By Gordon McCraw, Meteorologist for the Tillamook County Pioneer
Okay Tillamook, here is your Special Weather Update…get your waders out, it’s starting to look like you might need them. This morning you were seeing the first of several frontal systems expected to bring the area plenty of rain and gusty winds through the weekend and into the start of next week. Look for post-frontal showers tonight with westerly winds 8-12 gusting to 25, the low near 48.
Expect more showers tomorrow with a chance of thunderstorms during the day tomorrow, the winds westerly 5-10, except gusting around any thunderstorms moving through, the high near 54. The showers become more scattered tomorrow night, the winds ease, lows near 47.
A couple of things about today and tomorrow, we are still seeing the King tides affecting the area, so look for additional Tidal Overflow Flooding in all the usual areas in North, Central and South County today and tomorrow during the high tide period from around 11am to 2pm each day. As far as the rain goes, it is looking like the two-day total will be in the 1 to 2” range with up to 3” possible in the Coast Range.
Sunday brings another front with its associated rain, the winds southwesterly 8-12 gusting to 25, an afternoon high temperature of 57, the low near 49. This system looks to bring another ½ to 1” of rain into Tillamook with up to 2” possible in the Coast Range. While the King Tide levels are lower by Sunday, the river will also be rising and with the tidal anomalies, minor Overflow Flooding is still possible.
Monday we are looking at a moderate Atmospheric River event developing that will bring moderate to heavy rain with breezy conditions to the area. A guestimate currently, is for the area to see southwesterly winds 20-25 gusting to 30-35 in town with gusts 45-55 along the beaches and headlands. As far as rainfall totals, for now we go with 1’ to 2” in town, and 2’ to 4” in the Coast Range. During this period, we should start to see the river flow rates increasing steadily about this time.
We see another surge of moisture Tuesday then another one Wednesday. So, what do we think? Well, having worked a number of these events I offer the following. It is looking like, for now anyway, that the hose will be pointed somewhere between Astoria and south Lincoln County. What frequently happens is, the area of maximin or heaviest rainfall osculates north and south for a period. Looking at the current River Forecast models suggest the river slowly rise Monday and Tuesday then rise sharply on Wednesday before going down again Thursday on. The latest forecast shows the Nehalem and Wilson rivers cresting a little below Action stage, but it is early in the game so this can, and will, change up or down between now and then. The National Weather Service gives the rivers a 10 to 25% chance of reaching Moderate Flood Stage and an 8 to 15% chance of reaching Major Flood Stage. For those that need a refresher, for the Nehalem River, Minor Flood Stage is 15’, Moderate Flood is 20’ and Major Flood is 24’. Down at the Wilson River, Minor Flood Stage is 12’, Moderate is 15.5’ and Major is 19’.
Lastly, more rain is expected Thursday into Friday but the rates look to be much lower and less impactful.
So, to summarize, we have good confidence that we are looking at a multi-day event with the higher impact days being Monday through Wednesday. What we have less confidence in is exactly who will be under the maximum rainfall totals, and exactly what those rainfall totals will be. This all also impacts who will see the higher wind gusts and how high these wind gusts will be. The message I offer is, be prepared and ready for the worst and hope for the best! If you live or work in any of the flood prone areas, make your plans now on your actions, while things are less stressful, rather than waiting until the last minute. If the rivers do reach moderate or major flood levels, businesses along North Main will be impacted and there will be road closures, possible landslides with possible power outages. That is the worst case scenario. For now, the chances of that happening are low, but still higher than they have been in some time. Also know that during heavy rainfall periods you can experience Urban and Small Stream Flooding. The bottom line, keep an eye on the forecast as the future forecast models should help to paint a more accurate and clearer picture on what to expect.
I will be back Monday with an update.