulf Coast will cut off better Gulf Moisture from reaching the area, it does appear that a corridor of surface dew points in the middle 60s over the Plains will advect northeastward ahead of the front. This should be sufficient to result in MLCAPE values up around 1500 J/KG during peak heating in the afternoon. Initially, warmer temperatures aloft should act as a cap to surface based convective development, especially early in the afternoon. However, capping should weaken and likely will erode with time during the mid to late afternoon hours as falling heights and cooling temperatures aloft overspread the area in association with the digging upper trough over the western Great Lakes. This will thus support thunderstorm development over at least parts of northern IL and northwestern IN after 3 pm Tuesday. The storms may develop right overhead across northeastern IL Tuesday afternoon as the cap erodes. Storm coverage may initially be more widely scattered, and for this reason, parts of far northern IL in and around the Rockford area may see rather sparse coverage, with more storm development likely to their southeast. Storm coverage does then look to ramp up some later in the afternoon as the cold front shifts towards the I-55 corridor and the exit region of the aforementioned 115 kt upper jet begins to nose into the area. Given the favorable kinematics, organized linear storm clusters and supercells will be favored. Strong damaging winds look to be the primary severe threat, though some severe hail threat and even a brief tornado threat will exist with any super cell storm structures. The highest threat for scattered severe thunderstorm coverage is generally along and east of the interstate 55 corridor from around 3 pm through 8 pm. This includes much of the Chicago metro area. The threat of storms will come to a quick end from northwest to southeast early in the evening as the cold frontal passage occurs. KJB && .LONG TERM... Wednesday through Monday... 209 PM...No significant forecast concerns currently, though and active pattern is possible this weekend into early next week. Northwest winds will likely remain gusty on Wednesday, possibly into the 25-30 mph range. These strong winds and northwest directions will lead to higher waves along the northwest IN Lake Michigan shore though confidence is only medium for a high swim risk. Still a few days away to monitor trends, but a high swim risk is possible, mainly for Porter County. As cooler air spreads across the Great Lakes region Wednesday night into Thursday, there will be a chance for lake effect rain showers. Wind directions appear to stay northwest enough that only northeast Porter County would be effected by any possible showers but did include slight chance pops for this potential. High pressure will move across the area Thursday into Thursday night with a lake breeze expected Thursday afternoon. Southerly flow returns Friday with temperatures warming into the lower 80s. All of the models show a cold front moving across the area Saturday afternoon or into Saturday night but not much in the way of precipitation with the best forcing well north and northeast of the area. Blended pops are dry for this time period and maintained a dry forecast. However, ahead of this front there may be an axis of very warm air with highs in the mid to possibly upper 80s. Beyond this time period, models diverge with the GFS much cooler behind the front while the ECMWF slows, stalls, then lifts the front back north leaving Sunday/Monday generally in the 80s, except for any possible lake cooling. Confidence too low to differ from the blended guidance which maintains highs in the 80s for this time period along with no precipitation. cms && .AVIATION... For the 00Z TAFs... Concerns: -Gusty SW winds Tuesday morning through mid afternoon -Scattered to broken line of thunderstorms mid to late afternoon The lake breeze is still on the move this evening given the overall light wind profile in place under a ridge of high pressure. This should wash out fairly soon and then expect winds to shift to a SE direction this evening before increasing out of the SSW overnight. A fairly strong low pressure system will pass over northern/central Lake Michigan on Tuesday. SW winds will increase in advance of an associated cold front. Winds will veer to more of 230-250 direction by midday to hopefully alleviate cross runway concerns at ORD. Gusts into the mid to upper 20 kt range in the morning are likely, and the lower 30 kt range seem a fairly decent bet mid to late morning into the early afternoon, locally slightly higher. A scattered to broken line of thunderstorms should develop on Tuesday afternoon. These may develop right over the Chicago terminals. There is still some uncertainty as to the coverage, with the highest confidence from Chicago eastward over Lake Michigan, but confidence has increased enough to include 2 hr TEMPO windows for TS in the Chicago metro. Thunderstorms should not be too long lasting, but expect gusty NW winds in these also. KMD && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory...LMZ743-LMZ744-LMZ745...9 AM Tuesday to 10 PM Tuesday. Small Craft Advisory...LMZ740-LMZ741-LMZ742...9 AM Tuesday to 7 PM Tuesday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 303 PM CDT Mon Sep 6 2021 .Tonight and Tuesday: A vigorous short-wave trough over south-central Canada is forecast to undergo considerable amplification while moving into the Great Lakes on Tuesday. In the low levels, an associated cold front will advance through the northern Plains tonight and through the mid MO Valley on Tuesday. Current visible satellite imagery reveals a considerable amount of smoke over the northern High Plains, which will be advected into the area tonight into Tuesday as mid-level winds strengthen from the northwest. HRRR forecasts suggest that the majority of the smoke will remain aloft, resulting in mainly a hazy appearance to the sky. Smoke concentrations should begin to diminish by Tuesday night. In regard to the cold front, latest RAP/HRRR forecasts suggest that the boundary will move into our northwest counties by 10z (5 AM Tuesday) before reaching the Omaha and Lincoln areas by 13z (8 AM). Winds will switch to north-northwest behind the front with sustained speeds of 15-20 mph and gusts of 30-35 mph. Winds should gradually diminish during the afternoon hours. Highs on Tuesday will range from the upper 70s north to mid 80s south. No precipitation is expected with the frontal passage. .Wednesday through the weekend: A prominent mid-level ridge over the interior west is forecast to expand east into the Great Plains through the remainder of the work week. In response, high temperatures in the upper 70s to lower 80s on Wednesday will warm into the mid 80s to around 90 by Friday. By this weekend, a short-wave trough is forecast to move through the northern Plains with an associated surface cold front advancing through the mid MO Valley. That scenario would support slightly cooler temperatures. Measurable precipitation chances currently appear low. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 615 PM CDT Mon Sep 6 2021 Southerly winds will diminish shortly after 00Z this evening and veer to the west, and eventually northwest by early Tuesday morning as a cold front moves into the region. Northwest winds will be gusty from around 13-15Z through Tuesday afternoon. LLWS will be possible primarily at KLNK and KOMA between 07-14Z tonight. LLWS could also creep into KOFK briefly from 11-13Z as well. Otherwise, expect VFR conditions through the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Mead AVIATION...KG
Area Forecast Discussion
National Weather Service Phoenix AZ
512 PM MST Mon Sep 6 2021 .UPDATE...Updated 00Z Aviation Discussion. && .SYNOPSIS... Strong high pressure aloft will be the predominant weather feature across the Southwestern U.S. this week providing above normal temperatures for much of the region. Generally dry conditions will also prevail despite somewhat higher humidity levels, though slight chances for storms may become possible later this week across southeast California and the Arizona higher terrain. Daily high temperatures will mostly range from 105 to 108 degrees across the Arizona lower deserts to a couple of degrees warmer across southeast California and southwest Arizona. && .DISCUSSION... RAP streamlines depict a large anticyclone centered across the Great Basin. Abundant dry air aloft is also evident on water vapor imagery, though conditions remain somewhat moist at the surface, particularly across portions of southeastern California. In the Imperial Valley, dewpoints in the mid 70s are resulting in heat indices as high as 115 deg. Meanwhile, afternoon ACARS soundings out of KPHX reveal a warm and dry layer around 700 mb, which is yielding a considerable amount of convective inhibition. HREF confirms conditions will remain quite unfavorable for Monsoon thunderstorm activity for the remainder of today. The aforementioned anticyclone will remain the predominant weather feature through the week. GEFS/ECWMF/CMC ensemble suites remain in good agreement the high will shift eastward and then southward through the week. The models also indicate the strongest height anomalies will remain to our north and east. Main impact across the Desert Southwest will be a warming trend with temperatures likely peaking mid-late week. Latest NBM guidance puts the Phoenix Metro area a bit below criteria for an Excessive Heat Watch Wednesday/Thursday, though if trends continue, a Watch or Warning may ultimately be needed. For Wednesday and Thursday, there is currently a 25-35 percent chance the high temperature will reach or exceed 108-109 deg in Phoenix, which roughly corresponds to a high heat risk this time of year. Latest GEFS/ECMWF ensemble temperature distributions depict a reasonable amount of uncertainty, and it is still conceivable the record high temperature of 110 deg (both days) could even be reached. Uncertainty increases more Friday through Monday, though temperatures will likely remain above average. With relatively dry and warm air circulating around the ridge, conditions will remain unfavorable for Monsoon storms at least into the weekend. The only exceptions will be across the higher terrain of Gila County and extreme southern Maricopa County. Only a handful of GEFS/ECMWF ensemble members suggest precipitation will reach the lower deserts of south-central Arizona. Latest ECMWF ensembles suggest the best chance of precipitation may actually be along the Colorado River Valley Thursday-Saturday as GOC moisture is pulled northward. && .AVIATION...Updated at 0010Z South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Diurnal wind tendencies are favored through the TAF period at most terminals with speeds mainly 8 kts or less. At KPHX, winds are expected to remain westerly or southwesterly through the next 24 hours with a slight uptick in speed up to 12 kts tonight following a gulf surge. There are indications winds may still try to shift east, or become variable, around 11-12Z, but the probability is currently too low to include in the TAF. Skies will remain clear outside distant afternoon cumulus. Southeast California/Southwest Arizona including KIPL and KBLH: Winds will favor the south at KBLH and east to south at KIPL through the TAF period, with periods of variability in the morning. Speeds will mostly be 8 kts or less, besides typical afternoon gusts and a brief uptick to 10-15 kts tonight following a southerly gulf surge. Skies will remain mostly clear. && .FIRE WEATHER... Wednesday through Sunday: Strong high pressure will dominate over the Great Basin into the Desert Southwest late this week into the weekend providing generally dry conditions and above normal temperatures. Chances for showers and thunderstorms will be very limited through the period, especially over the Arizona lower deserts where chances will be less than 5%. High temperatures are likely to run a few degrees above normal throughout the period with some lower desert areas potentially seeing a return of 110 degree readings. Min RH levels will mostly range from 15-25% through the forecast period, while max RHs generally range from 40-60% (locally higher). Apart from thunderstorms, strong wind events are not anticipated. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...Excessive Heat Warning from 10 AM Tuesday to 8 PM PDT Wednesday for CAZ561-570. && $$ DISCUSSION...Hirsch AVIATION...Benedict FIRE WEATHER...Kuhlman