Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/13/19

Area Forecast Discussion
National Weather Service Grand Rapids MI
1129 PM EDT Thu Sep 12 2019 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 256 PM EDT Thu Sep 12 2019 - Wet Weather into Friday - Hazardous conditions for mariners Tonight into Saturday - Warmer than normal for much of next week && .UPDATE... Issued at 1058 PM EDT Thu Sep 12 2019 My thinking has not changed to much since the last update. There is a line of strong to severe storms over WI heading our way. However it is not moving east at any great speed, at 1045 pm the line was moving east at about 18 mph. The timing tool, with largely agrees with the ESRL HRRR and NAM12, plus the 00z run of the SPC HREF, has the line of storms moving on shore between 4 and 5 am north of Muskegon, reaching Grand Rapids around 7 to 8 am. Since the instability will be elevated I do not believe there is much of a severe weather threat but I could see many locations west of a line from South Haven to Grand Rapids to Clare getting between 0.75 inches and 1.50 inches by noon Friday. The severe storm threat seems real for Friday afternoon a quick look at the HREF STP... it has a large area of between 2 and 3 by 3 pm east of Lansing. Last night it never got much over 1 as a reference to the significance of those numbers. UPDATE Issued at 808 PM EDT Thu Sep 12 2019 The warm front is trying to push north into our southern CWA this evening. It seems to me questionable if it ever gets north of I-96 before the cold front comes through mid morning Friday. The RAP13 moisture transport in the 1000/850 layer shows a very large increase in deep layer moisture in the midnight to 3 am time frame. In fact the precipitable water rises over 2.0". The best moisture transport is over our west central and northern CWA toward morning. This is when our best forcing for rain is. Model sounding do not show fat cape but very narrow cape as the area of showers associated with front come through tonight. Likely there will be embedded thunderstorms but they should not be strong or severe, just very wet. So I see a soaking rain, more so north and west a line from Kalamazoo to Lansing. I could see some local rainfall amounts over 2 inches from this event tonight. Also there is an area of fog more or less near I-96 east to southern Lake Huron and Lake St Clair. Since I do not see the winds turning to southerly that far north of the front in the next few hours, the light fog will likely spread toward GRR but the fog should be light so not much of dense fog threat. The convection over northern Indian is moving northeast but it runs into the low clouds and stable air over our CWA once it gets near I-94 so I do not see much of threat from that convection. Likely isolated showers near and south of I-94 for the next 2 hours. && .DISCUSSION...(This evening through next Thursday) Issued at 256 PM EDT Thu Sep 12 2019 The main weather concern deals with the risk severe weather and heavy rain into Friday. This will be another situation where close monitoring will be needed. Tonight the tropical moisture streams back into the region with a low level jet arriving. Elevated instability moves in as well. Forecast sounding show the CAPE to the thin and deep with lifted parcels becoming colder than the environmental temperatures well below the trop. This is a signal for warm topped convection and efficient rainfall processes. PWAT values climb to near 2 inches. We issued an ESF for this scenario. As for severe weather tonight...there is strong destabilization going on south of the MI border right now. Further north the shallow cool airmass has prevailed so far. Clouds are in the process of scattering out along I94 so with a few hours of heating a small risk for a storm could develop. High res models are not showing any convection forecasted to develop this afternoon. In addition the deep layer shear is very low. For now the severe risk looks low. Friday is a different story. Moisture and lift will be in place as the cold front cuts through from the west late in the morning through mid afternoon. Favorable low level helicity will be in place...but initially the deep layer shear is progged to be on the low side. This changes through the afternoon though as the mid level jet max pivots in. On uncertainty will be instability. If the low clouds persist prior to the frontal passage...this would limit the severe risk. However any low level CAPE would increase the severe risk. Stronger heating prior to the frontal passage would bump up the instability and the severe risk as well. Either way it does look like the severe thunderstorm potential increases through the afternoon and the front is currently forecasted to push through the Lansing to Jackson region roughly 3 to 5 pm. Damaging winds and an isolated tornado risk could evolve. The PWAT values in the morning and into the early afternoon hours on Friday will be very high with near 2 inch amounts possible. Rainfall rates will likely be high with any convection and with a fairly unidirectional flow in the convective layer some training looks possible. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1128 PM EDT Thu Sep 12 2019 I was thinking 6 hours ago the line of storms in Wisconsin would reach our TAF sites by 1-2 AM. As it turns out, it now seems that would more likely be 5 to 7 am that it would move into our western TAF sites. This is based on a re-do of my timing tool and storm speed tool. This also agrees with the 00z HREF, the ESRL HRRR 00z and actually several other Hi-Res models. The area of drizzle and light fog I expect to expand west surely did as I through it would do. With the warmer and more moist air overriding the shallow cool air in place, I could see the drizzle and light fog persisting through a good part of the early morning hours. While the main line of storms will not move into our area until around Sunrise, I do expect scattered storms to keep developing in front of the primary line. The storms that impacted Berrien County a few hours ago has turned east and will impact the AZO and BTL TAFs over the next few hours. I do not think those storms will get to JXN, GRR or MKG. && .MARINE... Issued at 256 PM EDT Thu Sep 12 2019 Hazardous boating conditions for small craft are expected tonight into Saturday. A tightening pressure gradient tonight ahead of the approaching storm system will support higher winds. As the cold front pushes through on Friday the wind will veer with time from southeast to southwest then west. The gusty conditions will continue into Saturday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Small Craft Advisory until 5 PM EDT Saturday for LMZ845>849. && $$ UPDATE...WDM SYNOPSIS...MJS DISCUSSION...MJS AVIATION...WDM MARINE...MJS
Area Forecast Discussion
National Weather Service Indianapolis IN
1158 PM EDT Thu Sep 12 2019 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 217 PM EDT Thu Sep 12 2019 Strong high pressure south of Central Indiana will bring another night of warm...humid and dry weather to Central Indiana Tonight. A weak cold front is expected to push across Central Indiana on Friday. This is expected to result in some scattered showers and thunderstorms on Friday afternoon. Dry weather and somewhat cooler conditions are expected to arrive in the wake of the front for the weekend. Strong...warm and humid high pressure is then expected to reestablish itself across the region brining more late summer warmth next work week. && .NEAR TERM /Tonight/... Issued at 217 PM EDT Thu Sep 12 2019 Surface analysis early this afternoon shows strong high pressure in place across the Tennessee Valley. Low pressure was found across SW Minnesota...with a warm front protruding southeast across Illinois toward Indiana. GOES16 shows some sct cu popping across Central Indiana and dew points were humid and in the lower 70s with W-SW surface flow. Aloft...water vapor show ridging over Indiana and a deeper trough in place over the Dakotas. Disturbances within the SW flow between the two systems were resulting in some scattered showers and storms across KS/MO and NW to WI. With little upper support expected tonight...our only triggering feature for lift tonight will be waning daytime heating. Latest HRRR suggests minimal coverage with convection late this afternoon and coverage dissipating quickly with the loss of heating. Otherwise...forecast soundings reveal a dry column as Indiana remains under the influence of the departing ridge to the east. Thus will trend toward a dry forecast...and given the little change in the overall air mass will trend lows close to persistence. && .SHORT TERM /Friday through Sunday/... Issued at 217 PM EDT Thu Sep 12 2019 Main weather feature during this period will be a cold front passage on Friday afternoon. The GFS and NAm suggest the upper ridge will move well east of Indiana by Friday afternoon and the trough over the plains pushes toward the Great Lakes. The GFS and NAM suggest a few embedded short waves within the SW flow ahead of the upper trough to push across Indiana on Friday afternoon. Along with these upper waves...the tail of an associated cold front is expected to approach and pass across Indiana also. Given the warm and very humid air mass in place along with the upper support...showers and storms will likely develop ahead of the front. Forecast soundings show attainable convective temperatures on friday afternoon with CAPE over 2000 J/kg and pwats over 1.91. Thus with these favorable ingredients in play...will trend pops on Friday afternoon at or above the NBM blends. Also with much of the day in the warm sector ahead of the front...will also trend highs at or above the NBM with several hours of heating expected along with a very warm start to the day. GFS and NAM show the best forcing departing by Friday the upper low pulls quickly toward NW Quebec and nearly a zonal flow reestablishes itself across Central Indiana aloft. Forecast soundings dry out significantly...showing subsidence within the column. Meanwhile at the surface...strong high pressure was will be building across Illinois and Indiana. Thus will trend toward a dry forecast by Saturday and continue a slow progress across the region through Sunday. Thus will trend toward a dry forecast from late friday night through at least Sunday...with a dry column expected...subsidence and little in the way of upper support available. As for temperatures...will trend at or above the NBM as the impact of the cold air advection appears merely a glancing sw surface flow resumes on Saturday. && .LONG TERM /Sunday Night through Thursday/... Issued at 217 PM EDT Thu Sep 12 2019 ECMWF continues to build strong ridging in place across the Great Lakes and Ohio Valley on Sunday night into Monday. This upper ridge blocks the upper flow...sending all and any weather disturbances well northwest of Indiana. The ridge is expected to persist through Thursday. Meanwhile at the surface...a large area of high pressure is expected to develop and remain anchored across the area for the week. All of this adds up to a dry and warm work week...with above normal temperatures and abundant sunshine. Will try and trend toward a dry forecast. && .AVIATION /Discussion for the 13/06Z TAF Issuance/... Issued at 1149 PM EDT Thu Sep 12 2019 Confidence has increased in shower chances at TAF sites tomorrow, but will hold off on mention of thunder until it can be better pinpointed. A cold front is progged to drop through the central Indiana tomorrow, triggering showers and possibly some isolated strong thunderstorms. Regardless, conditions should generally be at VFR levels though outside of any convection. Meanwhile, winds will generally be west/southwesterly at 5 to 11 kts except for some brief sustained speeds of 12 kts or more on Friday afternoon. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...Puma NEAR TERM...Puma SHORT TERM...Puma LONG TERM....Puma AVIATION...TDUD
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
922 PM CDT Thu Sep 12 2019 .UPDATE... Issued at 921 PM CDT Thu Sep 12 2019 Showers and thunderstorms stretched from from eastern Iowa into northern and western Missouri this evening. This precipitation was occurring ahead of a cold front that extended from central Iowa into eastern Kansas. Latest runs from the RAP is showing the low level moisture convergence along the front will slowly weaken as it move southeast tonight. This goes along with the CAMS output which shows the precipitation decreasing in areal coverage as it move east overnight. Will keep with the going forecast which already shows this trend. Rest of the forecast looks on track and only needed on minor adjustments based on current trends. Britt && .SHORT TERM... (Through Late Friday Night) Issued at 357 PM CDT Thu Sep 12 2019 A strong short wave is moving through the Great Plains this afternoon. The surface low associated with this wave is currently over southwest Minnesota and short range guidance has it moving rather slowly to the northeast over the next 24-36 hours as the wave lifts into Ontario. The trailing cold front has been moving slowly east through Kansas and Nebraska all day with scattered showers and thunderstorms out ahead of it. Model guidance is in good agreement in pushing the front into central and northeast Missouri late this evening with precipitation ahead of it. There`s some disagreement as to how much rain will fall/what the coverage will be. However there is a decent consensus that the storms could be relatively well organized and strong as they enter central and northeast Missouri, but will lose strength and become more widely scattered as they move east through the night and instability diminishes. Latest runs of the convection allowing models show primarily just widely scattered showers as the convection moves into east central Missouri and southwest Illinois between 08-10Z Friday morning. QPF from the deterministic models drops off as well late tonight indicating weakening convection. Some redevelopment is possible Friday afternoon across far southeast Missouri southwest Illinois as instability rises again, but most guidance shows the front either most of the way or all of the way through our CWFA by that time. Cooler/drier air will build across the forecast area behind the front Friday and Friday night. Temperatures behind the front on Friday will be as much as 8-15 degrees cooler in the mid 70s to mid 80s and lows Friday night should drop into the mid 50s to low 60s. Carney .LONG TERM... (Saturday through Next Thursday) Issued at 357 PM CDT Thu Sep 12 2019 The upper level pattern will shift into quasi-zonal flow Saturday into Saturday night as the short wave mentioned in the short range continues lifting northeast. This should keep the surface pattern moving eastward, pushing the surface high into the Ohio Valley by 00Z Sunday. Return flow along with plenty of sunshine will produce a solid diurnal rise into the low to mid 80s. Medium range guidance is in good agreement that the upper level pattern will begin to amplify again on Sunday with a strong ridge building over the Midwest through the early part of the week...and persisting through Wednesday or Thursday. This ridge will bring more Summertime weather to the mid Mississippi Valley with temperatures in the mid 80s to low 90s. There may be some relief on Thursday if a back door cold front can sneak in from the Ohio Valley, but the GFS and ECMWF are not in good agreement with this feature so confidence is not high. Carney && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 609 PM CDT Thu Sep 12 2019 Showers and thunderstorms over western Missouri are expected to move east into central and northeast Missouri as well as west central Illinois this evening including KCOU and KUIN. These storms will have the potential to bring MVFR/possible IFR ceilings and visibilities. The coverage of these storms will decrease as they move east, though scattered storms will still reach the St. Louis area terminals overnight. A cold front will move across the area late tonight into Friday causing southerly winds to veer out of the west. SPECIFICS FOR KSTL: Mainly dry weather is expected through 06Z. Then scattered showers and thunderstorms will move into eastern Missouri and may affect the terminal between 08-12Z. Any thunderstorms has the potential to bring MVFR/possible IFR ceilings and visibilities. A cold front will move through the terminal late tonight into Friday causing southerly winds to veer out of the west. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
805 PM EDT Thu Sep 12 2019 .SHORT TERM...(This evening through Friday) Issued at 315 PM EDT THU SEP 12 2019 An amplified north-central CONUS pattern is in place this afternoon with mid-level troughing over the Dakotas and ridging over Ontario and lower Michigan. RAP analysis and observations indicate the sfc low is centered over SW MN as of 19Z, and a strengthening pressure gradient between it and the sfc high centered over James Bay has led to ESE wind gusts as high as 35 mph already over the western UP (highest over the Keweenaw). Drier air and a little bit of clearing was able to work into the far east, and as a result the warmest temperature of the day thus far has been 63 at Newberry. After a little AM upslope mist/drizzle over the north-central, conditions dried out as expected, but the leading line of rain showers is now moving through Gogebic County, pivoting WNW. Coverage and intensity of rain showers over the west half of the UP will gradually increase through this evening, with heavier rain arriving mainly after 8PM EDT. Some embedded thunder will be possible as the strongest forcing an weak instability trek across the UP overnight. Total rainfall amounts have been lowered somewhat, though in general a widespread 0.25-0.75" are expected, highest across portions of the Keweenaw as well as the south-central UP. Locally higher amounts up to about 1.25" will be possible in these areas. Behind the rainfall, winds will become southwesterly for Friday and remain breezy as the surface low passes north of Lake Superior. This will allow for a modest warm-up despite the lack of sunshine with forecast highs in the low 60s west but low 70s for some folks, which will be a welcome sight after the last couple of days. Lingering showers in the morning out east should exit by noon-time, but a slight chance for a a few isolated areas of light rain will remain in the forecast across the area through the day. The best chance for any measurable rain over 0.01" in the afternoon will be over the Keweenaw and the far eastern UP. .LONG TERM...(Friday night through Thursday) Issued at 351 PM EDT THU SEP 12 2019 By tomorrow night, the well-advertised low pressure system will be in northern Ontario, with just some lingering showers possible in the western U.P. due to wrap-around moisture on the backside of the low. With the close proximity and therefore the pressure gradient still rather tight, especially across Lake Superior, winds will remain elevated through the overnight hours into at least early Saturday. As for precip chances, expect a break in the wet weather later in the day on Saturday, with showers and thunderstorms returning by Saturday night. This will be thanks to a weak shortwave traversing through, triggering a bit of cyclogenesis, accompanied by enough instability to generate lightning even during the overnight hours. High pressure then moves in at the tail end of the weekend, allowing for a nice, albeit warmer-than-normal start to next week. Look for an unsettled pattern to emerge again later next week. As alluded to, and previously discussed, the overall trend of temps will be on the increase throughout this forecast period. Highs this weekend will remain seasonable, but by Monday, will rise well into the 70s to perhaps even 80s for the first half of next week. Could be the last gasp of summer.... && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 804 PM EDT THU SEP 12 2019 As low pres over w central MN lifts ne tonight, expect shra to affect KIWD/KCMX/KSAW for much of the night. While there will be some isold tsra, potential of KIWD/KCMX/KSAW being impacted appears low attm. Otherwise, MVFR cigs should prevail at KIWD. While KCMX should see prevailing low MVFR cigs, upslope ese winds may lead to periods of IFR thru the evening with another period of IFR late tonight near the time of fropa. At KSAW MVFR cigs will likely fall to IFR overnight, then to LIFR for a time Fri morning under southerly upslope winds. In addition to gusty winds to 20-30kt toight, LLWS is also expected as 45-55kt low-level jet translates across the area. Winds will become gusty from the sw to w on Fri as the low pres lifts into northern Ontario. Winds will become strongest at KCMX, gusting up to 35-40kt later in the aftn. MVFR cigs should generally prevail at all terminals Fri, though downsloping may support improvement to VFR at KSAW in the aftn. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 341 PM EDT THU SEP 12 2019 Easterly winds gusting up to 30 knots this afternoon will become southeasterly tonight with the potential for up to 40 knot gusts. Some model guidance suggests the chance for gusts up to 45 knots at times, first late tonight over the north-central lake and then over far eastern Lake Superior Friday morning through the early afternoon. On Friday evening, as a low pressure system lifts into Ontario, winds become southwesterly and gust up to 40 knots over the western half of the lake. As such, there is a gale warning out on Lake Superior across the central and eastern zones for tonight into tomorrow morning and then a gale watch for all lake zones except for 267 on Friday night into Saturday. On Saturday evening, winds calm down below 20 knots and will remain below 20 knots through the rest of the period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 2 AM to 2 PM EDT Friday for LSZ251-267. Gale Watch from Friday evening through Saturday morning for LSZ243>246-264>266. Gale Warning until 11 AM EDT Friday for LSZ244-245-247-248- 264>266. Gale Watch from Friday afternoon through late Friday night for LSZ162-241-242-263. Gale Warning until 6 AM EDT Friday for LSZ242-243-246-263. Lake Michigan... None. && $$ SHORT TERM...KCW LONG TERM...lg AVIATION...Rolfson MARINE...KCW
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
516 PM MDT Thu Sep 12 2019 .DISCUSSION...(This Evening Through Thursday) Issued at 140 PM MDT Thu Sep 12 2019 19z surface analysis had low near KATY with trough into eastern MT. Tight pressure gradient over the CWA with 25-50kt boundary layer winds per RAP analysis and KUDX VWP. 3-hour pressure rises modest with limited cold air advection which is keeping highest winds confined mainly to the squeeze areas of western SD. Upper low spinning over KD07 with wrap-around precipitation over western SD. System is starting to pull out per satellite loops, in line with numerical guidance. Winds will quickly die down after 00z with precipitation ending by 06z. Temperatures tonight will be tricky with clearing skies battling leftover gradient. Looks pretty cool, especially in the west. Friday, low amplitude shortwave ridge pushes into the northern plains. Result will be rebounding temperatures and plenty of sun. Fast moving shortwave trough drops a weak front through the CWA late Friday night, which may produce a few -SHRA in the far north. Saturday through Monday, upper trough develops over the western CONUS as an upper ridge amplifies over the Rockies and then into the Midwest early next week. Thermal ridge looks quite robust and thus, temperatures will rocket into the 80s for Sunday/Monday. Tuesday through Thursday, confidence fairly high that upper trough will move into central North American, but evolution into split flow the main question. Either way, looks like unsettled weather returns as temperatures drop below normal for Wednesday/Thursday. && .AVIATION...(For the 00Z TAFS Through 00Z Friday Evening) Issued At 516 PM MDT Thu Sep 12 2019 Northwest winds will diminish and lingering showers over mainly western SD will end early this evening. VFR conditions are expected overnight and Friday. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Wind Advisory until 6 PM MDT this evening for SDZ012-013-025-026- 031-072-073. WY...None. && $$ DISCUSSION...Helgeson AVIATION...26