Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/19/23


Area Forecast Discussion
National Weather Service Burlington VT
1053 PM EDT Mon Sep 18 2023 .SYNOPSIS... Unsettled, cool weather over northern New York and Vermont will take place into Tuesday as a deep upper level trough and developing coastal low pressure system will bring periods of light to moderate rain. High pressure returns for Wednesday and dominates the region`s weather through the upcoming weekend with dry conditions and slightly above normal temperatures expected. && .NEAR TERM /THROUGH TUESDAY NIGHT/... As of 1047 PM EDT Monday...Rain has finally ended in St Lawrence County but continues across southern Vermont and in parts of Eastern Vermont. Winds are very light and ceilings remain pretty low. Expect slow improvements overnight, and especially during the daytime hours on Tuesday. No big changes for the evening update, mainly adjusted pops to reflect current radar trends. Previous discussion follows. Surface observations suggest that the surface low that we`ve been tracking is nearing Long Island. Precipitation is expanding north and west as the surface low deepens. Increasing low-level convergence and modest frontal forcing will produce moderate rain east of the Greens, especially between 6 PM and about 2 to 4 AM, then taper off as the surface low lifts north. West of the St. Lawrence River, we continue to see a slow moving cold front produce scattered convection, with a few flashes of lightning here and there. Eventually, the front will completely stall and then get absorbed into the northwesterly flow imparted by the coastal low, and the exact placement of convection when that happens is somewhat up for debate. Noting the HRRR is suggesting it makes it east of the St. Lawrence River and nudged things in that direction this evening given present radar imagery. Rainfall amounts over the next 24 to 36 hours will be greatest in eastern Vermont at 0.75" to 1.50" and more scattered 0.10-0.50" forecast west of the Greens. Temperatures have been very cool this afternoon, except some upper 60s to lower 70s in parts of northern New York where the Sun has broken out. Elsewhere, upper 50s to mid 60s has prevailed. Despite increasing northwest winds, cold air will lag behind for sometime before a reinforcing trough shifts east Tuesday. So overnight temperatures aren`t going to budge very much, mainly in the 50s. On Tuesday, a reinforcing trough and a vort max working through the upper trough will swing east. With some diurnal instability and plenty of moisture, anticipate scattered showers to numerous up north. Orographic enhancement on the northwestern slopes will likely keep areas like Jay Peak showery all day. By evening into the overnight hours, moisture will begin to depart. Cold advection will make for another cool day, with upper 50s to mid 60s, except some readings near 60 in the lower Connecticut and into parts of far western Rutland or Addison County. Continued cold advection will result in a cool night with temperatures in the 40s to lower 50s near Lake Champlain. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As of 320 PM EDT Monday...Surface high pressure centered over the Great Lakes will gradually move eastward. Some lingering cloud cover in the morning should dissipate, bringing some sunshine to the region for a majority of the day. Daytime highs will be pleasant and seasonable, generally in the mid to upper 60s. With the high pressure building overhead, there will be a favorable set up for fog development in the favored valley locations, especially with the recent rainfall across the region. With clearing skies, overnight lows will be quite cool with temperatures dipping into the 40s. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 320 PM EDT Monday...The aforementioned surface high pressure will continue to build overhead, bringing a pleasant stretch of weather through the end of the work week into the start of the weekend. As the week progresses, there will be a gradual warming trend, with highs reaching the mid 70s by Friday. Overnight lows will be more seasonal as clear skies will allow temperatures to drop, generally into the 40s. Heading into the later half of the weekend, a plume of maritime moisture will move northward along the Atlantic Coast, however at this point there are still a number of disagreements across deterministic guidance, so the forecast relies on the NBM and blended guidance. Currently expecting an increase in cloud cover and some possible showers across the forecast region, particularly the southern portions for Sunday into next week. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Through 00Z Wednesday...Currently, conditions are VFR over New York and BTV while they are IFR over the rest of Vermont. These restrictions are mostly due to low ceilings, but there are some temporarily reduced visibilities in the heavier showers over Vermont. The rain will slowly shift north and east and become lighter during the night. This should cause visibilities to rise above 5SM where they are currently lower. However, there will be very light boundary layer flow for much of the night so low level moisture will remain in and the ceilings will likely remain low. A cold front will move through the region later in the night and begin to slowly increase the winds and cause them to turn northwesterly. Ceilings are forecasted to lower in SLK and MSS after it passes through as is typical in northwesterly flow. However this wind should eventually scour out some of the low level moisture, especially in the valleys in Vermont, so ceilings should rise to at least MVFR at all locations by 15Z. Outlook... Tuesday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: VFR. NO SIG WX. && .EQUIPMENT... The KCXX radar will be down for radome repairs, with a return to service around September 20th. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Haynes NEAR TERM...Haynes/Neiles SHORT TERM...Kremer LONG TERM...Kremer AVIATION...Myskowski EQUIPMENT...WFO BTV
Area Forecast Discussion
National Weather Service Des Moines IA
700 PM CDT Mon Sep 18 2023 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Monday/ Issued at 249 PM CDT Mon Sep 18 2023 Key Messages: - Scattered showers and thunderstorms expected this evening and overnight; No severe weather anticipated - Warmer tomorrow with lingering, sporadic precipitation chances south; Highs returning to the 70s rest of the week - Larger scale system on the horizon for Friday into the Weekend In wake of the upper level trough that moved through this last weekend, we see surface high pressure departing with the trough to the east and low pressure filling in behind. This, in conjunction with the weak shortwave moving through, has resulted in a tightening pressure gradient and strong southerly flow over the western half of the state today, causing breezy conditions with gusts over 25 mph this afternoon. A developing low level jet this evening will combine with warm air advection and increasing moisture to produce scattered showers and isolated thunderstorms over portions of central and eastern Iowa tonight. These look to first develop shortly after 00z at the leading edge of the LLJ in our far east and northeast before zippering southwest back into central and south central Iowa. Confidence is low in how far south and west precipitation will develop tonight into the early morning hours, as soundings indicate a drier profile over this region compared to those further north and east. However, better instability will be present further south and west, and if a storm could tap into some of that, the dry air would likely be overcome. Therefore, have included some isolated storm chances further south and west to account for any updrafts that can overcome the drier profile. That being said, even with the 35 to 40 kt LLJ producing decent shear profiles, the instability values still struggle to exceed 1000 J/kg for much of the area tonight into early tomorrow morning, making the chances for severe storms fairly low. The RAP and HRRR show these sporadic showers and storms lasting over southern Iowa through much of the day Tuesday and even lasting into Tuesday night as the layer continues to warm and moisten. These two models are outliers through tomorrow and drier air at the surface will continue to inhibit rainfall, but with increasing surface dewpoints, can`t rule out precipitation festering through the day. This trend of sporadic precipitation continue this week as lobes of forcing propagate through the agitated, quasi-zonal flow. This has resulted in a prolonged period of low-end precipitation chances over southern Iowa in the NBM. However, this should be interpreted as brief, occasional showers over the area rather than rain falling during this entire period. In addition to occasional precipitation chances, surface high pressure begins to leak back into the state Wednesday, resulting in slightly cooler temperatures than Tuesday and highs falling back into the 70s and low 80s through the rest of the week and into the weekend. Looking ahead to the weekend, we continue to watch an approaching upper level trough that will develop off the west coast before making its way east into the midwest by late week and into the weekend. Time of arrival varies slightly among current guidance, with the GFS being slightly faster than the Euro and Canadian. There is also some discrepancy on its departure as well, with the Euro/Canadian having the system linger overhead through Sunday but the GFS completely departed by this time. This has resulted in a smearing of precipitation chances from the NBM through the entire weekend. Needless to say, this likely doesn`t represent the actual timing of rainfall, but, depending on the evolution of the low, there may still be a decent period of rain falling this weekend. It`s a bit too early to get locked down into any specific details such as precipitation amounts or exact severe parameters, however, severe weather does look possible as the cold front first arrives on Saturday. The most likely location at this time would be over the western portion of the state where the better instability resides, but this is subject to change through the coming days. Colorado State Univeristy`s machine learning algorithm also highlights most of the area with severe probabilities on Saturday and CIPS Analog guidance pings the western half of the state as well. This will be the system to watch through the week and will continue to update as new information becomes available. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 641 PM CDT Mon Sep 18 2023 Forecast remains on track from previous issuance with LLWS and isolated to scattered showers or thunderstorms developing later tonight and continuing overnight. Confidence in shower to isolated storms remains highest over eastern sites (KALO/KOTM), though some VCSH remains plausible at all sites. Kept with shower to VCSH mentions due to isolated coverage of any thunderstorms and will adjust mentions if needed later on. Generally expecting VFR conditions to prevail though won`t completely rule out a temporary categorical reduction if a stronger shower/storm is to occur over TAF site. A few showers/storms may bring some gusty conditions but overall the breezy south winds from this afternoon are expected to decrease tonight resulting in the LLWS potential overnight. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Dodson AVIATION...KCM
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
315 PM PDT Mon Sep 18 2023 .SYNOPSIS...Isolated to localized scattered thunderstorm development across portions of Trinity and Northeastern Mendocino County will end this evening. Dry and locally breezy conditions are then expected Tuesday through Thursday. Cooler weather will arrive late week, with a wetter pattern developing over the weekend and especially next week. && .DISCUSSION...Afternoon visible satellite imagery depicts a band of mid to high level clouds associated with a weak front draping down from the north. RAP mesoanalysis showed surface cape values around 500 J/kg around Trinity County early this afternoon, as the cloudcover thus far had only a moderate optical thickness. Thunderstorms are beginning to fire up along the leading edge of the front in SE Trinity County. Confidence is highest for further convection in this area through the Trinity Horn. Breezy north winds will occur in the wake of the front, particularly during Wednesday, with gusts from 20 to 30 mph possible across exposed terrain. A deepening, cold trough will dive from the north through S Oregon Wednesday through late Thursday. This will bring gradual cooler temperatures and the chance for very light precipitation. Some weak, elevated instability may clip E Trinity County late Wednesday, but probabilities for thunderstorms are very low at this time. Can not rule out nocturnal convection given the forcing from the trough. A second cold upper trough will drive into the Pacific Northwest from the west this weekend. This will be followed additional troughing and then potentially an additional stronger trough with an associated IVT plume early next week. There is much uncertainty on the strength and timing of the system early next week, but high confidence remains on the pattern change and opportunity for early season rainfall. The probability for a wetting rain over a tenth of an inch has constantly ranged from 10 to 15% through the weekend, mostly for the northwest portion of the region. The probability for over a quarter inch of rain quickly increases early next week to 25 (south) to 45% (north), but there is still a high degree of run to run variability. && .AVIATION...A deep marine layer for the coastal terminals will meet inversion sooner at KCEC than KACV. Deeper and longer lingering low level moisture at KACV will keep ceilings 1500 to 2000 feet overnight. Expect an inversion to lower at KCEC by midnight, although it could be scattered and broken to overnight, post frontal. Otherwise. Models show moisture upstream as another deep upper level low approaches. Expect IFR conditions in the morning at the coastal terminals during early sunrise. && .MARINE...Northerlies are expected to quickly ramp up in the northern outers and spread to the southern outers, continuing to accelerate tonight with gusts nearing Gale Force offshore of Pt St George by early Tuesday morning. Northerlies continue to accelerate during Tuesday, likely reaching Gale Force in the outer waters by afternoon and evening. Winds further strengthen Wednesday then trend weaker Thurs and Fri. Short period seas quickly respond to the increasing winds, spreading to most zones by Tuesday, and possibly the southern inners as well on Wednesday. A more significant NW swell is expected to quickly fill in late this evening and tonight, currently forecasted to peak early Tuesday morning around 9 ft at 15 seconds, and likely leading to a chaotic sea state through much of the work week. This looks to be reinforced Wednesday night by another NW swell, peaking around 7 ft at 15 sec. && .FIRE WEATHER...Isolated to localized scattered thunderstorm development across portions of Trinity and Northeastern Mendocino County will end this evening. Storms will move slowly, which will yield wetting rains beneath storms. However, lightning will pose at least a slight risk for additional fire starts. Otherwise, a dry cold front will move south across the region during Monday night. A dry airmass will spread south across northern California behind the front, and periods of breezy north winds gusting from 20 to 30 mph across exposed terrain will be probable, especially over interior portions of Del Norte County during Wednesday. Elevated fire weather conditions will occur as a result, but a fire weather watch has not been issued due to marginal min forecast RH values in the 30s. && .BEACH HAZARDS...A moderate threat for sneaker waves will extend through this evening. Long period Northwest Swell can set in suddenly, surprising beachgoers or recreational aquatic enthusiasts near jetties or near shore. The timing of this event is during daylight hours when a majority of people are out and about. Please be aware as calm conditions can fool you into complacency. This is when tragedy strikes. Do not turn your back to the ocean and keep your distance as large objects, logs specifically, can be lifted and propelled onto beaches. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Beach Hazards Statement until 8 PM PDT this evening for CAZ101-103-104. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 9 AM Tuesday to 1 PM PDT Wednesday for PZZ450. Gale Warning from 1 PM Wednesday to 9 AM PDT Thursday for PZZ450. Gale Warning from 4 PM Wednesday to 9 AM PDT Thursday for PZZ455. Small Craft Advisory from 7 PM this evening to 7 AM PDT Tuesday for PZZ470. Gale Warning from 7 AM Tuesday to 9 AM PDT Thursday for PZZ470. Small Craft Advisory from 7 PM this evening to 9 PM PDT Tuesday for PZZ475. Gale Warning from 9 PM Tuesday to 9 AM PDT Thursday for PZZ475. && $$ Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Goodland KS
511 PM MDT Mon Sep 18 2023 .SHORT TERM...(This evening through Thursday Morning) Issued at 206 PM MDT Mon Sep 18 2023 Shortwave is currently moving into eastern Colorado where a noticeable uptick in cumulus has developed over the past hour. At the surface a trough is located across the area with light and variable winds along the axis and breezy winds gusting 25-30 knots ahead and behind it. RH values across the NW portion of the area have fallen to around 12% as of 1pm MT, as soundings support the potential for wind gusts up to 30 mph if enough mixing can occur have messaged near critical fire weather conditions for the remainder of the afternoon. For thunderstorm potential, dry line is currently placed near Highway 83, is overall not the strongest dry line at this time which may overall limit any additional ascent for storm development, this may be the reasoning as well that CAMs have backed off on initiation this afternoon. As a result of this have lowered overall pops down to 15%. If a storm were to initiate however given RAP forecast soundings of shear around 25-30 knots, MUCAPE of 1000-1300 j/kg and steep lapse rates, hail up to quarter size and 60 mph winds would be the primary hazards along with lightning. Tonight another round of mid level moisture moves off of the Palmer Divide in the form of mid level clouds, given the dry nature at the surface don`t think any precipitation should be observed other than some spotty sprinkles at best. Temperatures should remain a bit warmer than the previous nights in the low 50s to low 60s. Tuesday, some guidance tries to show showers or sprinkles across the area during the morning, however think given the drier air at the surface sprinkles or just mainly virga will be what occurs. Warm temperatures again are forecasted with low 80s across east Colorado to the low 90s across the east. During the afternoon another wave moves across the Plains leading to some showers and storms along and south of Highway 96. Severe storms aren`t currently anticipated with this activity as cloud to ground lightning would be the primary hazard. Wednesday, riding briefly again develops across the area ahead of a developing trough over the west. Temperatures will again be warm in the 80s to 90s. Winds will be out of the NW for the majority of the day before switching to a more southerly component as the effects of the developing trough a felt. Moisture ramps up from the south as well overnight so upcoming shifts may need to keep an eye on status or fog potential. .LONG TERM...(Thursday through Monday) Issued at 100 PM MDT Mon Sep 18 2023 Will start the long term with southwest flow aloft ahead of an upper low in the Great Basin. That system will evolve into an open wave as it ejects into the northern plains Friday night and Saturday. Ridging then follows for Sunday and Monday. Precipitation chances on Thursday will be east of Highway 25 where instability axis will set up and weak wave in southwest flow will provide lift for convection. Instability of up to 1500 j/kg is currently forecast with deep layer shear around 30 kts, which should be sufficient for a marginal risk of severe storms. Timing looks to be the typical mid afternoon initiation, peaking during the evening, then moving east and out of the area during the overnight hours. Highs will be in the 80s and lows Thursday night mainly in the 50s. On Friday, the western system will begin to move out of the Rockies. The local area appears to be dry slotted with the northerly track, with instability swept out of the area by Friday afternoon. If that verifies, may see only gusty westerly winds and a risk for critical fire weather conditions as relative humidity drops below 20 percent, especially in western areas. Cold front moves through Friday night, but moisture appears to be very limited and may see a dry frontal passage. High temperatures look to be at least in the mid to upper 80s, perhaps warmer with the downsloping surface winds. Lows Friday night will be in the 40s and 50s, coolest in Colorado. Main upper trough axis moves through on Saturday. Models suggest perhaps some light wraparound type showers, but instability is basically zero. May see gusty northwest winds, with ECMWF showing gusts in the 40-45 mph range, a bit lower in the GFS at 35-40 mph. Low level lapse rates are best early in the day for blowing dust, less favorable in the afternoon. Relative humidity forecasts are currently above 20 percent the entire day. So, a breezy day with a few isolated showers and marginal conditions for blowing dust and/or fire weather. Highs will be in the 70s and lows Saturday night in the 40s. For Sunday and Monday, dry conditions are expected with upper ridging. Highs will be in the 70s both days and lows in the 40s. Relative humidity forecast to be above 20 percent both days and wind gusts less than 25 mph, so not expecting any fire weather concerns. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 511 PM MDT Mon Sep 18 2023 VFR conditions with generally light winds are expected throughout the period for both KGLD and KMCK. Mid-level showers and low end thunderstorms are moving through the region currently, with a second wave of showers possible in the early morning hours tomorrow. Confidence is very low that they will impact flight categories at either TAF site. KGLD could see some near 20 kt gusts from the northwest around 9Z as the second wave comes through. Gusts are expected to die down around 14Z. There is another chance of showers and thunderstorms tomorrow evening to impact the area. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...Trigg LONG TERM...024 AVIATION...CA
Area Forecast Discussion
National Weather Service Gray ME
1145 PM EDT Mon Sep 18 2023 .SYNOPSIS... Widespread rains continue tonight with locally heavy rain possible. Some showers may linger in the mountains and northern areas tomorrow as high pressure begins to build in through the end of the week. Northwesterly flow brings dry air with seasonable temperatures through midweek with nighttime valley fog possible. Another chance for rain looks possible late in the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1145 PM Update... No significant changes to the going forecast with only minor refinements of PoPs and QPF based on incoming 00Z guidance. The focus from now through the next 4 to 6 hours will be a band of moderate to heavy rain forming on the NW side of low pressure now in the Gulf of Maine. This band looks to set up from south-central NH where both MHT and CON have reported bouts of heavy rain into the White Mountains and will pivot through western Maine over the coming hours. Instability is lacking although around 100 J/kg of MU CAPE has built into southern NH with a few instances of lightning as of this writing. Much of the area has seen a good soaking rain up until now with spots having 3 hour flash flood guidance drop below 2 inches. As this band will be capable of producing 1 to 2+ inches of rain over the coming hours will be watching portions of east-central NH into western Maine for any flood issues through tonight. 810 PM Update...Low pressure is currently just south of Cape Cod and will continue to deepen over the next several hours as it tracks northeastward through the Gulf of Maine. An area of moderate to heavy rain associated with Fgen forcing on the northeast side of the low has pushed through Cape Cod with observed rainfall rates around one inch per hour. Hi res guidance has been fairly consistent in keeping this area of moderate to heavy rain offshore as the low moves through the Gulf of Maine lowering flood concerns near the Mid Coast, although it will be close enough to keep an eye on. Another area of moderate to heavy rain looks to develop across central New Hampshire around midnight and pivots through western Maine through the pre dawn hours. Overall, rainfall rates with this second area look to top out around 0.75 inches per hour. So far area gauges suggest 1 to 1.5 inches has fallen throughout the past several hours. Have mainly refined PoPs and QPF with this update with an additional 1 to 1.75 inches forecast across east central NH into western Maine. Will continue to monitor the development of the second band of rain around midnight for potential flood concerns. Previously... The phasing is occurring at 500 MB attm and the trough is showing neg tilt, so the sfc low, now south of Cape Cod is deepening, and will continue to do so through this evening as it track across Cape Cod and into downeast ME by morning. There is some good mid level FG out ahead of the low and this will drive an increase in rainfall rates this evening, and into the overnight, although rain begin to shut off in the S by late evening. An then into the N and E zones during the pre-dawn. The first round of the heavier rains cross SE New England attm, and could just stay offshore as it passes early this evening, or perhaps move into the mid coast. A second round of heavy rain, as predicted by the last few HRRR runs comes around the west side of the deepening in the fairly deep FG on the CAA side of the storm, and this looks to move through srn NH and SW ME later this evening and into central around midnight or shortly thereafter. If we see rain rates of an inch an hour or more, this will be the most likely time and area. The rain should taper off quickly to scattered showers behind this feature, and will likely be over before sunrise across all but the NE zones. May see a brief burst of W winds behind this feature, but should settle back until daylight really breaks the inversion. Lows will be mostly in the 50s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday should be mostly dry outside the mountains ans a brisk WNW flow will downslope S and E of the mtns, while we see our first decent upslope event of the season in the mtns, although it will be RA at all elevations /OK, guess I can’t rule out some graupel on MWN./ Highs range from the the low to mid 60s in the mtns, and 70-75 in the S. Also it will be breezy with winds gusting to around 25 mph at times. Tuesday night should see enough pressure gradient to keep some light W flow at all but the sheltered locations, so rad cooling will be limited. Clouds will linger in the mtns through the evening before they start to clear after midnight. Lows range from the upper 40s N to the mid 50s S. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The extended period starts off relatively quiet as high pressure builds in at the surface through the end of the week. Northwest flow sets up behind exiting low pressure Wednesday and Thursday bringing dry air from the north and sunny skies with seasonable temperatures. As winds calm and decouple overnight, radiational cooling sets in bringing overnight lows into the 40s across the area with valley fog possible. While the surface stays quiet, the upper levels remain active through the week as the polar and sub-tropical jets diverge around building high pressure over the East Coast. The ensemble suite has shown good temporal and model-to-model consistency of a trof emerging out of the southern Rockies before dipping south and strengthening as it crosses the southeast US. Eventually, all the ensembles take this trof up the east coast from the Florida peninsula with most uncertainty lying in the northward speed of this system. As this happens, the polar jet begins a ridging pattern with several shortwaves passing along its north side. The ensemble suite has larger uncertainty in the strength and position of this ridge, possibly due to the complicated pattern of shortwaves in this timeframe. Eventual this ridge breaks down late in the week as the southern trof pushes up the East Coast with a tightening pressure gradient across the northeast for the start of the weekend. How this phases with the shortwaves within the polar jet is still largely uncertain, however a period of rain sometime this weekend looks possible whether it be from the shortwave to the south or the west. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Short Term...Terminals remain variable in terms of flight restrictions, as most are varying between MVFR and IFR, mainly die to cigs. KRKD should drop to MVFR or IFR shortly, and KHIE may bounce around for a few hours before they go to IFR, along with all the other terminals around or just after sunset. Should see some improvement to MVFR after sunrise Tuesday as the wind pick and mixing begins, and eventually to VFR by late morning at all but KHIE, which will stay MVFR in upslope flow. Long Term... High pressure will dominate through the end of the week keeping terminals at VFR with a northwest wind. Nighttime fog is possible mid to late week before ceilings thicken over the weekend. && .MARINE... Short Term...Low pressure moves through the Gulf of Maine tonight and produce SCA conditions. Thereafter, gusty NW winds and seas will remain above SCA levels into Tuesday evening. Long Term... Seas are expected to stay below SCA thresholds through the end of the week with a few hours of 5ft swells building in Thursday afternoon. Winds start out of the northwest before becoming light and variable Thursday. Southwesterly flow then builds in Friday as low pressure begins approaching from the south bringing SCA conditions back for the late weekend. && .HYDROLOGY... A general 1 to 2 inches of rain is expected through tonight in the flood watch area, however mesoscale banding, convection, and upslope winds could allow for local amounts of up to 3 inches. Localized instances of flash flooding will be possible along with a good chance of poor drainage flooding and small stream rises. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Flood Watch until 11 AM EDT Tuesday for MEZ007>009-012>014- 019>022-024>028-033. Flood Watch until 5 AM EDT Tuesday for MEZ018-023. NH...Flood Watch until 11 AM EDT Tuesday for NHZ002>006. Flood Watch until 5 AM EDT Tuesday for NHZ008>010-012>015. MARINE...Small Craft Advisory until midnight EDT Tuesday night for ANZ150>152-154. Small Craft Advisory until 4 AM EDT Tuesday for ANZ153. && $$ UPDATE...Schroeter NEAR TERM...Cempa SHORT TERM...Cempa LONG TERM...Thunberg
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 333 PM CDT Mon Sep 18 2023 Key Messages: - Continued well above normal temperatures early in the week, trending to cooler than normal this weekend and early next week. - Chance of showers and storms tonight, sporadic chances mid week, but showers/storms becoming likely by Friday/Saturday. Hot, breezy conditions this afternoon with southerly winds 20 to 30 mph and temperatures in the mid 80s to lower 90s, well above normal. There is a weak, slow moving disturbance moving through Central NE, and this could trigger isolated showers/storms tonight. Latest HRRR suggests this could be in the 1-3z timeframe in northeast NE, with continued development through the night as activity pushes east southeast through daybreak. And then a few models continue to show a chance of showers/storms along/south of I80 on Tuesday. All of this activity doesn`t look particularly strong with SPC outlooks only forecasting general thunder. And there could be additional slight chances of showers/storms south of I80 Tuesday night. Otherwise, it looks like another hot day Tuesday with well above normal temperatures again in the mid 80s to around 90. And then Wednesday/Thursday look mainly dry, but model blends have sporadic slight precip chances here or there, but it`s probably more dry than wet midweek. Highs still above normal Wednesday, but just slightly cooler, and then then near normal on Thursday with highs in the upper 70s to lower 80s. We definitely begin a transition to a wetter and cooler pattern for the end of the week into the weekend. A strong, closed low develops across the western CONUS. Diffluent flow aloft ahead of the trough leads to increasing rain chances by Thursday night, and especially into Friday as southerly flow draw surface moisture and instability northward. SPC hasn`t highlighted any severe probabilities in the Days4-8 outlook, but CSU machine learning algorithms suggest some low end severe probabilities to our west on Thursday, but then highlights the mid Missouri Valley region Friday, and then possible along/east of the Missouri River for Saturday for stronger and possibly severe storms. Still lots of time for things to change though, so it`s just a could be scenario a this time. Pattern recognition certainly suggests a severe threat somewhere on the Plains Friday, this would be as the upper low and attendant surface low/triple point move through the region. The NBM is pretty aggressive on 60-70% Pops Friday through Saturday, but there could be a dry slot Saturday as well, which could lead to precipitation chances trending significantly down, while we wait for wraparound precipitation to move in from the northwest by Saturday evening into Sunday. And that wraparound precipitation could certainly be out of the area by Sunday too. So there still is quite a bit of uncertainty in the details of the upcoming weather toward the end of the week through the weekend. It certainly looks breezy and increasingly cooler by the weekend, as southerly winds Friday become west and then northwest. Highs Saturday could struggle to reach the lower to mid 70s, and then highs Sunday mostly in the upper 60s to around 70, certainly well below normal, with the cool weather continuing into Monday. Fall is definitely a season of sharp transitions. The first day of astronomical Fall is Saturday, September 23. The cooler weather is right on schedule apparently. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 607 PM CDT Mon Sep 18 2023 Latest CAM output suggests the potential for isolated to widely scattered storm development between 01-03z in the KOFK vicinity with additional storms possible closer to KOMA and KLNK after about 04z. Confidence in the terminal sites being affected remains low, so TSRA will not be included in this forecast. As such, VFR conditions will prevail with gusty south winds diminishing this evening. Sustained winds are expected to remain at or above 12kt at KOMA and KLNK tonight. Additionally, LLWS will affect all sites tonight into Tuesday morning. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...DeWald AVIATION...Mead