Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/27/18


Area Forecast Discussion
National Weather Service Bismarck ND
1006 PM CDT Wed Sep 26 2018 .UPDATE... Issued at 1006 PM CDT Wed Sep 26 2018 Little change with this forecast update. A cold front approaching the US Highway 2 corridor across northwest and north central North Dakota as of 03 UTC will continue to propagate southeast through the night with scattered rain showers behind the boundary. UPDATE Issued at 643 PM CDT Wed Sep 26 2018 Did add a slight chance mention of thunderstorms to the Turtle Mountains through sunset per upstream trends across Canada. However, this activity is quickly weakening as of 2342 UTC. && .SHORT TERM...(This evening through Thursday) Issued at 320 PM CDT Wed Sep 26 2018 Scattered light showers will continue across the north central and northeast for the next couple of hours. A second wave of scattered showers will accompany a cold front that will sweep across the state north to south overnight. Various iterations of the HRRR have suggested an isolated lightning strike or two may be possible with this activity around the Turtle Mountains tonight and the latest HRRR and the RAP iterations show 0-3 km MUCAPE values possible ranging from 100 to 250 J/kg. However, confidence is extremely low so did not introduce any thunder in the grids at this time. Behind the initial cold front Thursday, expect brisk and cooler conditions. Northwest winds will range between 15 and 25 mph, and afternoon highs in the mid 40s north to the lower 50s south. .LONG TERM...(Thursday night through Wednesday) Issued at 320 PM CDT Wed Sep 26 2018 As a highly amplified upper level ridge remains firmly in place off of the west coast, widespread sub-freezing low temperatures will stream in from Canada Thursday night/Friday morning, ranging from between 27F and 32F. Freeze headlines will likely need to be issued at some point, tonight or Thursday, to reflect the anticipated freezing temperatures Friday morning. During the day on Friday, surface high pressure will slide into the Northern Plains from Saskatchewan, promoting well below normal highs in the 40s, clear skies, and northwest winds around 15 mph. These conditions will result in apparent temperatures to feel more like the upper 30s for most of the day. Nearly a repeat performance in low temperatures are expected Saturday morning with lows forecast in the upper 20s to lower 30s. A slight chance of rain and/or snow showers will be possible across the south central and southern James River Valley on Saturday. By the end of the weekend, global models are in good agreement that the ridge off the west coast will begin to deamplify and retrograde, transitioning us into a fast zonal flow aloft. With this pattern, expect periods of potential light snow/rain showers on and off Sunday and Monday. After Monday, model agreement begins to break down but a progressive northern stream trough may deepen over the pacific northwest, transitioning us briefly into southwest flow with more potentially active weather and near normal to below normal temperatures through mid week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 1006 PM CDT Wed Sep 26 2018 A cold front entering northwest and north central North Dakota as of 03 UTC will move southeast tonight with scattered rain showers. Ceilings may fall to MVFR across southwest North Dakota late tonight into early Thursday morning. Additional MVFR stratus may move into far northwest and north central North Dakota and the upper James River Valley during the morning on Thursday, possibly impacting KMOT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...PA SHORT TERM...ZH LONG TERM...ZH AVIATION...PA
Area Forecast Discussion
National Weather Service Marquette MI
753 PM EDT Wed Sep 26 2018 .SHORT TERM...(This evening through Thursday) Issued at 414 PM EDT WED SEP 26 2018 WV imagery and RAP analysis indicated a broad mid/upper level trough from north central Canada and Hudson Bay through the cntrl CONUS resulting in westerly flow through the northern Great Lakes. Upstream shortwaves were located over srn Manitoba and nrn Alberta. With 850/700 mb temps to around 1C/-10C, sct/isold diurnal that developed over wrn Upper Michigan were gradually shifting to the east. Tonight, The diurnal -shra should continue to move off to the east and weaken this evening as the 700 mb trough exits the area. Expect showers over nw MN associated with 700-300 qvect conv ahead of the Manitoba shortwave to gradually slide eastward into the northwest half of Upper Michigan overnight. Otherwise, clouds will increase and thicken over the rest of the area overnight. Persistent sw winds to around 10 mph will also keep temps from dropping off too far with readings remaining in the lower to mid 40s. Thursday, the initial band of showers should weaken during the morning over central Upper Michigan. As the second stronger shrtwv moves in during the afternoon, the shower coverage will increase over the west half by early afternoon and across the east through the rest of the afternoon. With moderate southwest winds continuing, highs will climb into the mid 50s west to the lower 60s south and east. .LONG TERM...(Thursday night through Wednesday) Issued at 254 PM EDT WED SEP 26 2018 Upper air pattern consists of a 500 mb trough across the central U.S. with a ridge in the desert sw and one off the sern coast 00z Fri. There is a shortwave in the upper Great Lakes 00z Fri. A trough remains over the upper Great Lakes through 00z Sun. Temperatures will remain below normal for this forecast period with periods of rain and dry weather and pretty active with weak systems moving through. Overall, did not make too many changes to the going forecast. In the extended, the GFS and ECMWF show a broad 500 mb ridge across the sern U.S. and a trough in the western U.S. with a broad trough across most of Canada with some colder air across the northern U.S. 12z Sun. A sfc cold front moves through the upper Great Lakes on Sun. This sfc front stalls out to the south on Mon with upper troughing remains in the western U.S. through Tue and the ridge remaining over the sern U.S. 12z Tue. This ridge builds on the east coast 12z Wed with troughing digging in the western U.S. and a sfc front still remaining over the upper Great Lakes. Temperatures look to be mostly below normal for this forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 741 PM EDT WED SEP 26 2018 VFR conditions are anticipated to prevail through the remainder of the evening hours, with more cloud cover expected overnight. The primary concern for aviation interests will be a nocturnally- driven low-level jet cranking up overnight, with wind shear looking likely at KIWD and KCMX. The confidence of LLWS coming to fruition at KSAW is much lower, given the placement of the LL jet, and have therefore negated mention there for this TAF issuance. Showers could once again pop-up as well later tonight, although there is higher confidence in more widespread shower activity early Thursday morning through much of the day. As the LLWS dissipates in the early morning hours, look for an increasing concern for reductions in ceilings as a stratus deck builds in. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 414 PM EDT WED SEP 26 2018 Tonight into early Thursday, an approaching low pressure system from the north will allow winds to become southwesterly at 20 to 30 knots. Expect winds to die down to 10 to 20 knots during the day on Thursday, then becoming northwesterly 15 to 25 knots Thursday night through Friday. Winds will remain between 15 and 25 knots through the weekend. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... Gale Warning from 10 AM to 8 PM EDT Thursday for LMZ248-250. && $$ SHORT TERM...JLB LONG TERM...07 AVIATION...lg MARINE...JLB
Area Forecast Discussion
National Weather Service San Francisco Bay Area
549 PM PDT Wed Sep 26 2018 .SYNOPSIS...Seasonably warm conditions are expected through Thursday. A cooling trend will begin Friday as an upper trough passes north of the Golden Gate with a slight chance of showers in the North Bay on Saturday. Dry and seasonable conditions expected on Sunday. Then a possibility of rain early next week when another upper trough moves through. && .DISCUSSION...as of 12:59 PM PDT Wednesday...Satellite imagery shows stratus has cleared back to the coast and current temperatures are running fairly similarly to those from 24 hours ago. Little change in marine layer depth, as well, and surface pressure gradients remain weak onshore near the coast, and tighter offshore with 7.6 mb between WMC and SFO. Look for another warm day on Thursday for inland locations, but this might be the last one for a while as the weather pattern shifts. The approaching upper level low over the Eastern Pacific is forecast to approach the Northern California coast by Friday, then move inland during the weekend. Although model solutions are still different, there is better agreement between the GFS and ECMWF regarding shower chances across Northern California on Saturday with this low as it moves through. Best chances would probably be north of our CWA but the slight chance pops we have for the North Bay continue to look reasonable. That feature will move inland on Sunday for dry and seasonable weather for Sunday. Early next week, the forecast gets interesting with the possibility of moisture from now Tropical Storm Rosa getting infused in an upper trough and upper low along the west coast bringing better rain chances to portions of California on Tuesday and Wednesday. There is still uncertainty with this and everything depends on the timing of the upper low with respect to when moisture from Rosa advects northward. Latest runs of medium range models have slight timing and placement differences regarding the Eastern Pacific low. The operational run of the 12Z GFS features a low center farther south, which places most of the rainfall over central and southern California and into Arizona. The 12Z ECMWF has the low center farther north as it moves eastward into California and spreads rainfall across much more of the state. In either case, cooler temperatures will occur, with highs in the 70s and 80s inland, with 60s along the coast. && .AVIATION...as of 5:49 PM PDT Wednesday...A late afternoon steepened ocean to land thermal contrast and a compressed marine layer between 500 and 1,000 feet deep will usher coastal stratus and fog inland on onshore winds through the evening. It`s LIFR-IFR along the coastline, VFR inland. Mainly light amounts of smoke and haze from wildfires on the CA/OR border will continue to advect into the Bay Area tonight and Thursday according to the 18z HRRR near smoke forecast; surface vsbys are good /greater than 6 miles/, but it does look hazy aloft on the webcams. Restricted slant range visibilities are very likely to extend into Thursday. Weak upper level divergence far ahead of a closed 500 mb height low pressure center 800 miles SW of the Bay Area will continue to bring sct-bkn cirrus clouds in tonight and Thursday. Fairly well established lower to mid level ridging over California will undergo little change tonight and Thursday. Lower level cooling near 925 mb begins to ramp up Thursday night through Friday, most likely deepening and weakening the marine layer in our forecast area. Vicinity of KSFO...Low to moderate confidence VFR holds into the evening, tempo bkn cig forecast 12z-16z Thursday. Westerly wind is picking up a bit stronger per recent 5 minute observations, gusts nearing 25 knots. VFR Thursday. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...IFR cigs developing early, IFR tonight into Thursday morning. VFR returning either by late morning or early afternoon Thursday. && .MARINE...as of 4:50 PM PDT Wednesday...A trough of low pressure near the coast will maintain generally weak west to northwest winds across the coastal waters through Friday. Winds will turn southerly this weekend as a low pressure system develops off of the Pacific Northwest Coast. A long period southerly swell will gradually build beginning late in the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...None. $$ PUBLIC FORECAST: Sims AVIATION: Canepa MARINE: RGass 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 Paducah KY
1019 PM CDT Wed Sep 26 2018 .UPDATE... Issued at 1019 PM CDT Wed Sep 26 2018 00z NAM adds support to expanding PoPs for light rains farther north into the CWFA for the late night into Thursday morning. We made this northward adjustment and upped QPF slightly, primarily west KY. The RAP and HRRR remain quite consistent that this light rain event will happen. Our PoPs are still not as high as the high res guidance. We continue to incorporate the uncertainty element given a dry forecast was inherited. The midnight shift will have time to make adjustments with the routine daytime forecast issuance around 3 or 4 a.m. CN UPDATE Issued at 644 PM CDT Wed Sep 26 2018 Updated aviation discussion. && .SHORT TERM...(Tonight through Friday night) Issued at 200 PM CDT Wed Sep 26 2018 The surface cold frontal boundary has pushed thru the FA, but is not too far away...stretching from eastern Ky southwestward across central Tn. It is progged to sink very slowly to the south and east with time. Even so, overrunning clouds may still impact, mainly, our southeastern counties. In addition, mid to upper level sourced moisture/clouds are possible as upper wind core steers across the mid Mississippi river valley, as an H5 2ndary trof makes passage during the next 24 hours. This may squeeze out an isolated shower even, but at this writing, we`re leaning toward a silent Pop, and leaving the forecast dry. Otherwise we see surface high pressure take over the entirety of the lower Ohio and Mid Mississippi river valley thru the remainder of the short term. 12z modeling of the drier air behind the front, is not as robust with the thrust of 40s dew points into/across the area. Still, it will be our first good taste of Fall, as 47-50F dew points have already entered our northwestern counties. These will extrapolate southeastward with time, as we see still mid 60s dew points existing at this writing across our southeastern counties. By trmw, we`ll all range right around 50F. Temps will be cool as Lows drop to/thru the 50s each night, and Highs in the 60s/70s warm slightly by week`s end with a little more sun on Friday. .LONG TERM...(Saturday through Wednesday) Issued at 200 PM CDT Wed Sep 26 2018 Good model agreement lends to high confidence to start the long term portion of the forecast. Confidence decreases somewhat towards the beginning of next week with greater model variability. Starting with the weekend, dry weather is forecast to persist as an expansive area of high pressure migrates southeast from the Great Lakes into the Ohio Valley and Mid Atlantic. As this occurs, expect a gradual warming trend through the period while an upper level ridge builds across the southeastern U.S. High temperatures should moderate from the 70s on Saturday back to near 80 Sunday and Monday and then perhaps the mid 80s by Wednesday. Lows are forecast to warm from the mid 50s Saturday night back into the 60s through the rest of the period. As southerly flow develops on the back side of the departing high, return moisture could result in a small chance of showers and thunderstorms early in the new week. However, models are not in the best agreement on exactly how and when this occurs. As a result, we will keep just a small chance across much of the area Monday into Tuesday. && .AVIATION... Issued at 644 PM CDT Wed Sep 26 2018 VFR conditions are expected across most of the area through the 24 hour TAF period, including the TAF sites. The only possible exception to this will be the southern Pennyrile region where cloud bases may drop below 3000 feet in the afternoon. Some shower activity is possible across most of western KY Thu morning, with no significant vsby restrictions expected. Generally light northerly winds will veer to a more easterly direction by Thu afternoon. Increasing clouds tonight will be on the wane by Thu evening. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$