National Weather Service Raw Text Product
Displaying AFOS PIL: AFDDMX Received: 2017-09-14 09:00 UTC
733 FXUS63 KDMX 140900 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 400 AM CDT Thu Sep 14 2017 .SHORT TERM.../Today through Tonight/ Issued at 400 AM CDT Thu Sep 14 2017 Primary focus in the short term is the very warm to hot conditions today then low grade precip chances tonight. Today...Forecast Confidence: Medium/High 00Z upper air analysis and water vapor imagery indicated a remnant trough from Irma over the Ohio River Valley...upper ridging over the central Plains...and another stronger shortwave trough over the 4- corners region of the desert Southwest. At the sfc...a ~1000mb sfc low was centered over srn SD yielding a broad sly wind flow over IA. A nocturnal LLJ developed overnight over NE/KS...which has yielded isolated/wdly scattered showers and thunderstorms. As of 09z...radar mosaic showed this activity drifting e/sely near the Missouri River. Current trends should keep most/all of this activity just southwest of the forecast area. Primary challenge today is the temperature forecast. WAA regime in the low levels will allow 850mb temps to climb a few more degrees C today into the +20C to +22C range. This combined with a breezy south to southwest wind and bone dry soil moisture conditions will lead to very efficient mixing /likely near 750mb/. Inched high temperatures up another degree or two into the upper 80s north to the lower 90s in the central. It should be noted that some of the raw 2-meter temp guidance is even warmer into the mid-90s...which would be near record territory. Due to the potential for mid-level clouds did not go quite that warm at this point. These hot and dry conditions /with low RH/ will also yield an elevated fire risk today. Luckily most vegetation has yet to cure...so this should temper an otherwise higher risk. Finally...a few of the hi-res CAM solutions do indicate the potential for a very isolated shower or storm this afternoon. Any coverage should be 10% or less...thus no explicit mention in the forecast. Tonight...Forecast Confidence: Medium LLJ is expected to re-strengthen overnight resulting in a period of isentropic ascent and a modest influx of moisture/thetaE between H8 and H7. While model soundings and cross sections show the potential for mid-level saturation and weak instability...the PBL will remain quite dry. At this point will keep PoPs confined to the slight chance /20 percent/ category...mainly across the north and west. Its quite possible that much of this will be virga or sprinkles...but at least a few areas could pick up measurable rain. With the thicker cloud cover and persistent southerly breeze expecting very mild lows in the low-mid 60s. .LONG TERM.../Friday through Wednesday/ Issued at 400 AM CDT Thu Sep 14 2017 Still expecting some rain chances and a fairly active extended forecast, with a developing western US upper level trough to end the week. Southerly flow expected to increase ahead of a developing surface trough across the mid-section of the country with a continued push of Gulf moisture and WAA. Best chances for precipitation appear to be Friday night into early Saturday and again Saturday night. Friday night the sfc trough is expected to be situated from central MN southwestward into ern NE and central KS, with a strong LLJ streaming moisture into the western portion of IA. Storms are expected to form in the afternoon closer to the sfc trough axis and then will spread eastward into the northwestern portion of the forecast area late Friday night. Additionally could see some storms develop across the west/central toward Saturday morning in the warm sector along a push of theta-e advection with the line dissipating some through mid-day. Additional storm development then expected into Saturday night with the sfc trough axis and subsequent cold front pushing through the state. Any storms moving through late Friday night should remain elevated with marginal shear and decent instability, so an isolated severe storm still possible. Better setup for sfc-based storms into Saturday afternoon/night, however deep layer shear still somewhat marginal suggesting again possibility of maybe only an isolated strong to severe storm. Cold front to stall south of the state into Sunday, and will wobble northward into early next week as a warm front with an isolated shower/storm possible in vicinity of the boundary early next week. Extended range model then diverge through mid-week, with the GFS the most bullish with the forecast. GFS tries to bring some tropical remnants from off the west coast of Mexico northward into the southwest upper level flow pattern and tap into Gulf moisture bringing the upper wave through Tuesday into Wednesday. This would suggest an increasingly wet scenario. However the EC keeps a central US upper ridge in place and tries to bring that tropical moisture into the western US trough later in the week and lifting the upper trough into central Canada. This would essentially make for a drier forecast across IA. At this time stuck close to the blend pops which have put some low chance pops across much of the forecast area for the middle of next week at this time. As for temperatures, warm air to remain in place into Saturday with mainly 80s to around 90 expected, with Friday the warmest day as H85 temps climb into the mid 20s Celsius. Cold front to drop H85 temps back into the mid teens by Sunday, which should send temperatures back into the 70s to around 80 Sunday into Monday. Slight warm-up then into the middle of next week with temps climbing back into the upper 70s to mid 80s. && .AVIATION.../For the 06Z TAFS through 06Z Thursday night/ Issued at 1120 PM CDT Wed Sep 13 2017 Few changes to going forecast. Slow return of warmer air across the region ovn will reduce any chances for fog across the region. Light/var to south winds will continue through 15z when winds mix significantly west...closer to KDSM/KFOD/KMCW until 23z. Otherwise mid level clouds expected through 18z and again aft 00z over the region as another impulse moves northeast. Airmass dry enough to keep mention of any thunder out of fcst./rev && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...Fowle LONG TERM...Beerends AVIATION...REV