Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/06/17

Area Forecast Discussion
National Weather Service Albany NY
1032 PM EDT Thu Oct 5 2017 .SYNOPSIS... Seasonably mild temperatures are expected Friday, becoming increasingly warmer and more humid into the weekend. Mainly dry weather is expected through Saturday aside from a few isolated light showers. A passing frontal boundary may bring scattered showers Saturday night into early Sunday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 1032 pm edt...IR satellite imagery shows a solid area to mid and high level clouds continues to be located across parts of the mid-Hudson Valley and into NW CT. These clouds are associated with some showers that are currently impacting eastern PA and northern NJ along a stationary boundary. Clouds are generally moving west to east across the area and they may gradually start to clear out of these areas after midnight. Based off the latest 3km HRRR and current radar trends, will allow for a slight chance for rain showers for far southern areas for the next few hours, but it appears most of these showers will continue to remain south of the area. Further north, skies are mainly clear for much of the Capital region and southern VT, but some clouds are starting to expand across Lake Ontario and into the Adirondacks. These northern clouds will continue to expand south and east through the overnight hours, allowing areas that are currently mostly clear to become partly to mostly cloudy by later tonight. Overnight, we remain beneath fast midlevel quasi-zonal flow that becomes slightly cyclonic. A weakly defined boundary will approach from the northwest and with weak forcing for ascent, we could see isolated showers or sprinkles fall out of a midlevel cloud deck towards daybreak, although there is expected to be a fair amount of low-level dry air which should serve as a limiting factor. Maintained mention of slight chance PoPs for late tonight for northern parts of the area. Otherwise, a mild night with partly to mostly cloudy skies helping to keep temps elevated mainly in the 50s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... Flow pattern during the period over the local area will transition from quasi-zonal to ridging as a strong shortwave trough crosses the Plains and deamplifies as it tracks into the western Great Lakes and southeastern Canada by the end of the period. Weak height rises will begin later in the day on Friday. Although we will likely start the day with some mid and high clouds and possibly a few sprinkles or light showers, a clearing and drying trend is expected by the afternoon and evening. High temperatures will be dependent on just how fast skies clear, with still a fair amount of spread in the guidance. Superblend temps represent a good compromise between cooler/cloudier METMOS and warmer/clearer MAVMOS. Regardless, expect temps to continue to be above normal, though perhaps slightly cooler than today. Warm front attendant to strong cyclone tracking from the Upper Midwest into Ontario will pass through the region Friday night. Convergence and lift along this boundary is expected to be better further west, so have just a slight chance for showers late Friday night into Saturday morning. Consensus puts us solidly in the warm sector for the majority of Saturday. Still could be some clouds around, especially early, which could impact high temperatures. Guidance has been trending warmer, and there is the possibility for overachievement if clouds dissipate early and deeper mixing occurs. Regardless, it is expected to be unseasonably warm and becoming more humid and a bit breezy. The aforementioned midlevel wave will deamplify considerably by the time it tracks north of the St. Lawrence Valley Saturday night. Ahead of the boundary, a strong southerly flow will keep temps very mild at night, with lows only falling into the 60s (closer to our normal highs for this time of year). The attendant frontal boundary will weaken as it tracks into the area during the same time frame, and there is not expected to be any cold advection behind it. In fact, Sunday may be the warmest day of the weekend, with guidance suggesting highs in the low 80s in the valleys are possible. Dewpoints rising into the mid-60s should give a little summer-like humidity as well. Some showers and perhaps a thunderstorm are possible along the weakening front and healthy low-level jet late Saturday night into early Sunday, but a clearing trend is currently expected for later Sunday. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Above normal warmth will continue through much of the long term period, as high upper level heights remain in place over the eastern CONUS and western Atlantic Ocean, thanks to an area of strong upper level ridging just offshore the southeastern US. However, there will be some chances for rainfall, as the remnants of TC Nate eventually work its way northward. At the start of the period, high pressure will be located north of the region, although clouds will be increasing on Sunday night, as the remains of TC Nate head northward across the Deep South. With a deep southerly flow at all levels, moisture will be increasing throughout the region. Although some showers are possible as early as Sunday night, the better chance won`t be until Monday, as the remnants are expected to track across the Ohio Valley. PWAT values to increase to around 1.50 to 2.00 inches, with the highest values across southern areas. Based off the 12z GEFS, these values are 2-4 STD above normal. Based off the latest model guidance and info from NHC/WPC, have gone with likely showers for Monday into Monday night, as the remnant low tracks towards Pennsylvania. Showers should taper off from west to east on Tuesday, as the best forcing departs off to the east. QPF amounts still vary between the models and ensembles, as a lot will depend on exactly where the remnant low tracks. The 12Z GEFS shows a mean of around an inch or so for Albany, with deterministic guidance showing little in some spots up to two inches or so for others. The fast movement of the remnants, the far removal from the Gulf Coast and the dry antecedent conditions should help limit the impact across our area, but will have to watch for brief periods of locally heavy rainfall at times early next week. Behind this system, there may be a brief break, before a northern stream shortwave and associated cold front approaches for the middle of the next with some additional rain showers. Have gone with a chance of showers for Wednesday into Thursday based on this possibility. Temps early in the week will continue to be very mild, with valley highs in the 70s and lows only in the 50s and 60s. Behind the mid- week cold front, daytime temps should cool down closer to normal, with highs only in the 60s by Thursday and lows down into the 30s and 40s. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... VFR conditions are expected overnight. Mid and high level clouds associated with a stationary boundary are in place across southern areas. Meanwhile, an upper level disturbance passing by to the north will make its closest approach for later tonight, which should allow for clouds to also increase for northern areas after 06z. With bkn cigs in place, no radiational fog is expected overnight tonight. Cannot totally rule out a brief shower thanks to the northern stream feature late tonight into early tomorrow morning (mainly for northern areas), but this will have little impact on visibility and ceilings. Winds overnight will be light to calm for all sites. On Friday, ceilings will continue to bkn around 6-12 kft throughout the day, with the lowest ceiling heights across northern and high terrain areas. Still, VFR conditions will continue to be in place and just a spotty light rain shower is expected for early in the day. Westerly winds will increase to around 5 kts for all sites. Outlook... Friday Night: Low Operational Impact. Slight Chance of SHRA. Saturday: Low Operational Impact. Slight Chance of SHRA. Saturday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Sunday: Moderate Operational Impact. Chance of SHRA. Sunday Night: Moderate Operational Impact. Chance of SHRA. Columbus Day: High Operational Impact. Likely SHRA. Monday Night: Moderate Operational Impact. Likely SHRA. Tuesday: Moderate Operational Impact. Likely SHRA. && .FIRE WEATHER... Seasonably mild temperatures are expected Friday, becoming increasingly warmer and more humid into the weekend. Mainly dry weather is expected through Saturday aside from a few isolated light showers. A passing frontal boundary may bring scattered showers Saturday night into early Sunday. RH values will remain elevated Friday into the weekend, likely not dropping below 50 percent. Winds will be westerly at 5 to 10 mph Friday, becoming a bit breezy over the weekend from the south at 10-15 mph with some gusts in excess of 20 mph. && .HYDROLOGY... A few showers are possible at times through the weekend in association with weak frontal boundaries, but QPF totals are expected to remain below a quarter of an inch. There is the potential for a more widespread rainfall early next week associated with the remnants of Tropical Cyclone Nate approaching from the southeast CONUS, although confidence is low at this time. Due to antecedent dry conditions, flooding is not anticipated at this time, but conditions will continue to be monitored. This would be the first widespread rainfall since early September if it does occur. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Thompson NEAR TERM...Frugis/Thompson SHORT TERM...Thompson LONG TERM...Frugis AVIATION...Frugis FIRE WEATHER...Thompson HYDROLOGY...BGM/Thompson
Area Forecast Discussion
National Weather Service Caribou ME
1029 PM EDT Thu Oct 5 2017 .SYNOPSIS... Temperatures on Friday will be near normal as a more seasonable airmass moves into the state. High pressure will crest across the region Friday night with a warm front lifting through on Saturday. Unsettled weather is expected early next week. && .NEAR TERM /THROUGH FRIDAY/... 1025 PM Update... Added some pops(20%) across the n as radar showed some light returns and KFVE showing light rain in the latest ob. Activity was moving through pretty quick(20 mph). Upper Air analysis showed disturbance moving into the region. RAP sounding w/the support of the KCAR sounding showed moisture available in the 850-700mb layer w/a decent wsw jet streak of 30+ kts. Rainfall amounts will be around a trace. Hrly temps/dewpoints were adjusted to fit the current conditions. Satl imagery showed clouds moving across the region but showed signs of clearing coming into wnw areas. Decided to stay w/the daycrew`s setup of going partly cloudy skies later tonight. Overnight lows of mid to upper 40s across the northern 1/2 of the CWA w/low 50s central and downeast areas. Previous Discussion... The front has pushed off the coast with secondary cdfnt located acrs nwrn Quebec this aftn. This fnt wl head south ovrngt but only expect an increase in clds as CWA wl lkly receive just a glancing blow fm fropa as it mainly heads east into the Maritimes. Upr lvl s/wv mvs thru the state in the aftn which may result in an isold shower acrs cntrl sxns drg the main part of the day Fri. Min temps for tonight ahd of the weakening bndry wl run in the u40s acrs the north to arnd 50F for the south. Max temps wl be near normal if not slightly abv for tomorrow aftn. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... High pressure and quiet for Friday night with seasonably cool temperatures generally in the 30s, cooler in the lower valleys. High pressure quickly moves east on Saturday. Look for increasing and thickening clouds ahead of a warm front. A chance of showers western areas late in the day. Best chance of showers is Saturday evening as the warm front moves through, but even at that, expect at most about a quarter inch far Northern Maine and lesser amounts further south. Expect temperatures to remain steady or possibly slowly rise Saturday night. Also expect areas of fog and low clouds as we get into a warm and muggy airmass (by October standards). Sunday will be warm, breezy, and fairly muggy with highs in the 70s. A potential decent shortwave moving through aloft gives us a decent shot at showers, but it won`t be an all day rain by any means. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Forecast confidence very low Monday onward. Appears at least somewhat unsettled Monday and Tuesday with moist SW flow, potentially with some moisture from what`s leftover of Nate. However, models disagree a lot on precip amounts. It`s possible the rain gets to all of the forecast area and brings over an inch of rain. It`s also possible the moisture stays south and only Downeast gets clipped with a bit of rain on the far north edge of the moisture plume. Most models agree on cooler and drier air working in for Wednesday and Wednesday night. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... NEAR TERM: VFR next 24 hours. Gusty WNW winds will diminish this evening. SHORT TERM: VFR Friday night into Saturday outside of patchy valley fog late Friday night. Saturday night, however, expect widespread IFR ceilings to develop after midnight with moist onshore flow. Toward the coast, these IFR conditions may persist most of the day Sunday. Somewhat unsettled pattern continuing Monday and Tuesday. && .MARINE... NEAR TERM: Wind and seas will remain below small craft levels into Friday. SHORT TERM: Quiet Friday night and Saturday, but then expect small craft winds and seas on Sunday. Small craft conditions could persist into early next week, but forecast confidence is low. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Hewitt
Area Forecast Discussion
National Weather Service Cheyenne WY
817 PM MDT Thu Oct 5 2017 .UPDATE... Issued at 803 PM MDT Thu Oct 5 2017 Visibility is dropping along I-80 especially between Cheyenne and the summit early this evening. HRRR and other hi-res guidance suggests fog will thicken and persist through around 10-12z. Issued a Dense Fog Advisory for the summit area through 12z. && .SHORT TERM...(This evening through Saturday) Issued at 311 PM MDT Thu Oct 5 2017 Fog is expected to develop once again along the I-80 corridor from Laramie to Sidney by 03z this evening given weak low-lvl gradients and considerable boundary layer moisture already pushing west into far southeast Wyoming per GOES-16 Visible data. Moist E-SE surface flow will promote areas of fog/drizzle through the night, probably spreading across the rest of the high plains by 12z Friday. Expect to see some improvement by about 15z as model soundings show rapid erosion of low-level moisture in the early AM hours. The latest WV satellite loop shows an upper-level low spinning along the Idaho & Nevada border. Increasing southwesterly flow aloft, along w/strong jet dynamics and low-level convergence invof a weak cold front may support a good chance for showers across the CWA from late tonight through mid-day Friday. Winds are the main concern after 00z Saturday. A significant upper level disturbance is progged to blast southeastward along the US & Canada border over the Pacific NW on Friday evening, with the nose of a 120-130 knot H25 jet over much of MT by 12z Saturday. This is likely to be a favorable position for strong subsidence across the CWA, especially for southeast Wyoming. Low-level gradients will be nothing short of impressive for early October, with what should be a classic orientation for our wind prone areas. The H85 CAG to CPR gradient climbs above 60 meters by 03z Sat, and above 70 meters by 06 Saturday per the GFS while the NAM is only slightly weaker, but still significant w/ the gradients. The models are showing a swath of 50-60 knot H7/H75 flow over the wind corridors from 6z Sat thru 0z Mon, and some of this stronger flow may be near the surface per 0.5 km AGL wind progs. This is a classic high wind pattern for the area, and in-house probabilistic guidance suggests this as well at Bordeaux. Downward momentum transfer will easily occur given large scale subsidence in place. We decided to go ahead and issue a High Wind Watch for the wind prone areas (ARL/BRX/VDW) from 3z Sat thru 18z Sat, when gradients appear to weaken somewhat. We are a little concerned about Cheyenne early Saturday AM as well as models still show stronger omega spreading over I-25, and 50+ knot flow is less than 1500 feet off the ground per BUFKIT soundings. The next shift will want to consider adding Cheyenne to the Watch. Strong downsloping is expected along the I-25 corridor on Saturday afternoon, so critical fire weather conditions may become a bit of an problem as well. We lowered dew points about 5F below consensus guidance between Cheyenne and Wheatland, and increased highs about 5F above consensus. This resulted in RH values as low as 10 pct w/ strong and gusty winds. This could require a Fire Weather Watch in the next 12 hours or so. .LONG TERM...(Sunday through Thursday) Issued at 334 AM MDT Thu Oct 5 2017 Flow continues to back on Sunday as a trough carves into the intermountain west. Model solutions have become a bit more congruent in overall pattern progression, but still differ on precipitation on timing and residence time. Initial push of the cold front arrives on Saturday night, with a second stronger reinforcing front pushing thru later on Sunday. The 00z ECMWF has trended toward previous GFS output, digging the the trough deeper. The ECMWF still doesn`t cut-off energy near the four corners as is (and has been) progd in GFS solutions. As a result, precip onset is earliest in the ECMWF perhaps as early as Sunday afternoon/night. The progressive nature of the ECMWF pushes precip out sooner too, drying things out for Monday & beyond. In comparison, the GFS is slower with the front and precip, not impacting the region until Sunday night and continuing thru Monday night. Not sure which way to lean here just yet, but am beginning to thing a compromise more in line of the slower GFS makes the most sense given how the last few systems have behaved. So, have increased precip chances especially across southeast Wyoming Sunday night and Monday. Even though details still need to be ironed out over these next few days, what is NOT in question is the strength of the cold air mass that moves behind the front. Likely the coldest of the season thus far. Snow levels will fall to 4500-5000 feet Sunday night and Monday. In fact, high temps on Monday will only reach the 30s above 5000 feet, with 40s for elevations below. A period of accumulating snow remains a possibility Sunday night and Monday. Those with travel interests Monday will want to keep an eye on later forecasts. Dry and slowly moderating temperatures return Tuesday-Thursday as broad ridge and/or more zonal flow ensues. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 525 PM MDT Thu Oct 5 2017 Large low cloud deck continues to expand over the plains. Ceilings should gradually lower through the evening with widespread IFR developing between 06 and 10z for all areas with the exception of the far north and west where MVFR was maintained. Some drizzle or light rain can`t be ruled out which actually may help to prevent widespread dense fog formation but still expect pockets of IFR vis as well. Ceilings will be slow to lift tomorrow morning especially over the panhandle. VFR is expected to return by early morning over SE Wyoming as a cold front crosses the area. West winds will likely gust to around 35 kt over and west of the Laramie Range on Friday. && .FIRE WEATHER... Issued at 311 PM MDT Thu Oct 5 2017 Saturday will be the warmest of the next several days, and as such will feature the only concerns for critical fire weather. The main area of concern will be the I25 corridor from Cheyenne - Wheatland as strong downsloping winds develop. Wind gusts over 45 MPH should occur with highs in the mid 70s. Significant drying is also likely to push RH values into the lower teens. No concerns after Sat as a strong cold front brings sub-freezing temperatures and wide-spread snow by Sunday night/Monday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Watch from Friday evening through Saturday morning for WYZ106-110-116-117. Dense Fog Advisory until 6 AM MDT Friday for WYZ116. NE...None. && $$ UPDATE...DEL SHORT TERM...CLH LONG TERM...CAH AVIATION...DEL FIRE WEATHER...CLH
Area Forecast Discussion
National Weather Service Des Moines IA
632 PM CDT Thu Oct 5 2017 .SHORT TERM.../Tonight through Friday/ Issued at 343 PM CDT Thu Oct 5 2017 Stalled boundary over southern Iowa remains the focus for showers and isolated thunderstorms tonight into Friday morning before the main precipitation shield develops and spreads across the state by Friday afternoon. Leaned toward the 05.17z/05.18z HRRR for radar trends this afternoon into tonight and then closer to the 05.12z ECMWF/GFS after 12z Friday. Weak ripples of theta-e advection and moisture convergence remains over western to southern Iowa this afternoon into the evening before the isentropic lift and omega wane b/t 03z-09z Friday allowing for a potential break in the heavier/moderate rain. Still may see a few showers during this time and had low confident going completely dry across the south. Further north, there should be enough subsidence and dry air tonight into Friday morning for a break in the rain. Thus, trended drier on pops during this period and could even trend the advancement of pops over northern to northeast Iowa until after 15z Friday morning as the next slug of theta-e advection is slower to advance than previously anticipated. The better moisture transport, stronger isentropic lift (especially along the 310-320K surface), and decent theta-e advection move into the state b/t 09-15z Friday. The heaviest rain looks to develop by around 12z or shortly after as the condensation pressure deficit along the 320K surface becomes less than 10mb. This strong piece of energy pulls east-northeast of the area by 21z Friday but there is still plenty of weaker forcing for ascent to allow rain to persists through at least 00z Saturday. .LONG TERM.../Friday night through Thursday/ Issued at 343 PM CDT Thu Oct 5 2017 The primary concern remains precip to end the week, followed by less significant temp and precip trends into next week. At onset the current northern NV system will be maturing through the MO Valley Friday evening with cyclogenesis occurring from Iowa into the Upper MS Valley or at least a deepening inverted trough. Strong 850/700mb QG forcing will already be in place across IA at 00z with the warm/theta-e advection max starting to exit to the northeast. Stronger kinematic forcing and frontogenetic response will also be building a bit farther west toward the developing deformation zone. There may be a window for surface based convection and severe weather west as well with MLCAPEs up to +/- 1000 j/kg and 0-6km shear over 40kts. This would introduce some wind and hail potential and depending on where the weak surface waves along the inverted trough develop there could be sufficient warm frontal development and low level backing to boost 0-1km shear and SRH for brief tornado potential. Would not be surprised if the SPC Day 2 severe probs are eventually raised a bit to the north and east. HRW ARW and NMM reflectivity both show strengthening convection 00-03z over the NW half of IA. There will continue to be a heavy rain threat Friday evening and overnight as well. Individual cells will likely be moving fairly quickly to the NE but the overall system movement will be slower with the mean wind parallel to the inverted trough/front. Heavy rain parameters remain pegged and near climatological maxes with 4km warm cloud depths and precipitable waters pushing 2 inches. Many parameterized and convection allowing models suggest 1-2 or more 00-06z Friday evening. Those with outdoor events Friday evening, especially the northwest half of the forecast area, will need to monitor conditions for multiple weather hazards. Flood or Flash Flood Watches may be needed by tomorrow depending on how rains play out tonight. The active weather potential will decrease into Saturday but confidence still remains low somewhat low on timing. Although other guidance is faster, The 12z ECMWF continues to depict a stronger mid level wave and slower deformation zone progression so PoPs have continued to increase into the day. The weekend will end with dry conditions but little overall change in temperatures. Looking ahead into next week there will be another iteration of the western long wave trough cycle but with the baroclinicity pushed a bit farther to the south and east. This will bring a short of mid level kinematic and frontogenetic forcing through IA in the cool air sometime late Monday into Tuesday. Recent run to run blends have currently centered PoPs around Monday Night, but timing consistency has been poor so this is certainly subject to change in later forecast cycles, most likely later. The rest of the extended forecast looks dry with fairly flat WSW flow and seasonal temperatures. There could very well be a window with favorable conditions for frost during the early to middle portions of next week, but model timing differences currently make it difficult to pin down when favorable temperatures, light winds and clear skies would phase. && .AVIATION.../For the 00Z TAFS through 00Z Friday evening/ Issued at 632 PM CDT Thu Oct 5 2017 With onset of precipitation and lowering cigs...conditions will vary from IFR to LIFR for most of the period. Periods of -shra and potential for -tsra...especially aft 03z south and again aft 16z Friday spreading from west sites to east until the end of the period. Confidence remains low on exact timing...but a few periods where possible breaks in rain have been indicated by VCSH. Also... vsby may need downward adjustments especially aft 12z when front begins to lift north into area. Will make needed adjustments with next package at 06z and monitor through that time for changes. /rev && .HYDROLOGY... Issued at 343 PM CDT Thu Oct 5 2017 Event total QPF brings rainfall to widespread 2+ by 12z Saturday. RFC river guidance suggests this will mainly be within bank rises with currently only Estherville along the W Fork Des Moines River projected to reach minor Flood Stage where a targeted Flood Watch has been issued. This is heavily weighted on QPF however and is based on 48 hours of forecast rainfall during the cool season versus 24 in the warm season so confidence is medium at best. As one would expect, contingency forecasts suggest locally heavier amounts could also produce more widespread or significant flooding with the Des Moines River Basin favored. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Podrazik LONG TERM...Small AVIATION...REV HYDROLOGY...Small
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1042 PM EDT Thu Oct 5 2017 .UPDATE... In light of radar trends upstream, have updated the forecast to read numerous showers or showers likely tonight mainly north of I 69. Larger scale support for ascent continues to be midlevel equivalent potential temperature washing into the state due to the anticyclonic branch of the low level jet axis. The coverage of precipitation is really surprising given nil shortwave energy amidst what is a fairly broad ridging structure yet at 500mb. Adding it all together but honoring the observational evidence, expecting insignificant total rainfall but carrying likely PoPs tonight. Despite some lightning obs creeping closer, will not be add thunder to the forecast. Forecasted midlevel lapse rates are putrid and Rap based mesoanalysis suggests almost non existent MUCAPES. With no cyclonic flow trajectories, not expecting that to change tonight. Any activity that would be able to persist at daybreak should end quickly at daybreak. Given anticyclonic circulation still expecting quiet weather for the beginning of daylight Friday. && .PREV DISCUSSION... Issued at 726 PM EDT Thu Oct 5 2017 AVIATION... Enhanced midlevel moisture content is washing back into southeastern Michigan this evening. Greatest moisture transport aloft is occurring over sections of central Lower Michigan including the northern cwa. This is in response to the anticyclonic branch of meridional low level jet pushing towards the central Great Lakes. Greatest response for shower activity has occurred along ribbon of moisture/isentropic ascent at 800-700mb. Largely unorganized activity will generally stream eastward during the next couple of hours with some isolated to scattered showers then possible to the south over Detroit metro as outflow sags southward. Low confidence in timing of any singular activity overnight. Conditions on whole should be relatively quiet during the first half of Friday as a midlevel anticyclonic circulation will need to push across the area. Most organized potential and strongest synoptic scale forcing will then ramp up after 20Z Friday from south to north as a strong midlevel warm front at 700-500mb lifts into the region. Rain chances will be highest within this corridor of deep midlevel moisture. //DTW THRESHOLD PROBABILITIES... * Low for ceiling heights at or below 5000 ft agl tonight, high late Friday afternoon. * Low for thunderstorms at any point during the TAF period. PREV DISCUSSION... Issued at 333 PM EDT Thu Oct 5 2017 DISCUSSION... Full sunshine through most of the day has allowed temperatures to climb well into the 70s. Low levels remain dry, as indicated by the surface dew pts currently in the upper 30s to mid 40s Strong mid-upper level westerly flow over the Northern Great Lakes at the top of the ridge axis, with a reservoir of steep mid level lapse rate (7-7.5 C/KM) associated with the 700 mb Theta-E coming out of the Fargo area, spilling over into the Western Great Lakes this evening/tonight, which could support a few high based light showers extending into our area. Otherwise, mid clouds increasing/thickening up at the very least. Strong upper level energy/wave out in the Great Basin will be tracking off into the Central Plains by Friday evening, which will draw the abundant moisture over the Southern/Central Plains northward toward the Great Lakes Region. Respectable warm front to lift into lower Michigan tomorrow, lifting through during the evening hours. Max isentropic ascent/moisture advection displaced just to the northwest, but still expecting eastern arm of the rain shield/showers to extend into the CWA. Would not totally rule out an isolated thunderstorm as well, as showalter index drops slightly below zero. Very warm mid levels (10 C at 700 MB) will then arrive on Saturday, which should set us up for a warm but windy Saturday as southeast Michigan enters the well mixed warm sector. Local probabilistic SREF weighted guidance indicating wind gusts around 40 MPH late in the day, which certainly looks reasonable as 850 mb winds reach at least 50 knots. A wind advisory is not out of the question. 925 MB temps up at 21 C, per 12z NAM, and expecting high temps to easily reach into the lower 80s. The excellent large scale forcing associated with the upper level PV advection looks to be arriving just after 21Z Saturday, but there remains timing and magnitude differences with the phasing/merging height fall centers tracking across the Central Great Lakes/Ontario Saturday night. Thus, tough to have a lot of confidence in the secondary wind pop from the 6hr rise/fall couplet-post frontal cold advection, but model trends do favor the rapid deepening low over Ontario, with less cold advection sweeping through southern Lower Michigan toward Midnight. Even so, any modest instability/possible convection along the front as it tracks through around/just after 00z Saturday will present damaging wind concerns with 850 mb jet exceeding 55 knots. Quieter weather conditions for Sunday as Low over Ontario pulls away and ridge of high pressure builds in. For the extended, the 12z European has deviated from it`s 00z run. Previous run was indicating a longwave trough tracking through the Great Lakes Region early next, with 850 mb temps progged to bottom out around 0 C by Wednesday. The 12z run has now indicated a cutoff low developing by Four Corners region, and more split flow, with northern stream shortwave trough tracking just through the northern Great Lakes, resulting in above normal temperatures continuing over southeast Michigan. In either case, will still need to keep track of the remnants of Nate as they accelerate off to the northeast on Monday, with potential to get clip with some rain across the far southeast. MARINE... Modest west-southwest winds will gradually veer to the southeast over the next 24 hours as a warm front begins to lift into southern Michigan from the Ohio Valley. This warm front will be driven northward Friday night into Saturday as deepening low pressure lifts across the Upper Mississippi Valley. This low is forecast to continue to deepen as it pushes into northern Ontario on Saturday. This will place the region within strong southerly flow in the warm sector. There is a chance that wind gusts may approach gale force on the lakes Saturday. The limiting factor will be the degree of warm air advection across the lakes, which may limit the over-lake mixing depths. This leads to fairly low confidence for gale force gusts, so a gale warning will not be issued attm. Frequent gusts to 30 knots are however highly probable. The associated sfc occluded front will pass across Lake Huron and Southeast Michigan Saturday evening. There may be a brief period of higher wind gusts with this front. The passage of the front will be marked by a wind shift to the southwest. Modest post frontal southwest winds, gusting up to 25 knots, will then persist into the first half of Sunday before the gradient relaxes and winds and waves decrease late Sunday into Monday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ UPDATE.......CB AVIATION.....CB DISCUSSION...SF MARINE.......SC You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Hastings NE
707 PM CDT Thu Oct 5 2017 .UPDATE... Issued at 647 PM CDT Thu Oct 5 2017 Most forecast models are indicating that showers and thunderstorms will be more isolated this evening and then pick up in both intensity and coverage after midnight. The 22Z HRRR finally seems to be coming in line with the ECMWF, GFS, and NAM in brining a heavier shield of showers and thunderstorms into our area after midnight. Therefore, have greatly lowered rain chances prior to midnight with generally only isolated precipitation prior to midnight and then continued to go with the high rain chances moving across the area from west to east after midnight. Fog has largely cleared out of the region for now, but may quickly move back into some areas after dark. && .SHORT TERM...(This evening through Friday) Issued at 251 PM CDT Thu Oct 5 2017 Once again the biggest issues for the short term will include fog development and chances of rain tonight. Also, we could see a strong storm or two this afternoon/evening over north central Kansas where the sun has popped out. The forecast tonight will follow a similar track as last night, only this time the surface boundary will be sagging south. I don`t see why fog development would not occur again, as conditions will be quite similar compared to last night and rounds of rain should develop tonight, especially along and north of the surface boundary. As this boundary sags south, the area in our CWA that stands to see the most rain will be in the southeast where I kept the flood watch going through Friday evening. Superblend temperatures look appropriate with highs in the 50s and 60s north of the boundary and 70s to the south of the boundary where it is stalled. We will likely have enough instability to support some severe storms in our southern CWA, depending on how far south the front stalls. .LONG TERM...(Friday night through Thursday) Issued at 251 PM CDT Thu Oct 5 2017 Still looks like we dry out for the weekend as a strong shortwave trough will finally kick the front through Friday night. Another wave moves in and introduces much colder air by Monday night. Tuesday and Wednesday morning look the coldest as a surface ridge approaches. Our low temperatures will depend quite a bit on where this ridge is when we hit our low temperatures. Any rain that occurs later in the week, I have left thunder out as instability is lacking. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 647 PM CDT Thu Oct 5 2017 This is a very challenging aviation forecast and expect we could flip back and forth between ceiling and visibility categories several times. Overall we will generally be stuck under IFR ceilings and we could see visibility slip down into the IFR range as well. Can not rule out LIFR ceilings and visibility primarily prior to the rain moving in around midnight. Once the rain moves in we should see at least some minor improvement regarding ceilings and visibility. Expect several unscheduled TAF updates for changing conditions. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Flood Watch through late Friday night for NEZ064-076-077-085>087. KS...Flood Watch through late Friday night for KSZ006-007-018-019. && $$ UPDATE...Wesely SHORT TERM...Heinlein LONG TERM...Heinlein AVIATION...Wesely
Area Forecast Discussion
National Weather Service Grand Junction CO
Issued by National Weather Service SALT LAKE CITY UT 347 PM MDT Thu Oct 5 2017 .SHORT TERM...(Tonight through Friday night) Issued at 333 PM MDT Thu Oct 5 2017 An upper level trough currently stretching from central Montana to northeastern Nevada will push eastward into the Plains states by Friday afternoon. Ahead of this trough, sufficient instability, relatively deep moisture and favorable orographic forcing continue to bring a threat of convection to the San Juan Mountains east of Cortez. So far this afternoon, much of the convection has remained south of the Colorado/New Mexico border. The last several runs of the HRRR as well as several other CAMS have indicated convection will build into the far southern portions of the CWA in the next 1-2 hours. Current forecast supports this trend, so decided to leave pops as is across far southern Colorado. As the long wave trough that has been over the West for days finally leaves the region, a few isolated showers or even a thunderstorm will be possible across much of western Colorado Friday afternoon. Shortwave ridging will build into the area behind this trough Friday evening into Friday night. .LONG TERM...(Saturday through Thursday) Issued at 333 PM MDT Thu Oct 5 2017 After a period of shortwave ridging this weekend, another cold Pacific trough will dig into Utah by Sunday evening. Global models have trended somewhat deeper and colder with this system, particularly for late Sunday into Monday evening, with widespread precipitation possible across western Colorado. 700mb temperatures fall to as cold as -10C across northwestern Colorado and northeastern Utah by Monday afternoon. Increased pops with the afternoon package to reflect global model trends. Another period of shortwave ridging is expected through midweek. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 333 PM MDT Thu Oct 5 2017 VFR conditions should prevail at most TAF sites this afternoon/evening as thunderstorm activity looks to remain south and east of most TAF sites. However, there is a small chance of a thunderstorm and/or MVFR ceilings at KDRO over the next couple hours. Gusty southwest/west winds should drop off around sunset at most locations. Mostly clear skies will prevail overnight before mid- high lvl cloud cover increases tomorrow morning over NE Colorado. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...Kruse LONG TERM...Kruse AVIATION...Carr
Area Forecast Discussion
National Weather Service Grand Rapids MI
944 PM EDT Thu Oct 5 2017 LATEST UPDATE... Update .SYNOPSIS... Issued at 300 PM EDT Thu Oct 5 2017 Scattered showers will continue to develop late this afternoon and tonight and the warm front will continue to lift north through Michigan Friday and bring numerous showers Friday afternoon through Friday night. It will be unseasonably warm and breezy Friday night through Saturday and an approaching cold front will bring showers and possibly a few thunderstorms Saturday afternoon and early evening. && .UPDATE... Issued at 944 PM EDT Thu Oct 5 2017 I have increased the pop to over 90% tonight as two areas of convection moves west to east across the our forecast area. The first area of convection (with thunder) will moves west to east near US-10 but the second area, now over SW and central WI will cross our southern and central forecast area between 11 pm and 5 am. The storms are the result of jet lift entrance region of 90 knot upper level jet core moves west to east over northern Lower Michigan overnight. There is a weak instability (200 j/kg of most unstable cape) with a narrow cap profile. The EL is forecast by the RAP model to be near 25,000 ft which fits what the radar is showing and is only 3,000 above the -20c height. Also the TQ index rises to near 18 as the core of the convection crosses the CWA overnight (15 is the threshold for thunderstorms). There is a low level jet axis near I-96 tonight with is in response to the upper level jet. So all of this tells me we will see convection tonight but it will not be strong, just some generic thunderstorms with locally heavy rainfall. The HRRR is doing well with the forecast so I used that for our POP and QPF grids with some minor smoothing. Bottom line is most area will see some rain tonight. && .SHORT TERM...(This evening through Saturday night) Issued at 300 PM EDT Thu Oct 5 2017 Primary short term fcst concerns involve determining probabilities for rain through most of the short term fcst period. Scattered light rain showers will continue to develop and drift east across our northern fcst area late this afternoon. Scattered light showers will then develop across most of our fcst area late tonight into Friday as a warm front lifts slowly north into far southern lower Michigan by early Friday afternoon. An isolated thunderstorm is also possible Friday as weak elevated instability develops north of the warm front as h8 li/s go slightly negative. More widespread rain will develop Friday afternoon through Friday night as moisture ramps up and the warm front lifts northward. Pcpn potential will also be aided by the llj and 1000-850 mb moisture transport ramps up significantly Friday afternoon. It will be very breezy and unseasonably mild Friday night in the warm sector south of the warm front. Unseasonably warm wx will continue Saturday sith strong south winds of 20 to 30 mph which will help to boost max temps well into the 70`s in spite of rather extensive cloud cover. Scattered showers and perhaps a few thunderstorms will develop Saturday afternoon and early evening along and just ahead of the front. Convective potential is mitigated primarily by weak instability. However upper level forcing will be very strong as will wind fields so heaviest showers and isolated storms will contain gusty winds. .LONG TERM...(Sunday through Thursday) Issued at 300 PM EDT Thu Oct 5 2017 Upper energy diving through western North America and strong ridging off the east coast will allow southwest flow to become reestablished Sunday and Monday. This will keep post-frontal cold air advection short-lived, and allow max temperatures to climb into the low to mid 70s each day, which is about 10 degrees above normal. Dry weather is expected at this time, with the remnants of Tropical Storm Nate forecast to stay south and east of the area. Large differences then appear in medium-range model solutions with how western energy is handled as it progresses eastward, yielding a lower confidence forecast for the mid-week period. Main piece of energy and attendant cold front will push across the the Great Lakes sometime between Monday night and Wednesday. Showers will accompany the front, but will need to wait to refine timing more as model come into better agreement. Cooler air should allow temperatures to fall closer to normal values in the low to mid 60s. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 656 PM EDT Thu Oct 5 2017 Expect VFR conditions to continue through 16z on Friday, then as the warm front gets closer ceilings will lower to IFR during Friday afternoon as the warm front pushes northward toward Lower Michigan. Most areas should be 1 to SM in light rain, drizzle and fog by 21z or so. Current model runs do not show enough instability for thunderstorms. The area of showers moving through this evening is assoicated with an upper air disturbance and that will be east of the area by midnight. After that expect VFR cigs until the lower clouds move in during the afternoon on Friday. .MARINE... Issued at 300 PM EDT Thu Oct 5 2017 Fairly minimal wind speeds and wave heights are forecast tonight into Friday. Winds and waves will increase considerably Friday night into Saturday when a small craft advisory will be needed. && .MARINE... Issued at 300 PM EDT Thu Oct 5 2017 Fairly minimal wind speeds and wave heights are forecast tonight into Friday. Winds and waves will increase considerably Friday night into Saturday when a small craft advisory will be needed. && .HYDROLOGY... Issued at 300 PM EDT Thu Oct 5 2017 A few rain showers are expected over western Michigan tonight. Coverage will be limited, however, and amounts are expected to be light. A warm front lifting northward will provide a much better chance for rain by late Friday afternoon through Friday night. At this time, it looks like most locations will see some rain during this period, with amounts ranging from a few tenths of a inch to a half inch (highest north of Grand Rapids). Thunderstorms will also be possible, and will bring potential for heavy downpours. A passing cold front will provide another good chance for showers and a few thunderstorms on Saturday, most likely in the late afternoon and evening. Heavy downpours will again be possible with any thunderstorms that develop. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...WDM SYNOPSIS...Laurens SHORT TERM...Laurens LONG TERM...HLO AVIATION...WDM HYDROLOGY...HLO MARINE...Laurens
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
711 PM CDT Thu Oct 5 2017 .SHORT TERM... (Through Late Friday Afternoon) Issued at 329 PM CDT Thu Oct 5 2017 The warm front is now over northern Missouri and central Illinois moving slowly northward with just isolated showers over eastern Missouri and southwest Illinois. The RAP/GFS shows the front lifting north of the area early this evening that will likely stay there through tomorrow. An area of showers and thunderstorms over northwest Missouri will move east along the Missouri/Iowa border late this afternoon. Northeast Missouri and west central Illinois is where the best chance of showers and possible thunderstorms will be tonight over the CWA because it is where the best low level moisture convergence will be focused. Will keep the mention of locally heavy rainfall going in the hazardous weather outlook over the northern CWA as the RAP is showing PWATS near 2" with warm cloud depths over 12,000ft. The front will begin to lift farther north into Iowa and northern Illinois by Thursday afternoon, so rain chances will lessen through the afternoon. Farther south, only expect isolated showers to the south of I-70 tonight and Sunday. The above normal temperatures will continue through tomorrow afternoon as the warm front lifts northward and the CWA will be in the warm sector. Highs on Friday will be 10-15 degrees above normal. Britt .LONG TERM... (Friday Night through Next Thursday) Issued at 329 PM CDT Thu Oct 5 2017 A deepening low pressure system with attendant cold front over western Kansas will push east toward the region on Friday night. An increase in wind speeds after midnight to breezy conditions will start initially over central Missouri early Saturday morning then spread east to the rest of the region after mid morning Saturday. The southwesterly flow will continue to usher in warm air allowing for the continuation of above normal temperatures. The breezy conditions will end late Saturday afternoon into the evening behind the frontal boundary. There will also be some scattered showers and isolated thunderstorms over central Missouri late Friday into Saturday morning as the low pressure deepens over northwest Missouri and moves northeast away from the region. There will be a break from showers and thunderstorms for most of the region except for extreme southeast Missouri and far southwestern Illinois on Sunday. There are some timing and placement differences with the orientation of the remnant tropical system that is now Tropical Storm Nate. The remnants are expect to track through the Missouri bootheel and then northeast into the Ohio Valley late Sunday night into Monday morning. It is possible that extreme parts of extreme southeast Missouri and far southwestern Illinois could see some rainfall from the system. This is highly dependent on the approaching upper trough and associated cold front that will pass through the region on Monday into Tuesday. There will be scattered showers and thunderstorms associated with this system early next week. The GFS is faster than the ECMWF in the progression of the frontal boundary. The front should clear the area by mid week with high pressure building into the area with temperatures returning back to seasonable values. Kelly && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 701 PM CDT Thu Oct 5 2017 VFR flight conditions are expected to prevail across the majority of the forecast area tonight and Friday. The exception will be over northern Missouri into west central Illinois in the vicinity of the warm front. An area of showers with embedded thunderstorms will move across those portions of the area later this evening and precipitation is expected to persist for much of the night once it starts. Decided to be pessimistic with ceilings dropping to low MVFR and then intermittent IFR late tonight. This may be too low, but models haven`t handled the low ceilings very well over the past couple of days. Hopefully ceiling trends will become more clear over the next few hours. Regardless, expect any low ceilings to eventually drift north with the front on Friday afternoon. SPECIFICS FOR KSTL: VFR flight conditions and light southerly flow will prevail at Lambert through Friday. There`s a chance that some showers will drift into the vicinity of the terminal very late tonight or Friday morning, but most guidance keeps Lambert dry and VFR through the period. Carney && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Mount Holly NJ
730 PM EDT Thu Oct 5 2017 .SYNOPSIS... A frontal boundary is expected to remain stalled across the area through Friday night, then begin lifting to our north Saturday. A cold front will approach the area over the weekend, and may stall out near the area into early next week. The remnants of Tropical Storm Nate are expected to move northward up the Appalachians and toward the Mid Atlantic through early next week, potentially bringing unsettled weather to the area. High pressure may build to our north on Wednesday, which may help to bring drier weather. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... The regional radar loop shows an area moving through Berks County and the Lehigh Valley at 730 PM. Some of this rain is moderate to heavy, and a few lightning strikes are being observed moving into Schuylkill County. The PoP grids have been adjusted upward to over 90 percent through the evening hours along and north of the I-78 corridor as the HRRR indicates this shower activity will hold together as it moves east. While isolated lightning/thunder cannot be ruled out, it won`t be widespread enough to warrant more than a mention of "isolated" in the forecast. Up to one- half inch of rain is possible in the spots that happen to experience the heaviest showers, but most places should sees around one-quarter inch or less in and around the I-78 corridor. Light precipitation is still expected between I-78 and the PA turnpike, with little or no precipitation expected south of the C&D canal on the Delmarva. Shower activity is expected to taper off from west to east later this evening, becoming more scattered in nature after midnight...before ending all together during late overnight hours. Cloud cover will keep overnight min temperatures somewhat warmer than this morning. Some fog is possible in the areas that receive rain this evening. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... For Friday...the ill-defined west-east frontal boundary will still be hanging around the PA/NJ area. However with no shortwave aloft or other forcing for UVV the chance for more shower development seems quite low. The forecast has slight chance PopS in the afternoon for northern NJ and adjacent PA, but most areas will likely be rain free. Max afternoon temps should be similar to today, except maybe a couple of degrees cooler north of the frontal boundary. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... The stalled out frontal boundary remains stalled out across our area overnight Friday, and by Saturday, the front will begin to lift to our north. Mostly dry weather is expected overnight Friday through Saturday, but there will be a couple of short wave vorticity impulses moving across the area. A few showers cannot be ruled out late Friday into early Saturday morning. Another frontal boundary begins to approach the area from the west overnight Saturday into Sunday morning and may slow down and stall out as it reaches our area. Several short wave/vorticity impulses are expected to move into the area withing the developing southwest flow aloft which could help increase shower chances overnight Saturday into Sunday. Around the same time the front is approaching the east coast Sunday morning, Tropical Storm Nate, possibly a hurricane at that time, will be making landfall along the central Gulf of Mexico coast. Nate is then expected to begin moving inland and dissipate as it tracks across the Appalachians toward the Mid Atlantic region. Please refer to the National Hurricane Center for the latest official track. Moisture from Nate is expected to lift into our area well ahead of the system itself as southwest flow from the surface to the mid/upper levels transfers the moisture northward. Several short wave/vorticity impulses are expected to lead to an extended period of rainfall from Sunday night through Monday night, before the actual remnants of Nate move across the area Monday night into Tuesday. PW values will be on the increase and could exceed 2 inches, so a period of moderate to heavy rainfall is possible. It has been quite dry as of late, so this would be much needed rain and would not likely lead to river flooding. However, if any heavy rain falls in a short period of time, urban and poor drainage type flooding could be possible. The remnants of Nate move offshore Tuesday through Tuesday night, then it is possible high pressure may briefly build to our north on Wednesday. Rain chances decrease through Tuesday through Wednesday, but not completely as there will remain a couple of weak short wave/vorticity impulses moving across the area. Temperatures through the extended are forecast to be above normal each day through Wednesday. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. MVFR or even IFR conditions are possible at RDG and ABE during the evening hours as showers and isolated thunderstorms move through...then generally VFR conditions are expected through the TAF period. Southwest winds early this evening will become light and variable overnight and into Friday morning. Any rain should be over by sunrise Friday, but some patchy fog or stratus could linger into the morning...especially where the rain falls this evening. Fog is mentioned in the TAFS at RDG, ABE, and MIV early Friday morning. OUTLOOK... Friday night-Saturday...A stalled frontal boundary being lifting northward overnight Friday int Saturday. Patchy fog possible around daybreak Saturday, with conditions improving to VFR during the day. Southwest winds could gust 20-25 knots. Saturday night-Monday night...Conditions lower to MVFR overnight Saturday, and will likely lower further into IFR range over the weekend into early next week. Periods of rain becoming more likely, possibly moderate to heavy at times. South to southwest winds could gusts 15-20 knots at times. Tuesday...Conditions begin to improve some on Tuesday, but may remain MVFR at times. Rain chances decrease through the day. && .MARINE... Sub-SCA conditions are expected to continue through this evening and then diminish overnight and for Friday. Some limited visibility in showers is possible late this evening or overnight in scattered showers, especially north of Atlantic City. Fair weather is expected on Friday. OUTLOOK... Friday night-Saturday...Sub Small Craft Advisory conditions expected. Saturday night-Monday night...Small Craft Advisory conditions possible as seas increase to 5 feet. Winds may also gust around 25 knots at times. Tuesday...Conditions may drop below advisory levels during the day Tuesday. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Robertson Near Term...Miketta Short Term...AMC Long Term...Robertson Aviation...AMC/Robertson/Miketta Marine...AMC/Robertson/Miketta
Area Forecast Discussion
National Weather Service Pueblo CO
332 PM MDT Thu Oct 5 2017 .SHORT TERM...(This evening through Friday) Issued at 332 PM MDT Thu Oct 5 2017 Showers were streaming across portions of southeast and south central CO early this afternoon, with tstms staying just to the south of the area. Good heating has occurred today over southern portions of the eastern plains, where temps have risen into the 70s. SPC meso analysis shows 2000 J/kg of CAPE in that area, along with fairly strong deep layer shear. SPC has a marginal risk of severe storms today for the far south and southeast plains. The HRRR continue to show the best chances for stronger storms over that portions of the forecast area this afternoon and very early this evening, with just some isold showers/tstms over mainly the southern mtn areas. Then early this evening the HRRR has the storms that were over the far southeast plains, moving east of the area. However it shows another round of storms developing around 01Z to 02Z along or near the eastern mtns, from the El Paso and Teller county area, south to the NM border, and then moves this line eastward acrs the plains, reaching the far eastern counties around 06Z. After about 07Z or so, most if not all showers/tstms are expected to end. Low clouds and areas of fog are again expected tonight acrs most of the southeast plains, and there could be some areas of drizzle. On Fri, an upper trof will move acrs CO with some windy conditions expected, especially over the mountains, high valleys and southern portions of the I-25 corridor. A cold front will move south into southeast CO in the afternoon hours, with the NAM showing pcpn in areas behind the front. The NAM shows about 1500-2000 J/kg of CAPE over the far southeast plains Fri afternoon, with 0-6km shear values of 60-70 kts. SPC has the far southeast plains in a Slight risk area for severe weather. The high temp forecast for Fri acrs portions of the southeast plains could be a little tricky with the front coming thru. However, it looks like most areas will see 70s for highs, but cooler in El Paso county. The high valleys should see highs in the 60s. .LONG TERM...(Friday night through Thursday) Issued at 332 PM MDT Thu Oct 5 2017 Friday night-Sunday...Flow aloft becomes increasingly northwest across the region Friday night, as a broad upper trough translating across southeast Colorado late Friday afternoon continues into western Kansas Friday evening. Still have the chance for strong to severe storms across the far southeast plains early Friday evening, with storms diminishing from west to east through the late evening, as strong subsidence develops behind the passing system. Dry air and clearing skies, along with slowly decoupling winds behind the system could lead to chilly overnight lows across portions of the plains Friday night/Saturday morning. Warmer and dry conditions still remain in the offing for Saturday and Sunday, as weak west to southwest flow aloft develops across the region. Should be a dry and warm weekend with highs in the mid 60s to mid 70s for much of south central and southeast Colorado. All eyes turn toward next potent system taking aim on the Rockies in the Sunday night through Tuesday timeframe. Latest models are still showing some timing and strength differences with this system, however, the latest ECMWF has now slowed down and is indicating a more closed system than its previous runs, and is now closer to the stronger GFS solution, which develop a closed low across the Four Corners Region Monday morning, before lifting it out across south central and eastern Colorado through Tuesday morning. Although there are still differences in how deep the system will be and its timing and location of how it moves across the region, it is looking more likely to see much colder temperatures with highs in the 30s and 40s Monday, along with areas of rain and snow showers across much of south central and southeast Colorado in the Monday and Monday night timeframe, with the best pops over and near the higher terrain. Snow levels still in question, though could see snow down to between 6000- 7000 feet Monday and possibly down to 5000 feet or lower Monday night and Tuesday morning. Subfreezing temperatures still seem likely across portions of the plains, especially across the higher elevations along and west of the I-25 Corridor Tuesday morning. Wednesday-Thursday...Winter makes a quick exit across the area for the middle and into the end of next week, as upper level ridging building into the Rockies will allow for warmer and drier weather, with temperatures back to at and above seasonal levels. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 332 PM MDT Thu Oct 5 2017 Forecast soundings for KCOS and KPUB show low clouds over the area beginning late this evening and continuing thru midmorning Fri, along with some fog. There is also the potential for showers/tstms until about 03Z or 04Z. On Fri, a front will move through these areas in the mid to late afternoon time-frame, with the potential for showers and thunderstorms behind the front. Breezy southerly winds will continue into the early evening hours at KALS, with the possibility of a few showers/tstm early this evening. Tonight and Fri morning, it looks like KALS should have VFR conditions, however model sounding shows the potential for some low clouds overnight, but model guidance does not. Gusty west to northwest winds are expected to develop again at KALS Fri morning. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...MW AVIATION...28