Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/20/20

National Weather Service Albany NY
1013 PM EDT Sun Jul 19 2020 .SYNOPSIS... A few showers and thunderstorms are possible tonight as it will remain warm and muggy. A cold front will move across the region on Monday with only isolated shower and thunderstorm potential. Dry and slightly cooler weather is expected on Tuesday. The next chance for showers and thunderstorms arrives during the middle of the week. && .NEAR TERM /THROUGH MONDAY/... A Heat Advisory remains in effect for portions of the Capital Region, central and southern Taconics, mid-Hudson Valley, southern Berks, NW CT and eastern Windham County of VT from 11 to 8 PM EDT Monday. As of 945 PM EDT...Most of the convection has weakened yet still lingering instability as seen in the 00Z sounding. Nighttime satellite imagery reveals layers of clouds with lower stratus developing under the canopy of high and mid clouds. Rather chaotic H2O vapor imagery due to all of the convection so difficult to ascertain embedded waves for future development overnight. However, some hints within the HRRR suggest a weak wave across western NY and Lake Ontario may touch off additional isolated to scattered convection overnight across most of the region. So with this update, we will taper back the higher PoPs, leave in the mention of thunder, and adjust temperatures a bit per observations and NY Mesonet. Overnight lows look okay at this time as it will remain rather warm and muggy overnight as dewpoints hang out well into the 60s and lower 70s. Then a weak cold front will track southeast during Monday as winds gradually back to the west then west-northwest with a slight drop in the humidity levels from the Capital Region and points west and north. Just to the south, another hot and humid day where the heat advisory remains in effect. Could touch off a shower or thunderstorm with the frontal passage as PWATs remain around 2 inches, negative Showalter values and SBCAPES around or just above 2000 J/Kg. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/... The focus for this evening will be the advancement of showers and thunderstorms and how intense they will be upon arrival. Guidance continues to show a weakening trend as they move eastward, mainly due to the loss of daytime heating and weak upper-level forcing and shear over the area. Should storms maintain themselves long enough, some gusty winds and heavy rainfall will be possible to just west and north of Albany. The Storm Prediction Center continues a Marginal Risk for severe thunderstorms for this area with a Slight Risk clipping far northwestern Herkimer County. Outside of this area, slight chance to chance pops are maintained for showers. However, 850mb theta-e values remain very high overnight and PWATs rise to 1.5 to 2 inches across the area so an isolated robust thunderstorm with a heavy downpour is not out of the question. With an increase in cloud cover and the continued southerly flow, it will be a warm and muggy night with lows ranging from the upper 60s in the higher terrain to the low to mid-70s in the valleys. Monday, a cold front will push eastward across the region during the day. Latest guidance has the front clear Litchfield County in the far southeast around 2 PM. Isolated showers/thunderstorms are anticipated with the better chances south and east of the Capital District (where the front will be crossing during the late morning/early afternoon). High temperatures will range from the upper 70s to lower 80s across the higher terrain to the upper 80s and lower 90s in the valleys (with the highest values in the mid-Hudson Valley). Heat Index values between 95 and 103 are still possible from the Capital Region and points south and east; therefore the Heat Advisory will continue in these areas. High pressure will then build eastward across the region with dry weather Monday night through Tuesday. The air mass will be a bit more comfortable than the previous days. Lows Monday night will range from the upper 50s in the higher terrain to the low to mid-60s. Highs Tuesday will range from the 70s in the higher terrain to the 80s in the valleys. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... The long term period will look fairly summer-like with afternoon highs each day in the 80s and a few chances for afternoon thunderstorms. To start the period, a low pressure system will track across the Great Lakes and into New England. This will allow for a warm front to lift north through the region Wednesday, bringing increased humidity levels and chances for showers/storms. The low tracks further east into western Maine Thursday-Thursday night, sending its surface cold front through the region. This will lead to the threat for showers and thunderstorms throughout the day Thursday with highs reaching the upper 80s in the valleys (low 80s elsewhere). Depending on the timing of the frontal passage, could see some of the storms getting strong to potentially severe with ample surface based instability and lift with the front. High pressure builds in behind the front, bringing a reprieve to humidity levels and above normal heat. Friday and Saturday look dry with mostly sunny skies and highs in the upper 70s to mid 80s. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Challenging TAFs through this evening with respect to convective potential as isolated to scattered convection on the 88D continues to track east-southeast. We will carry TEMPO groups through this evening to cover the potential of convection. Overnight, subtle hints at the potential for more showers/storms, however the coverage remains in question as we will leave it out for now overnight and monitor upstream trends. Some haze/mist may develop but expected to remain above MVFR thresholds. Ceilings should also remain above thresholds with VFR conditions anticipated. Frontal boundary will slide southeast during Monday. This will result in VFR conditions as winds become west-northwest with an increase in magnitudes and a few gusts near 20kts. There also could be a shower/storm to the south of Albany but confidence remains low to include in KPOU-KPSF at this time. Outlook... Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Moderate Operational Impact. Likely SHRA...TSRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. NO SIG WX. && .FIRE WEATHER... Humidity will increase to between 80 and 95 percent tonight along with the chance for showers and thunderstorms, mainly north and west of the Capital District. Minimum RH values Monday afternoon will be 40 to 50 percent. RH values are forecast to recover Monday night back to 85 to 100 percent. && .HYDROLOGY... No problems are expected on the main stem rivers in the ALY Hydro Service Area over the next week. Forecast rainfall during this period ranges from 0.75 to 2 inches. Isolated to scattered showers and thunderstorms are expected tonight into Monday, mainly north and west of the Capital District with some locally heavy downpours possible, but not over a wide enough area to have big impact on main stem rivers. The next chance of precipitation will be on Wednesday. Much of the area remains in abnormally dry to moderate drought conditions per the latest US Drought Monitor, with streamflows well below normal. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Heat Advisory until 8 PM EDT Monday for CTZ001-013. NY...Heat Advisory until 8 PM EDT Monday for NYZ052-053-059>061- 064>066. MA...Heat Advisory until 8 PM EDT Monday for MAZ025. VT...Heat Advisory until 8 PM EDT Monday for VTZ015. && $$ SYNOPSIS...SND/BGM/Rathbun NEAR TERM...SND/BGM/Rathbun SHORT TERM...SND/Rathbun LONG TERM...JLV AVIATION...Evbuoma/BGM FIRE WEATHER...SND HYDROLOGY...SND
Area Forecast Discussion
National Weather Service Caribou ME
909 PM EDT Sun Jul 19 2020 .SYNOPSIS... A cold front will approach overnight and cross the region Monday. High pressure will build across the region Tuesday. A weather disturbance will begin to approach from the west Wednesday then move into the region Thursday. High pressure will begin to build toward the region from the west Friday. && .NEAR TERM /THROUGH MONDAY/... 9:09 pm update: The 00z KCAR sounding had a PWAT of 1.7" and MU Cape of 1155J/KG. Area radars show showers & thunderstorm moving into northern Maine from Quebec. Shear is expected to increase with time the remainder of the night and this will keep the threat of thunderstorms going across northern Maine overnight. The greatest threat from the storms will be heavy rain. The threat of hail looks relatively low due to high freezing levels, but some gusty wind is certainly possible with any stronger storms. Made some adjustments to the PoPs based on the latest radar trends. The past couple of runs of the HRRR do not appear to have a very good handle on the convection that is now tracking across northern Maine. Previous discussion: An increasingly unstable environment will develop this evening in northern zones as an MCS propagates from the Ontario and the eastern Great Lakes region. This complex will mostly affect northern Aroostook County. In spite of the loss of daytime heating, SBCAPE will continue well into the night and shear will increase in the evening. As a result, expect the complex to hold together rather than falling apart after sunset. With PWATs in excess of 2 inches, dew points near 70F, a deep warm cloud layer, a strengthening LLJ and favorable Corfidi vectors, have some concerns about heavy rainfall in the North Woods and northern Aroostook tonight. The MCS passage will correspond with the thermal ridge at 850 and 925mb. A second round of thunderstorms with the cold front will reach the North Woods early Monday morning and quickly weaken as it moves eastward across the state Monday morning. At this point, it looks like stabilization and dry air will kill another round of convection towards the Downeast region for Monday afternoon...and SPC agrees as the marginal risk has been removed from the forecast area. Monday will be another hot day with morning lows near 70F...allowing daytime highs to push into the upper 80s to low 90s before cooler air arrives late day. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... The cold front will slide off the Maine coast Monday evening. NW flow behind the front will bring in some cooler and much drier air. Winds will stay up between 5 and 10 mph keep temps up overnight w/low to mid 50s across the n while further s, upper 50s to lower 60s. Tuesday will feature high pres pressing east toward the region. There will be NW breeze sustained at 10-15 mph. Plenty of sunshine w/seasonal temps. High pres moves overhead Tuesday night w/winds dropping off and clear skies leading a chilly night. Decent radiational cooling overnight w/allow some low lying sites hitting the upper 40s especially across the Allagash region and far NW Maine. Wednesday will start sunny, but increasing clouds are expected as high pres slides off to the east. The cold front sitting off the coast is forecast to start advancing back to the n. The 12z model guidance showing some differences in timing of rainfall later in the day as a low pres wave lifts up along the boundary. The latest GFS run was slower and keeps the high ridge in longer keeping rainfall at bay. The ECMWF on the other hand is faster in bringing rain northward w/that weak wave of low pres and giving a good dose of necessary rainfall to the central and downeast areas. The Canadian Global is similar to the ECMWF in timing. Decided to blend the pops w/a lean toward the ECMWF for the placement given its last 3 consecutive runs being consistent in showing that wave of low pres. Plus, the last 2 runs of the Canadian Global were similar to the the ECMWF timing and placement. Decided on showers w/some embedded tstms later in the day across the srn 1/2 of the CWA. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Wednesday night through Sunday...Continuing w/the blended apch, this first batch of showers and embedded tstms is forecast to end by later Wednesday night. A brief break in the action early Thursday and then another round of showers and possible tstms in the offing for later Thursday afternoon into the evening as a cold front crosses the region. The long range guidance is remarkably in close agreement w/the timing the rainfall and frontal passage. Much cooler air arriving by Friday w/breezy conditions but seasonal temps. NW winds of 10-20 mph w/some higher gusts. Continued dry for Saturday w/a moderation in temps as a SW flow takes hold as high pres slides off to the se. Another frontal system is shown by the long range guidance to approach the region on Sunday with showers and perhaps some tstms. Given that this day at the end of the extended forecast period, stayed w/just showers. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... NEAR TERM: Mostly VFR except from KPQI north where showers and storms overnight may locally produce IFR/MVFR cigs following into Monday morning. There`s also a chance of IFR conditions at BHB overnight. SHORT TERM: VFR Monday night through Wednesday. The exception to this will be for KBHB as some IFR cigs/vsby possible Monday night. SW winds becoming WNW 10-15 mph Monday night into Tuesday. Winds will drop off Tuesday night to less than 5 mph. Variable winds less than 10 mph will become S on Wednesday. Wednesday night into Thursday...MVFR to IFR w/showers and possible tstms. The bulk of the activity looks like it will be across the KBGR and KBHB airfields. SSE winds 5-10 mph. Thursday night into Friday...Showers and tstms into Thursday evening w/MVFR and IFR. Improvement to VFR will be across KBGR and KBHB Thursday evening while the northern terminals hang on to MVFR into early Friday morning. VFR all terminals for Friday. SSW winds 10 mph Thursday night becoming WNW 10-15 on Friday. && .MARINE... NEAR TERM: Fog continues late this evening, but is expected to be swept out later tonight...and then move back over the waters Monday afternoon. Winds pick up later tonight into Monday morning with gusts over 20 kt, but it`s not expected that an advisory will be needed. Shorter period waves will respond to the winds and occasionally reach as high as 5 ft by Monday morning. SHORT TERM: SW winds 10-15 kt Monday evening becoming WNW later Monday night right into Tuesday. Seas 2-3 ft. Some fog is possible early in the evening before the frontal passage and wind shift. Tuesday night into Wednesday...NW wind less than 10 kt becoming S around 10 kt on Wednesday. Seas 2-3 ft. Wednesday night into Thursday...S wind around 10 mph becoming SW on Thursday ahead of the front 10-15 kt. Seas build to 3 ft. Thursday night into Friday...SW wind 10-15 kt becoming WNW by Friday 10 kt. Seas 2-3 ft. && .CLIMATE... Today was the 30th day this year with a high of 80 degrees (F) or warmer in Caribou, Maine. This the most year-to-date on record. The all-time record for an entire year is 51 days, set in 1999. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/MCW Short Term...Hewitt Long Term...Hewitt Aviation...CB/MCW/Hewitt Marine...CB/MCW/Hewitt Climate...CB
Area Forecast Discussion
National Weather Service State College PA
1115 PM EDT Sun Jul 19 2020 .SYNOPSIS... A subtropical ridge over the southern half of the CONUS and a broad Bermuda High will continue to provide PA with hot and humid weather for the next few days. A weak cold front moving southeast from the Upper Great Lakes will generate strong storms this evening. After a few generally dry days to start the week, the risk of showers and thunderstorms will increase next week with typical summertime conditions across central PA. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Compact shortwave riding over the northern edge of some very warm air aloft (+10-11C) will support a few small clusters of showers and tsra across the NW and Ncent mtns of PA through 08z before they weak near and to the NE and E of KIPT toward daybreak. Past few HRRR runs have depicted the formation and track of this convection nicely. Elsewhere it will be partly cloudy and muggy with just a brief shower possible late. Temps will be much warmer overnight compared to recent night, and dewpoints stay sticky in the mid 60s to low 70s, so this should make the conditions unbearable for many in the SE tonight. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... The heat advy continues through Monday aftn for the SE. In fact, the HIs Mon may even be a deg or two lower than Sunday aftn, as dewpoints should be a hair lower. The drier air will be more noticeable across the NW 2/3rds of the area. Temps should also be a little cooler in the NW, too, thanks partly to some early lower clouds and perhaps fog. Just a small chc of showers exists Mon along the MD border. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... High heights forecast to remain in place through the long term period with weak westerly flow aloft. Thus, the hot and generally dry weather continues on Tuesday with little changes. Forecast becomes a bit more uncertain beginning Tuesday night for the rest of the week. GEFS more progressive with an approaching trof and associated fropa then the Euro. For now, will increase pops into Wednesday and Thursday with convective systems moving in from the west. Subtle cooling aloft will bring temperatures closer to average, with no significant cooling likely. Lower pops look in good order for Friday and Saturday behind the trof, then slowly increasing next Sunday. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... At 03z, a few lingering thunderstorms were moving across west- central PA. Thunderstorms will likely fizzle out by around 05-06z. Some lower clouds in the NW - maybe IFR at BFD - are expected to develop after 07z, but wind will not be light enough for much fog. Elsewhere, conditions should be VFR with mid to upper level clouds. Cigs will improve to VFR in the NW by 14z and there will be a clearing trend through the day as drier air moves in. Any chc of a TS/SHRA Mon aftn will be along or, more likely, to the south of the PA Turnpike (JST- LNS line)... but left it out of the TAFs for now. Outlook... Tue...Mainly VFR, very hot and humid. Isold-sct PM showers/t-storms. Wed-Thur...Mainly VFR conditions again, but chc of showers/storms with slightly lower temperatures & humidity. Fri...MOrning fog poss N. Mainly VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM EDT Monday for PAZ036-057-059-063>066. && $$ SYNOPSIS...Lambert/Dangelo NEAR TERM...Lambert/Dangelo/Colbert SHORT TERM...Dangelo LONG TERM...Ross/Gartner AVIATION...Dangelo/Colbert
Area Forecast Discussion
National Weather Service Duluth MN
1004 PM CDT Sun Jul 19 2020 .SHORT TERM...(This evening through Monday night) Issued at 346 PM CDT Sun Jul 19 2020 Gusty winds out of the west this evening with cooler temperatures than the previous day thanks to the cold front that swept through overnight. Another cold front is currently pushing southeast this afternoon with some increased clouds and some light showers peppered across the Northern MN. A few short lived thunderstorms could populate across the Arrowhead this evening but the overall dynamics are not favorable for any sustained convection. Winds will taper off this evening and a weak surface high builds in behind the front. Less windy conditions will be on tap for tomorrow with another diurnally driven cumulus field developing over the Northland. Temperatures will be near the seasonal averages of mid to upper 70s. Monday afternoon into Tuesday morning will bring the next round of precipitation for the region. An upper level trough moves in from the west with a surface low developing over ND and marching east towards MN. The CAMs are currently not in good agreement with the onset time. HRRR has the fastest progression with activity entering the Brainerd Lake region in the afternoon, the other models have a slower ramp up time with initiation later in the evening. Overall, the instability at the start of the event is fairly minimal with MLCAPES between 500-1000 J/Kg. Bulk shear is also on the lower end of the scale around 25-30 kts. This could generate a few strong storms but at this time severe potential is not overly favorable. Tuesday evening shows a little more favorable dynamics for storms. The cold front attached to the low pressure system moving through MN swings across the region and intersects with some more favorable instability across our southern regions. MLCAPES will have risen to over 1500 J/Kg and bulk shear values will have increased as well. However, these parameters are likely incumbent on how much surface heating we can ingest into the area prior to the afternoons start time. .LONG TERM...(Tuesday through Sunday) Issued at 346 PM CDT Sun Jul 19 2020 Rain showers move out Tuesday night and high pressure settles in for the next couple days. High temperatures fluctuate around the mid to upper 70s for Wednesday and Thursday. Model discrepancy is rather high going into Friday and the weekend. The current consensus is that the upper level ridge will begin to break down and give way to a more quasi zonal flow. However, there is poor agreement on the timing. For now, we have left the mention of POPs for Thursday but trimmed back the percentage as there seems to be fairly higher agreement that the upper level ridge axis will still be to the west. As the ridge flattens out periodic rain chances will percolate through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 640 PM CDT Sun Jul 19 2020 Windy conditions continue at most of the terminals, but the mixing layer near the surface will decouple in the next couple hours as the sun sets and high pressure develops over the area, leading to light winds less than 10 kt after 02Z and becoming calm overnight. Several short range models continue to hint at some fog development primarily at HIB/BRD where the likelihood is highest for calm winds overnight. The fog will likely be patchy, and the visibility will likely be VFR most of the night but drop to MVFR or IFR for brief periods during the morning. Otherwise, high pressure will keep ceilings and visibilities VFR with light winds on Monday. && .MARINE... Issued at 1002 PM CDT Sun Jul 19 2020 Some blustery winds are continuing over the nearshore waters this evening with post-cold frontal northwesterly flow. Most sites are reporting wind gusts to 20 kt or less, so the Small Craft Advisory is allowed to expire at 03Z. There may still be some gusts to around 20 kt for the next couple hours, but the overall trend will be for wind speeds to diminish as high pressure builds into the region. Light and variable winds are expected Monday and Monday night with high pressure in place. A chance for showers and thunderstorms return on Tuesday as an area of low pressure develops and passes just south of Lake Superior. This will create a period of northeasterly flow over Lake Superior which may be breezy with gusts up to around 20 kt possible. && .PRELIMINARY POINT TEMPS/POPS... DLH 54 76 57 70 / 0 10 70 80 INL 49 75 56 67 / 0 0 70 70 BRD 55 77 60 74 / 0 10 80 70 HYR 52 77 57 75 / 0 10 60 80 ASX 57 76 57 75 / 0 0 60 80 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 10 PM CDT this evening for LSZ121- 140>148. && $$ SHORT TERM...Britt LONG TERM...Britt AVIATION...JDS MARINE...JDS
Area Forecast Discussion
National Weather Service Grand Forks ND
1002 PM CDT Sun Jul 19 2020 .UPDATE... Issued at 1002 PM CDT Sun Jul 19 2020 A weak mid level wave is moving east along the Canadian border with ND this evening. An area of low level convergence along a stalled frontal boundary across eastern ND will be the focus for an isolated shower or two this evening. Some runs of the HRRR try to keep activity going all night, but other CAMs have been rather quiet with it. The weak low level forcing...combined with MUCAPE of 1000 J/kg exists...but the upper support is more to the north. Believe a mostly dry forecast is the best route. Will update as needed. UPDATE Issued at 651 PM CDT Sun Jul 19 2020 A quiet night is expected tonight with a dissipating cumulus field across much of the area. However, an area of weak low level convergence exists from NW to SE across southeastern SK through the Devils Lake Basin and extending through the Fargo area. Some of the CAMs have a few isolated showers/thunderstorms in this area this evening, but radar trends indicate this is likely overdone a little. Still, there area a couple of weak cells in the Turtle Mountain region and north of the Canadian border...and with 1000 J/kg of MUCAPE currently, we could see a few cells make it into Towner/Cavalier/Ramsey counties. Impacts will likely be minimal and confined to lightning alone. && .SHORT TERM...(This evening through Monday night) Issued at 322 PM CDT Sun Jul 19 2020 Gust northwest winds and an extensive cumulus cloud field have developed across the northern RRV and much of northwest MN in the backwash of departing low pressure system, now in southern Ontario. A brief shower or isolated thunderstorm is possible through the remainder of the afternoon and early evening, mainly of far northwest MN, otherwise clouds and winds should diminish with sunset as surface high pressure settles over the area. Fair skies and light winds are expected this evening and overnight, though bands of thin mid to high level clouds are moving into the area from southern MB and central ND, so this may reduce clarity for any early evening Comet Neowise viewing. Else, overnight low temperatures should settle into the 50s. Monday will see light and variable winds early, with winds turning back from the south, and increasing throughout the afternoon. Late afternoon into the evening will see increasing clouds across central and eastern ND, with thunderstorms likely from late afternoon into the evening and overnight hours. Clouds and thunderstorms will spill across the Red River corridor through early evening, and across much of northwest and westcentral MN through the evening and overnight periods. Widespread wetting rains are expected across most of the area from late Monday into Tuesday morning, with isolated strong to severe thunderstorms possible. .LONG TERM...(Tuesday through Sunday) Issued at 322 PM CDT Sun Jul 19 2020 The pattern continues to be unsettled as the mean jet position remains over the northern tier of states. This will lead to periods of unsettled weather through the period. For upper level shortwave and associated surface low will depart the area decreasing precipitation chances. By Wednesday...surface high pressure remains in control. Upper pattern shows shift toward ridge amplification and return flow will help increase temperatures by Thursday...when another system crosses the forecast area and chances for showers and storms increase again. Behind the system...expect moderating temperatures and more pleasant conditions to end the period. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 651 PM CDT Sun Jul 19 2020 A few dying showers or isolated thunderstorms will approach the DVL terminal from the NW this evening. However, they`re not expected to reach DVL. Otherwise, expect dissipating clouds across much of the region, except we`ll see some more lingering clouds in the DVL area than other areas tonight. Expect winds becoming light and switching to the southeast across eastern ND by tomorrow, but remaining light. A better chance for showers and thunderstorms comes tomorrow by early afternoon to DVL and then pushes east to the rest of the area through the late afternoon and evening hours. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...Knutsvig SHORT TERM...Gust LONG TERM...Hopkins AVIATION...Knutsvig
National Weather Service Hastings NE
849 PM CDT Sun Jul 19 2020 .UPDATE... Issued at 842 PM CDT Sun Jul 19 2020 Updated the forecast tonight to slow down introduction of convection from the west. I did leave in a slight chance for the western half of the CWA during the evening as we got some very small pop-up showers, which might have a stray bolt of lightning. I did lower chances of precipitation a tad overnight, and as mentioned earlier, brought in the higher chances later into the night, and more likely toward dawn, especially in the eastern half of the CWA. && .SHORT TERM...(This evening through Tuesday night) Issued at 452 PM CDT Sun Jul 19 2020 Focusing on the first 5 night/day forecast periods in this section, by far the main issues/challenges are: 1) VERY tricky- to-pin-down rain/thunderstorm chances (PoPs)...2) A risk of severe thunderstorms mainly for tonight, but perhaps also for Monday- Tuesday (although these chances are still quite murky/unclear)...3) A tricky high temperature forecast for Monday (especially by July standards). Briefly looking at the current/recent weather scene as of 4 PM: As expected, the vast majority of the day has been dry across the vast majority of the coverage area (CWA) once the overnight/early AM thunderstorm activity faded away (most of this affected our KS zones last night, but a separate area of isolated-scattered non- severe storms affected areas near the I-80 corridor a few hours either side of sunrise). Under mostly sunny to partly cloudy skies, high temps this afternoon are on track to nearly match or perhaps very-slightly exceed expectations from the early-AM forecast package, with most of our CWA topping out 87-91. In the mid-upper levels, water vapor satellite and short term model data confirm fairly typical mid-summer, quasi-zonal (west-east) flow over our region, with the departed subtle disturbance from the overnight crossing the eastern KS/MO area, while more little waves to our west are kicking off convection mainly over the High Plains of the CO/NE/KS border area. That being said, a bit of weak convection has recently fired up within 50 miles north-northwest of the CWA as well, likely aided by some weak mid level warm air advection. At the surface, breezes are generally out of the southeast at sustained speeds 10-15 MPH/occasional gusts up to around 20 MPH. Now going over the basic expectations of these next 60 hours... This evening-tonight: First of all, want to make it VERY CLEAR that confidence in exactly how things play out is not overly-high. While PoPs were trended down most areas for the evening (pre-midnight) hours, maintained some fairly high values (as high as 60-70 percent) mainly for the late night time frame (especially in our Nebraska zones). That being said, even at this close time range, there is noticeable disagreement between two of the more heavily-relied- upon shorter-term models. On one hand, the NAMNest depicts fairly widespread coverage of rain/storms overnight, both as a potentially-organized complex (MCS) rolling in from the west and also perhaps activity initiating directly over the CWA within the exit region of a modest low-level jet. On the other hand, several recent runs of the HRRR have been less generous with thunderstorm coverage/potential overnight, instead splitting the majority of convective potential around/near the northern/southern and even eastern fringes of our CWA (while largely missing some of our driest central counties that truly need rain the most). Given this inherent uncertainty, was not willing to raise PoPs any higher than the 60-70 percent featured in the previous forecast, but also did not lower them either. Just lots of question marks. Either way, whether convection ends up being more widespread or more spotty, at least a limited risk for severe storms exists, given fairly healthy mixed-layer and elevated CAPE into the 2000+ J/kg range, although deep-layer shear should be on the modest side (only around 30KT at most). Especially if an organized complex manages to roll in from the west, damaging winds would be the main threat. Localized heavy rain of at least 1-2" in could also occur overnight, but assuming that much of this would fall in our drier Nebraska zones, am just not overly-concerned about much of a flooding threat. Timing-wise, will obviously need to watch some of the ongoing late-afternoon development that has sprung up near the northwest corner of our CWA, but for the vast majority of our area, the main potential for storms should hold off until after 10 PM (and for many after midnight). In other departments, opted to keep any formal mention of fog out of the late night/early AM forecast, but especially if storm coverage ends up being sparse, at least some patchy fog probably cannot be ruled out. Low temps were nudged up slightly, with most areas bottoming out mid-upper 60s. Monday daytime: As if you already haven`t read enough about forecast uncertainty just for tonight`s period, it simply continues right on into tomorrow. Although PoPs were trended down a bit from previous forecast, it is likely that at least isolated-scattered convection will continue into the first part of the day (especially eastern zones). Could even see a few stronger storms (mainly with small hail potential), mainly before 10-11 AM. Otherwise, while most areas will probably be dry during the afternoon, enough uncertainty exists that some low-confidence 20-40 PoPs were maintained all areas. Another big question mark Monday is cloud cover, as models such as NAM/RAP have been fairly aggressive in lingering lower clouds across especially northern/eastern zones much of the day, with better potential for at least partly cloudy skies south/southwest. While feel that this cloud cover could be a bit overdone (it`s hard to remain truly overcast all day in July after all), the resultant temp forecast is a bit tricky. Ended up lowering northern zones slightly and raising southern zones slightly, resulting in a more pronounced gradient between upper 70s-low 80s north and mid-upper 80s south-southwest. But could easily see some areas missing this forecast by 5-ish degrees depending on clouds (or lack thereof). Wind generally easterly around 10-15 MPH (similar to today). Monday evening-night: Although the entire CWA is in a Marginal Risk of severe per SPC Day 2, the finer details of storm coverage remain quite murky, and models such as the NAMNest are considerably drier than tonight. As a result, held PoPs under 50 percent all areas, but of course at least small chances for convection certainly exist. Low temps similar to tonight, mainly mid-upper 60s. Tuesday-Tues night: This looks to be the last "cooler"/slightly below average temp day of the week, as we begin a transition to slightly warmer temps thereafter (see Long Term Below). Highs are aimed mid 80s most areas, with any upper 80s most favored far southwest. At least small PoPs continue through these 24 hours as we remain subject to weak waves drifting in from the west. As is typical of mid- summer, the seemingly better chances should favor the night hours versus the day. At least for now, roughly the western 1/3 of our CWA is included in the SPC Marginal risk for severe, but this is very subject to further refinement as it gets closer in time. .LONG TERM...(Wednesday through Sunday) Issued at 452 PM CDT Sun Jul 19 2020 General overview of this 5-day period: Very generally speaking, this stretch is looking mostly dry (fewer rain chances/PoPs compared to early-week) and also continues looking warmer than early-week, with slightly above normal temperatures prevailing, but nothing overly/oppressively hot either. That being said, factoring in humidity, each of these 5 afternoons could feature heat index values up to around 100 degrees in various portions of the area. Basic weather pattern/precipitation overview: In the mid-upper levels, the mid-week starts out with generally quasi-zonal (west-east) flow over the Central Plains. However, by Friday and especially into the weekend, both the ECMWF/GFS are in relatively good agreement depicting a large-scale ridge building northeastward out of the south-central CONUS and becoming more centered over MO and vicinity. As a result, we will reside more on the northwestern periphery of this ridge as opposed to the heart of it. This means that while our rain/storm chances will not truly be zero most days/nights, they will be overall-lower compared to the early-mid week time frame. In fact, at least for now, the official forecast remains dry CWA-wide for the Friday-Saturday time frame, with only fairly spotty/low-confidence chances on either side of this from Wed-Thurs and also by Sat night-Sunday. Put another way, if you don`t get the rain you are looking for prior to Wednesday, it will likely be tougher to come by from Wednesday onward. Temperature overview: Overall, very little change from previous forecast here. As it currently stands, Wednesday is a bit of a "transition day" between the slightly cooler early-week periods, and the warmer later week- weekend days. More specifically, highs Wed are currently aimed upper 80s-low 90s, most areas, with low-mid 90s then more common from Thurs-Sun. As mentioned above, while not anticipating any need for formal Heat Advisories at this point, the combo of slightly above-normal heat and fairly high humidity could easily drive heat index up to around 100 degrees on several afternoons (especially southern/eastern zones). Overnight lows are also aimed into slightly above normal territory, with most nights expected to hold up into the low-mid 70s. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 650 PM CDT Sun Jul 19 2020 This is a low-confidence forecast largely because thunderstorm chances are low confidence. Short term CAMs continue to diverge with solutions. Stratus development could be greatly disrupted by any thunderstorm activity and conditions are conducive to a sunrise surprise thunderstorm, especially for KGRI and farther east for Monday morning. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Heinlein SHORT TERM...Pfannkuch LONG TERM...Pfannkuch AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Gray ME
1029 PM EDT Sun Jul 19 2020 .SYNOPSIS... Hot and humid conditions are expected to last one more day into Monday. A cold front will be slipping south across the region, but ahead of it will remain well into the 90s with high humidity. Isolated showers or thunderstorms are possible with the front but overall dry weather will continue. More comfortable temperatures arrive for the middle of the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 1025 PM...Mesoscale models have actually panned out reasonable well given where they were 3-4 hours ago, and for the most part, convection to the west of the CWA has diminished. Still a few SHRA and maybe some rumbles of thunder with be possible across the Ct vly of NH, and the mtns through 4-5Z, but the general trernd for these showers will be downward. Will see another chc for showers and maybe a TSRA toward daybreak in SW NH as we deal with storms forming on leftover to boundaries to our W and shifting into the CWA. 630 PM...Forecast update mainly involves approaching convection over NY attm. Meso models not in sync with current convection there, with actual storms outpacing the HRRR by an hour or so. So have adjusted POPS this evening to cover the chance of some sct SHRA/TSRA moving into wrn NH after 00Z. All the models do diminish the intensity and coverage by that time, but could see a few weaker TSRA move into CT vly and then die as they cross NH this evening. Otherwise no signif changes to the forecast, with a very warm in store for most places. Previously...Widespread 90s across the forecast area today...with upper 90s over Srn NH. Dewpoints are just starting to mix out apparent temps have maxed out around 100 degrees. A little bit more of a seabreeze is keeping temps down from PWM on N...but even PWM is sitting at 88. The real relief is felt at RKD with a comfy reading of 78. A well organized line of thunderstorms has formed across Wrn NY with very isolated convection ahead of it. The question for late this evening is how long this convection survives before weakening. Current speed and direction would have the storms in Wrn zones around 10 pm. However...CAM guidance weakens convection quickly after sunset as storms outrun S/WV support. So I have some chance PoP in Wrn zones...but very little confidence that it extends much farther E than that. That just leaves a sticky air mass overnight...with plenty of near 70 readings. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Cold front will settle thru the area during the first half of the day. Again CAM guidance is very bearish on any convection forming along the front...and SPC has removed the marginal risk for the area. I will continue to have some isolated thunderstorms in the forecast...but even this is very low confidence. Ahead of the front it will remain hot and humid. With WSW winds it will heat up quickly...and I expect some 90s early in the day near the coast. Heat advisory remain in effect for Srn and Ern zones Mon. Drier air really begins working into the area from the N overnight...though I expect most of that to mix down Tue. But we will see more widespread readings in the 60s than 70s for some relief. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Overview: High pressure moves into the area from the west on Tuesday bringing with it drier and more seasonable temperatures. An unsettled pattern returns for both Wednesday and Thursday as a series of disturbances bring increased chances for scattered showers and thunderstorms. Tranquil weather returns for Friday before another potential disturbance arrives for the upcoming weekend. The long term portion of the forecast begins quiet on Tuesday as high pressure moves into our region from the west behind the cold front. High temperatures will be about 10 degrees cooler compared to Monday with dewpoints also falling into the 50s to lower 60s. The pattern then becomes a little more interesting as we head into Wednesday and Thursday as an upper level trough moves in from the upper Great Lakes and southern Ontario. There remains some differences in model guidance in terms of the timing, placement, and strength of this trough along with an expected associated low pressure system. The greatest chances for scattered shower and potentially thunderstorm activity will come in two waves with the first arriving during the day on Wednesday and the second arriving on Thursday in the form of a cold front. Depending on the timing of this front, scattered thunderstorms will be possible, especially across the coastal plain where the passage will likely better coincide with peak daytime heating. A few strong to severe thunderstorms will be possible if the front cross the area later in the day given mid-level winds of 40 to 50 kts and decent CAPE. This front will be affiliated with an area of low pressure which model guidance has forming to our west on Thursday before traversing northward towards northern Maine and southern Canada later in the day. The eventual track, strength, and timing will play a key role in determining both the coverage and severity of any potential thunderstorm activity. For now PoPs were kept at chance with thunder added for portions of south-central New Hampshire as well as portions of the coastal plain in southwestern Maine where the greatest instability is currently expected to be located. A return to quiet weather is expected on Friday as high pressure builds to our west and the cold front moves offshore. A return to more unsettled weather returns for both Saturday and Sunday as a disturbance that will be located somewhere in the Northern Plains on Friday may ride along the northern ridge axis and into our area by Sunday. The ECMWF remains more bullish on this idea while the GFS has this system mostly diminishing before reaching us. Nonetheless, there will likely be enough forcing to allow for at least a few scattered showers across the area during this time period and therefore Chance and slight chance PoPs were left in. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Short Term...Generally expecting VFR conditions to prevail thru Mon night. A lot of uncertainty with how long TSRA survive across the Northeast. CAM guidance decays TSRA before they reach the Wrn zones...and so I have no precip in the TAFs at the moment. Guidance is also light on activity early Mon and it is possible we see little RA. Long Term...VFR conditions on Tuesday as high pressure moves into the region with accompanying light surface winds. Scattered rain showers on Wednesday may result in MVFR conditions. On Thursday scattered showers and thunderstorms will be possible with continued VFR/MVFR conditions expected. The greatest chance for thunderstorm development currently looks to be across the coastal plain where the greatest instability will be located. Confidence in forecast for Tuesday is high while confidence in forecast for Wednesday and Thursday is moderate to high. && .MARINE... Short Term...Increasing SW flow will allow seas to build overnight. Some 5 to maybe 6 ft seas are expected N of Cape Elizabeth and so I have issued a SCA for those zones. Otherwise thunderstorm risk has decreased over the waters into Mon. Long Term...High pressure approaches the area from the west on Tuesday allowing for light surface winds. Southerly winds expected Wednesday afternoon to around 10 to 15 kts before turning northwesterly Thursday night behind a passing cold front. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Heat Advisory until 8 PM EDT Monday for MEZ018>020-023-024-033. NH...Heat Advisory until 8 PM EDT Monday for NHZ008>015. MARINE...Small Craft Advisory until 5 PM EDT Monday for ANZ150-152. && $$ SYNOPSIS...Legro NEAR TERM...Cempa/Legro SHORT TERM...Legro LONG TERM...Tubbs AVIATION...Legro/Tubbs MARINE...Legro/Tubbs
Area Forecast Discussion
National Weather Service North Platte NE
643 PM CDT Sun Jul 19 2020 .SHORT TERM...(This evening through Monday night) Issued at 302 PM CDT Sun Jul 19 2020 The main forecast challenges through early week are thunder chances, including severe potential. A warm front is bisecting the forecast area today and will likely hang around through tomorrow, which will help provide forcing for thunderstorms. Synopsis/Today... As of 19z, southwest Nebraska was primarily in southeast surface flow while the northern Sandhills were east to light northeasterly. Significant moisture pooling was also occurring in the Platte River Valley with dew points reaching the mid 60s. Scattered rain showers traversed far northern Nebraska since this morning, while bouts of clearing were experienced in the south. This evening and tonight... Expecting some convective initiation in the panhandle sometime around 23z near the surface low and possibly along the warm front into the southern Sandhills. Early development will likely be isolated to scattered in nature, with the capability of growing into supercells. RAP mesoanalysis indicates ample instability south of the front and decent deep layer shear to the north. However, shear may increase this evening across the south as a weak shortwave works off the Rockies. Forecast soundings indicate veering winds in the lowest 3km and CAPE originating above the mixed layer. Hail will probably be the bigger threat while convective mode is still discrete. This also presents a non-zero tornado threat, primarily in the far western zones. Toward sunset, cloud layer winds become more aligned with the boundary orientation, and cells become cold pool dominated as they progress eastward. While shear may still be borderline for an organized widespread MCS, most CAMs are suggesting at least a couple clusters or mini complexes. Thinking wind and heavy rain will be the bigger threats in the latter stages, especially as DCAPE values remain above 1000 j/kg and PWATs near 90%ile of climo. Made little change to previous forecast regarding min temps with upper 50s northwest to lower 60s elsewhere. Monday and Monday night... The surface low slowly meanders across the High Plains, dragging the warm/quasi-stationary front with it. Fairly significant discrepancies exist in the short range solutions regarding precipitation chances during the day. Certainly can`t rule out scattered activity, similar to the far north experienced today, with the front providing forcing and abundant moisture still in play. Not expecting widespread activity early on, in the wake of tonight`s anticipated storms and instability being at a relative minimum. Later in the afternoon and evening, when the atmosphere has time to rejuvenate, most of the thunderstorms should redevelop. Deep layer shear will be marginal, on the order of 30 kts, while mid level lapse rates barely push 7C/km. The strongest forcing will be confined to western Neb near the sfc low and where the greatest low level upslope flow takes place. Although severe parameters don`t appear great, agree with SPC analysis that some potential still exists. Max temps were lowered a smidge to lower 80s north and mid 80s south to account for weak CAA at H85 and potential cloud cover. .LONG TERM...(Tuesday through Sunday) Issued at 302 PM CDT Sun Jul 19 2020 Tuesday and beyond... Broad northwest flow transitions to southwest this week as the upper ridge regains strength over the southern and central Plains. Closer to the surface, the thermal ridge returns to the High Plains with strong southerly flow and H85 temps approaching 30C. So after a brief retrieve from the summer scorcher, highs should reach the mid/upper 90s once again to round out the week. The highest precip chances exist early in the week during the upper ridge transition and with a surface front in the vicinity. The next best potential comes closer to the weekend with a weak cool front or surface trough passage. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 642 PM CDT Sun Jul 19 2020 Thunderstorms will begin to move into western and southwest Nebraska this evening. Confidence is high enough that they have been included in the LBF and VTN TAF`s. Thunderstorms should clear out of the area after midnight with stratus expected to develop behind the thunderstorm activity. Probability is fairly high that IFR conditions will occur across portions of southwest Nebraska including the LBF TAF. Farther north ceilings are expected to be a bit higher with MVFR conditions expected across northern Nebraska including the VTN TAF. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Snively LONG TERM...Snively AVIATION...Meltzer/Taylor
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
651 PM CDT Sun Jul 19 2020 .SHORT TERM... (Through Late Monday Night) Issued at 210 PM CDT Sun Jul 19 2020 Cold front has now moved to near Springfield Illinois to Columbia line. Satellite imagery is showing a well developed CU field along and south of this front in an area where the SPC mesoanalysis shows MLCAPES of 2500-3500+ J/kg with little CINH. The HRRR has been consistent in developing thunderstorms along the front between 21-23Z, so kept likely PoPs for late this afternoon into this evening. There remains the possibility of one or two severe thunderstorms given the amount of instability, with a wet microburst and hail up to the size of quarters being the main concerns. Thunderstorms will continue through at least mid evening before they begin to weaken with the loss of daytime heating and passage of weak mid level vort max that is currently over eastern Kansas. Then focus for convection will shift for additional storms developing across western Missouri later tonight as a broad 25kt low level jet sets up. These storms will move east into the CWA tomorrow morning as the jet veers to the northeast. There will be some threat for locally heavy rainfall given the PWATS around 2" and deep warm cloud layers, particularly if any storms train. Additional storm development is possible tomorrow afternoon along the front in the unstable atmosphere. On late Monday night, there will be another weak shortwave move along the front as a low level jet sets up bringing another MCS potential. Even though it will be humid tomorrow, expect highs to be mainly in the 80s tomorrow with the clouds and rain potential so will not extend the heat advisory. Lows the next two nights will be around 70. Britt .LONG TERM... (Tuesday through Next Sunday) Issued at 210 PM CDT Sun Jul 19 2020 There remains relatively good agreement between the EPS and GEFS means Tuesday into this weekend. The front will still likely be stalled across Missouri and Illinois Tuesday into Thursday. The front will lie beneath zonal flow with several low amplitude shortwave troughs moving through the region. CIPS severe analogs suggest that there will at least some chance for severe weather during this time period given the very unstable atmosphere on the southern edge of the westerlies. In addition, still expect the threat of MCSs in a high PWAT atmosphere which will bring the threat for locally heavy rainfall. By Friday, the front will move north of the area as both the ensembles are still showing a 594dm high building over the central CONUS next weekend. Forecast guidance by next weekend suggest highs will be in the mid 90s. Britt && .AVIATION... (For the 00z TAFs through 00z Monday Evening) Issued at 640 PM CDT Sun Jul 19 2020 Thunderstorms can be expected this evening from COU to the St Louis metro area near a cold front which has dropped southward to near the Interstate 70 corridor. These storms should dissipate by late evening as the atmosphere stabilizes. There will be the potential for another round of scattered storms Monday afternoon and early evening as the front becomes nearly stationary just south of the taf sites. Winds may be chaotic and gusty early this evening near storms, but should become light by late evening, mainly from a north-northeast direction. SPECIFICS FOR KSTL: Thunderstorms can be expected this evening from COU to STL near a cold front which has dropped southward to near the Interstate 70 corridor. These storms should dissipate by late evening as the atmosphere stabilizes. There will be the potential for another round of scattered storms late Monday afternoon and early evening as the front becomes nearly stationary just south of the STL area. Winds may be chaotic and gusty early this evening near storms, but should become light by late evening, mainly from a northerly direction. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Heat Advisory until 7 PM CDT this evening for Audrain MO-Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO- Iron MO-Jefferson MO-Lincoln MO-Madison MO-Moniteau MO- Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO- Saint Louis MO-Sainte Genevieve MO-Warren MO-Washington MO. Flash Flood Watch until 1 AM CDT Monday for Boone MO-Callaway MO- Cole MO-Franklin MO-Gasconade MO-Jefferson MO-Lincoln MO- Moniteau MO-Montgomery MO-Osage MO-Saint Charles MO-Saint Louis City MO-Saint Louis MO-Warren MO. IL...Heat Advisory until 7 PM CDT this evening for Bond IL-Calhoun IL- Clinton IL-Fayette IL-Greene IL-Jersey IL-Macoupin IL- Madison IL-Marion IL-Monroe IL-Montgomery IL-Pike IL- Randolph IL-Saint Clair IL-Washington IL. Flash Flood Watch until 1 AM CDT Monday for Bond IL-Calhoun IL- Clinton IL-Fayette IL-Jersey IL-Macoupin IL-Madison IL- Marion IL-Monroe IL-Montgomery IL-Saint Clair IL-Washington IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
854 PM CDT Sun Jul 19 2020 .UPDATE... A hot and muggy night across the Mid-South at this hour. Temperatures are mainly in the mid 80s to as hot as 90 degrees. Heat index values still range from the lower to upper 90s. The latest GOES Nighttime Microphysics RGB imagery shows an expansive southward advancing MCS along the I-44 corridor. This system is progged to weaken and skirt across northern portions of the CWA overnight. As it does, the HRRR suggests a few light showers or isolated thunderstorms could form. Went ahead and increased POPs to slight across this area and adjusted sky grids accordingly. Monday morning temperatures will bottom out in the low to upper 70s across the region. Made a few minor tweaks to the forecast and removed today`s wording in the HWO. AC3 && .PREV DISCUSSION... /issued 626 PM CDT Sun Jul 19 2020/ UPDATE... See the 00z aviation discussion. && .PREV DISCUSSION... /issued 357 PM CDT Sun Jul 19 2020/ DISCUSSION... Isolated showers and storms have developed this afternoon as a weak perturbation moves along the weak mid-level high located over the southeast, in addition to strong surface heating. Radar currently shows a few showers over SW TN and far northern MS. Weak outflows have formed over Tipton and Fayette counties in TN from showers downstream. Goes-16 satellite imagery shows cloud tops cooling and indicating some towering cumulus clouds are likely located over northeastern AR and northwestern TN, just north of the outflow - indicating that further development of showers and storms is possible. However, coverage is expected to remain isolated and any storms that develop will likely remain weak due to low bulk shear. Heat Index Values have mainly behaved across the Mid-South as we sit in the low 100s across most locations - remaining below the 105 degree threshold that`s needed to warrant a heat advisory. Current temperatures are in the low to mid 90s with dew points in the low to mid 70s. The high over the southeast will slowly push east which will allow a stationary boundary to drag south into the lower Ohio Valley and northern Mid-South over the next couple of days. Rain chances will go up as the boundary pushes south with likely outflows pushing into the MO Bootheel, eastern AR, and northwestern TN. With the area remaining in a highly unstable airmass as far as CAPE is concerned, showers and storms are expected to develop, however, coverage will remain isolated to scattered. The best chance for rain will be on Wednesday as a weak upper-level disturbance clips the northern portions of the County Warning Area (CWA). Storms are still forecast to be weak due to low bulk-shear. Temperatures will remain consistent as they tend to do during the Summer months in the Mid-South. Rain chances will decrease as we end the week with a building ridge from the east. Diurnally driven showers and storms will still be possible as the heat and humidity remains. Temperatures will be in the low to mid 90s with heat indices mostly remaining at or below 105 degrees. KRF && .AVIATION... /00z TAFs/ Isolated thunderstorms continue along the I-40 corridor but will diminish by 01z. Expect dry weather overnight with mostly clear skies. There is a potential for patchy fog, so will keep an eye out, mainly for TUP/MKL terminals. Otherwise, expect VFR conditions through the period with generally light south to southwest winds. Isolated to scattered storms are possible again Monday afternoon, but will not be included in current TAF given anticipated limited coverage. MJ && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
759 PM PDT Sun Jul 19 2020 .SYNOPSIS...Limited mid level moisture moving up from southern Arizona will bring scattered clouds and a few showers and isolated thunderstorms to the area through Tuesday. More significant monsoonal moisture may begin to creep into the region toward the end of the work week resulting in thunderstorm chances for at least northwest Arizona and slight chances for southern Nevada. Temperatures should also begin to slowly decline towards the end of the week. && .UPDATE...Isolated storms over Mohave, Lincoln, Esmeralda and northern Inyo Counties all going to bed early this evening. We`ve also been monitoring the Stewart Canyon Wildfire in south central Lincoln County. Fire really got going late in day with an estimated 2000 acres burned. HRRR and other convective allowing models look to be picking up on a feature presently over southwest Arizona. As the feature lifts northward tonight those models show light rain showers and potentially embedded thunderstorms into southern Mohave County and the lower Colorado River Valley. By late morning and tomorrow afternoon it will be another day of isolated to scattered thunderstorms over Inyo County, southern Nevada and northwest Arizona. This looks to be well covered in our current forecast. && .DISCUSSION...through Tuesday. A slight chance of showers continues through the afternoon hours across portions of Clark and Mohave counties, along the Sierra and northern parts of Inyo County and across parts of south central Nevada. A few embedded thunderstorm cells are possible as well featuring brief rain and occasional lightning. The primary concern however will be locally strong wind gusts near showers/storms. Shower chances diminish rapidly this evening and should end by sunset. Breezy winds 15-25 mph will push into the western portions of the Mojave Desert late this afternoon into the evening. Shower chances return Monday with hi-res guidance showing an uptick in coverage and a few more robust cells. Again, locally strong wind gusts will be the primary concern but with the potential for embedded, potentially more robust thunderstorm cells, there could be some areas that see brief heavy rain and occasional lightning. The moisture profile is forecast to remain generally shallow in most areas both Monday and Tuesday with a somewhat deeper moisture profile forecast over Mohave County with a rise in PWATs and 850 mb dewpoint temperatures. The activity forecast for Monday and Tuesday is likely associated with a weak trough currently located along the SoCal coast but forecast to move east and settle over the area on Monday and Tuesday. Temperatures on Monday are expected to be 3-5 degrees above normal but only slightly above normal on Tuesday. Wednesday and Thursday...A change in the weather pattern is forecast when a weak low pressure system moves to the central California coast. This low kicks the Mon/Tue trough east of the area and the closed circulation associated with the low begins to tap into deeper moisture over SW Arizona and draw it northward. However, at the same time, shortwave ridging passes over the area with elevated temps aloft possibly capping any convection early in the day. Then, an increasing SW upper level flow associated with the low is forecast to bring mid level drying in the afternoon. Depending on how the pattern plays out, this could be a decent setup for a more robust thunderstorm day on Thursday for Mohave County and possibly parts of Clark County with a fairly deep moisture profile along with modest instability and increasing shear associated with the incoming low pressure system. Too early to say for sure and confidence is low. Friday through the weekend...currently looks like we will have afternoon breezes each day with temperatures a few degrees below normal. Looks like a down period for active weather as the deeper monsoon moisture is forecast to be east of the area. && .AVIATION...For McCarran...Isolated showers and storms should diminish through the evening, with dry conditions anticipated overnight. Sudden gusty winds from area storms are possible, with gusts 35-40kts possible if any outflows get close enough to the terminal. The risk for gusty outflows should end by 06Z, with dry conditions and light south to southwest winds expected after that. For Monday, a similar set up is expected to what we saw this morning. There may be scattered precipitation around with isolated thunderstorms, however there is low confidence that showers and storms will impact or be in the vicinity of the terminals. If convection is close by, more gusty winds are possible from outflow. Outside of thunderstorm influence, light winds Monday more will become east then southwest through the day but remaining less than 10kts. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered showers and thunderstorms are expected nearby BIH through the early evening, with vicinity storms potentially causing sudden outflow winds from the northwest or west, gusting to around 35kts. Elsewhere, isolated scattered precipitation with isolated convection is possible through southern Nevada and western Arizona, however activity should be waning. Outflows are possible in this area but less likely. For tonight, any precipitation should end around 03Z with typical drainage winds will returning through tonight. For Monday, another round of isolated to scattered precipitation is possible, including a few thunderstorms, with the best chances in northern Inyo County. Winds will be light before becoming south to southwest in the afternoon, with gusts to around 20kts possible in spots. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE...Pierce DISCUSSION...Salmen AVIATION...Nickerson For more forecast information...see us on our webpage: or follow us on Facebook and Twitter