Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/04/24


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1012 PM EDT Sat Aug 3 2024 .SYNOPSIS... A slow moving cold front will gradually move east across the region through Sunday. This system will bring a few more rounds of showers and thunderstorms, which will be most prevalent across areas south and east of Albany. Some storms will likely produce locally heavy rainfall. A stronger cold front approaches from the northwest on Monday, potentially resulting in some strong to severe thunderstorms. && .NEAR TERM /THROUGH SUNDAY NIGHT/... .UPDATE...A few light, patchy showers still exist mainly south and east of Albany as the upper trough continues to push farther east. Latest guidance continues to trend down the already scattered coverage of showers overnight, so adjusted PoPs accordingly. Otherwise, all else remains on track with additional details in the previous discussion below. .PREV DISCUSSION[0347]...Radar showing several clusters of showers and thunderstorms have developed across SE NY, with most of the activity still upstream of our forecast area. Will have to see how this evolves, as the convection is occurring where it is more unstable (MLCAPE > 2000 J/Kg) vs. in Ulster, Dutchess and Litchfield counties where MLCAPE is 1000-2000 J/Kg. Effective shear is ~30 kt so will still need to monitor for some strong to severe storms in these 3 counties. Locally heavy rainfall is the other threat, although the Slight Risk(level 2 of 4) outlook was trimmed southward to just include the far southern part of the forecast area, with a Marginal Risk(level 1 of 4) across most of the rest of the area. Mainly isolated instances of flash flooding are anticipated. Showers/T-storms (mainly southeast of Albany) will linger into this evening as the upper trough axis and weak cold front start to gradually move eastward across the area. Locally heavy downpours may occur, especially through midnight with PWAT anomalies still running high (+1 to +2 STDEV). The coverage and intensity of convection should gradually wane with loss of daytime heating. Isolated to scattered activity is expected after midnight, although increased PoPs to 30-40% overnight from around Albany northward as several runs of the HRRR indicating a possible flare up of convective showers and a few storms. It will remain warm and humid with lows in the 60s to around 70F. The upper trough axis and surface cold front will continue to slowly push eastward across the area on Sun. Guidance in good agreement the trough will weaken as is moves through. The surface front also should lose its definition and become somewhat diffuse. So the result is expected less coverage of showers/T-storms compared to prior days. Despite expectation of mostly cloudy skies, with a relatively moist air mass still in place and a few breaks of sun from time to time, SBCAPE values may reach 1000-1500 J/Kg. The deep layer shear looks fairly weak < 25 kt, so organized/severe storms are not anticipated. Brief/isolated gusty winds and locally heavy rainfall may occur in some of the taller storms. High temperatures look to be in the mid to upper 80s in lower elevations with continued humid conditions. Dewpoints will still be in the lower 70s in lower elevations, with max heat indices in the lower 90s. A few showers/T-storms may linger into Sun evening, although should then dissipate through the rest of the night as a small area of surface high pressure builds in from the west. Lows will still be slightly above normal mainly in the 60s. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... On Mon, an upper level trough will be digging across SE Canada, the Great Lakes and into the Northeast. A short wave disturbance embedded in the mean trough will drive a cold front southeast across the area. Timing looks to be during the afternoon to evening hours. The Storm Prediction Center has a Marginal Risk (level 1 of 5) for severe storms, as the deep layer wind shear is forecast to increase to substantial levels for this time of year > 40 kt. There are some discrepancies in the magnitude of instability, however if there ends of being overlap of instability/shear ahead of the front the threat for severe storms could increase. Will monitor for possible upgrade in subsequent outlooks. High temperatures could get quite warm ahead of the cold front, with upper 80s to lower 90s in lower elevations. With dewpoints in the mid/upper 60s, max heat indices could reach the lower/mid 90s. A Heat Advisory may eventually be needed south of Albany. Showers/T-storms could linger into Mon night depending on the cold front timing, although the severe threat should diminish by later in the evening. The cold front should clear the entire area by early Tue morning. Low temperatures Mon night look slightly cooler than recent nights, ranging from the mid 50s in the Adirondacks to upper 60s in the Hudson Valley. Despite the cold front being positioned south of the region on Tue, it could still be unsettled with showers developing on the cool side of the boundary as a weak wave of low pressure moves along it. The southward progress of the front is expected to stall across the northern mid Atlantic region. The environment will be much more stable north of the front, so no severe weather is anticipated. High temperatures will be much cooler with mid to upper 70s in most lower elevations, except lower 80s near Poughkeepsie. The front over the mid Atlantic is forecast to drift slightly southward Tue night, so chances for showers will decrease through the night from north to south. Lows will be cooler than we have seen in a while with lower 50s to lower 60s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Temperatures are expected to remain cool (slightly below normal) through much of the long term period, which will be a big change from the persistent hot/humid conditions we`ve seen since early July. In terms of rain chances, Wed looks mainly dry at this time with a stalled front positioned over the mid Atlantic region. If the front shifts slightly north, there would be an increasing chances for some showers, mainly for areas south of Albany. Will continue to mention 20-40% PoPs to account for this possibility. Thu into Fri looks mainly dry with surface high pressure positioned over the region, although some guidance showing a possible northward shift in the front over the mid Atlantic approaching so will mention 30-50% PoPs. Will continue to closely monitor the progress/evolution of the tropical system near the southeast and coastal Carolinas, as moisture from it may interact with the old front positioned to our south. This may evolve into a heavy rain set up for part of the area towards next weekend, although the forecast is very low confidence at this time. For the official track of the tropical system visit the National Hurricane Center website: hurricanes.gov. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Through 00z Monday...VFR conditions currently prevail across all terminals this evening with this afternoon`s showers having dissipated and/or moved out of the forecast area. Throughout the overnight period, some additional showers are possible as an upper-level disturbance moves across the area. TEMPO groups were added to account for this possibility at KALB/KGFL/KPSF where probabilities of conditions being impacted are higher. With these showers, MVFR ceilings are possible with brief reductions to MVFR visibility, but VFR visibility is more likely outside of a heavier shower. Once showers move out of terminal bounds or dissipate, VFR conditions will be resumed again into tomorrow morning and afternoon. Another round of showers and thunderstorms is possible tomorrow afternoon with an approaching cold front but plenty of model discrepancy lowered confidence enough to keep this convection out of the TAFs for now. Will provide additional details in future updates when confidence increases. Winds throughout the 00z period will prevail primarily out of the south to southeast through the overnight, becoming variable throughout the day tomorrow. Sustained speeds will range from about 2-6 kt throughout this cycle. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: Moderate Operational Impact. Chance of SHRA...TSRA. Monday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday: Moderate Operational Impact. Chance of SHRA. Tuesday Night: Moderate Operational Impact. Chance of SHRA. Wednesday: Moderate Operational Impact. Chance of SHRA. Wednesday Night: Low Operational Impact. Slight Chance of SHRA. Thursday: Low Operational Impact. Slight Chance of SHRA. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...JPV NEAR TERM...Gant/JPV SHORT TERM...JPV LONG TERM...JPV AVIATION...Webb
Area Forecast Discussion
National Weather Service Bismarck ND
940 PM CDT Sat Aug 3 2024 .KEY MESSAGES... - Chances (30% to 60% north and 20% southwest) for showers move into western and north central North Dakota after midnight. - Much cooler over the coming days with highs mainly in the 70s through Friday, the exception to that being Tuesday with some lower to mid 80s. At least some chance for showers and thunderstorms each day. The risk of severe thunderstorms is very low. && .UPDATE... Issued at 920 PM CDT Sat Aug 3 2024 Overall only minimal changes to the forecast overnight. Initially thought pops might be moving in too quick. Latest HRRR and RAP 00Z 08/04 guidance is even quicker to bring mainly light precip into the northwest and north central overnight. A couple of impulses can be seen just north of the International Border moving from Alberta into western portions of Saskatchewan. Bufkit soundings indicate initially dry mid levels quickly moisten overnight in response to the approaching waves. In the end, we kept pops pretty close our given pops, but we did blend in a bit of the quicker RAP/HRRR guidance. There is some slower guidance and didn`t want to completely buy into the quicker guidance given the initially dry mid levels over western and central ND. Updated text products will be transmitted shortly. UPDATE Issued at 549 PM CDT Sat Aug 3 2024 Cold front has now pushed through the James River Valley with chance for strong to severe storms this evening diminishing quickly. There is some elevated instability and strong shear behind the front so will monitor for the next hour or so before completely pulling precipitation chances here. Otherwise a quiet evening looks to be in store with north to northeast surface flow turning more northeast to east. Clouds will also be on the increase this evening with precipitation chances moving into the northwest after midnight. Will take a closer look at timing of precipitation here with the next update. && .DISCUSSION... Issued at 214 PM CDT Sat Aug 3 2024 Surface low pressure is located over southeastern ND. Thus, associated cold frontal boundary has moved through all but the southernmost portions of the forecast area. As a result, highs have mostly peaked and are expected to remain in the upper 70s to low 90s, with most 90 degree readings either along or near the ND/SD border. Breezy northerly to northeasterly winds are prevalent behind the cold front. Thunderstorm chances for this afternoon remain low overall with a 20 percent chance in the southern James River Valley of ND. A strong cap that was in place earlier today is beginning to erode with a combination of daytime heating and more importantly the aforementioned frontal passage. Should the cap break before the frontal boundary passes into South Dakota, then with plenty of instability (4000 J/kg or more) and adequate shear (30 to 40 kts 0 to 6 km bulk shear), the ingredients are there for any thunderstorm to rapidly become strong to severe. Golf ball size hail and winds up to 60 mph are the primary threats. The residency time for any thunderstorms in North Dakota will be relatively brief before moving off into South Dakota. For tonight, Canadian low pressure will continue to flatten the west CONUS ridge that has been talked about over the past many days. Weak shortwave energy will slide through the area resulting in the potential for showers tonight in the west and especially northwest. Instability is very limited, so while a rogue lightning strike isn`t completely out of the question in areas of 100 to 200 J/kg of CAPE, a rumble or two of thunder wouldn`t be completely surprising. Other than on Tuesday when the ridge attempts to briefly recover and reamplify, moderately below average temperatures mostly in the 70s are expected for most locations, most days. And even on Tuesday, most locations progged to reach the 80s are those along and south/west of the Missouri River. Periodic showers, along with a few thunderstorms, are possible through most of next week. The threat for severe weather is very low. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 549 PM CDT Sat Aug 3 2024 VFR conditions are expected through the 00Z TAF period. A cold front has moved through western and central ND this afternoon. Expect a north to northeast surface flow this evening shifting more northeast to east through the TAF period. Winds generally 8 to 15 mph tonight and Sunday morning, although there may be gusts to around 25 mph early this evening. Winds will pick up later Sunday morning and Sunday afternoon 15 to 25 mph generally from the east. Shower chances increase late tonight and slowly through the day Sunday with better chances occurring after the TAF period, but will include a VCSH at KXWA and KMOT Sunday morning. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...TWH DISCUSSION...Telken AVIATION...TWH
Area Forecast Discussion...Updated
National Weather Service Billings MT
826 PM MDT Sat Aug 3 2024 .UPDATE... High-based showers and a couple isolated thunderstorms were found over the southwest mountains and adjacent foothills this evening. The convection will continue to lift north and east through the rest of the evening, with additional isolated showers and thunderstorms possible over central and eastern areas overnight as a low level jet sets up with easterly flow. Temperatures are gradually dropping into the 80s and have cancelled the Heat Advisory for the area. PoPs and weather have been updated through tonight. The previous discussion is below. STP && .DISCUSSION... Through Sunday Night... The backdooring easterly winds have slowed today`s warming, and as of 1pm, temps are in the 80s to lower 90s (5-12F cooler than Friday at this time). Lofted smoke has also thickened a bit. Today`s temp forecast may end up underachieving a little, but we will still see highs well into the 90s, and near 100F in spots, per 700mb temps near an anomalous +16C. Satellite imagery shows cumulus beginning to develop over the Beartooth-Absarokas. As mid and high level monsoon moisture continues to increase, we should see isolated high-based weak thunderstorms in the late afternoon and evening over the west half of our cwa. Later tonight, w/ a southeasterly low level jet, rising pwats and modest elevated instability, some showers and thunderstorms should affect our east overnight. High res models show fair confidence with regard to nocturnal activity. Going back to satellite imagery, note the subtropical wave lifting through the Sierras today. This energy will lift to the northeast and supply ascent in our region tomorrow at a diurnally favorable time. In addition to the tap of monsoon moisture, easterly winds will increase low level moisture, and we expect pwats to increase to 1-1.25" tomorrow. In fact, the latest HREF shows pwats near 1.5" east of Billings by late afternoon. A very healthy value for our region regardless of the time of year. All ingredients point toward showers/thunderstorms being likely tomorrow afternoon & night, with activity exiting our east late Sunday night per the track of the shortwave. Storms will produce brief heavy rain and perhaps hail (freezing levels fall sufficiently for hail). HREF also suggests a few notable updraft helicity tracks over our east in the evening, with seems plausible given a pre-frontal easterly low level jet. SPC has highlighted our cwa for a marginal risk of severe storms tomorrow. Wind is the highest risk but hail is also possible, in addition to heavy rain. Please keep all of this in mind if you have outdoor plans. Wetting rain (0.10" or more) is likely (50-70% chance) for all but the far south/southeast (20-40% in this area). The probability of 0.25" or more is 30-50% over our western mountains and along/ north of a line from Billings to Ekalaka. This will be a welcomed drink of water for many. After a warm night tonight, temps Sunday will again be above normal but not quite as hot as today. Look for highs in the 90s, with near 100F in our southeast at places like Sheridan & Broadus. That said, a Heat Advisory remains in effect today, but do not see a need to extend it into tomorrow. Sunday night will be post- frontal and cooler. It is possible that the cold front/subsidence allows some smoke from the west to surface in our region, but the HRRR currently does not show this happening. JKL Monday through Saturday... An active weather pattern will bring cooler temperatures, especially to midweek, and a daily chance of precipitation. Monday into Tuesday morning will be one of the drier days of the weak, with PWATs briefly falling under 1 inch, however, a weak shortwave moving through will still bring a 30-50% chance of showers and thunderstorms over the western mountains and a 15-30% chance over the rest of the region. Then, Tuesday afternoon through Wednesday, PWATs are expected to increase to 1-1.25 inches. Coupled with more energy moving into the region, there is a 60-80% of showers and thunderstorms over the mountains and a 50-70% chance over the plains. The pattern then looks to remain open to additional energy moving through for Thursday into the weekend, bringing a daily 40-60% chance of precipitation over the mountains and a 20-40% chance over the plains. Highs on Monday and Tuesday will be in the upper 80s to low 90s. Then, a push of cooler air will drop highs into the mid 70s Wednesday and into the upper 60s to low 70s by Thursday. Thursday continues to look like the coolest day with temperatures starting to increase again into the weekend, reaching the upper 70s to low 80s by Saturday. Archer && .AVIATION... Increasing lofted smoke from the west will continue to reduce slant range visibility. Look for isolated high-based thunderstorms along the western foothills late this afternoon (i.e. near KLVM & KHWQ). A few showers and weak thunderstorms will spread eastward across the lower elevations tonight. Storms may produce brief/ erratic wind gusts late this afternoon and evening. All TAF sites have a <10% chance of seeing a TS. Otherwise, VFR will prevail over the next 24 hours. There is a much higher probability of showers & thunderstorms Sunday afternoon/evening. JKL && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 069/094 061/089 063/092 060/074 056/071 054/077 056/082 24/T 61/U 23/T 56/T 44/W 32/W 23/W LVM 059/092 054/092 056/092 054/078 049/072 047/077 049/082 28/T 51/U 35/T 55/T 34/T 23/T 35/T HDN 067/097 060/089 060/092 058/075 053/072 052/078 053/083 22/T 61/U 22/T 65/T 44/T 32/W 23/W MLS 071/095 060/081 062/090 060/074 053/071 053/076 057/082 22/T 71/B 12/T 55/W 33/T 23/W 33/T 4BQ 070/099 062/084 061/095 062/076 055/070 055/076 057/083 22/T 61/B 12/T 55/T 44/T 23/T 33/T BHK 064/090 055/071 054/087 057/077 051/073 050/078 053/082 22/T 72/T 12/T 55/T 23/T 22/W 33/W SHR 062/098 058/089 059/094 057/076 051/071 050/079 052/082 22/T 41/U 12/T 55/T 55/T 33/T 24/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Forecast Discussion at weather.gov/mqt.

&& .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...None. && $$ DISCUSSION...Huyck AVIATION...Rothstein MARINE...Huyck
Area Forecast Discussion
National Weather Service Des Moines IA
1051 PM CDT Sat Aug 3 2024 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - Showers and thunderstorms north tonight and again Sunday night, a few severe possible. - Hot through Monday with temperatures in the 90s. - Two back to back waves Monday into Tuesday and Wednesday into Thursday will reinforce cooler air into the area, sending highs back to the 70s. && .DISCUSSION... Issued at 251 PM CDT Sat Aug 3 2024 Warm and dry today as high pressure has suppressed any cloud development this afternoon. Meanwhile, low pressure is off to the northwest, across the Dakotas and Minnesota. Convection associated with the low will develop later this afternoon and evening, slipping into northern Iowa late this evening and overnight. A few stronger storms are possible as ML CAPE exceeds 1000 J/kg. RAP soundings show modest lapse rates under 7 C/km which may support small hail and Dcape around 1000 J/kg supporting a few stronger gusts. Overall the environment is borderline for severe potential overnight, however a few stronger storms may be possible. CAMs struggle with the evolution into the overnight as some solutions squash convection through the overnight while others continue sparse activity Sunday morning into central Iowa. Given the recent poor performance of CAMs, there is low certainty in any one solution. Sunday will be another hot one in the 90s as thermal ridging continues to dominate the central US. The only uncertainty here is whether those sowers and storms persist into the late morning as a few CAMs suggest. If so, that may put a damper on temperatures which occurred a few times this past week. As the northern extent of the thermal ridge just touches northern Iowa, the area is primed for passing perturbations across the area. Yet another weak impulse is expected on Sunday evening passing across northern Iowa. The parameter space improves here with better lapse rates, more instability, and a more focused area of forcing as the baroclinic zone shifts south. This will allow for more widespread convective activity late Sunday evening and into the overnight. Temperatures peak Monday across central and southern Iowa in the mid to upper 90s , however the northward extent of the heat is less certain due to the potenitial lingering convection and cloud cover from the overnight convection. By Monday afternoon overnight into Tuesday a more compact shortwave will pass across the area, however models indicate a little less instability to work with which my inhibit more robust convection. Much cooler air filters in behind the system as highs Tuesday remain in the upper 70s to near 80. A reinforcing shot of cooler air accompanies another shortwave across the area Wednesday into Thursday, bringing another round of showers and thunderstorms to the area. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 1050 PM CDT Sat Aug 3 2024 Scattered storms in central MN expected to diminish, but may brush the IA MN border near MCW. For now, low confidence on arrival and have left out. Otherwise, light winds with next potential for any showers mainly late in the period aft 00z Monday. /rev && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hagenhoff AVIATION...REV
Area Forecast Discussion
National Weather Service Gray ME
1019 PM EDT Sat Aug 3 2024 .SYNOPSIS... A series of frontal systems will track through the region late tonight, Sunday and again on Monday, bringing chances for showers and thunderstorms, some of which could produce locally heavy rainfall. A weak area of low pressure will track off the southern New England coastline on Tuesday and Wednesday, bringing scattered showers to southern Maine and New Hampshire while high pressure allows for dry conditions for northern areas. Another frontal system will bring scattered showers to the region late in the week as tropical activity remains across the Southeastern US. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 1015 PM Update...Dry but very muggy conditions exist for the most part late this Saturday evening. Height falls will occur later tonight and that may allow for renewed shower and thunderstorm development. Will keep chance PoPs going. Thunderstorms will be capable of torrential rainfall rates. Otherwise, fog is likely in valley locations once again late. 650 PM Update...Not much going on at the moment as lack of forcing has limited precipitation to isolated showers. The question is whether or not subtle height falls near an approaching boundary in the mountains allows for a redevelopment of showers and thunderstorms much like last night. CAMs are at odds with the HRRR continuing to be most robust. Will continue to monitor. Previously... Not expecting much in the way of showers thru this evening. There is some sort of boundary that sit across the NH and W ME mtns and this setting some small and short-lived convective showers, but this too should weaken before sunset, as we head into an area of relative ridging at different levels. This has also help clear out a lot of the CWA. However, there is another wave in the 500 MB and mid level floe that approaches after midnight and should be the focus for another late night into early morning round of showers. I have followed much closer to the CAMs than the global models, and this would lead to something to similar to what happened Sat morning, with the central and srn half of the CWA seeing the more potent convection, mainly in terms of rain and lightning, and less to the N, which would linger across E zones into the mid-morning. Overnight lows are not expected to change from previous nights and will mostly be in the upper 60s to low 70s with patch fog developing. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/... While any showers will end by mid morning, there is a much better chance of a secondary round of convection, especially S of the mtns Sunday afternoon into early evening. This is the result of that boundary we see in the mtns today slowly drifting S during the day on Sunday. Given the air mass and water content, any convection could produce torrential downpours. It wound be as warm on Sunday, with highs probably staying in the 80-85 range in many spots, but may be upper 80s in SE NH and far SW ME. Tds will not change much though, and itll still be very humid. That boundary moves offshore Sunday evening, but also deteriorates, and there is little change in the air mass behind it. Maybe dew points drop off by 2-3 degrees, which we could see in lows ranging from the low 60s in the mtns to the upper 60s in the S, but thats about it. This will probably lead to fog in more places given the rain and the very saturated air mass trying to squeeze out some water as temps fall a slightly lower than previous nights. However, it should stay mainly dry with some clearing overnight. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... The last in a multiple, series of frontal systems will finally cross the forecast area on Monday from northwest to southeast. Ahead of this front, hot and humid conditions will continue with air temperatures reaching the lower 90s and surface dew points topping out near 70 degrees. This will bring heat indices as high as the mid 90s over southern portions of Maine and New Hampshire. Showers and storms will form in proximity to the front as instability increases during the day as an abnormally high PWAT scenario continues. Some of the storms may have locally very heavy rainfall and gusty winds. On Tuesday we can expect much lower dew points as the front settles south of our region with high temperatures mainly in the 70s which will be a significant cool down for the region. The challenging portion of the forecast is how far south the front settles over southern New England before a weak wave travel along it on Tuesday and Wednesday. This weak area of low pressure will bring clouds to southern areas as well as a chance for showers. Northern areas are expected to remain dry. Operational models and ensemble solutions differ in agreement as to whether tropical moisture will interact with a trough late in the week well ahead of any potential tropical activity. Jet dynamics may very well play a role in the formation of heavy rainfall, however that axis may end of falling south of our region. In the meantime, with low confidence in late next weeks forecast, will continue with scattered showers in the grids. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Short Term...Tonight looks very much like previous nights, with fog and low cigs developing in the usual spots, and like early Sat morning, expecting another cluster of TSRA to move through just before and after sunrise. It may end up slightly further N than Sat, but they will include another found of very heavy rain and frequent lightning. Then after a brief improvement to VFR another line of TSRA develops across central NH into coastal ME Sunday afternoon into early evening. Fog may be prevalent and hit all the terminals on Sunday night. Long Term...Mainly afternoon and evening scattered showers and thunderstorms expected tonight, Sunday and into Monday. Localized IFR conditions with LIFR conditions possible in late night fog as well. Conditions will be variable on Tuesday with showers possibly developing along the exiting cold frontal boundary. Drier air follows midweek before more showers enter the region late in the week. && .MARINE... Short Term...Any fog that was over the eater is now gone, but should develop, at least around and S of Pen Bay later tonight, but it may dissipate again Sunday morning, only to return Sunday night. Otherwise winds/seas remain below SCA levels. Long Term...Winds and seas stay below SCA levels into next week. We may see patchy fog into next week limiting visibilities. && .HYDROLOGY... A series of front will cross the region tonight, Sunday and Monday. Multiple rounds of showers and thunderstorms with locally heavy rainfall are possible during this period as PWATs remain around 2" and renew the threat for flash flooding. An important takeaway remains is that the airmass is anomalously moist and any organization could support rain rates over 2"/hr and a threat for flash flooding, particularly in areas that have recently seen heavy rainfall. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Ekster SHORT TERM...Cempa LONG TERM...Cannon AVIATION... MARINE... HYDROLOGY...
Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Sat Aug 3 2024 .UPDATE... Updated Aviation && .SYNOPSIS... Extreme heat will be the main story this weekend and into Monday as high temperatures soar upwards of 110 to 116 degrees and overnight temperatures only cool into the middle 80s to lower 90s across the lower deserts. Daily thunderstorm chances will continue over the next few days, but storm coverage will be primarily focused over Arizona high terrain. An upper level disturbance arriving early next week will bring better potential for more robust storms and greater coverage of storms, as well as a cooler temperatures. && .DISCUSSION... An unseasonably strong ridge of high pressure has become established over the 4-Corners region with 500 mb hghts now approaching 598 dam. Hghts aloft have also increase over south-central AZ and are now up to 595-596 dam according to the latest RAP 500mb analysis. This expansive area of high pressure is expected to persist into early next week, resulting in excessively hot temperatures across the Desert Southwest through Monday. Today, we will see highs approaching 115 degrees in some locations such as Phoenix, Yuma, Blythe, and El Centro. There is currently a 75% chance that Sky Harbor will exceed the record high of 114 this afternoon (see climate section for more information on records). Low temperatures tonight will be very uncomfortable, with many locations not falling below 90 degrees. As far as rain chances go today, instability will be much more limited today (SBCAPE largely below 1000 J/kg) and therefore storms are expected to remain isolated across our region. The highest rain chances will be around 30-40% across S Gila County and 20% or less in the lower elevations of south-central AZ. The only caveat will be a complex of storms expected across Pima County which could send an outflow boundary into Pinal and Maricopa Counties this evening, which may result in patchy blowing dust along I-8. It is not out of the question that a storm or two could form along said boundary as it progresses towards the Phoenix Metro area tonight. On Sunday, the subtropical high over the 4-Corners region is not expected to move much at all which will allow temperatures to yet again climb well above normal. Lower desert highs will be similar to today in the 108-115 range which will result in areas of major to extreme HeatRisk. Therefore, it is important to continue to practice heat safety measures to keep yourself safe during this stretch of very hot temperatures. Latest hi-res guidance including the HREF does indicate slightly better instability tomorrow afternoon across south-central AZ up to 1000 J/kg. Forecast soundings also show very high DCAPEs approaching 2000 J/kg. Thus, convection may be more robust with slightly higher coverage across the central deserts Sunday afternoon and evening with the main threats being strong, gusty outflow winds. && .PREVIOUS DISCUSSION... Signs still point toward a more active monsoonal pattern, with greater storm intensity and coverage during the early to middle portions of next week as an inverted trough (IT) moves in from the east and undercuts the subtropical ridge. Global ensembles have the IT reaching the Sonoran Desert as early as Monday afternoon or evening next week. Global ensemble means have the core vorticity passing mostly through northern Mexico, but regardless of whether a track staying just to the south limits the full potential of thunderstorm activity, there is strong agreement that the wave will help push moisture levels back up, and thus instability, as well as bring increased mid-level easterly winds. Global ensembles have PWAT values climbing back into the 1.6-1.7" range and mixing ratios to around 11-12 g/kg by Tuesday. GEFS probability for >1000 J/kg of CAPE respectively goes up to around 40-50% for most of southern AZ with this moisture increase. NBM PoPs remain highest on Tuesday, with widespread 30-40% across southern AZ. This shortwave during the first half of the week should help moderate and lower high temperatures slightly, but based on the current NBM forecast not enough to fall below normal. Then by the end of the week, as the influence of the wave wanes and moisture levels drop slightly again, temperatures may go right back up with the persistent strong high still in place over the region. && .AVIATION...Updated at 2310Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Distant outflows causing potentially more than one abrupt wind shift this evening will be the primary weather issue through Sunday afternoon. While storms with SCT mid/high cloud decks will be common around the periphery of the Phoenix airspace, odds of any direct TS impact is well under 20% and not considered in this TAF package. Instead, weakening northerly outflow would be most likely to impact KDVT/KSDL early evening with a separate long traveling southerly outflow potentially sweeping into KPHX/KIWA mid/late evening. Confidence in exact directions and timing still remains low with the possibility of outflows dying before reaching any given terminal. An eventual shift to easterly should be established after midnight with a return to a westerly component near/shortly after noon Sunday. Probabilities for more direct outflow and TSRA impacts appear much higher Sunday evening. Southeast California/Southwest Arizona including KIPL and KBLH: No major weather issues will exist through Sunday afternoon under a few occasional midlevel cloud decks. Wind directions will vary between a daytime SE component and a general veering towards an overnight SW component. TS well east of KBLH may result in a period of evening easterly winds, however confidence is too low to include in this TAF package. && .FIRE WEATHER... Scattered thunderstorms will be possible this weekend across the AZ high terrain. Although storm chances will remain low (20% or less) in most lower desert locations, there will still be the risk for strong outflow boundaries which could result in a sudden wind shift and gusty winds at active burn areas. Much better chances for widespread wetting rains will arrive early next week, with possibility for isolated flash flooding across the new burn scar locations. Aside from thunderstorm outflows, winds will should remain light and diurnal with afternoon gusts into the teens. Minimum RH values will mostly reside in the 10-20% range through this weekend with overnight recovery to 30-50% most areas. Temperatures this weekend will be several degrees above normal, with lower desert highs reaching the 110-116F range. Temperatures will cool down closer to normal by Tuesday with the arrival of better moisture and cloud cover. && .CLIMATE... Phoenix Daily Record Temperatures High Warm Low ---------- ---------- 8/3 114 (2020) 92 (2023) 8/4 116 (1975) 91 (2018) 8/5 116 (2023) 95 (2009) && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Monday for AZZ530>555-559- 560. CA...Excessive Heat Warning until 8 PM PDT Monday for CAZ560>570. && $$ DISCUSSION...Salerno PREVIOUS DISCUSSION...Benedict AVIATION...18 FIRE WEATHER...Salerno CLIMATE...Benedict
Area Forecast Discussion
National Weather Service Reno NV
129 PM PDT Sat Aug 3 2024 .SYNOPSIS... * Showers and thunderstorms will continue through this evening. A few storms are possible again Sunday, then mainly dry conditions prevail for next week. * Smoke from ongoing wildfires will impact areas mainly north of I-80 at times through this weekend. * Above average temperatures return Sunday and continue through next week, with moderate HeatRisk in most lower elevations. && .DISCUSSION... THUNDERSTORMS THROUGH THE WEEKEND, THEN DRY: * Showers and thunderstorms began developing around 11 AM south of US-50 in western NV and in Mono County, with a general northward movement of 15-20 mph. Most cells were pulse type with shorter life spans, but additional activity developing upstream has produced some training cells. * Storm activity will continue pushing northward across western NV and eastern CA through this afternoon, then the high resolution guidance favors additional development over northeast CA- northwest NV from late afternoon into the evening. While moisture is relatively plentiful with PW values around 1 inch, the risk of a few lightning fire ignitions outside the rain cores exists, especially for northeast CA/northwest NV where faster cell motions of 25-30 mph are anticipated. Other hazards with today`s stronger storms include periods of heavy rainfall with potential for isolated flash flooding if cells train or anchor to a terrain feature for sufficient duration, small hail, and outflow gusts near 50 mph. * The upper level shortwave supporting today`s convection will lift northward into southern Oregon this evening, taking the best forcing out of CA/NV. Some outflow interactions could linger across northwest and west central NV until around sunset, with clearing expected overnight. * Residual moisture and a weaker upper disturbance may bring isolated short-lived showers and thunderstorms Sunday afternoon to parts of Mono, Mineral and southern Lyon counties. Otherwise, a drier pattern is expected to prevail for the upcoming week with less than 10% chance of thunder each afternoon. SMOKE AND HAZE: * Smoke and haze from the Park Fire will continue to affect northeast CA and parts of western NV this weekend. Southerly flow should bring some relief and improved air quality later today to Lassen and northern Washoe counties, although smoke could return tonight as winds shift to westerly over northern CA. HRRR smoke trajectory models showed less smoke coverage compared to yesterday, but the thick cloud cover over the fire area could be underestimating the smoke output captured by the model. Keep an eye on fire.airnow.gov for the latest air quality measurements. TEMPERATURES/WINDS THIS WEEK: * Temperatures for the upcoming week will run about 3-6 degrees above average due to a prevailing ridge over the southwest US, with highs in the upper 90s-near 100 for lower elevations and mid-upper 80s for Sierra communities. HeatRisk will generally reach the Moderate category each afternoon. * A slight cooling may arrive by late week as a bit more troughing over the northwest US could flatten/weaken the ridge`s western extent over CA/NV. Most afternoons should see typical SW-W breezes with gusts to 25 mph, with a potential slight increase by late week if the flatter ridge scenario occurs. MJD && .AVIATION... * For the main terminals around Tahoe and far western NV, the best chances for thunderstorms will continue until around 23-00Z, while for KMMH the threat for storms has already diminished. Storm activity then shifts farther north and east for the late afternoon and evening, ending by midnight. Plan on short periods of MVFR/IFR conditions from brief heavy rain and/or small hail, lightning, and gusty winds to 30-35 kts with today`s storms. * VFR conditions then return overnight and continue through the upcoming week, with more typical SW-W breezes around 20 kt for most afternoons between 21-04Z. Haze from the Park Fire may produce minor reductions in slantwise visibility, especially for areas north of I-80. MJD && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$
Area Forecast Discussion
National Weather Service Salt Lake City UT
216 PM MDT Sat Aug 3 2024 .SYNOPSIS...A monsoonal surge will expand the potential of showers and thunderstorms throughout the area on Saturday. Temperatures will cool slightly before becoming hot again early next week. Daily shower and thunderstorm chances will continue across southern and eastern areas through next week while northern areas dry back out early next week. && .SHORT TERM (Through 12Z/6AM Tuesday)... Satellite imagery shows an area of mid and high level cloud cover that continues pushing northward through northern Utah this afternoon. This band of cloud roughly marks the northern periphery of the monsoonal moisture working northward across the state today. Mesoanalysis shows a sharp gradient in PW values from around 0.5 inches in southwest Wyoming to around 1 inch over central Utah (with values continuing to increase to around 1.25 inches in Washington County). Surface-based CAPE also increased along this same axis to 1000 J/kg along and south of Millard to Emery Counties. Deep southerly flow across the region resulting minimal shear values, largely less than 20 knots, and supportive of northward storm motions around 10-15 knots. At 700 mb to the surface there is evidence of a convergent boundary along the central spine of mountains into central Utah, which should help to further increase the forcing for ascent over the terrain in central Utah this afternoon. Thunderstorms developing over the central mountain terrain will quickly upscale via colliding cold pools as it move northward in the mean flow. However, with the drier environment in place across northern Utah, storms will start to collapse moving off the terrain, with the drier sub-cloud layer will favor strong, gusty outflow winds advancing northward along the Wasatch Front into this evening. Largely expect wind gusts in the 30-50 mph range, however, a few isolated wind gusts to 60 mph cannot be ruled out, especially in terrain favored locations. Farther south, for much of central Utah, the slowish storm motions, deeper moisture, and potential for training/backbuilding will setup a marginal risk for flash flooding. The most prone areas through central Utah would be area burn scars, so long as a storm can train or backbuild over the scar. Meanwhile, into southern Utah, the southerly flow will primarily carry the storms initiating in Utah away from the more sensitive basins and slot canyon areas. However, the wild card remains how well storms can maintain moving off of the higher terrain in Arizona. Many members of the HREF have little in the way of thunderstorms making it into far southern Utah this afternoon. However, recent runs of the HRRR have supported the idea of some heavier rain producing storms moving out of Arizona into southern Utah later this afternoon and early evening. Surface dew points are in the mid 50s largely from the Paria River basin westward through Zion and Washington County. This corner of southern Utah would have the best chance of realizing any heavy rain and thunderstorms, while points east from the Escalante basin through Capitol Reef to the Swell have dew points in the mid 40s limiting the potential today. On Sunday, the ridge flattens slightly as it shifts almost due south of us, allowing a drying westerly flow to develop across Utah. While the column will start to dry, low-level moisture will still be in place, supporting developing instability in the afternoon. Showers and thunderstorms developing over the higher terrain will largely track off to the east, which will favor locally heavy rainfall into eastern basins such as Capitol Reef NP and the Swell. Elsewhere across Utah, isolated to widely scattered showers and thunderstorms are expected through the afternoon, and in the Salt Lake Valley, there will probably be a storm moving off the Oquirrhs mountains by early to mid afternoon. This flattening of the ridge with lower-level moisture still in place will give us a one day "reprieve" from the hotter temperatures, allowing the HeatRisk to back off to moderate (orange level) on Sunday, although daytime highs will only be a few degrees cooler. .LONG TERM (After 12Z/6AM Monday), Issued 355 AM MDT... High pressure will continue its hold over our region early next week, allowing for hot triple-digit temperatures for many valleys. Monsoonal moisture also remains in our forecast, bringing a daily chance for showers and thunderstorms across southern Utah and portions of central/eastern Utah. Each afternoon/evening will bring an enhanced risk for heavy rains/flash flooding of sensitive areas such as slot canyons, normally dry washes and recent burn scars or areas of very steep terrain. Toward the latter half of the week, we continue to see trends toward a weaker area of high pressure. This would allow temperatures to cool off ever so slightly. Monsoonal moisture looks to remain toward the end of the week though amounts and locations continue to be fuzzy and range from similar trends from earlier in the week to more widespread across the state. && .AVIATION...KSLC...Scattered showers and thunderstorms capable of gusty, erratic outflow winds and lightning are likely from 00-06Z. Winds will prevail from the south, but directions and speeds will be altered through 06Z by showers and thunderstorms. Conditions will clear after 06Z with light southeast winds overnight. Dry conditions are likely for the end of the weekend, with isolated showers and thunderstorms likely around terrain to the east. Winds will transition from southeast to northwest around 19Z. .REST OF UTAH AND SOUTHWEST WYOMING...Scattered showers and thunderstorms through roughly 03Z in southern Utah and 06Z elsewhere will be capable of gusty, erratic outflow winds, lightning, and locally heavy rain. Clearing conditions are likely overnight with light winds. Showers and thunderstorms are likely after 18Z for locations east of a line from roughly KEVW to KCDC. && .FIRE WEATHER... Monsoon moisture continues to move in from south to north across the state today as a ridge of high pressure is in place just to our east. The moisture will maximize across Utah later today and tonight. This will lead to numerous to widespread showers and thunderstorms developing over central Utah this afternoon and forming a strong cold pool which will push northward through northern Utah as strong/gusty outflow winds. Gusts largely in the 30-50 mph range, but isolated gusts to 60 mph are possible mainly for Juab, Utah, Tooele, Salt Lake counties. For central and southern Utah, deeper moisture in place will promote locally heavy rainfall which could lead to isolated flash flooding and areas of wetting rains A drier westerly flow will start on Sunday, reducing moisture levels early in the week. As the ridge builds over the area along with drier air, temperatures will become quite hot again, surging 5-10 degrees above normal. The ridge shifts a bit more eastward later in the week opening the door for a return of monsoon moisture into southern Utah. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Heat Advisory until 9 PM MDT this evening for UTZ101>107-114-116- 118>120. Excessive Heat Warning from 10 AM Monday to 11 PM MDT Tuesday for UTZ101-103>106-116-123-124-131. Heat Advisory from 10 AM Monday to 11 PM MDT Tuesday for UTZ102- 107-114-115-118>122-128>130. WY...None. && $$ SHORT TERM...Church LONG TERM...NDeSmet AVIATION...Wilson FIRE WEATHER...Church For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity