Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/19/18

Area Forecast Discussion
National Weather Service Bismarck ND
921 PM CDT Mon Jun 18 2018 .UPDATE... Issued at 920 PM CDT Mon Jun 18 2018 Latest iterations of short term high res models indicate scattered/isolated showers reaching into north central North Dakota tonight. Latest radar loops continue to show this as well. Thus added chance or slight chance mentions of showers into north central ND as well as continuing chances southwest and south central this evening before ending from west to east by daybreak. UPDATE Issued at 626 PM CDT Mon Jun 18 2018 Main focus this update is extent and duration expected of rain showers moving northward in southwestern and south central North Dakota. Current radar loops indicate northern extent of showers is along I-94 from the Montana border through Dickinson, Bismarck, and to near Steele. In fact light rain has begun here at the Bismarck Airport. The precipitation is associated with an upper level energy impulse moving north/northeast, which is progged to arc northward and eastward through the evening. However, as the impulse moves northward, it runs into/over a large dry surface high pressure system. Current short term high res models depict the area of showers becoming more scattered/isolated in nature as the impulse tracks north and east this evening, but the models differ on the northward extent. Consensus of the models suggested only a slightly more northward extent of the showers, thus adjusted precip chances a little farther northward to include Garrison and Harvey, but these changes are minor. There is still a possibility of thunder within the area of showers, as some elevated CAPE is still depicted in a mesoanalysis. && .SHORT TERM...(This evening through Tuesday) Issued at 317 PM CDT Mon Jun 18 2018 Precipitation potential across southwest and south central North Dakota this afternoon through tonight highlights the short term forecast. As of 2030 UTC, rain has entered far southwest North Dakota, and will continue to spread north across the I-94 corridor through early this evening. With weak mid level lapse rates, thunderstorm potential is minimal. Overall, the HRRR through its 18 UTC iteration has a good handle on this area of precipiation and will follow closely its time lagged solution for PoPs through the night. Rain, with perhaps an embedded thunderstorm or two, will focus across the James River Valley tonight. On Tuesday, high temperatures will range from the 60s across the southwest under mostly cloudy skies, to the 70s across the northwest and central with surface high pressure. There is a chance of a rain shower or thunderstorm across the far southwest Tuesday evening and night on the periphery of the upper level low across Montana. .LONG TERM...(Wednesday through Monday) Issued at 317 PM CDT Mon Jun 18 2018 Quiet weather Wednesday and Thursday with perhaps increasing thunderstorm chances Friday into the weekend highlight the extended forecast. Rather quiet weather is forecast across western and central North Dakota Wednesday and Thursday north of the deep low that will propagate into the Central Plains. Thereafter, the 12 UTC global suite favors rather weak upper level flow and troughing across the Northern Plains Friday into Saturday. This may support a bit greater precipitation potential. However, forcing is uncertain and confidence is low. Confidence remains low into next week given the spread in the potential track of the upper level low across the central CONUS. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 626 PM CDT Mon Jun 18 2018 Rain showers with a few embedded thunderstorms will continue across southwest and south central North Dakota this evening, moving/expanding north and east during the evening. The showers should affect southern TAF sites of KDIK and KBIS at or before 00z...then KJMS by around 01/- 02z. Showers ending from west to east at KDIK and KBIS later this evening, and ending at KJMS after 06z. Ceilings should remain VFR with the showers. MVFR ceilings may develop across southwest and south central North Dakota late tonight into Tuesday morning, affecting mainly KHEI and KDIK. Otherwise, VFR conditions are expected across western and central North Dakota for the 00z TAF cycle. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...PA LONG TERM...PA AVIATION...JV
Area Forecast Discussion
National Weather Service Denver/Boulder CO
823 PM MDT Mon Jun 18 2018 .UPDATE... Issued at 823 PM MDT Mon Jun 18 2018 Thunderstorms will continue to roll east across northeast Colorado this evening and even after midnight. Mix layer CAPE from the RAP are 1000-2500 J/kg north of I-70 through the evening, so expect the severe threat to continue through most of the evening. Not easy to pick out on water vapor satellite imagery, but appears there is a wave helping to produce the thunderstorms. Low clouds will reform late tonight and Tuesday morning. There will also be some drizzle and patchy fog with this, mainly 3am-9am. More thunderstorms are expected Tuesday. Left exit region of the jet will help provide lift. The latest RAP shows surface based CAPEs 2000-2500 J/kg with mid 70s temperatures and upper 50s for dew points. Shear will again be favorable for super cells. This will lead to a good chance for another round of severe storms Tuesday afternoon and evening. && .SHORT TERM...(This evening through Tuesday) Issued at 340 PM MDT Mon Jun 18 2018 This afternoon into the evening, storms are expected to predominantly form north of a line from the northern fringes for the Palmer Divide to Akron. With slight QG ascent and the Denver Cyclone ramping up and providing enough lift for the moist atmosphere to develop some vigorous storms. CAPE values are expected to reach 1500- 1700 J/kg which will allow for large hail and damaging winds. Both low level and bulk shear are forecast to be sufficient for potential tornado formation. When looking at guidance for the duration of showers and storms the GFS, NAM, and European models show precipitation continuing this evening through Tuesday night with much more areal coverage, while the HRRR and RAP end things early Tuesday morning with more isolated drizzle on the plains near the Front Range Foothills. I am leaning toward the models that end convection earlier and bring in stratus and drizzle to start the morning as the atmosphere should become more stable with the stratus moving in. The GFS and NAM show the QG increasing, so will keep a slight chance in the grids. Tonight stratus is expected to move back onto the plains and remain until mid to late morning. This could cause drizzle similar to what we experienced this morning. Once the could cover burns off, high temperatures are expected to reach around 70 degrees in Denver. If clouds dissipate earlier than expected, surface heating could allow for warmer high temperatures. Tuesday there will bring a chance for severe storms over the far eastern plains. Another batch of stronger QG ascent will be present over the eastern portion of the CWA. The GFS also indicates a 700mb trough with associated upslope winds, and increasing PWs due to southerly flow into the area. CAPE values will also increase with lower 700-500mb temperatures Tuesday. .LONG TERM...(Tuesday night through Monday) Issued at 340 PM MDT Mon Jun 18 2018 A moderate westerly flow aloft will be over the region on Tuesday night with a closed upper low over swrn MT/nwrn WY. Good moisture and instability over the northeast plains of CO with severe thunderstorm potential carrying over into Tuesday evening. Layer precipitable water values still around 1.5 inches over the northeast plains, with heavy rain still an issue with the developing thunderstorms. Storm motions by Tuesday evening, west/northwest around 20 mph. Focus for the heaviest rainfall Tuesday night appears to be east over central KS/NE. Wednesday and Wednesday night, the upper trough will shift southeast into central NE on Wednesday, with a building ridge centered over Baja CA. End result will be a moderate northwesterly flow aloft over the cwa. A cold front will push into the area from the northeast on Wednesday morning, with anticyclonic low level low level upslope developing in the afternoon and evening. Increasing stability behind the front will diminish the potential for severe thunderstorms. Fcst soundings generate CAPES around 400 j/kg in the afternoon, a far cry from those on Tuesday. Best chance for storms will be along the elevated terrain, in and near the Front Range Foothills and Palmer Divide. There does appear to be a passing jet max overhead around 00Z Thu which could help initiate thunderstorms Wednesday evening. Precipitable water value only around 0.25 inch west of the Continental Divide, but still range from 0.50-1.0 inch over the northeast plains. On Thursday, increasing mid level subsidence associated with building ridge axis over western CO, and low level stability associated with the sfc high will nix the CAPES across the northeast plains in the afternoon and evening. Temperatures will be closer to normal on Thursday. Friday and Saturday, a return to warmer and drier weather across the region. The upper level ridge will remain over the region on Friday with a dry westerly flow aloft. A weak system will pass to the north and east of CO Friday night, with a generally dry northwesterly flow aloft. There could be a weak and shallow cold frontal push into the northeast plains, Saturday morning but it should not be around for very long. Some qpf primarily over the higher terrain Saturday. Another upper low dropping into the western WY/nrn UT could allow for more showers and thunderstorms into the region late Saturday and Sunday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 823 PM MDT Mon Jun 18 2018 The threat for thunderstorms will continue through about 06Z at KDEN and end around 04Z at KBJC. At KAPA, threat for thunderstorms is low. HRRR does show a few storms after 06Z over northern Colorado, so the chance for storms is not zero but will be low. Low clouds will reform around 09Z with ceiling falling below 1000 feet. Good chance ceilings fall below 500 feet with visibility around a mile or less. Low clouds will be slow to burn off again and are expected to persist until around 18Z. Another round of thunderstorms will move across the area Tuesday afternoon and evening. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Meier SHORT TERM...Sullivan LONG TERM...Cooper AVIATION...Meier
Area Forecast Discussion
National Weather Service Boston/Norton MA
1003 PM EDT Mon Jun 18 2018 .SYNOPSIS... Heat and humidity will come to an end tonight as a cold front from the northwest pushes through. A few strong thunderstorms are possible especially across western MA and northern CT. A much nicer day is on tap for Tuesday behind the cold front with plenty of sunshine and much lower humidity. Low pressure passes off the South Coast Wednesday, with a chance of showers along the coast. High pressure from Canada brings dry weather Thursday and Friday. a cold front them brings a chance of showers over the weekend, followed by dry weather early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 10 pm update... Strong to severe thunderstorms have concluded. Only the chance of thunderstorm activity continues overnight. No longer any appreciable threats other than occasional lightning, brief heavy downpours, enough to wake you out of bed given a renewed threat along and ahead of a cold front pushing S across the NE CONUS presently, expected offshore by morning. Evaluation of latest SPC / RAP near-term high-res mesoscale guidance, convective-supporting parameters by way of instability have for the most part diminished. Only a chance of a thunderstorm through the remainder of the overnight hours. However, still a deep, moist airmass in place with precipitable waters on up to 2 inches. Confluent low-level SW jet along and ahead of the forcing cold frontal boundary beneath mid-level energy through the digging weak H5 trof boundary and some favorable diffluence aloft, can`t rule out heavy rainers through the overnight hours. Beneficial rains for certain given how dry it has been as of late, the lack of rain. Best chance of rain across S/W areas of S New England associated with energy out of Upstate NY into N PA, moving with a more WNW mean wind. Accompanying decent K-indices. Additional rainfall amounts upwards of around 0.50 inches possible. Low risk of nuisance flooding issues in the way of urban / poor-drainage. Dewpoints remaining sticky right on through morning with values in the 60s, will keep overnight temperatures stable and mild. Looking at lows down around the upper 60s. Fog and low marine stratus remain an issue along the S-coast and likely so through the early morning hours till frontal passage. Will be looking at visibility as low as a quarter of a mile, presently ongoing at Nantucket. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Tuesday... A few lingering showers early Tuesday as a cold front finally pushes offshore. Dewpoints and K values will be quickly dropping in the late morning into afternoon and thus expect clearing skies and dry weather. Northwest winds will be gusty in the morning before high pressure moves into the area. Gusts to near 20-25 MPH are possible. Otherwise a pleasant weather day. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Big Picture... Longwave pattern shows above normal heights across the western and southern USA with a persistent trough over the Great Lakes and Northeast USA. Northern stream jet flows from far northern Canada southeast across New England eventually moving north of us by the weekend. A shortwave embedded in this flow moves across New England Wed night or Thursday. A weaker southern flow across the central USA carries a closed low from the Northern Rockies to the Western Great Lakes. The low then ejects into the northern stream and crosses New England during the weekend. Mass fields over the Eastern USA are similar through Saturday, then diverge. Thermal fields agree on cooler temps Thursday-Friday followed by warming temps over the weekend, then trending cooler again early next week. Forecast confidence is high through Friday, trending to moderate over the weekend. Concerns... Tuesday night-Wednesday... High pressure builds over the region Tuesday night, then shifts offshore Wednesday. Northern stream shortwave dives southeast into New England. This shortwave will be supported by a 105 knot jet and drive a surface cold front toward our area. The jet may also provide enough upper divergence and lift to support a developing low along the Mid Atlantic coast late in the day Wednesday or Wednesday night. W values climb to 1.5 inches along the South Coast Wednesday evening before drier air pushes south across New England overnight. Expect dry weather Tuesday night and Wednesday. The Mid Atlantic system mostly passes offshore, but the upper lift may allow for rain to graze the South Coast. Thursday-Friday... High pressure builds over the region with dry weather and cooler temperatures. Saturday through Monday... Midwest upper low and associated surface system eject into the Northern stream by Saturday, then cross New England Sunday. Rain out ahead of the system arrives Saturday, with rain along the cold front Sunday afternoon or night. PW values increase again, with 2 inch values possible Saturday night and Sunday. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...Moderate confidence. Tonight... SCT SHRA continue, renewing over S/W MA and CT towards 5z. Lesser threat of TSRA, rather RA/+RA threats along with IFR CIGs and VSBYs, especially along the S-coast with ACK reporting 1/4SM FG presently and likely to continue so through midnight, gradually improving towards morning. Otherwise VFR. SW winds through early morning, LLWS for S-coast along with MVFR-LIFR CIGs and VSBYs in fog and stratus, before winds shift NW by Tuesday morning. Tuesday through Wednesday... VFR conditions expected. Breezy out of the NW Tuesday, SW on Wednesday. KBOS Terminal... RA threat concluding. Can`t rule out brief lower CIGs and VSBYs towards MVFR, otherwise BKN low-end VFR into early morning. KBDL Terminal... SCT -SHRA/SHRA redeveloping shortly after midnight and then concluding into the early morning hours. TEMPO MVFR-IFR possible with CIGs and VSBYs, otherwise BKN low-end VFR. Outlook /Wednesday Night through Saturday/...Moderate confidence. Wednesday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Thursday through Friday Night: VFR. Saturday: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA. Saturday Night: Mainly MVFR, with local VFR possible. Chance SHRA. Sunday: Breezy. Chance SHRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday/...High confidence. Tonight... Seas starting off low, however should build with persistent SW flow around 15 kts and gusts upwards of around 25 kts. Small Craft headlines persist. Dense fog is the bigger issue with visibility as low as 1/4 of a mile down around the S-coast including the Cape and Islands. Some SCT showers, otherwise lower conditions and wet weather threats conclude into early morning behind a sweeping cold front and a NW wind shift. Tuesday through Wednesday... Lingering small craft swell across our southern most outer-waters diminishes by late morning. Otherwise...winds/seas should remain below small craft advisory thresholds. Outlook /Wednesday Night through Saturday/...Moderate confidence. Wednesday Night: Winds less than 25 kt. Chance of rain showers. Thursday: Winds less than 25 kt. Slight chance of rain showers. Thursday Night through Friday Night: Winds less than 25 kt. Saturday: Winds less than 25 kt. Slight chance of rain showers. Saturday Night through Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Air Quality Alert until 10 PM EDT this evening for CTZ002>004. MA...Air Quality Alert until 11 PM EDT this evening for MAZ003>007- 009>016-026. RI...None. MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ230>237-251. Small Craft Advisory until 4 AM EDT Tuesday for ANZ250. Small Craft Advisory until 10 AM EDT Tuesday for ANZ254>256. && $$ SYNOPSIS...WTB/Dunten NEAR TERM...Dunten/Sipprell SHORT TERM...Dunten LONG TERM...WTB AVIATION...WTB/Dunten/Sipprell MARINE...WTB/Dunten/Sipprell
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
647 PM CDT Mon Jun 18 2018 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...Light east to southeast winds and multi layer cloud decks prevail across deep south Texas this evening. Radar continues to indicated some convection near HRL and BRO. This activity is expected to diminish by late evening. Later tonight, the HRRR model is suggesting that convection will redevelop near the coast, so will continue to mention TEMPO`s with thunder at BRO and HRL but just showers at MFE. Additional showers and thunderstorms are expected to develop over the area Tuesday afternoon. So will include TEMPO`s with thunder at all TAF sites mid to late Tuesday afternoon. VFR conditions should continue for the next 24 hours, except for intermittent MVFR ceilings/visibilities in any heavier showers. && .PREV DISCUSSION... /issued 401 PM CDT Mon Jun 18 2018/ ..More rain on the way through Thursday with drought relief and local minor flooding potential increasing... SHORT TERM (Tonight through Tuesday Night): Still expecting good rain chances for much of the area over the next 36 hours. Locally heavy rainfall will be a threat, with some instances of minor flooding possible in low-lying or poorly drained areas. KCRP radar/water-vapor channel imagery/RAP 500-mb analysis indicates that the trough aloft may have a closed circulation, with center near the Texas Coastal bend. 12Z runs of NAM/GFS in reasonably good agreement that the low/trough will begin to drift westward and a bit south overnight. For Tuesday, the upper low wobbles over the BRO CWA before possibly drifting back south of the Rio Grande Tuesday night, though there is some more uncertainty there. Rich tropical moisture will be continuously present, especially on the east side of the trough axis where precipitable water values will run 2.3-2.5" (near the high end of the climatological range). WPC has been leaning away from the GFS with its somewhat lower overall QPF values and more toward the ECMWF/NAM. Differences this far south are less significant than farther north along the Texas coast, however, and latest QPF progs have been well-collaborated. Through early Wednesday morning, generally looking at around 2-3" of rainfall along the coast, with lower totals of 1-2" expected farther west. Localized areas could see higher amounts, such as happened around 2- 4am today when 2-3"+ quickly dumped along an axis from Harlingen toward Los Fresnos. Favored late Tuesday night for possible heavier rain along the coast, in line with latest WPC QPF and some upward forcing aloft moving in. In concert with other offices, will hold off any Flash Flood Watches until (if?) more widespread/heavier rains materialize. FFG values still fairly high, but this will be something to watch if any areas get dumped on again overnight. Nighttime low temps should run in the mid-upper 70s, with daytime temps for Tuesday of course trickier with clouds and precip in the mix. Took a degree of high temps for starters, which should put them similar to today`s (outside of MFE hitting 96 before a thunderstorm came through)...low-mid 80s along the coast, upper 80s to near 90 in the more populated RGV, and perhaps lower 90s in Starr/Zapata counties. Rip current risk will also remain elevated, but with swells a bit slower to arrive (see below) and unfavorable beach weather, will hold off any statements at this time. LONG TERM (Wednesday through Monday): In the grand scheme of things...only minimal change to the messaging in the mid to late week which focuses on Wednesday but also into Thursday as model consenus keeps the rain machine going for one more morning and perhaps into the afternoon farther west. Thereafter, the trend for drying begins with models in some disagreement on the pace of the drying. Either way, appears that everything is cleared out in time for the weekend, but unlike previous hot/dry weekends this one may face additional higher dewpoints in wetter areas as well as greening grasses and brush after so many weeks with rain missing many areas especially toward the coast. The difficulty with the forecast is intensity and some timing. GFS and ECMWF are less bullish on vertical motion on Wednesday morning, but the bigger picture still has the elongated 500 mb shear axis/trough just to our west which keeps the Lower RGV on the favorable side of lifting. The NAM-12, though not often reliable, shows a "fire hose" of strong lift right at the coast in a north to south line. While this could be far overdone, the idea may not be and if a banded/training type line were to form, rainfall east of US 77 could easily top 4 inches in a number of areas on Wednesday morning alone. Because this system has been disorganized and should remain so, have gone with the WPC QPF forecast which is in the 0.75 to 1.25 range in these areas. Regardless, locally heavier rains of 2" or more falling over urban poor drainage or possibly saturated locations could lead to flooding so something to keep an eye on. By afternoon, the coastal counties and perhaps a bit farther inland should be worked over, but scattered to numerous showers/storms are likely across the ranchlands with a bit more heating through debris cirrus and mid level clouds. Tropical nature of air mass will create downpours similar to today and Tuesday which in turn could cause very local urban flooding. Wednesday night is a repeat of Tuesday night as land activity wanes while the Gulf recharges and lights up toward or just after midnight. Thursday morning now looks very similar to Wednesday, and have nudged up rain chances to categorical (80 percent) near the coast with mention of heavy rain. The ECMWF is doing squirrelly things with the 500 mb low again for a brief time Thursday, which really dumps rain in most areas from pre-dawn through midday. Recent track record suggests this is convective feedback or an outlier and has been discounted...78 hours out there`s plenty of uncertainty as well as time to see how this evolves. Through the period, average rainfall for the coast looks to be 1 to near 3 inches (highest averages near the coast) with locally higher amounts 4 inches or more. Bottom line? By the end of the week, we should have a completely different drought condition and things should begin turning green fairly rapidly with plenty of humidity left. Friday could be a transition day or go completely dry...GFS continues to be driest with ECMWF a bit slower to modify but either way temperatures should return to near or just below normal. The rebuilding of La Canicula over the weekend as the remains of the upper system slide southwest and dissipate will bring temperatures back above average by a couple degrees along with increasing southeast flow...a hint of the Valley Wind Machine. Another weak perturbation may approach from the southeast toward Monday and owing to this introduced low rain chances to placehold...but confidence is low and temperatures should continue in the 95-98 range away from the coast. MARINE: Tonight through Tuesday Night: Previously advertised SE swells have been underperforming a bit. Latest ob from Buoy 42020 shows light SW winds with 4-5 ft. swells with 8-9 second period but total seas holding just under 6 ft. Earlier on, had cancelled the inherited Small Craft Advisory for Hazardous Seas but reissued beginning at 4pm for the 20-60nm Gulf waters (which should be in good shape if trends continue) and 7pm for the nearshore (somewhat lower confidence here, though). SCA in effect until 1pm Tuesday for now. May need to be extended, but will have to watch observational trends. Moderate to fresh SE winds will also be in play throughout the period. Numerous showers and thunderstorms will produce periodic downpours as well as locally gusty winds, higher seas, and reduced visibilities, making for overall poor to hazardous boating. Wednesday through Saturday Night: Ekman forcing arguments may have been part of the reason why seas close to shore have risen but not cranked up toward 8 feet, with a rightward curl of the highest waves from the persistent southeast flow in the west central Gulf pushing the highest values northward rather than westward. With this in mind, loaded WaveWatch to see how it was handling and sure enough seas remain steady state at 5-6 feet through Thursday before gradually dropping back into the weekend. That said, numerous gusty showers/storms will remain a feature through at least midday Thursday which pretty much wipes out any chance of an enjoyable outing. Friday will still see residual seas and chop but sensible weather will improve, and Saturday (cross fingers) will have fair weather. However, if strong low level southeasterlies develop in the gradient flow, wind waves and chop could be back on the rise and make for somewhat tough conditions despite the lack of thunderstorms. Overall, the work is Exercise Caution through the period for seas and some wind, though gusty numerous storms will produce localized higher and more dangerous conditions into Thursday. && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Small Craft Advisory for hazardous seas until 1 PM CDT Tuesday for GMZ170-175. Small Craft Advisory for hazardous seas until 1 PM CDT Tuesday for GMZ150-155. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV 63
Area Forecast Discussion
National Weather Service State College PA
1140 PM EDT Mon Jun 18 2018 .SYNOPSIS... Heat and humidity will be broken by a cold front dropping down from the north tonight. The front will remain nearly stationary near or over southern PA through the end of the week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A new line of showers/thunderstorms extends from just south of Wellsboro back into northern Clearfield county as of 10PM. The HRRR keeps the line settling south and brings it through the South-Central Mountains between about 11PM and 1AM with a tendency for the line to lose organization as it moves into my far southern zones. SPC meso anal shows that the line is embedded within a zone of strong moisture convergence, but the atmosphere out ahead is becoming increasingly stable hinting that storms will tend to become more elevated and less of a wind threat over the next several hours. A deep plume of moisture depicted by PWATs in excess of 2 inches is associated with the frontal trough that is driving the convection. SREF/GEFS show this 2-4 sigma PWAT plume settling south overnight with drier air moving into most of the CWA for Tuesday. Until then, some of the thunderstorms could bring locally heavy rain. So far there are no signs of training cells so the threat for flooding rain seems minimal at this time. From earlier... Moist llvl air, and initially weak WNW flow behind the cold front will lead to some low clouds (and at least light fog) over the northern mountains between midnight and daybreak Tuesday with some lingering scattered showers possible. The expected cloud cover overnight, and the weak llvl dry advection will lead to another very warm/muggy night over most of the region (except for the far northern zones where temps will slide into the low 60s late). Elsewhere, mins will range from the upper 60s to mid 70s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Deep dry air advection in the wake of the cold front will lead to a much more comfortable day with respect to temperature and humidity as sfc dewpoints slide through the 50s across at least across the northern half to two thirds of the CWA during the day (and perhaps below 50F by late in the day across the Northern Mtns). Most model and short range ensemble guidance paints a generally dry day across the south Tuesday. However, NBM guidance still holds onto scattered showers/poss TSRA over our SW zones, so we left in approx 50 percent pops in there.. The push of dry air continues and almost everywhere over South-central PA late Tues/Tues night (and the Laurel Highlands will be below 60 by Midnight Tues night). Most of the showers should be shunted off to our SW for Tuesday night. Max temps Tuesday will vary from the upper 70s over the north, to the mid-upper 80s in the SE or still near to several Deg F above normal. Mins early Wed morning will range from the low- mid 50s across the northern tier, to the mid 60s in the south. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Stalled frontal boundary stretched out to our south looks to edge back northward midweek, bringing mention of tstms back into central PA. Activity looks to be mainly scattered, though storms will be more numerous across the southern tier. By Thu, building high pressure over the northeastern U.S. should push any lingering showers south of the area. Drier air pushing in from the north will allow lows to fall into the upper 40s over the northern mountains both Thu and Fri morning. As the high pulls off the East Coast over the weekend, returning southerly flow and a filling upper low over the midwest will bring moisture and a renewed chance of unsettled weather - mainly scattered showers - back into the area from the SW. Temperatures will remain close to June normals through this period. Hugh pressure builds in across the Great Lakes for early next week, bringing dry weather and cooler mornings. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Regional radar at 0330Z showing a line of pre-frontal showers and thunderstorms along the I-80 corridor pushing southward. A brief period of reduced visibility and gusty winds is possible as this line passes. This activity should continue to slowly diminish as it progresses southward overnight. A plume of higher moisture, combined with upslope flow ahead of the approaching cold front, is already producing low (IFR) cigs over the northwest mountains (KBFD) as of 0330Z and models indicate a similar scenario will play out over the the Laurel Highlands (KJST) later tonight into Tuesday morning. For areas east of the Appalachians, the drying effect of downsloping flow should yield no worse than MVFR cigs early Tuesday morning from KAOO northeast through KUNV/KIPT and VFR conditions over southeast Pa (KMDT/KLNS). Improving and mainly VFR conditions are expected later Tuesday morning and afternoon, as drier air pushes into the region from the north. Model soundings suggest MVFR cigs may linger until mid afternoon over the southwest airfields (KJST and KAOO). .Outlook... Wed...PM rain/cig reductions possible southern Pa. Thu...Early AM rain/cig reductions possible southern Pa. Fri...PM showers/cig reductions possible central mountains. Sat...AM showers/cig reductions possible. Sct PM tsra impacts possible. && .CLIMATE... Record max temperatures for June 18th: Harrisburg:97 in 1957 Williamsport: 97 in 1994...tied today Altoona: 92 in 1994 Bradford: 87 in 1994 State College: 94 in 1923 && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Lambert LONG TERM...RXR AVIATION...Fitzgerald/Evanego CLIMATE...
Area Forecast Discussion
National Weather Service Des Moines IA
635 PM CDT Mon Jun 18 2018 ...Updated for Hydrology Discussion... .DISCUSSION.../Tonight through Monday/ Issued at 412 PM CDT Mon Jun 18 2018 Thunderstorms have been developing over northern Iowa along the meandering front and can already see the upscale growth back to the southwest toward the Omaha area. Airmass in this area is characterized by MLCAPE uninhibited with 1500+J/kg with shear up towards 30 knots near the boundary. More impressive is the precipitable water values of nearly 2 inches. The storm that is east of Webster City brought around 1.5 inches in 30 minutes to Fonda. So heavy rain and hail will be the primary concerns through early this evening. South of this boundary, plenty of cumulus have formed within the warm sector with heat indices in the upper 90s to around 103. Heat advisory will be allowed to expire at 7pm or be canceled early if thunderstorms move over a significant portion of the advisory. As for tonight, convection is expected to continue into the evening with more uncertainty after midnight, but confidence high in heavy rainfall. CAMs like the HRRR, NAMNest, NAM12, RAP, and NBM show it continuing after this time with less activity in the ESRL HRRR and WRF cores. While the mean flow would suggest storms moving off the boundary, the set up still has moisture transport into the state and this boundary along with a shortwave trough moving overhead. With the atmosphere moisture-laden with precipitable water (PW) values around 2 inches tonight (00z NAEFS shows this as 97.5th percentile or higher for PW), held on to high PoPs throughout the night. 12z HREF probability matched mean (PMM) showing widespread 2 to 3 inches with the localized PMM having maxima of around 5 inches of rainfall through tomorrow morning along and south of Highway 20 to near I-80 primarily west of I-35 to our western forecast border. Deterministic models such as the NAM, GFS, CMC Regional, and CAMs show varying location, but similar message of 1 to 2 inches over a wide area with maxima of 4 to 6 inches possible. QPF was therefore a blend of the WPC and NBM, which lined up well with much of the model guidance for where heavy rainfall is expected. Amounts are generally 1 up to 2 inches in much of the watch area, but higher potential is certainly there given ensemble/deterministic guidance. Given the recent stretch of wet weather and in spite of the relatively dry, hot weekend, have issued a flash flood watch from the Highway 3 counties down to the Highway 34 counties tonight through noon tomorrow. Area may be too broad, but unable to focus it any further than this and don`t want to leave future shifts having to extend to new areas (hopefully!). The boundary will push into southern Iowa by later Tuesday with a relatively lull from the rain by the afternoon over a majority of the area as the shortwave departs. However, the next in the series of shortwaves will arrive Tuesday night with precipitable water values still around 2 inches and the mean flow a bit more favorable along the boundary for training storms. Likely much of the activity will be toward or after midnight Tuesday into Wednesday morning and new flash flood watches will likely be needed. As a more substantial, slow moving, shortwave trough begins to move into the area Wednesday into late Friday as shown by the GFS and ECMWF and the front meanders into northern Missouri, expect more rounds of storms with locally heavy rainfall. With placement of the boundary and lift, this will focus much of the heavier rainfall over central to southern Iowa Wednesday through Friday. Throughout much of this period, precipitable water values will remain in the 1.5 to approaching 2 inches so locally heavy rainfall is possible. For the Tuesday night through Friday night period, widespread rainfall of 2 to 3 inches is likely over central to southern Iowa. Of course, locally higher amounts are expected. High temperatures Tuesday through Friday will be more seasonable ranging from the low 70s to the lows 80s in most areas. As the shortwave trough moves into the Great Lakes Saturday, a break from the rain is becoming more likely on this day. However, another shortwave trough will pass over the state Saturday night into Sunday with additional storms possible. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 635 PM CDT Mon Jun 18 2018 Stalled/slow moving frontal boundary will be the focus for storms with heavy rainfall. MVFR or IFR conditions likely near to and north of the boundary with low cigs and reduced vsbys in storms. && .HYDROLOGY... Issued at 508 PM CDT Mon Jun 18 2018 Last week saw heavy rain fall over parts of central Iowa with some areas receiving between 2 to 4 inches with a few localized places upwards of 6 to 7 inches. While the weekend was relatively dry and hot, antecedent soil conditions are or will soon be primed for flash flooding. In addition, while there are no rivers above flood stage at this moment, flows remain above base flow so capacity is reduced along with soils favoring quicker runoff. Already this afternoon we have seen locally heavy rainfall in a narrow band just north of Highway 20 from near Storm Lake to near I-35 with 0.5 to 1 inch total so far. Fonda, IA recorded 1.5 inches in 30 minutes with other personal weather stations showing 0.75 to 1.25 inches as well as these storms moved through earlier this afternoon. WPC continues to highlight parts of our forecast area for excessive rainfall the rest of today through Wednesday. Our official 5 day rain forecast along with WPC 5 day QPF forecast has broad area of 3 to 5 inches over central to southern Iowa, which agrees or is slightly higher than the deterministic models. However, higher end potential is expected and WPC shows locally 7 inches over the next 5 days. While not inside our forecast area at this time with this set of model runs, there are 10 inch bullseye from some deterministic models, which lends to the idea of what is in the realm of possibility for 5 day rain totals across some part of the region within this moisture-laden atmosphere. As for rivers, RFC ensemble forecasts today based off of 72 hour, maximum future rainfall would have numerous gauges into moderate to perhaps major flood stage. However, 72 hour, best estimate future rainfall would take only the Des Moines River at Southeast 6th Street and the North Raccoon River at Perry into minor flood stage by middle to late in this week. A better handle on river flooding will obviously be known after the rain falls in the various basins and is routed into the rivers. && .DMX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 7 PM CDT this evening for IAZ049-050-057>062- 070>075-081>086-092>097. Flash Flood Watch through Tuesday afternoon for IAZ023>028- 033>039-044>050-057>062-070>075. && $$ DISCUSSION...Ansorge AVIATION...FAB HYDROLOGY...Ansorge
Area Forecast Discussion
National Weather Service Sioux Falls SD
1029 PM CDT Mon Jun 18 2018 .SHORT TERM...(This evening through Tuesday) Issued at 415 PM CDT Mon Jun 18 2018 In the storm term, the concern is the threat for severe weather in northwestern Iowa this evening and then heavy rain overnight. First the severe weather. Based upon satellite an obs, the warm front appears to extend from far southern Woodbury county into southern Ida County. Just north of the front, temperatures are in the low to mid 80s and dew points are in the low to mid 70s. Although lapse rates are around 6.5 to 7 C/km, the extreme heat and humidity still produces MLCAPEs over 2000 J/kg. Temperatures cool north of Hwy 3 in Iowa and MLCAPEs quickly fall below 1000 J/kg. At the same time, 0-6 km bulk shears ranges from around 30 kts near Hwy 20 to 40 kts in southeastern SD. The shear is enough to produce some storm organization - most likely multicells with supercells less likely. On the surface boundary, a local enhancement of the storm relative helicity could produce some short-lived supercells. So the primary threat will be wind gusts to 60 mph with hail to ping pong size. If a supercell or two are able to form then could see hail up to golf ball size as well as a threat of a tornado near the boundary. The severe threat will gradually end toward sunset as the surface front is forced southward as the upper wave moves to the east. Then the focus is on how convection evolves through the night. Certainly convection currently in western SD will continue to move east this evening and move into the James Valley by sunset. This is associated with a wave moving out of Nebraska. As the night progresses, more convection is expected to develop between the 850 mb and 925 mb front around or after midnight. With this evening`s convection in Iowa and Nebraska, models are hinting that the 850 mb front will be forced farther southward closer to Highway 18. So the convection from western SD will continue to move eastward through the night until the new convection develops over northwestern Iowa. At this time, expecting this convection to develop around 06Z although the latest HRRR is a couple of hours later. Once the new convection develops, the "old" convection to the north will slowly begin to diminish. Expecting some rain will make it into far western Minnesota but it is much more questionable if it will survive to Marshall and Windom. Meanwhile, convection will become more numerous somewhere between Hwy 18 and Hwy 20 in northwestern Iowa. Corfidi vectors are less than 10 kts late tonight in northwestern Iowa and that indicates that there could be training echoes which would bring a flash flood threat. Considered a flash flood watch for northwestern Iowa for later tonight but with uncertainty as to where the storms will develop due to impact of this evening`s storms, have held off and let evening shift re-examine the threat in a few hours. Convection is expected to move east of Hwy 71 during the morning. Then expecting a lull in the convection much of the late morning into the afternoon. As the next wave moves into the high plains in the afternoon may see new development in the vicinity of the Missouri River into northwestern Iowa. It will remain humid over the area with dew points in the 60s to lower 70s but cloud cover will keep temperatures in the 70s. .LONG TERM...(Tuesday night through Monday) Issued at 415 PM CDT Mon Jun 18 2018 For the extended period, the primary concern is heavy rain from late Tuesday night through Thursday morning. With a long wave trough over the area, another wave will move from Colorado into Nebraska by Tuesday evening. Cyclogenesis is expected over eastern Colorado with a warm front across southern Nebraska. The NAM and GFS both show convection developing well north of the surface front along the Nebraska and South Dakota border while the ECMWF and Canadian favor new developing from the Black Hills and western Nebraska into south central Nebraska. With the position of the surface boundary and location of this lead wave, have favored a ECMWF and Canadian solution with most of precipitation initially west and south of the area. As the main wave slowly move east-southeast into western Nebraska and western South Dakota, convection will spread northeast into the Missouri through the night. That will begin a long period of rain with embedded thunderstorms. All models agree that there will be 20 to 30 kt southeasterly flow at 850 mb bringing deep moisture into the Missouri Valley. PWs are expected to be from 1.75 to 2 inches through Thursday morning across the Missouri Valley. In addition, MUCAPEs of 500-1000 J/kg will be present. Finally, a strong warm front will be in place and able to interact with the upper low that will take 24 to 36 h to move across Nebraska. This is a set up for widespread heavy rainfall through the period. The current forecast has 3 to 4" of rain in the Missouri Valley from Tuesday night through Thursday. Most of this rain falls after 12Z Wednesday. While one cannot rule out flash flooding, the rainfall rates may not support widespread flash flooding given limited instability. However, 3-4" of rain could have an impact on larger rivers such as the Little Sioux, Maple, Vermillion and Big Sioux. Fortunately, the heaviest rain is closer to the Missouri River where the rivers can handle a bit more water than farther upstream toward I-90. Given the event is 2 days have decided not to issue an ESF for river flooding at this time to see if models continue to show this much rainfall. Those living near larger rivers over southeastern South Dakota and northwestern Iowa will need to be aware of the latest river forecasts through the week. With the ample clouds and rainfall, there will be a small diurnal range with highs in the 70s and lows in the 60s. It could also be breezy on Wednesday as the pressure gradient tightens north of the surface cyclone moving across Nebraska. Due to the rainfall threat, no significant changes made to the forecast for the weekend and beyond. As skies clear, temperatures will slowly warm back into the 80s by Sunday and Monday. The unsettled weather will also continue with chances of rain through Monday although widespread heavy rain is not anticipated at this time. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1027 PM CDT Mon Jun 18 2018 Scattered showers and thunderstorms will remain a threat across the area through mid morning on Tuesday. With this activity, MVFR/IFR ceilings will persist, before improving on Tuesday afternoon. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ SHORT TERM...Schumacher LONG TERM...Schumacher AVIATION...JM
Area Forecast Discussion
National Weather Service Lincoln IL
847 PM CDT Mon Jun 18 2018 .UPDATE... Issued at 844 PM CDT Mon Jun 18 2018 Outflow from convection over northern IL evident on KLOT radar this evening as it pushes south toward I-74. CAM models are relatively consistent in slowing progress of boundary as it approaches. Convection behind this boundary is shallow as show on GOES 16 Clean IR Imagery and will likely diminish as southern push slows. Have decreased PoPs somewhat from afternoon forecast package, otherwise forecast is in good shape. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 257 PM CDT Mon Jun 18 2018 Tough call on the heat advisory, but will go ahead and let it expire at 7 pm. With additional clouds expected, heat index values on Tuesday should still reach 100-105. While that`s a bit below the normal criteria, the duration of the 100+ heat index values could warrant an extension. Will let the midnight shift re- evaluate that after overnight convective trends are established. Speaking of convection, isolated storms have been popping up over the last hour or two, generally from I-72 north to near Peoria. These were handled rather well with recent HRRR runs, and its latest guidance suggests they should fade toward dinner time. Main concern will be with showers/storms over southern Wisconsin this afternoon. With time, this will push a frontal boundary southward, which some of the high-res models have located over the northern CWA by late evening. Have gone with likely PoP`s later this evening over that area, but activity should diminish toward midnight. Additional storms will be possible there late night, as convection currently over the Plains rides over the top of the upper ridge. After a lull during the mid-late morning on Tuesday, high-res models are in good agreement with a line of storms coming in mid to late afternoon Tuesday. While CAPE`s will be high again in this environment, lower bulk shear values would favor pulse- type strong to isolated severe storms. .LONG TERM...(Tuesday night through Monday) ISSUED AT 257 PM CDT Mon Jun 18 2018 Welcome break from the heat is on tap through mid to late week, as the ridge continues to break down. Several periods of showers and thunderstorms are expected, especially later in the week as an upper low cuts off over the central Plains. Longer range models are in decent agreement with a slow ejection of this low into Illinois toward Friday, before shearing out as it reaches the Great Lakes. Later in the weekend, another upper low will cut off over the Rockies. A skinny upper ridge over the Mississippi Valley is agreed upon by the longer range models, but the low`s impacts on it are less certain. The pattern suggests some rain chances across at least the southern CWA late weekend into early next week, but a surface high pressure over Ontario will play a role as well. At the present time, will keep Monday dry as a result. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 621 PM CDT Mon Jun 18 2018 Models remain consistent in surging the boandary over northern Illinois southward and approaching the I-74 terminals later tonight. Difference is whether it will push far enough to bring convection to those terminals before stalling out prior to the approach of the next shortwave late Tuesday. Storm outflow is currently reinforcing push through Chicago currently, but boundary over northwest Illinois not showing the same fast southward push. For now will support the model consensus that the convection will likely stop short of the central IL terminals. May be close enough to include a VCTS and will include that in I-74 terminals during the early morning hours. Otherwise, increased convective changes will likely hold off until additional support approaches later Tuesday from incoming shortwave && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barker SHORT TERM...Geelhart LONG TERM...Geelhart AVIATION...Barker
Area Forecast Discussion
National Weather Service Marquette MI
739 PM EDT Mon Jun 18 2018 .SHORT TERM...(This evening through Tuesday) Issued at 357 PM EDT MON JUN 18 2018 WV imagery and RAP analysis indicated a mid/upper level low over Idaho, a ridge over the se CONUS, and another mid level low over ne Canada resulting in wrly flow through the nrn Great Lakes. At the surface, high pressure from srn Saskatchewan into nw Ontario was building into the region with anticyclonic n to ne flow. With drier air filtering into the region, clouds have move out of all but the far south with only sct cu over the inland west half. Tonight, expect good radiational cooling conditions under mostly clear skies. HOwever, since dewpoints still lingered in the mid 50s north and lower 60s south, temps are only expected to drop off to around 50. Tuesday, high pressure and a relatively dry airmass dominating the area will bring mostly sunny skies with some afternoon cu again developing. With 850 mb temps around 10C-12C, inland readings in the mid to upper 70s are expected, except along the Great Lakes where lake breezes will keep readings in the 60s to around 70. .LONG TERM...(Tuesday night through Monday) Issued at 357 PM EDT MON JUN 18 2018 Models suggest that a slowly progressive pattern will prevail with the northern Great Lakes in a quiet zone between the northern and southern streams. Mainly dry weather will prevail with temperatures near or slightly above seasonal averages. Wednesday into Thursday, sfc high pressure will remain into control with persistent light n to ne winds. Highs will climb into the upper 70s to around 80 inland while lows drop into the upper 40s. Fri-Sat, the models were in reasonable agreement with the evolution of the plains mid level trough as it moves through the Great Lakes, keeping pcpn chances mainly over the se portion of Upper Michigan on Saturday. However the GFS/GEFS remained the most aggressive with the rain potential compared to the ECMWF. Overall, only chance POPs were mentioned given potential for the system to remain south of the region. Sun-Mon, there was good models agreement that sfc and mid level riding will again build into the area with dry weather. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 739 PM EDT MON JUN 18 2018 With a dry air mass settling over the area, VFR conditions will prevail at KIWD/KCMX/KSAW thru this fcst period. Winds will be under 10kt. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 357 PM EDT MON JUN 18 2018 Winds will stay at or below 20 knots through the forecast period. Fog over eastern Lake SUperior will slowly dissipate this evening as drier air works into the area. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JLB AVIATION...Rolfson MARINE...JLB
Area Forecast Discussion
National Weather Service Spokane WA
439 PM PDT Mon Jun 18 2018 .SYNOPSIS... Another band of rain will impact the Idaho Panhandle and portions of eastern Washington through the evening and overnight hours. Showers will persist through mid week with slow moving and wet thunderstorms possible in the afternoon and evening. Temperatures will peak on Wednesday and Thursday with highs in the 80s to low 90s and then moderate into next weekend. && .DISCUSSION... Tonight: Upper level low pressure system that is currently in southern Idaho will weaken and move towards the northeast. Wrap around moisture will continue to stream into the area from the east. We are finally seeing some radar returns across portions of north ID and into Spokane county. The rain will continue through the evening hours, with the best threat for rain to be across the Palouse into Shoshone county and the Camas Prairie. The HRRR has been persistent all day in showing precip stretching as far north as the ID/Canadian border and down through Spokane this evening. Have increased our chance of rain this evening. Chance of rain will decrease through the evening and overnight hours, except for locations south and east of Pullman, where rain will continue through the night. Given the extensive cloud cover that will remain across the region, overnight lows will be pretty the mid 50s to lower 60s. Tuesday through Wednesday afternoon: Unsettled weather is expected as instability grows each afternoon and evening. Precipitable water values of over an inch are forecast. We are in between systems, and storm motion for any convection that fires up will be very slow. Have kept the mention of heavy rain with any thunderstorms that develop each afternoon and evening. The main impact areas for heavy rain will be in the Cascades and areas south of a line from the Blue mountains to Lookout Pass. Wednesday evening through Thursday: A trough will move into the region and bring some strong energy from northern California up into northern Oregon and southern WA late Wed night into Thur morning. Models are showing some elevated instability which would promote thunderstorms through the overnight hours. Have added thunder through the night for the Columbia Basin and into southeastern WA (up to the Spokane area) and the southern ID Panhandle for the early morning hours on Thursday. There is a better chance of thunderstorms Thursday than any other day this week as this shortwave trough moves through the region. Almost all locations have a chance of seeing thunderstorms. (the one exception may be around Wenatchee) Precipitable water values still remain high will very slow storm motion. Very heavy rain will once again be the main impact with thunderstorms. Have looked at the hail threat, but for now have kept mention of it out of the forecast. Wet bulb zero heights may be too high to support large hail. This isn`t a typical strong wind pattern either. The only strong winds I could see happening is if they develop out of the heavy rain falling with thunderstorms. For now, our main impact will be heavy rain with the thunderstorms on Thursday. Friday through Monday: The wave moves out of the area, but there is another trough that moves in, this time from the northwest. It is a rather quick mover, and there could be some showers and thunderstorms possible Friday afternoon and evening across northern WA and the ID Panhandle. Saturday showers will remain across the higher terrain of the ID Panhandle and then a dry forecast for Sunday. Monday another trough will move into the Pacific Northwest. Currently it looks to be a dry cold front where the main impact would be winds and not precip. But a lot can change with the models between now and then. && .AVIATION... 00Z TAFS: A band of rain from Sandpoint to Walla Walla will persist through this evening. This will bring rain to KCOE, KPUW and KLWS. Conditions should remain VFR at KCOE, but at KPUW and KLWS MVFR cigs are possible overnight and Tuesday morning. Confidence in this too low at KLWS to include in the TAF, but I did put a low cig in the KPUW TAF. Conditions should be VFR at KEAT and KMWH. RJ && .PRELIMINARY POINT TEMPS/POPS... Spokane 58 80 59 84 61 82 / 70 10 10 10 10 50 Coeur d`Alene 57 78 56 84 59 81 / 70 20 20 10 10 60 Pullman 55 74 55 81 59 78 / 90 50 40 10 10 60 Lewiston 60 78 59 87 64 84 / 90 40 40 10 10 60 Colville 58 84 57 87 58 86 / 10 10 10 20 10 50 Sandpoint 57 79 54 82 57 80 / 40 20 10 10 10 60 Kellogg 52 73 52 80 57 78 / 70 50 30 20 10 60 Moses Lake 58 87 60 91 63 90 / 20 10 10 10 20 20 Wenatchee 62 87 66 88 65 87 / 10 10 10 10 10 10 Omak 61 87 62 90 61 89 / 0 10 10 40 20 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
Area Forecast Discussion
National Weather Service Pendleton OR
649 PM PDT Mon Jun 18 2018 .UPDATE...Elongated upper low along the ORE/ID border is circulating moisture and light rain westward into eastern Oregon/SE Washington as far west as the Blue Mountain Foothills. The rain is very light falling mostly out of a mid cloud deck and amounting to only a few hundreths per hour in most places. The latest HRRR runs show this activity shifting eastward during the late evening and slowly diminishing. Have updated the pops for the overnight to reflect this trend. Otherwise the current forecast is on track. Wednesday still looks to be the most convectively active day with the potential for afternoon and evening thunderstorms areawide. 78 && .PREV DISCUSSION... /issued 500 PM PDT Mon Jun 18 2018/ SHORT TERM...Tonight through Friday morning...A large upper level low over southern Idaho will slowly shift eastward and be centered over southwest Montana by Tuesday morning. Will continue to see widespread light precipitation over a large portion of the forecast area through this evening and then decreasing overnight except in the far east. On Tuesday the main area of precipitation will be over the far eastern mountains. There will be a slight threat of thunderstorms there as well as along the east slopes of the Washington Cascades. Less cloud cover will mean warmer temepratures. Tuesday night and Wednesday an upper level ridge will move over the region. Late Wednesday an upper level trough along the coast sends a shortwave into the region which will serve as the trigger for some convection late in the day...overnight and into Thursday before exiting. Expecting thunderstorms during this period impacting the forecast area with the potential for some strong storms. This shortwave exits Thursday night bringing an end to the storms and precipitation. LONG TERM...Friday afternoon through Monday...Model consensus is that a mid to upper level shortwave makes landfall Friday afternoon and then moves east of the Cascades late Friday night through Saturday afternoon. The GFS and Canadian models show less amplitude with the system and thus move it through the two state area faster than the ECMWF. ECMWF shows significantly more amplitude with the shortwave and is slower. I split the difference and gave the ECMWF weight for the forecast on Saturday thus introducing a slight chance of showers along the east slopes of the Cascades during the day on Saturday and a chance of showers in the northern BLue Mountains through Saturday afternoon. The shortwave exits the region by late Saturday afternoon while a mid to upper level ridge of high pressure builds over the region for dry conditions Sunday through Monday. The ridge will bring a warming trend Sunday and Monday with high temperatures in the upper 80s to lower 90s in the lowlands and highs in the mid 70s to mid 80s in the mountains. Polan AVIATION...00Z TAFs...Showers expected for the next 6-9 hours at all TAF sites except KYKM and KDLS. Brief MFR conditions may occur in and near heavier showers. The best chances for rain showers are at KPDT due to orographic lift associated with northerly upslope winds along the north facing Blue Mountains foothills. Showers tapering off and ending at TAF sites by late this evening. Winds will be 5-10kt until 04Z, then diminish and become weak drainage winds around 5kt overnight. Polan && .PRELIMINARY POINT TEMPS/POPS... PDT 57 78 62 90 / 60 10 10 10 ALW 57 80 63 92 / 70 20 10 10 PSC 59 86 63 93 / 60 10 10 10 YKM 58 88 64 89 / 10 10 10 20 HRI 58 86 63 94 / 60 10 10 10 ELN 57 88 62 88 / 10 20 20 20 RDM 52 83 55 88 / 40 10 0 20 LGD 54 73 54 81 / 70 40 20 20 GCD 54 75 56 85 / 60 20 10 10 DLS 64 89 68 93 / 20 10 10 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 78
Area Forecast Discussion
National Weather Service Mount Holly NJ
941 PM EDT Mon Jun 18 2018 .SYNOPSIS... A cold front will move across the area tonight into Tuesday, before pushing south of the area later Tuesday into Tuesday night. Weak high pressure will briefly affect the area Tuesday night, before shifting offshore Wednesday. An area of low pressure will develop along this boundary across the Ohio River Valley On Wednesday, then move eastward along this boundary Wednesday into Wednesday night, while a cold front moves across the area from the north. High pressure builds across the northeast Thursday night, before shifting offshore Friday. A warm front is expected to lift across the area later Saturday, followed with a cold front on Sunday into Sunday night. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... A broken line of showers and thunderstorms continues to dissipate as it tracks SE through NJ and into Philly. Locally heavy rain, frequent lightning strikes, and locally damaging winds possible for the next hour or so. Conditions then should be relatively quiet until after midnight. Cold front extending from eastern Canada, through just north of NY state, and back through the Great Lakes will approach, and showers and thunderstorms will fire up ahead of that front. With temperatures falling, the airmass will become more stable going through the overnight, but there will still be around 1000-1500 J/kg of ML MUCAPE ahead of the front. Line of showers and thunderstorms currently extending from south-central NY state back through NW PA, and are tracking to the southwest. By the time they reach the southern Poconos and Lehigh Valley, it should be around midnight or so, and current radar trends match up fairly well with the latest HRRR trends. 0-6 km shear values will increase to 30-35 kt, so despite the decrease in instability, there should be another round of strong to locally severe thunderstorms going through the overnight. Hi-res guidance indicates this line of convection will pass through the region as the cold front works its way south through the region, and move off the southeast NJ coast by daybreak or so. Storms should weaken a bit once they get south of the Fall Line. With PWATs up around 2", can expect heavy rain with any storms, but they should be fairly quick movers, and not expecting widespread flooding concerns. Cannot rule out some localized poor drainage flooding. Cold front will be through the southern Poconos and northern NJ, and will be into the Lehigh Valley by daybreak Tuesday. Warm and muggy with lows generally in the 70s, and surface dewpoints not much lower. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... The aformentioned cold front will be situated close to the I-95 corridor across SE PA to start the day but will continue to progress slowly southward through the day. The good news is this will lead to a drying trend with lowering dew points from north to south. This will result in conditions feeling much more comfortable by afternoon except across the Delmarva where humidity will linger closer to the front. Along and south of the cold front, there will continue to be chances for some showers and storms with most of this activity occuring in the afternoon over the Delmarva coinciding with peak heating. Not expecting any of these storms to be severe though as the best instability should be just to the south. Farther north across SE PA and central and northern NJ any early morning showers and isolated storms with the front will give way to clearing by afternoon with the N/NW flow behind the front. Highs will generally be in the 80s to around 90 but with falling dew points so we won`t see the high heat indicies of today. Also, a sea breeze is likely in the afternoon bringing cooler temperatures along the coast. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Weak high pressure is expected to briefly build across the northeast Tuesday night as the cold front continues to sag south of the area. This is expected to lead to dry conditions across the area through the overnight period. The weak high pressure builds offshore on Wednesday, while the frontal boundary remains to our south. During the day, an area of low pressure is forecast to develop along this boundary across the Ohio River Valley and begin moving eastward along the boundary. A short wave/vorticity impulse is forecast to move across the area well ahead of the actual low, so there could be some scattered showers/thunderstorms develop during the daytime. Overnight, the actual low itself will move across the area, which will also likely lead to scattered showers and thunderstorms. On Thursday, the front will have pushed south of the area while an area of high pressure begins to approach from the northwest. The high will fully build across the northeast Thursday night, before shifting offshore Friday. This will lead to fair conditions through Friday. However, as we go into Friday night and into the weekend, some unsettled weather returns to the forecast. With the high offshore of the east coast, return flow strengthens across the area, which will allow for warm/moist air to return to the forecast. The front to our south will return northward as a warm front as an area of low pressure lifts through the Great Lakes Saturday. The warm front is likely to lift into the area later Saturday into Saturday night. While the warm front may be south of the area on Friday night, there could be a couple of short wave/vorticity impulses lift across the area to create some isolated showers overnight. But as we move into Saturday and Saturday night when the front gets closer to the area and eventually passes through, the chances of showers and thunderstorms increase. The aforementioned low pressure will move across southeastern Canada Saturday night into Sunday, eventually dragging a cold front across the east coast on Sunday. There will remain a chance of scattered showers and thunderstorms through Sunday and Sunday night as the cold front moves across the area. An area of low pressure may develop along the front as it moves south of the area Sunday night into Monday. However, depending on how far south the front sags to our south, shower and thunderstorm chances could continue into Monday of next week. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight...Initial line of SHRA/TSRA moving south and east of the I-95 corridor terminals and continues to weaken. KACY may be impacted from around 02z-03z. Other line of showers and thunderstorms will approach KABE/KRDG around midnight tonight, and then that line will impact the I-95 corridor terminals (KTTN-KPNE-KPHL-KILG) from around 05-08z, and then KMIV-KACY from 08z-10z, but storms should weaken by then. Brief MVFR, possibly IFR VSBY in heavy rain, otherwise, VFR. SW winds 5-10 kt, becoming W late, and possibly NW at KRDG/KABE. Tuesday...Mainly a VFR forecast. Some SHRA/TSRA may impact KILG in the afternoon, but confidence is low. Winds shift from W-SW to NW late in the morning with the passage of a cold front at 8-12 kt with gusts up to 20 kt. OUTLOOK... Tuesday night...Generally VFR conditions expected. Wednesday-Wednesday night...Generally VFR early, MVFR conditions may develop later in the day into the evening with a chance of showers. Thursday-Friday night...Generally VFR conditions expected. Saturday...MVFR conditions likely to develop as a warm front approaches and lifts across the area with a chance of showers. South to southeast winds may gust 15-20 knots during the day. && .MARINE... Sub-SCA conditions. S winds 15-20 kt on the NJ ocean waters tonight, but gusts to 25 kt not expected. Winds will diminish through the overnight. SW winds become NW Tuesday morning behind the passage of a cold front with wind speeds 10-15 kt with gusts up to 20 kt. Showers and thunderstorms may result in gusty winds, lightning, and VSBY restrictions in heavy rain mainly during the overnight. RIP CURRENTS... On Tuesday, seas will average 2-3 feet with a dominant period of 6-7 seconds. The risk for the development of dangerous rip currents is low for the Delaware and New Jersey beaches. OUTLOOK... Tuesday night-Wednesday...Conditions expected to remain below advisory levels through Wednesday. Wednesday night...Winds may increase Wednesday night as an area of low pressure moves off the coast and over the coastal waters. However, conditions will likely remain below advisory levels, although winds may gust around 20 knots at times. There is a chance of showers and thunderstorms which could lead to locally higher winds and waves. Thursday-Friday night...Conditions expected to remain below advisory levels, but winds may gust around 20 knots at times. Saturday...A warm front is forecast to lift north of the area later Saturday into Saturday night. Winds may gust around 20 knots at times, but are expected to remain below advisory levels. There is a chance of showers and thunderstorms which could lead to locally higher winds and waves. && .CLIMATE... The high temperature at Allentown, PA reached 95 degrees today. This tied the old record previously set in 1957. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...MPS Short Term...Fitzsimmons Long Term...Robertson Aviation...Fitzsimmons/Robertson/MPS Marine...Fitzsimmons/Robertson/MPS Climate...MPS