Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/31/20


Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1159 PM EDT Sat May 30 2020 .AVIATION... High pressure will bring generally clear skies (aside from a few diurnal cu/strato-cu Sunday afternoon) and light winds under 10 knots. Winds will back from northwest to west to southwest with time tonight into Sunday evening. DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 324 PM EDT Sat May 30 2020 DISCUSSION... The initial surface ridging that developed over Southeast Michigan in post cold frontal environment late Friday has now since faded and generally expanded to the Mid Atlantic. Much stronger surface high pressure exists over the Upper Mississippi River Valley and is being forced by strong synoptic scale support of jet dynamics with confluence aloft and differential anticyclonic vorticity advection. Southeast Michigan remains sandwiched between these features at the moment, influenced by the deep polar trough that is in place from James Bay southward through Lake Huron. Strong shortwave within broader H5 trough axis swung through the Straits to N. Lake Huron as of 18Z. Numerous showers invof of Grand Traverse Bay throughout the morning persisted due to combo of steep 900-800mb lapse rate plume, 1000-850 mb shoreline convergence, and lead edge of 1000-500mb geopotential height fall region. For the remainder of the afternoon, tail end to absolute vorticity max will settle into the remainder of Southeast Michigan with axis of lower tropospheric frontogenesis becoming organized north to south along Thumb/Lake Huron shoreline due to the difference in diabatic surface heating across land/water interface. Providing relatively greater support for shower coverage in the Thumb between 19-23Z is pool of higher 825-675mb ThetaE content that gets shoved southward in advance of +65kt midlevel jetlet. HRRR soundings corroborate with some better support for high based-low topped shower activity north of I 69/east of I 75. Increased PoPs into entry level chance late this afternoon. Coherent midlevel anticyclone center will settle to Lake Superior tonight. Loss of depth to planetary boundary layer due to nocturnal cooling will then allow for overwhelming increase in near surface anticyclonic flow trajectories and systematic cold air advection overnight complete with requisite increase in 900-800mb static stability. A drying out of this layer will lead to extremely quiet and sunny conditions Sunday. No environmental wind in the lowest 6kft agl will yield light northwesterly winds. Significant low to midlevel thetaE plume will advance towards Southeast Michigan from the west on Monday as southerly flow tries to bust into the state. Some uncertainty with how fast the warmer/moist midlevels will arrive. Current timing suggests Monday will remain under a more influence of the anticyclonic trajectories. However, there is some signal that enough warmth/moisture will bleed in on southerly flow to allow for some overachievement potential on moderating temperatures. Textbook warm advection wing is forecasted to track across Lower Michigan Monday evening and Monday night. The warm advection will likely support a mature MCS type structure tracking through northern Wisconsin/U.P. during the day on Monday then for the forecast area that evening. Convective updraft strength appears limited due to lapse rates remaining at moist adiabatic with high static stability in the lowest 3.0 kft agl. Quality and depth of moisture could be impressive with PWATS spiking up toward a 1.5 inch. Most interesting aspect is the potential for a longer duration convective rain Monday night as the eastward push to the elevated warm front could be on the slower side. Will need to monitor QPF trends for Monday night. Current model signal suggests shortwave anticyclonic gyre rolling across Southeast Michigan for a good part of Tuesday. Much warmer and more humid conditions set for Tuesday with heat indices approaching 90 degrees possible. A zonal cold front is then progged to settle due southward late Tuesday/Wednesday morning. A severe weather threat will exist conditional on timing of this cold front boundary. Also, there appears to be some potential for a boundary parallel flow that could bring a training of thunderstorm activity during this timeframe. MARINE... Moderate northwest flow continues through the evening before weakening late tonight. Small craft advisories are up for the Saginaw Bay due to gusts around 25kts and along the Thumb due to higher waves clipping the nearshore waters. Strong high pressure builds over the region early Sunday and remains overhead through the day Monday bringing quiet marine conditions for the period. Shower and thunderstorm chances increase again late Monday into Tuesday as the next low pressure system begins to move into the central Great Lakes. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Lakeshore Flood Advisory until 10 AM EDT Sunday for MIZ049-055-063. Lakeshore Flood Advisory until 4 AM EDT Sunday for MIZ054. Lake Huron...Small Craft Advisory until 10 AM EDT Sunday for LHZ441>443. Small Craft Advisory until 5 AM EDT Sunday for LHZ421-422. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....DG DISCUSSION...CB MARINE.......KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Hanford CA
132 PM PDT Sat May 30 2020 .SYNOPSIS... Low pressure will move northward along the coast today bringing a threat of showers and a thunderstorms to the northern half of the district. Another area of low pressure will develop off the CA coast next week for continued seasonal temperatures and a chance of showers in the Sierra. && .DISCUSSION... Short term focus this afternoon will be the chance of showers and thunderstorms in the Sierra and SJV, primarily north of Fresno County. Current GOES17 mid-level water vapor imagery and 500 mb RAP analysis is indicating a vorticity max moving into the northern half of the district. In combination with decent instability, SBCAPES of ~500 J/kg, will help initiate showers and thunderstorms this afternoon. Storms will be capable of producing heavy rain as well as small hail. Snow can not be ruled out in the higher elevations above 10,000 feet toward the Yosemite area. With the continued synoptic cooling aloft, high temperatures this afternoon across the central California interior are very pleasant, with mostly upper 70s to low 80s. From Sunday into Monday, the NAEFS and deterministic models are showing a trough setting up just offshore, keeping a cool onshore flow in place and a chance of showers in the Sierra on Monday. 500 mb heights do slightly increase during this period, and temperatures will trend back up to seasonal conditions by Monday. From Tuesday through Thursday, deterministic models and ensembles show an area of low pressure setting up off shore. This will increase our chances of precipitation across the Sierra. Temperatures will stay near seasonal averages. && .AVIATION... Mountain obscuration in showers and storms over the Sierra Nevada are possible through 03Z. Showers and thunderstorms are possible in Merced and Mariposa counties after 19Z Saturday through 03Z. Otherwise, VFR conditions will prevail across the interior of Central California through the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ public...CMC aviation....Andersen weather.gov/hanford
Area Forecast Discussion
National Weather Service Marquette MI
746 PM EDT Sat May 30 2020 .SHORT TERM...(This evening through Sunday) Issued at 342 PM EDT SAT MAY 30 2020 Still a bit chilly for the end of May across Upper Michigan this afternoon as colder air aloft and morning CAA has allowed plenty of low-level clouds across the region. RAP analysis and soundings earlier this morning actually showed a very small amt of CAPE with the low-level CAA and steep lapse rates. This aided the early morning -SHRA given the relatively shallow saturation. As rising heights, increasing 850mb temps, and sfc high pressure continue across Upper Michigan, skies will continue to clear into this afternoon. Expecting temperatures to increase this afternoon slightly under increasing sunshine, but should remain generally in the 50s with low 60s across the south. With sfc high pressure tonight and generally lighter winds expected tonight, opted to issue a frost advisory across much of the CWA. Model guidance was a little separated with deterministic and BC guidance suggesting a little warmer lows than MOS and adjusted MOS guidance. Looking upstream and running backwards HYSPLITs suggest our airmass tonight will be similar to that over Dryden, Ontario (CYHD) last night. The winds last night there remained near 5kts or so with a little more clouds than were expecting here tonight. Their lows fell to around 34F last night which brings the best chances for frost tonight across much of the interior, away from the Great Lakes. By tomorrow, high pressure will be over Upper Michigan with mostly sunny skies expected. There may be some clouds across the far east in the morning on the edge of an exiting shortwave and mid-level ridge shifting east. Model soundings backed off slightly on deeper mixing tomorrow, with mixing up to 5k-6kft. With this, raised the Tds only slightly from the going forecast, but still on track to bring minimum RH values into the mid 20s tomorrow across the interior. High temperatures will be generally in the 60s with low 70s across the west and south. .LONG TERM...(Sunday night through Saturday) Issued at 339 PM EDT SAT MAY 30 2020 Models suggest that the high amplitude pattern with a ridge from the Southern Plains to northwest Canada and a trough through Quebec and the mid Atlantic will become more zonal through much of next week as the ridge expands through the southern CONUS. Models then indicate the pattern will become amplified again next weekend as a deep trough digs into the West Coast, inducing a broad amplified downstream ridge across much of the central CONUS. Temps will climb above average next week and likely remain that way into next weekend. Beginning Sun night, high pressure over the western Great Lakes will continue the dry conditions over the area. The approach of a shortwave rounding the Plains ridge and the WAA/isentropic ascent response ahead of it should result in increasing mid-high clouds from the west after midnight. The increasing clouds combined with increased low-level mixing should keep min temps from dropping off too much. Expect readings generally in the 40s. Mon-Tue, models generally in good agreement showing thickening clouds and increasing rain chances in association with the northern Plains shortwave moving through the area, especially Mon afternoon into the Mon evening, supported by strengthening WAA and moisture transport. Elevated instability should generally remain farther to the south and west, but could be enough elevated CAPE (near 400 j/kg) to support isolated thunderstorms near the Wi border. Most places should see overall rainfall amounts in the 0.10-0.25 inch range, although amounts up to 0.50 could be possible south with any t-storms that occur. Increasing clouds will help keep max temps in the upper 60s and lower 70s Mon. Much warmer air will move in Tue with drier conditions as 850 mb temps climb to 14C-17C supporting inland temps into the mid and upper 80s west and the mid 70s east. Wed-Sat, confidence is lower given model differences and variability in handling any additional shortwaves moving through the area. Right now it looks like a shortwave moving through the area could bring shower and possibly t-storm chances on Wed with another shortwave bringing in another round of showers late Thu into Fri time frame. At some point next weekend, most likely late Sat into Sun, the deterministic GFS and ECMWF advertise a more vigorous shortwave rounding the Plains ridge into the Upper Great Lakes resulting in a strengthening WAA southerly flow and increasing moisture return and instability to support showers/t-storms into the area. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 744 PM EDT SAT MAY 30 2020 SKC will roll into Upper Michigan over the next few hours as high pressure and dryer low levels continue to work their way into the region. Gusty winds blo 20 knots have ended for today, although they will return again tomorrow. VFR conditions will last at all TAF sites through the TAF period. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 148 PM EDT SAT MAY 30 2020 Northwest winds will back more to the west by this evening as high pressure moves over Upper Michigan. This high pressure will then linger over the lake for Sunday bringing west to southwest winds over the lake. A warm front on Monday evening may bring gusts up to 25 knots from the south across the east half of Lake Superior, otherwise winds are expected to remain blo 25 knots through the rest of the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Frost Advisory from midnight EDT /11 PM CDT/ tonight to 9 AM EDT /8 AM CDT/ Sunday for MIZ002-004>007-009>014-084-085. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JAW LONG TERM...Voss AVIATION...TAP MARINE...JAW
Area Forecast Discussion
National Weather Service San Francisco Bay Area
449 PM PDT Sat May 30 2020 .SYNOPSIS...Scattered showers and isolated thunderstorms will continue through late afternoon as an area of low pressure passes across the Bay Area. Precipitation is expected to end by this evening as the low shifts north of the area. Seasonable to slightly below normal temperatures are forecast for Sunday into Monday, along with dry conditions. Midweek warming is then likely, especially inland, although the magnitude of the warming is uncertain at this time. && .DISCUSSION...As of 1:35 PM PDT Saturday...The center of an upper low is currently passing directly over the SF Bay Area as it continues to move to the northeast. KMUX radar indicates shower activity has been increasing since late morning, especially across interior portions of the East Bay where heaviest showers are currently located. In addition, an isolated thunderstorm recently developed over Henry Coe State Park in eastern Santa Clara County and a cloud flash was recently detected near Clayton in Contra Costa County. Isolated thunderstorms will likely continue for the remainder of the afternoon. Rain totals from last night and today have generally been less than a tenth of an inch. The exception is in the Santa Lucia Mountains near the Big Sur Coast. Upslope precipitation enhancement near the Big Sur Coast has resulted in rain totals of between a quarter and a half inch. One location in far southwest Monterey County (Three Peaks) has picked up nearly an inch of rain. The upper low is forecast to accelerate to the northeast by late this afternoon and most models indicate shower activity will quickly come to an end by early evening. However, the latest HRRR keeps isolated pockets of light rain near the coast well into the evening hours. Considerable low level moisture left over from this system will likely result in widespread low cloud cover overnight. The upper low will have moved well to our northeast by Sunday, and dry weather is expected to return to all areas. However, temperatures will remain slightly cooler than normal through Monday as the next trough deepens offshore along 130W. Also, residual low level moisture and onshore flow may mean persistent low cloud cover in coastal areas into the afternoon hours. The trough will continue to deepen offshore and form a cutoff low off the southern California coast by Tuesday. It is at this point when the models diverge significantly on temperatures. The ECMWF, which develops the cutoff low farther offshore compared to the GFS, and therefore develops higher highs and a warmer airmass over California, forecasts significantly warmer temperatures than the GFS from Tuesday through Thursday. The model temperatures differences peak on Wednesday when the ECMWF MOS forecast high temperatures are anywhere from 10 to 15 degrees warmer than the GFS MOS guidance. The model blend (NBM) temperatures are in between, as would be expected, but slightly favor the warmer ECMWF. The NBM temperatures are probably the best option for now. In the longer range, models agree that another trough will approach from the west late in the week, ejecting the cutoff low to the east. The latest GFS develops precip across the far southern portion of our area late on Thursday as the upper low moves inland across southern California. Rain chances then develop across the northern portion of our area next weekend as that next trough moves in. && .AVIATION...as of 4:48 PM PDT Saturday...for 00z TAFs. Scattered showery activity is ongoing around the Bay Area, but the heaviest of rainfall is done. Lingering showers will continue for the North Bay as the system moves northeastward out of our region. Winds have already begun to switch to the northwest behind the center of low pressure and will continue to do so through the evening. Cloud cover will remain overnight. Most terminals will be MVFR, with isolated areas becoming IFR. VFR returns Sunday afternoon, with clouds remaining in the area above 3000 ft AGL. Winds will be more predominantly onshore and breezy in the afternoon. Vicinity of KSFO...With the exception of a few low clouds, conditions are VFR with strong southerly winds. Scatter showers remain east of the terminal, and are decreasing. Lingering shower activity is expect tonight in the North Bay as the system moves northeast. Winds will slowly shift to the west through the evening, before easing overnight. Expect lowering cigs after 9z for MVFR conditions overnight. Cigs will lift above 3000 feet after 18z Sunday, but expect cloud cover to linger. Winds will be out of the northwest and breezy in the afternoon. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR with clouds bases above 3500 feet. A few weak showers are over the ocean, but not expected to impact terminals overnight. Cigs will lower to MVFR after 4z, with IFR cigs possible early Sunday morning. A return to VFR Sunday afternoon as onshore winds return with a few stronger gusts in the Salinas Valley tomorrow. && .MARINE...as of 01:56 PM PDT Saturday...Low pressure west of San Francisco will bring scattered showers and possible thunderstorms through the afternoon hours. Moderate southerly winds along the inner waters will turn southwest tonight and decrease. Northwest winds will increase Sunday and Sunday night. A mixed northwest swell and a building southwest swell will impact the waters through the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Mry Bay SCA...Pigeon Pt to Pt Pinos 0-10 nm && $$ PUBLIC FORECAST: Dykema AVIATION: DK MARINE: W Pi Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Riverton WY
545 PM MDT Sat May 30 2020 .SHORT TERM...Tonight through Sunday Night This afternoon and evening look to be fairly active with widespread convection. SPC has much of our CWA in a marginal risk, with the exception of our southwest zones. A well developed circulation just off the San Francisco Coast will move northeast through tonight and morph into an open wave/vigorous shortwave. This shortwave will track northeast across western Wyoming by 15Z Sunday. In addition, a "ridge rider" or vort max will crest the exiting ridge across our northern zones around 00Z this evening ahead of the main approaching shortwave. This means two distinct periods of convection and two distinct areas of enhanced convection. The HRRR depicts the first thunderstorms to lead off this afternoons performance across Sweetwater County by as early as 18Z this afternoon. This activity will eventually migrate into juicier air over our northern and eastern zones by 00Z this evening, coincident with the aforementioned lead vort max. The highest capes are progged to be over northeast Natrona and Johnson Counties between 21Z and 03Z this evening. The GFS has been insistent on placing a bulls eye of higher precip over southern Johnson County between 01Z and 03Z this evening for the last couple of days. PW values are 160 percent of normal. It could be that right around 00Z, when the "ridge rider" vort lobe rides right over the ridge axis, which will likely be overhead by 00Z this evening, could slow down these anticipated heavy rainers enough to where we actually do see some copious amounts of rainfall in the area of the progged bulls eye over Johnson County as depicted by the GFS. Something to watch for anyway. In addition, lifted indices are progged to be -7 in northern Johnson County by 00Z this evening (-9 in nearby Sheridan County). Lifted indices of -4 are expected in far western Wyoming as early as 18Z this afternoon (minus 6 in nearby eastern Idaho). However, moisture and lift will not arrive in that particular area unto 00Z this evening when the far west gets grazed by some thunderstorm activity by the aforementioned lead vort lobe. Scattered less intense thunderstorms are expected across the rest of the CWA this afternoon and evening, more so east of the Divide, with the greatest threats locally heavy rainfall, small hail, and gusty winds. Then later tonight, the actual main shortwave trough tracks across the CWA from the southwest. The increasing southwest flow will become more difluent ahead of this approaching shortwave. The last of the significant thunderstorm activity should be exiting our northeast zones to the northeast by around 06Z tonight. By 04Z, the second wave of thunderstorm activity associated more directly with the main shortwave will move northeast over the southwest quarter of the southwest zones. The HRRR depicts enhanced activity as late as 08Z tonight, with one enhanced area of thunderstorm activity over South pass and the other over the Jackson area. Then this convective activity will continue to march northeast across the northeast half of the CWA in the form of decreasing shower activity before exiting to the northeast in the wee hours of the morning. The shortwave, as mentioned earlier, should come through around 15Z Sunday morning tracking southwest to northeast. Then drier air will filter in from the southwest behind it more anticyclonically, leading to an influx of dry stable air for an enhanced critical fire weather day. With southwest winds of 25 to 35 mph, minimum relative humidity 13 to 15 percent east of the Divide and in Sweetwater County, and some temperatures east of the Divide will ranging from 90 to 96 degrees (hottest temperatures so far this season), an RFD may be needed for some of our zones for Sunday afternoon, especially in areas that may not see much rainfall form todays thunderstorms. Even though 700mb temps will climb to around 15C on both sides of the shortwave, there will be more solar insulation Sunday. One side note, northeast Johnson County could see a rogue strong thunderstorm due to lingering dynamics and instability, with SPC placing this area in a marginal risk. Sunday night will be clear and cool. Another side note, we will continue to monitor area streams and creeks as river stages continue to rise due to very warm ambient air temperatures and anticipated rainfall on snow pack. Right now, significant main stream river flooding is not anticipated, but river stages due to spring run off conditions will continue to rise. .LONG TERM...Monday through Saturday Medium-range forecast models in very good agreement with overall pattern evolution on the synoptic scale. Monday will find southwest flow across the forecast area as an upper-level ridge axis stretches north through the Northern Plains. Surface wind speeds Monday afternoon should be similar to those seen Sunday with widespread southwest 15 to 30 mph. Temperatures will be 15 to 20 degrees above normal with the southwest and areas east of the Continental Divide in the 80s to lower 90s. Temperatures will be cooler across the far west where 700mb temperatures are 3-5C cooler. Monday and Monday night will be dry although a stray shower cannot be ruled out across the far northwest Monday night. Any stray shower would likely be associated with the tail end of a shortwave set to swing through Alberta. This tail end will drape west-to-east across the far north Tuesday afternoon thereby improving shower and thunderstorm chances across the far north. A weak frontal boundary will also begin a southward trek Tuesday afternoon with a better push coming Tuesday evening. Temperatures will be cooler Tuesday as this shortwave dampens the upper ridge and the flow becomes more zonal. This zonal pattern will prevail Wednesday and Thursday with diurnally-driven convection anticipated. Temperatures will still be 10 to 15 degrees above normal. The next chance for more widespread convection is likely to be Friday in response to an upper low off the California Coast moving onshore and through the Great Basin Friday. Moisture and instability will increase Friday and linger Friday night as this feature approaches and cross the forecast area. The track and timing of this system could impact the potential for stronger convection, especially across southwest Wyoming, Friday afternoon. Drier conditions along with a slight cool-down can be expected Saturday in the wake of this upper low. The next upstream system approaches the Pacific Northwest Saturday, which will again place Wyoming in southwest flow aloft. Expect an increase in southwest Wind in the Wind Corridor. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 544 PM MDT Sat May 30 2020 Convection already erupting across southwest Wyoming and then higher terrain of central and northern Wyoming this afternoon. The convection will begin to merge and intensify east of the Continental Divide later Saturday afternoon with the potential for strong thunderstorms. These storms are likely to produce small hail and gusty outflow wind by early Saturday evening. Moisture profiles for late May are plenty wet, so heavy rain will produce brief periods of IFR/MVFR conditions between 00Z-04Z/Sunday. The best chance for heavy rain will be at KCPR, and to a lesser extent KRIW and KLND. All terminals to be VFR after 06Z/Sunday. A secondary weather disturbance will approach from the southwest late Saturday evening. After a dry afternoon, this secondary wave may provide an opportunity for showers and a lone thunderstorm at KJAC toward 06Z/Sunday. Expect at least isolated light showers through the overnight hours in association with this wave. Conditions dry out around sunrise Sunday with much drier weather Sunday afternoon as the moisture is shunted to our east. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... A series of weather disturbances will cross Wyoming from southwest to northeast between Saturday afternoon and early Sunday morning. The showers and thunderstorms will produce brief bursts of heavy rain, particularly over Johnson and Natrona counties, most likely Saturday evening. Some thunderstorms could become strong east of the Continental Divide. Coverage is expected to be much less across the Teton and Yellowstone dispatch areas. Conditions turn drier Sunday and Monday regionwide. Cooler air will slide into far west Wyoming, while a return to southwest flow aloft will boost temperatures east of the Divide. This southwest flow will also favor gusty southwest wind across the High Desert District northeast into Natrona County both days. The wind will further aid warming temperatures and lower relative humidities. This combination could lead to elevated fire weather conditions both afternoons. Smoke dispersal will be excellent each afternoon for almost all areas, buy most definitely across the windy areas of southwest and central Wyoming. The trend Tuesday will be toward slightly cooler temperatures and at least widely scattered afternoon showers and thunderstorms across the Teton, Yellowstone, and northern Cody dispatch areas. && .RIW WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Lipson LONG TERM...CNJ AVIATION...Jones FIRE WEATHER...CNJ