Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/06/24


Area Forecast Discussion
National Weather Service Boston/Norton MA
1042 PM EDT Mon Aug 5 2024 .SYNOPSIS... Hot and humid conditions end today with a more comfortable airmass settling in for the rest of the week. Showers expected to form overnight and last into tomorrow morning. Another round of moderate to heavy rain likely Tuesday night into Wednesday. Driest period of the week occurs late Wednesday into Thursday. Impacts from Debby will begin Friday and persist through Sunday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Update: 10:45pm Thunderstorms across NY State continue to weaken this evening, but we still expect a few showers, maybe a rumble of thunder to move across parts of southern New England overnight. Interesting 00z CAMs show a spread in the guidance, even in the near term, over the next couple of hours. Given the spread in the newer guidance and the current forecast still aligns with radar trends have not made any whole sale changes to the forecast over the next several hours. The HRRR and NAM performed pretty well in keeping convection to our north this evening, so heavily relied on a combination of those two hi-res models to derive the near term update. Do anticipate that showers and isolated thunder will eventually push into the region, between 06-10Z tonight. Mid level lapse rates and MLCAPE deteriorate rapidly after sunset, so while bulk shear remains supportive of organized cells and 0-1km helicity increases over the next several hours, am not keen on a continued severe threat into the overnight hours with shortwave forcing diminishing. Previous Update... Up to 2500 J/kg of SBCAPE is available per SPC meso analysis, but the atmosphere remains quite capped off in SNE. The best chance for thunderstorms remain in southern VT and NH where the best forcing from the shortwave is present. Tonight: Cold front drops south from northern New England tonight which should bring a round of light to moderate rain showers starting late tonight. Hi-res guidance is in fairly good agreement that shower activity will move from west to east late overnight and last well into tomorrow morning. There may be some residual elevated instability overnight which could bring a rumble or two of thunder overnight, but not expecting any severe weather after 8pm. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tomorrow: Cold front looks to stall near the South Shore tomorrow which will allow showers to continue into the late morning hours. Showers possibly redevelop into thunderstorms over the Cape and Islands late tomorrow morning into the afternoon where some elevated instability will be present. Inland, drying conditions expected in the afternoon, however, strato cumulus clouds likely hang around and keep the skies mostly cloudy. Behind the front, winds turn NNE allowing for cooler air from northern New England and the Gulf of Maine to stream down. Highs look to top out in the low 70s near the coasts, and upper 70s in CT River Valley. Dewpoints also fall to a more comfortable levels into low 60s north of the Pike, to mid 60s along the South Coast Tomorrow Night: Still some uncertainty with how far south the cold front stalls. Guidance seems to want to stall the front along or south of Long Island stretching to Nantucket. A weak surface low looks to ride up the stalled front overnight which will bring a widespread soaking rain to much of the region. PWATS range from 1.0 north of the MA Pike to 2.0 near the stalled front over the southern waters. With strong forcing from a shortwave aloft and warm cloud depth in excess of 10-12 kft, expecting moderate to heavy rain showers. The best chance for seeing 1-2 inches of rain appears to be across CT, RI, and SE MA. Further north, QPF totals will likely fall off quickly ranging from 0.25-0.75 inches. Overnight lows finally drop to a more comfortable level into the low 60s and even some upper 50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... * Potential for heavy rain to linger through Wednesday morning associated with a stalled frontal boundary to our south * Longest stretch of dry weather this week will occur Wednesday evening through early Friday * Impacts from Debby will begin late Friday, potentially lasting through Sunday Wednesday and Thursday... There remains uncertainty in the location of a cold frontal boundary come Wednesday morning, with the threat for the heaviest rain occurring prior to 12Z. Still, cannot rule out some shower and downpours persisting through the first half of the day. Shortwave trough moves east of the region by Wednesday evening with weak mid level ridging and surface high pressure building in for Thursday. Do anticipate the period of Wednesday afternoon to late Thursday evening will be the driest 36 hour period of the week. With frontal boundary still south of the region, do anticipate much more temperate highs for the mid week period, generally in the 70s with much cooler dewpoints. Many locations will drop into the 50s overnight Wednesday/Thursday, the coolest temperatures we have seen in several weeks. Friday through Sunday... There appears to be some moderate consensus in that the impacts from Debby will begin on Friday, and will likely persist through Sunday; generally in the form of heavy rain and potential flash flooding. The impacts felt here in southern New England will be highly dependent on the exact track of the system, with a more coastal track shifting the heaviest rain potential across our entire region and a more inland track, like the GFS portrays, isolating the heaviest rain threat to our western zones. It is much too early, given mesoscale models have yet to include the period, to deduce the exact location of heavy rain banding and rainfall totals, but will note that ensemble probabilities continue to be quite notable for 24 hour QPF above 2" (up to 40% in the GEFS), and greater than 4" (up to 20%) for portions of SNE, for the period of late Friday through Saturday evening. While ensemble probabilities are beginning to hint at a considerable rainfall event for our region, there remains substantial spread between ensemble members with the 10th and 90th percentile GEFS painting very different scenarios; with as low as 2" (10th) and as high as 6-7" (90th) of QPF through the next 7 days. 50th percentile guidance settles around 3-4" for the region. So, while it is quite possible that portions of our region see upwards of 5"+ of rain, uncertainty remains too high to place much confidence in our QPF forecast this far in advance. In collaboration with WPC and other northeastern forecast offices, elected to keep the Day 5 ERO in the Slight category, holding off on any upgrades to Moderate until if/when confidence increases in our forecast. In any case, do expect trough digging south across the Great Lakes and eventually southern New England to sweep the remnants of Debby to our east by late Sunday evening and Monday morning, setting up for what looks like a much drier period next week. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight...Moderate Confidence. VFR becoming MVFR overnight, with IFR/LIFR over the Cape and Islands. Winds stay out of the SE at 5-10 knots, gusting 20 knots over the Cape and Islands. Light to moderate showers move from west to east late overnight with showers starting around 09z and lasting into Tuesday. Tuesday...Moderate Confidence. MVFR/IFR to start the day with light to moderate rain showers. Showers eventually sink south in the Cape and Islands where some residual instability could bring some thunderstorms, but was not confident enough to include in TAFs at this time. Guidance remains varied on the geographic extent of rain tomorrow, but there remains a possibility that showers are widespread from ~10Z to as late as 19Z before a lull develops ahead of another round of rain Tuesday night. Tuesday Night...Moderate Confidence Another round of moderate to heavy rain is expected across much of the region. There could be embedded thunderstorms overnight. CIGS turn back to MVFR/IFR again. KBOS TAF... Moderate confidence in TAF. Low chance for a thunderstorm this evening mainly between 00z-04z. Rain chances increase again overnight with light to moderate rain showers possible between 09z-15z, possibly even lingering into 18z. KBDL TAF... Moderate confidence in TAF. VFR. Rain chances increase overnight with light to moderate rain possible between 09z-16z. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA, isolated TSRA. Wednesday Night through Thursday: VFR. Slight chance SHRA. Thursday Night: MVFR/IFR conditions possible. Chance SHRA, isolated TSRA. Friday: Mainly MVFR, with areas IFR possible. SHRA, isolated TSRA. Friday Night: Mainly MVFR, with areas IFR possible. Breezy. SHRA, isolated TSRA. Saturday: Mainly IFR, with areas MVFR possible. Breezy. SHRA likely, isolated TSRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight through Tuesday night...Moderate Confidence. Persistent southwest flow results in marginal small craft seas across the southern outer-waters right into Tuesday. Showers and possibly some thunderstorms move over the southern waters Tuesday morning and linger into Tuesday afternoon. Widespread moderate to heavy rain expected Tuesday night into Wednesday. Outlook /Wednesday through Saturday/... Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, isolated thunderstorms. Wednesday Night through Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, isolated thunderstorms. Local visibility 1 to 3 nm. Friday: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, isolated thunderstorms. Friday Night: Winds less than 25 kt. Local rough seas. Rain showers likely, isolated thunderstorms. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Rain showers likely, isolated thunderstorms. Areas of visibility 1 to 3 nm. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ254. Small Craft Advisory until 8 PM EDT Tuesday for ANZ255-256. && $$ SYNOPSIS...KP/KS NEAR TERM...Dooley/KP/KS SHORT TERM...KP LONG TERM...KS AVIATION...KP/KS MARINE...KP/KS
Area Forecast Discussion
National Weather Service Billings MT
119 PM MDT Mon Aug 5 2024 .DISCUSSION... Through Tuesday Night... Last night`s shortwave scoured out the moist air mass in place, and pwats are much lower today, but we are already seeing signs of re-moistening. Satellite imagery shows monsoon moisture lifting thru the northern great basin, where pwats are analyzed to be near an inch, and in fact there is lightning in southern ID. A weak shortwave combined with modest and very elevated (near 700-600mb) instability should produce isolated showers & weak thunderstorms beginning early this evening in our west and ending Tuesday morning in the east. Upstream there is a deepening trof over BC and this feature will induce height falls in our region tomorrow. As this happens, pwats will continue to increase, and ensembles show values back to 1+ inches by late afternoon. This is setting up our next round of scattered thunderstorms, some of which may produce severe wind gusts and locally heavy rain (and perhaps small hail...but wind is the much greater severe risk w/ wet microbursts possible). Current indications are for the 20-04z time period being favored for severe wx tomorrow. Please stay alert if you have outdoor/travel plans. As the severe risk fades Tuesday evening, another shortwave approaching from the west will combine with a Canadian cold front/wind shift to keep a good chance of showers and embedded thunderstorms going thru the night. Guidance is starting to hint at the advection of low clouds from the north, aided by the onset of upslope winds. Also, there are a number of active wildfires in northern Canada, and we could see an increase in surface-based smoke in the post-frontal air mass into Wednesday (high uncertainty here). Another item to watch is the area of stratus that is lingering over our east, and slow to erode as it is associated w/ seasonably strong high pressure over the Dakotas. Some component of low clouds may linger tonight, and w/ some clearing there is a risk of fog in our far east (Fallon & Carter) late tonight into early Tuesday. Regarding temperatures, it is looking like Tuesday will be the hottest day of the week with temps into the low-mid 90s, ahead of the Tuesday night cold front which will signal the start to a cool second half of the week. JKL Wednesday through Monday... Wednesday, an upper level low will begin to drop into the region bringing precipitation chances and significantly cooler temperatures. Most locations will have a 40-70% chance of precipitation making it one of the best chances during the long term. Temperatures will drop even further Thursday with most locations having a 30-60% chance of having a high temperature below 70F. The ECMWF EFI tables show -0.8 to -0.9 values indicating anomalously low max temperatures. Temperatures will hold steady Friday around 15 degrees below average in the low to mid 70s. Temperatures will start to rise over the weekend as upper level ridging to our south starts to impact the region. Temperatures will remain about 5 degrees below average however with highs generally in the low 80s. Anomalously high dewpoints and PWAT values will persist over long term with 850mb winds holding onto a persistent easterly/southeasterly component advecting plains moisture into the region. This will lead to daily precipitation chances of 30-50% for Thurs, Fri, and Sat, increasing to 40-70% for Sunday. The precipitation from these showers and thunderstorms will add up with WPC showing greater than 0.5 inches of precipitation across the region with some locations seeing greater than 1 inch over the next week. Those traveling into the high country Wed, Thur, Fri should prepare for cooler temperatures and the potential for wet and rainy conditions. Torgerson && .AVIATION... Broken stratus w/ MVFR-IFR ceilings continues to impact far southeast MT (east of KMLS) this afternoon, and it is becoming more probable that these low clouds will linger near the Dakotas border into this evening and perhaps longer. If/when stratus dissipates there is a reasonable opportunity for fog in this same area late tonight, as recent HRRR runs are suggesting. This is something to watch, but otherwise VFR will prevail thru midday Tuesday. Disturbance from the west will bring isolated showers and weak thunderstorms tonight (exiting the east early Tuesday). Beginning around 20z Tuesday, there is a greater chance (20-50%) of showers and thunderstorms, some of which may produce strong wind gusts and locally heavy rain. All TAF sites are at risk of seeing a TS tomorrow afternoon & evening. Lofted smoke will continue to reduce slant range visibility at times. JKL && .PRELIMINARY POINT TEMP/POPS... Tue Wed Thu Fri Sat Sun Mon ----------------------------------------------------------- BIL 064/093 063/078 057/070 053/075 056/082 058/084 057/083 24/T 55/T 44/W 22/W 33/W 54/T 34/W LVM 056/093 054/081 049/071 047/074 049/082 050/083 049/083 25/T 45/T 44/T 33/T 45/T 55/T 34/T HDN 062/093 061/078 053/070 050/077 054/084 055/084 055/083 23/T 65/T 34/W 32/W 32/W 54/W 33/W MLS 059/092 063/076 053/071 050/074 054/080 059/083 057/083 22/T 64/T 11/B 12/W 33/W 55/W 33/W 4BQ 062/094 063/079 056/070 053/074 054/081 059/084 057/083 22/T 64/T 24/T 33/T 33/T 54/T 43/T BHK 054/088 059/077 049/070 046/074 049/079 055/083 054/083 12/T 63/T 11/B 12/W 23/W 44/W 43/W SHR 059/095 059/077 051/068 048/076 050/083 053/084 051/083 23/T 45/T 67/T 54/T 33/T 45/T 35/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$ weather.gov/billings
Area Forecast Discussion
National Weather Service Columbia SC
914 PM EDT Mon Aug 5 2024 .SYNOPSIS... Tropical Storm Debby will be moving slowly northward toward the area tonight spreading across the state. Confidence is high for potential heavy rainfall and flooding over the next several days. Drier air should finally move into the region by the weekend leading to lowering rain chances. && .NEAR TERM /UNTIL 8 AM TUESDAY MORNING/... Key Message(s): - Rain and potential for flooding remains the highest concern - Flood Watch now in effect for portions of the SC Midlands and CSRA. - Highest rainfall through tonight over the southern/eastern Midlands CSRA. At 8 PM EDT, Tropical Storm Debby was about 50 miles WNW of Jacksonville, FL with max sustained winds of 45 mph, moving toward the NE at 6 mph. The slow northeastward movement is expected to continue overnight, with the storm center reaching far southeastern GA by Tuesday morning. The outer rain bands of Debby are spreading across the area from south to north this evening. Rainfall intensity right now is on the lighter side, but heavier convective bands are not far to the south, along with cooling cloud tops and increasing lightning activity off the southeast coast of SC near Charleston and Savannah. The heaviest rainfall potential tonight still appears to be in areas south and east of I-20. A Flood Watch for Flash Flooding remains in effect through Thursday evening to account for the expected heavy rainfall. It should be noted that it is difficult to pin down exactly where the heaviest rainfall could occur, because even minor shifts in the track of Debby will change the locations which receive the heaviest rain bands. That said, parts of the area, especially south of I-20, could be looking at 1-2" of rainfall through the overnight period. Outside of the rainfall threat, there is also a small threat of gusty winds and saturated soils combining to bring some trees down across the region. Sustained and winds gusts through tonight will gradually increase, however gusts into Tuesday morning are expected to reach a maximum of 25 mph in the CSRA and southeastern Midlands, around 20 mph in the Columbia and Lexington areas and slightly less in the western Midlands and Pee Dee. With overcast skies now over the area and temperatures in the upper 70s, only slight cooling is expected and low temperatures will fall into the low to mid 70s. && .SHORT TERM /8 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/... Key Message(s): - Potential for life threatening flash flooding in the short term - Portions of the area are in a rare High Risk for excessive rainfall - A Flood Watch is in effect through Thursday evening Debby will bring deep moisture into the forecast area for much of the short term forecast. Guidance remains in agreement that heavy rainfall is likely Tuesday through Thursday which will pose a significant and life threatening flooding threat. The rain shield from Debby is expected to push further north early Tuesday morning spreading rain over most of the FA. As we progress through the morning and into the afternoon we will see bands of heavy rain with embedded thunderstorms pick up. These bands of higher rain rates may be slow moving, potentially leading to flash flooding especially south and east of I-20 where PWAT values will be around 2.5 to 2.75 inches. In this area along and south/east of I-20 there`s potential for 3 to 6 inches of rainfall Tue and Tue night, with locally higher amounts. These amounts in addition to very wet antecedent conditions contribute to a high risk of excessive rainfall. The banding of heavy rain and thunderstorms should lead to a tight gradient in rainfall over the central FA. This somewhat hampers confidence in flooding for areas north of I-20. Though a lesser threat than the flash flooding, there may be a period on Tuesday afternoon conducive to severe weather. Although the right- front quadrant of the storm is expected to remain east of the area there may be sufficient instability on Tue that thunderstorms develop. Storm Relative Helicity values are high enough to warrant a low threat of tornadoes in the extreme eastern FA where 0-1 km EHI values from the RAP approach 1. This may support brief, weak tornadoes in the eastern portion of SC. There may be a brief reprieve from the heaviest rainfall on Wednesday as Debby moves eastward. However, given the potential for heavy rain on Tuesday it may not take as much rain to produce flash flooding. Therefore it is still possible that the eastern Midlands could see conditions stay the same or worsen with lower rain rates. Wednesday night and Thursday, Debby is forecast to lift northward potentially bringing another round of heavy rain to portions of the forecast area. This far out, confidence is limited due to the exact positioning and intensity of the storm, however there is potential for another round of heavy rain and flash flooding on Thursday. && .LONG TERM /FRIDAY THROUGH MONDAY/... Key Message(s): - Improving conditions this weekend but river flooding is likely Friday and into the weekend, the deepest moisture is forecast to pull away from the forecast area. Clouds will likely clear from west to east as drier air pushing in through the day on Friday. Despite PWAT values lowering, atmospheric moisture may still be high enough for showers or thunderstorms to develop. Global ensemble means show moisture continuing to decrease into the weekend leading to lowering rain chances. Temperatures in the long term will be near normal. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Tropical Storm Debby remains well south of the area with moisture associated with the system moving over the terminals. Rain has moved into the Augusta and Orangeburg terminals and is leading to some MVFR visibilities developing. In addition, MVFR ceilings are expected to develop over the next few hours which will then transition to IFR ceilings late tonight which will likely continue through the day tomorrow. Rain will increase in intensity overnight and into the day tomorrow, especially at OGB. As a result, while periods of IFR visibilities in rain are possible at all the terminals, the most likely IFR visibilities will be at OGB. Winds will shift from easterly to northeasterly with gusts around 25kts possible Tuesday. EXTENDED AVIATION OUTLOOK...Low ceilings, reduced visibility and rain, heavy at times, are expected to continue through at least Thursday. Gusty winds may be possible through Wednesday night as Debby moves through the region. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...Flood Watch through Thursday evening for SCZ022-027>031-035- 037-038-041-135>137. GA...Flood Watch through Thursday evening for GAZ063>065-077. && $$
Area Forecast Discussion
National Weather Service State College PA
1135 PM EDT Mon Aug 5 2024 .SYNOPSIS... A dying cold front will move in from the north overnight and stall out in southern PA Tuesday. This front may waggle north and south some through the next few days, providing a focus for heavy rain and strong thunderstorms. Hurricane Debby should move slowly up the East Coast, diminishing to a depression and then going extra- tropical as it does so. The heaviest rain directly associated with the circulation should remain to the south of PA until Friday or Saturday. && .NEAR TERM /UNTIL 7 AM TUESDAY MORNING/... Short wave trough moving across the nrn tier and wrn NY is generating numerous SHRA with a few TSRA embedded clustered over the Allegheny Plateau N of I-80. They are producing 0.25-0.50" rain as they pass, but just a spot or two has picked up around 1". This is well below FFG thresholds. The showers are being handled well by the recent HRRR runs, and confidence is high that they will continue sliding eastward steadily over the next 3-4hrs and exit to the east around 06Z. Have tapered PoPs after the cluster passes, hanging onto a little tail of 20 pct trailing along to the SW of the cluster for another 1-3hrs. But, much of the night will be dry as we`ll be in the short wave ridge. Additional SHRA/TSRA may move in just after sunrise from the NW. Latest surface analysis puts the cold front along the long axis of LO at this time moving south. It should drop into nrn PA late tonight. The dewpoints will stay high (m60s-l70s) overnight and keep the muggies around. The cloud cover will vary widely but much of the time could be described as partly cloudy after the current SHRA move past. Fog will probably form across the nrn tier where rain has fallen recently, but the varying clouds may make it difficult to get dense. Will mention patchy fog at this point N of I-80. && .SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY/... WPC did expand the MDT risk of ex rainfall slightly north-west. Prev... Main change for Tuesday is for slightly farther southward drift of stalling frontal boundary. Latest model guidance halts the weakening cold front over the South Central Mountains by 12z Tuesday as upstream shortwave approaches from the Grt Lks. Plenty of cloud cover, especially on the cool side of the front over Northern PA, should hold temps down and limit the severe weather threat Tuesday. Given farther south settling of the stationary front, Tuesday could be a relatively quieter day as far as stronger storms go, although there will certainly be scattered shra and garden variety tsra around, esp along and south of the front. Locally heavy downpours are also possible, especially heading into Tuesday night when the approaching wave and deep layer moisture combine focused along the stationary boundary to bring a local heavy rainfall threat Tuesday night into Wednesday in areas that have been very wet just recently. 1 hr FFG values as low as ~1.4", 3-hr and 6-hr FFG values as low as 2.4" will be challenged from Tuesday evening through Wednesday morning as widespread 1-2"+ is expected from parts of the Lower Susq River Valley eastward, with local amounts GT 4" possible. Will hold off on watches for our area until we are within a 12-24 hour window of expected impacts and heaviest rainfall. The bulk of model guidance indicates the quasi-stationary front will slip just southeast of PA Wednesday with decreasing showers throughout Wednesday morning. A weak wave of low pressure riding along this boundary will likely result in lingering cloud cover and the chance of showers over the southern half of the state. Can`t even rule out a tsra near the Mason Dixon Line, where models show a bit of elevated CAPE. GEFS 2m temp anomalies indicate max temps will likely be 5-10 degrees below average Wed due to the cloud cover and easterly flow. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Late evening update will hold minor changes for the days 4-7 time frame. So much uncertainty with the track/devolution of Debby that making too wild of swings at this range unwise. We have been messaging through many means that from Fri onward is when we might see some heavy rain from direct influence of the remnant low. Prev... Rather dry air works into the area by Wed, especially across the north and west. This may support not much going on during the first part of Thursday. The first part of Thursday thinking in line with what I saw the last few days. Main concern is moisture being advected back to the north and west after early Thursday, with weak blocking high to the north. Thus looking at a wet period after early Thursday into at least the first part of the weekend. Next chance of drier conditions early next week. WPC working on rainfall outlooks for later in the week. Still a lot of spread in the details at this range for late week. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... New round of showers moving west to east first part of the night, mainly north airfields. Some fog and low clouds possible overnight. For Tuesday, looks like drier air works into the north and west later in the day, main chance for storms would be across the southwest later in the day at sites like JST. Outlook... Wed-Sat...Showers and storms expected at times. Impacts expected. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...DeVoir/Dangelo NEAR TERM...DeVoir/Dangelo SHORT TERM...DeVoir/Fitzgerald LONG TERM...Dangelo/Martin AVIATION...Martin/Gartner
Area Forecast Discussion
National Weather Service Dodge City KS
654 PM CDT Mon Aug 5 2024 .KEY MESSAGES... - Hottest day of the forecast period will be Wednesday as much of southwest Kansas will heat to 100 to 105 degrees. A few 106 degree readings will be possible, especially across far western Kansas. - Significant pattern change toward cooler and wetter is still on track beginning Thursday, August 8. - Widespread 1-2" rainfall over the course of a roughly 5-day period is increasingly likely in the August 8-14 time frame (12Z ECMWF EPS 25-75th percentile for DDC of 0.60 to 2.25" through August 15th). && .DISCUSSION... Issued at 323 PM CDT Mon Aug 5 2024 The mid-afternoon water vapor imagery and RAP analysis showed the summer subtropical high extending from the Four Corners region east across Oklahoma. A shortwave trough was moving east- southeast across the Dakotas into Minnesota, which was responsible for pushing a surface cold front south across the Nebraska Sandhills into northeast Colorado. This front will continue its slow, by steady push south this evening, reaching the central portion of our forecast area during the pre-dawn hours, around 09Z Tuesday or so. This front will stall out just south of a Liberal to Pratt line late Tuesday before dissolving and we start seeing post-frontal upslope east-southeasterly winds develop. Along and south of the front late in the day Tuesday, temperatures will still reach mid to upper 90s, so these locations will not see a reprieve from the 100 or near-100 degree heat. Mid level heights will remain high (500mb heights around 597 decameters), which will result in quite a bit of deep tropospheric subsidence such that no thunderstorm activity is expected along the front across southwest Kansas. None of the CAMs show a convective signal via Composite Reflectivity across any of Southwest Kansas, so we will keep POPs generally 10% or lower through Tuesday Night. Any large convective system that develops across the higher terrain of southern/southeastern Colorado is likely to remain out there as it weakens through the evening/night given the absence of any steering flow. One more hot day is forecast Wednesday with much, if not the entire forecast area sees southerly winds redevelop and 850mb temperatures on the rise (+30C isotherm reaching U283 corridor by 00Z Thursday). This will be the hottest day of the forecast period, and this will be reflected in the official hourly temperature and MaxT grids well into the lower 100s (around 105 from roughly Elkhart-Johnson northeastward to Scott City- Dighton, continuing northeast up to Hays). Dewpoints will be low enough to prevent Heat Index values from exceeding the actual air temperature, and areas out west will be dry enough such that the Heat Index will likely be at least a couple degrees lower. Wednesday will be the last of the heat for awhile. A fairly significant pattern change remains on track with confidence continuing to grow in numerous days of fairly high precipitation chances. Latest models and ensemble systems are starting to show an even farther south push of the front, putting much of western Kansas in favorable post-frontal moist upslope. The 100-member Grand Ensemble of the NCEP GEFS, Canadian EPS, and ECMWF EPS all point to a similar picture with each ensemble system showing Mean Precipitable Water values in excess of 1.50" across pretty much all of western Kansas starting late Thursday 8 August and continuing through at least Tuesday 13 August. It is starting to look like the pattern we saw back in June which brought a fair portion of southwest Kansas much above average rainfall. Of course, the devil is in the details with respect to individual mesoscale convective systems within this pattern, but the potential longevity of this pattern warrants a very good chance for much of our southwest Kansas region to see well over an inch of rainfall over a 3 to 5 day period coming up late this week into early next week. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 650 PM CDT Mon Aug 5 2024 Light south winds are forecast this evening at 10 kts or less. A weak cold front will pass across the TAF sites between 12 and 14z, resulting in a windshift to the northeast at 10-13 kts. VFR conditions will prevail even on the cool side of the front. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Umscheid AVIATION...Finch
Area Forecast Discussion...UPDATED
National Weather Service Gray ME
1049 PM EDT Mon Aug 5 2024 .SYNOPSIS... A cold front will cross the region tonight, bringing chances for showers and thunderstorms, some of which could produce locally heavy rainfall, damaging winds and large hail. A weak area of low pressure will track off the southern New England coastline on Tuesday and Wednesday, potentially 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 lingers near the East Coast. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Update...Mostly minor changes to PoP as the front begins to push its way south thru the forecast area over the next few hours. Otherwise no significant changes to the forecast other than to remove enhanced wording from thunderstorms. Previous discussion...The first round of convection well ahead of a cold front will continue to cross through the forecast area the rest of this afternoon. For late this afternoon and this evening, the latest HRRR continues to depict showers and thunderstorms ahead of and associated with the passage of a cold front. Despite surface dew points and PWATS lower today, some of the storms still have the capability of producing very heavy rainfall and flash flooding. As dynamics increase through this evening, the threat for damaging winds will also increase. As height falls begin, the possibility for large hail exists as well as an isolated tornado. Latest mesoscale models continues to indicate the precipitation tapering off after midnight and shift off the coastline and into the Gulf of Maine. Although drier air will be entering the region, patchy fog will develop once again, especially in areas that receive heavy rainfall. Overnight lows will be much more comfortable than the last several with readings in the 50s north to the 60s south. Winds will be light but switch to the northwest. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... Clouds will continue Tuesday and moreso Tuesday night as the frontal system becomes stalled south of our forecast area. Models suggest a weak wave may ride up the front Tuesday night which will increase the chance for showers over southern areas of Maine and New Hampshire. A few of these showers may be heavy as there will be a sharp gradient in moisture from south to north. It will be much cooler during this period with slightly below normal temperatures which has been a rare case this summer. We then shift towards the long range portion of the forecast as tropical moisture potentially moves towards northern New England. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... ----------------------------------------------------------------- Summary: *Generally cooler, more seasonable temperatures are expected during the second half of this week. *Remnants of TC Debbie could move into NH and ME towards the end of the week, with flooding and heavy rain possible early on this weekend. For more information, see `HYDROLOGY` section. *Unsettled weather remains in the forecast after the passage of Debby`s remnants. ------------------------------------------------------------------ Discussion: A brief shortwave trough passes through the region on Wednesday, bringing less humid and more seasonable temperatures into the northeast. Zonal upper-level flow should allow these more seasonable temperatures to last through the end of the week. Otherwise, Wednesday and Thursday should be tranquil days with partly cloudy skies. A large plume of moist air from the south arrives on Friday, bringing increasing clouds and humid conditions. A system associated with the remnants of Debby may impact the region, bringing notable rainfall this weekend. Despite the connection to a tropical storm, we are not forecasting strong winds or other tropical-related hazards. Flooding is the main concerning factor with this weekend`s system. For more details, please see the Hydrology Discussion near the bottom of this AFD. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Short Term...A cold front will bring another round of showers and storms through the region for late afternoon and through portions of the evening hours. Strong to severe storms are possible, and TEMPO IFR (possibly LIFR) are likely for many terminals. Most storms should push east of the area by 04Z tonight, but there may be lingering showers across southern areas through the night. Even though some drier air will be working in behind the front, expect there to be some fog and low stratus once again, especially in and around areas that receive heavy rainfall. VFR expected Tuesday with a few showers possible across, mainly south of a PWM-LEB line. Showers may become more widespread with lowered ceilings Tuesday night, especially over southern areas. Long Term... Some MVFR is possible at MHT and PSM Wednesday morning due to scattered showers, otherwise sites should stay VFR through Friday morning before restrictions lower as thunderstorms move into northern New England. && .MARINE... Short Term...SCA conditions are not expected, but south to southwest winds will become northwest behind a cold front. This front will also bring increasing potential for strong to potentially severe thunderstorms to push offshore this evening. A few showers may linger a bit past midnight tonight, but then winds will turn out of the northwest tonight into early Tuesday. Winds the return to onshore Tuesday afternoon. Long Term... 2-3 foot seas with light and variable winds less than 10kts expected from Wednesday morning through early Friday morning. A storm system moves in on Friday, with strengthening winds and seas from the east expected during the day on Friday. Seas increase to 2-4 feet by the end of the day Friday. Seas are expected to be elevated this weekend and SCA issuance over the weekend is likely. && .HYDROLOGY... TONIGHT... Scattered showers and thunderstorms later today will generate locally heavy rainfall between 1-3, returning an isolated risk for flash flooding. The airmass as a whole has lost some moisture so rainfall rates would be 1-1.5/hr versus the 2-3/hr from yesterday, however the repeat nature of some storms could reintroduce some flash flooding. Areas of concern continue to be those hit hard in recent days and where soil absorption will be slower. Drier air will filter into the region midweek allowing for a drying out period ahead of heavy rain potential late week. THIS WEEKEND... WPC has expanded a slight risk for flash flooding in the Day 5 ERO highlighting some tropical moisture from Debby lifting into New England late week. A frontal boundary north of the remnant storm will be a focus for heavy rainfall over the northeast, regardless of the ultimate track of Debby remnant circulation. However, the timing and location of this frontal boundary has very low confidence. Precipitation amounts are likewise very low confidence along with any specific impacts. Nonetheless, a wet pattern is likely to set up Fri-Sat with a ridge offshore and an approaching trough from Canada in an airmass rich with tropical moisture increasing the risk for flash flooding and will be monitored closely. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro
Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Mon Aug 5 2024 .Update...00Z Aviation Discussion && .SYNOPSIS... Excessive heat conditions will continue today across portions of the area and through Tuesday for the Lower Colorado River Valley and Southeast California. Thunderstorm chances today will mainly be confined to the Arizona high terrain before spreading westward on Tuesday. Shower and thunderstorm chances on Tuesday will become fairly widespread across all of the Arizona lower deserts with strong winds and blowing dust a good possibility. Rain chances should persist over portions of the area on Wednesday before retreating to mainly over higher terrain areas late week as conditions begin to dry out. Temperatures should be closer to seasonal normals during the middle of the week before heating back up into next weekend. && .DISCUSSION... Mid-level water vapor imagery at this hour depicts somewhat drier air pushing over the southeastern portion of AZ ahead of a well- defined cyclonic circulation centered over Northern Mexico (south of El Paso). This inverted trough south of El Paso will be the main feature to bring us active weather during the middle of this week, particularly tomorrow. Current RAP analysis shows abundant moisture (PWATS >1.5") over South-Central AZ and MUCAPE between 750-1000 J/kg, but the environment should be well capped through tonight such storms surviving/forming into the lower deserts is very unlikely. This is also supported by the fact that we observed somewhat widespread atmospheric overturning yesterday, and cloud cover continued to linger overhead into early this afternoon. Showers and thunderstorms should remain confined to the high terrain to the north and east of Phoenix through this evening, with some stronger storms in the southeastern corner of AZ and over the Northern Sonora of Mexico. These stronger storms far to our south will help surge moisture into the region overnight and set the stage for a potential robust monsoon day on Tuesday. In anticipating a more active day tomorrow, the SPC has outlined much of the Arizona lower deserts in a marginal risk for severe thunderstorms due to wind and the WPC also depicts a broad area south of Phoenix in a slight risk for flash flooding. As the four corners high remains in place with analyzed 500 mb heights in excess of 596 dam, high temperatures will continue to reach into the low 110s for the eastern deserts and near 115 for the hotter locales of the western deserts. With more abundant moisture than previously forecast and increased cloud cover, there is a chance that NBM high temperatures will end up being too high for this afternoon, but areas of Major HeatRisk persist nonetheless. As such, a widespread Excessive Heat Warning continues through 8 PM tonight. Areas along the Lower Colorado River Valley and in SE CA will see mostly Moderate HeatRisk tomorrow, but heat indices will still be in excess of 115 degrees thanks to the surge of moisture expected overnight tonight, and so the Excessive Heat Warning for those locations will be in effect through 8 PM MST/PDT tomorrow evening. .PREVIOUS DISCUSSION... As the inverted trough moves through Sonora Mexico on Tuesday, the northern fringes of the trough will extend into southern Arizona providing decent forcing for thunderstorm development by the afternoon hours. The added moisture from the overnight hours should boost PWATs back into a 1.5-1.7" range, while lower level mixing ratios improve to 11-12 g/kg. This improved lower and mid level moisture along with daytime insolation should result in MUCAPEs of 1000-2000 J/kg. Easterly mid-level flow and 0-6km bulk shear of 20- 30 kts are also expected across south-central Arizona on Tuesday. The added forcing from the inverted trough is expected to bring higher terrain thunderstorm development during the afternoon hours, especially across southeast Arizona. The combination of the instability and the decent winds aloft should help thunderstorms to persist into the lower deserts with further redevelopment during the evening hours along expected deep and/or colliding outflows. The ingredients for some severe thunderstorms are likely to be met on Tuesday, especially across Pinal and southern Maricopa counties. If enough convection can form along the Mogollon Rim in the afternoon, this may provide for colliding outflows and decent thunderstorm development over Phoenix, but this is still uncertain. The main thunderstorm impacts on Tuesday should be strong to potentially severe winds along with areas of blowing dust. Heavy rainfall will also be a threat, but given the easterly steering flow of 10-15 kts, any flash flooding should be quite localized. By late evening, an organized thunderstorm outflow with blowing dust and even some isolated thunderstorms are likely to continue to progress westward through southwest Arizona reaching the Yuma area by midnight. Guidance then shows the inverted trough moving over the northern Gulf of California by Wednesday afternoon. Storm chances for Wednesday are quite uncertain at this time, but given the likely active monsoon day on Tuesday, Wednesday should be much quieter. The best areas for possible showers and storms on Wednesday may be across southwest Arizona into southeast California and possibly across the Arizona higher terrain. Temperatures Wednesday will also be noticeably cooler with highs only between 103-106 degrees in the Phoenix area to 105-109 degrees across the western deserts. Starting Thursday, guidance shows drier air already beginning to move into the western deserts and more dry air moving out of the southeast into Arizona Friday into Saturday. This should mostly end rain chances across the western deserts on Thursday and severely cut back chances across the south-central Arizona lower deserts by Friday. At the same time, the subtropical high is forecast to restrengthen and recenter itself over New Mexico. This is expected to bring hotter temperatures back over our region late this week into the weekend with highs at or just over 110 degrees returning by Saturday. && .AVIATION...Updated at 2320Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation concerns are expected over the next 24 hours. Winds will continue to follow typical diurnal trends, with occasional gusts early this evening around 15-20 kts. There hints of an outflow boundary moving through the region tonight but confidence surrounding this boundary is low and therefore not included in the TAFs at this time. However, if an outflow were to be realized, it would likely turn the winds to the E/SE earlier than was is currently in the forecast, and produce gusts near 20-25 kts for a brief period. Skies will be generally SCT, to perhaps sometimes BKN, through tomorrow morning, with the lowest bases around 12k ft. Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected through the TAF period. Winds at IPL and BLH through much of the period will emanate out of the SE and S respectively. Hi-res guidance points towards a potential outflow boundary moving through the region by mid-morning Tuesday but overall confidence in this is low. If this outflow were to come to fruition, it would likely emanate out of the S/SE and push gusts towards 20-25 kts at both terminals for a brief time. FEW-SCT mid and high level clouds will be present through Tuesday morning, before skies begin to gradually clear. && .FIRE WEATHER... Moisture will be on the increase through Tuesday with a disturbance approaching the region from the east. Thunderstorm chances today should mainly be confined to higher terrain areas, while Tuesday will bring widespread chances (30-50%) for showers and thunderstorms through much of the Arizona lower deserts. On Wednesday, wetting rain/storms will likely be much less widespread, especially if we have an active day tomorrow, but the western deserts could see isolated thunderstorm development over prominent terrain features. Aside from thunderstorm outflows, winds should remain light and diurnal today before increasing southerly winds are expected tonight. MinRHs will be around 15-20% today before increasing to 20-25% on Tuesday and Wednesday. Overnight recoveries will improve through Tuesday night increasing from 30-45% to 45-60%. Temperatures will cool down closer to normal by Wednesday with shower and thunderstorms remaining through midweek. Drier conditions will eventually move back into the area late week into next weekend with rain chances retreating to only over higher terrain AZ areas and temperatures heating back up to over 110 degrees. && .CLIMATE... Phoenix Daily Record Temperatures High Warm Low ---------- ---------- 8/5 116 (2023) 95 (2009) && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Tuesday for AZZ530-532. Excessive Heat Warning until 8 PM MST this evening for AZZ531- 533>555-559-560. CA...Excessive Heat Warning until 8 PM PDT Tuesday for CAZ560>570. && $$ DISCUSSION...Whittock PREVIOUS DISCUSSION...Kuhlman AVIATION...RW FIRE WEATHER...Whittock/Kuhlman CLIMATE...Benedict
Area Forecast Discussion
National Weather Service Reno NV
122 PM PDT Mon Aug 5 2024 .SYNOPSIS... * Dry, southwest flow prevails this week with typical afternoon breezes each day. Localized enhanced fire weather concerns possible today and Tuesday. * Above average temperatures persist through the week, with a moderate HeatRisk for lower elevations. * Plan on a slight cooling trend to near normal August temperatures for the weekend. && .DISCUSSION... * Dry and Warm This Week: Dry, southwest flow will dominate across the region as the western extent of a high pressure ridge extends into the southern half of NV. Latest short and medium range guidance still shows potential for late day cumulus buildups in areas south of Highway 50 through much of this week which could produce a few brief showers, but potential for measurable precipitation is less than 10% areawide. Temperatures will be about 3 to 6 degrees above early August averages, with highs in the upper 90s-near 100 for the lower valleys and mid- upper 80s for Sierra communities. * Winds and Fire Concerns: With the warm temperatures, our typical afternoon southwest-west breezes return each day through the week. This could lead to short periods of elevated fire weather concerns for isolated portions of northeast CA/northwest and far western NV with afternoon wind gusts 25-30 mph and minimum RH down to 10-15%. Latest HRRR smoke forecasts from existing fires in northern CA show minimal smoke impacts for much of the region. However, parts of northeast CA and northwest NV are projected to see a return of smoke/haze later today and again Tuesday afternoon with the Park Fire showing increased activity due to the warmer, drier and breezy conditions. * Cooler Weekend into Next Week: Ensemble cluster analysis highlights an upper level trough dropping into the Pacific Northwest Friday-Saturday which pushes the high pressure ridge away from CA/NV. This would lead to a gradual drop in temperatures to near mid-August averages for the weekend. We could also see some increased winds arrive this weekend if the trough continues progressing farther south, with additional cooling to slightly below average by early next week. Most scenarios keep dry weather over CA/NV, but a few simulations (about 10%) that evolve the trough into a closed low over northern CA could generate isolated rain showers by early next week. MJD && .AVIATION... * Plan on VFR conditions this week along with typical afternoon breezes. Daily southwest to west wind gusts of 20-25 kts will develop between 21-03Z. Some minor reductions in slantwise visibility will be encountered in northeast CA/northwest CA due to haze from ongoing fire activity. * Dry, southwest flow will limit precipitation chances for much of the week, but a few cumulus buildups and brief showers are possible for areas south of Highway 50. MJD && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$
Area Forecast Discussion
National Weather Service Tucson AZ
123 PM MST Mon Aug 5 2024 .SYNOPSIS...A disturbance aloft will result in an active monsoon pattern for Tuesday with numerous showers and thunderstorms, especially from Tucson westward. Otherwise, expect scattered showers and thunderstorms each day through this week, with potential for heavy rainfall and strong wind gusts. Temperatures cool to near normal levels Tuesday through Thursday, then warm up to above normal levels Friday through the weekend. && .DISCUSSION...Latest IR/WV satellite imagery shows mostly sunny to partly cloudy skies across southeast Arizona. The subtropical mid/upper level high is currently east of the Four Corners with an inverted trough now pushing into Chihuahua from west Texas. This feature will have a more significant impact on our weather Tuesday. In the near term, scattered showers and thunderstorms are a bit slower to develop today than we`ve seen the past couple of days. The HREF/CAMs are showing the bulk of these scattered showers and thunderstorms through the afternoon to the south and east of Tucson primarily near the Int`l border from Nogales eastward and then another area in the White Mountains. The HRRR has been consistent for a number of runs in bringing another push of storms from the Gila region of New Mexico pushing westward this evening and perhaps through the Tucson area after about 8 or 9 PM this evening. Main concerns today into this evening will be gusty winds and locally heavy rain. The aforementioned inverted trough will move into NE Sonora Tuesday. This will result in a stronger mid level flow of around 15 to 20 kts from the east and additional synoptic scale lift to result in an expected active afternoon and evening for monsoon thunderstorms. There will be a push of moisture northward from the Gulf of California/Sonora tonight which will help increase the PWAT levels a couple tenths of an inch compared to today. This additional moisture combined with daytime heating should result in widespread SBCAPE values of 1000-2000 J/KG with DCAPE values near 1500 J/KG. This setup is favorable for both strong to severe thunderstorms with a wind threat and a flash flooding threat. The SPC has outlined much of our area in a marginal risk for severe thunderstorms due to wind and the WPC also depicts much of the area in a slight risk for flash flooding. The strongest storms based on the HREF are expected to be from Tucson westward. The faster flow will help storms move along at a decent clip but locales that see cell mergers will be most susceptible to flash flooding. Additionally, blowing dust will be a threat to the west and northwest of Tucson late Tuesday afternoon into Tuesday evening. The amount of monsoon activity Wednesday will somewhat be dependent on how worked over the atmosphere is Tuesday. The inverted trough/upper low does hang around the northern Gulf of California/adjacent northern Baja through much of the week with our under southeasterly flow. This pattern should yield a continuation of daily thunderstorm chances with day-to-day specifics still uncertain. Near normal temperatures are expected Tuesday through Thursday, then warmer temperatures return Friday through the weekend as heights increase with perhaps a bit of drying. && .AVIATION...Valid through 07/00z. Scattered -SHRA/-TSRA thru 06/06z then diminishing thereafter Tuesday morning. Another round of Scattered to Numerous -SHRA/-TSRA expected to develop aft 06/19Z. MVFR conds and local gusts to 50 kts near thunderstorms. Outside of thunderstorms expect wind speeds less than 12 kts and following typical diurnal trends. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Scattered to numerous showers and thunderstorms are expected Tuesday, otherwise expect scattered showers and thunderstorms each day this forecast period. Min RHs will trend upward Tuesday through Thursday to about 25 to 50 percent in valleys, then decreasing to around 20 to 30 percent Friday through the weekend. Outside of thunderstorm winds, 20-foot winds will generally be 15 mph or less, with afternoon/early evening gusts to 20-25 mph and light winds overnight. && && .TWC WATCHES/WARNINGS/ADVISORIES... None. && $$ Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson