Hydrological years are measured from October 1st, to September 30th. The following graphs report the precipitation at various stations from the beginning of the 2004 hydrological year through June. The blue line represents the normal amount of rain expected to be received, based upon a 30 year average at that station. The yellow line represents the actual rain reported from observations taken daily at each site.
Spokane has been below average throughout the entire year. October to mid-November was fairly dry. However, from the last part of October into December precipitation was much more pronounced, bringing totals back up to a near normal amount. Starting in mid-December a slightly below average amount was maintained, leaving Spokane a half-inch below normal by February. A marked dry trend began in February, with only three main precipitation events until mid-May. The total of these three events amounted to only slightly over two inches in the three month span. This dry trend came to an end with the large amount of rain that was received beginning on May 20th. Over the next two days more than two and a half inches of rain fell. This event combined with another small one in June brought totals back to near normal amounts by the end of June.
Beginning at the onset of winter Lewiston was dry and over an inch and a half below normal. Due to many precipitation events December was rather wet and amounts were brought back up to near normal. Rates matched average until mid-March at which point a dry spell ensued. This period is similar to the one seen previously in Spokane, except for one added rain event in April which contributed an additional inch. This added event combined with the rains beginning again on May 10th were, unlike Spokane, enough to bring the total precipitation amounts for Lewiston back up above the normal. The remainder of the period was dry, except for two significant events, one on the 8th giving us .46'' and one on the 19th giving us .41''. Both of these were crucial to keeping the precipitation above the normal.
Wenatchee began the season relatively dry, with one small brief event bringing above normal amounts, it was short-lived however. From November until late-January most days were dry, interspersed with moderate events that kept Wenatchee close to its normal. Then in early February the sporadic precipitation was small and Wenatchee fell behind. There was a marked change in the latter half of the month, in which the total precipitation went from 3.05'' on the 15th to 5.04'' on the 25th in just three events. This was followed by another dry period until May 10th which started a wet trend that brought over another inch of rain and Wenatchee back up above its normal. This was essentially the end of the precipitation for the season in Wenatchee.
Winthrop began with a drier October, which set the stage for an overall below average year. A normal amount fell from November to mid-March keeping Winthrop just below its average. Less fell after this, bringing a drier two months starting in mid-March. This dry patch was broken by an extremely wet period extending from May 16th to the 30th in which 8.24'' of rain fell. This combined with another 1.38'' that fell on the 6th, 7th and 8th of June were still not enough to cancel out the previous dryness and bring Winthrop back up to the usual total here of 17'' for the year. Little precip has been received since these events making June drier than normal.
Mazama had two extremely large events in a dry period early on in the season, one on the 20th of October and another on the 18th of November, bringing them 3.23'' and 2.29'' of precipitation, respectively. An average amount of precip fell up until the first of the year, at which point a drier trend ensued. The rate of precipitation continued until late May, however the normal rate was matched as precipitation tends to usually fall off at the beginning of spring. June is accented with the usual amount of sporadic rain due mainly to thunderstorms.
October was relatively dry except for one major event which dropped over an inch and a half of rain on the 20th and 21st. This was followed by another large event on the 17th and 18th in which 2.58'' of precipitation fell. After this good start to the year Leavenworth leveled out and remained on par with their average until the first of the year, at which point precip began to slacken. From January until May less and less precipitation is received, bringing the accumulated precip down to the normal of 20.64'' on April 13th. This trend is reversed however in the latter half of May in which a wetter trend returns and brings 1.73 more inches of rain. June so far has received little precipitation.
Republic began the year out with a few precipitation events, but in mid to late October was below average for nearly a month. Beginning in December however, rates reached normal amounts and accumulated precip continued to follow just below the normal trend. This pattern persisted up until early-March, at which point a dryer trend ensued up until May 11th, broken only by two small rains centered around February and March 26th. A much wetter trend begins on the 11th of May, slowly bringing the accumulated precip back up the normal levels. One noteworthy event, on the 25th of June, brought 1.62'' of Rain in one day.
Lind began the year with less rain than normal, but quickly made up for it with the wet period of mid-November to mid-December, evident as well in Spokane, Lewiston, Porthill and on many other graphs. This section was wet enough though, to bring Lind above their normal accumulated precip. After remaining at their normal rate for a month, Lind increased in precipitation from February to March, then had less for the next month and a half. April 14th brought the start of more rain, with .2'' over the next two days, followed by .38'' a few days later. This stepping trend continues for the rest of the season, similar to Wenatchee and other locations known for rainstorms which bring sporadic precipitation events.
Porthill had a wet end of October, a dry first-half of November, followed by another month of above average precipitation. December 15th showed the beginning of a drier trend for another month, which ended with increased rainfall in the end of January. February until May had slightly less than average precipitation, with the greatest rainfall dropping .97 of an inch down over a two day period. June brought 1.07'' of rain on the 6th and 7th, after which precipitation continues at a normal rate.
Moscow began drier than usual, having only a few rain events, but soon picked up in mid November to bring the accumulated precip back to normal by mid-December. Precipitation remained the closest of any station to near normal until mid-January, where it then begins to waver. The station falls below then above the normal, but maintains a near average amount of precipitation until March 6th, at which point a dry trend is entered. This lasts until May when on the 16th it changes to a wetter pattern and by the end of the month 3.95'' of precipitation has fallen.
Beginning in October Kellogg was slightly above average in total precipitation received. Then in mid-November rates increased for approximately a month starting winter off wetter than normal. Precipitation continued slightly below until February and then returned to normal until mid-May with a few larger events including one on February 16th and 17th that precipitated out 1.13'' and another March 25th, 26th and 27th that precipitated 1.43''. The end of May was extremely wet dropping over 3'' of rain after the 19th. June has been somewhat below normal, but this dry trend is not enough to negate the fact that the season remains above average.
By Jeremy Harbeck
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