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Displaying AFOS PIL: AFDDMX Received: 2018-02-09 06:01 UTC
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568 FXUS63 KDMX 090601 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1201 AM CST Fri Feb 9 2018 .SHORT TERM.../Tonight through Friday/ Issued at 334 PM CST Thu Feb 8 2018 Still online for significant snow event across northern Iowa overnight as system passes through the upper Midwest. Strong isentropic lift has moved into the state this afternoon and is currently producing snowfall across the northern half of the state. Have seen good amount of dendrites with the snow and picked up a quick 0.8" at this office through 3PM and reports of around 2" near Churdan. This axis will be shifting configuration from NW-SE axis to more of an W-E the next few hours. This should keep the bulk of precipitation into this evening along and north of Highway 30. Eventually stronger mid level forcing associated with the shortwave will arrive later this evening with another round of relatively intense lift. Cross sections show relatively weak static stability across central/northern Iowa which will aid in lift. In fact, some upright instability was noted with the equivalent potential temperature surface folding over on themselves. Banded snow is likely if not one intense band somewhere near the Highway 20/30 corridor. Anticipate a rather quick decrease in conditions with any northward travel to the north of I80 tonight. The upgrade to warning also appears in line with 5-7 inches likely in those areas. Surrounding these areas the advisory will also remain in place with amounts of 3-6 inches in northern Iowa and 2-5 on the southern edge, although anticipate a very rapid drop off in amounts to the south. Forcing will become progressive late tonight with the approach of the shortwave and lift will drop southward. The overall lift will also be decreasing with dynamics shifting eastward with the upper system. Snowfall rates will begin to slowly diminish by daybreak with areal coverage also decreasing. However, with snow occurring just before or during the early portions of the commute, difficult travel conditions are expected in the headline areas. Lingering lift will persist into Friday with some snow continuing but with drier air arriving and the passage of the shortwave, the snow should decrease through the morning. However, some very weak forcing will exist across the southern half of Iowa into the afternoon and may be sufficient for some additional light flurries or even some freezing drizzle with some drier air at mid levels and loss of ice introduction at times. .LONG TERM.../Friday night through Thursday/ Issued at 334 PM CST Thu Feb 8 2018 Friday night...the next short wave pushes through Friday night into Saturday but by this time the cold front is well into Missouri. Models show the forcing into central Missouri but mid levels still have some across southern Iowa and as such, we will see another potential for snow mainly across southern Iowa but some very light snow still possible as far north as the I-80 corridor. This will not be on the magnitude of the snow earlier Friday but we will still see around 2 to 3 inches for the far south. On Saturday/Saturday night another deep trough sweeps the region with surface high pressure in place over Iowa. This system will be impacting areas further south and Iowa should be mainly dry but we will be cold. As the trough exits, it may bring some light snow into far southeast Iowa but for the most part, this will be negligible. Beyond Sunday, a system digs deep into the southwest U.S. buckling the flow over the central Plains/Upper Midwest and brining warmer temps back to the region and we should finally get a break from the snow. For the most part we will be dry through at least Wednesday in the extended. A couple of caveats would be a a weak impulse riding through the flow that may bring light snow or flurries north Tuesday morning. The GFS wants to bring a system through in the Wednesday/Thursday timeframe but the Euro is dry so with model discrepancy that far out, I left model blended solutions in the forecast for now. && .AVIATION.../For the 06Z TAFS through 06Z Friday night/ Issued at 1201 AM CST Thu Feb 8 2018 Low CIGS and VSBYS with the snow across the northern TAF sites to continue through the overnight hours. Snow to being to taper off from north to south toward sunrise into early Friday morning. Snow then to move south toward late Friday. Some VFR periods expected across the north, with clouds moving back in late. Winds to be northerly and increase through the critical taf period. && .DMX WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM CST Friday for IAZ044-057>062- 073>075. Winter Storm Warning until 9 AM CST Friday for IAZ023>028- 033>039-045>050. Winter Weather Advisory until 6 AM CST Friday for IAZ004>007- 015>017. && $$ SHORT TERM...Cogil LONG TERM...FAB AVIATION...Beerends