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<\/a>High moisture content has been a staple across most of Colorado for the past two weeks. The map below shows the composite Precipitable Water<\/span> (PW<\/span>) anomaly across the southwest United States over the past 2 weeks, from NOAA ESRL’s excellent composite page<\/a>. Note the broad positive anomalies (units are kg per square meter…multiply by 0.03937 to get inches), generally equating to anywhere from 10-20% above normal east of the Continental Divide<\/span> to as much as 30% above normal across far western Colorado. Individual days have seen even higher anomalies.<\/p>\nAfter a rather dry start to July, rainfall has quickly accumulated across large portions of Colorado. This has not been so much in the form of organized events, as opposed to isolated<\/span> to scattered<\/span> storms that produce localized heavy rainfall as they slowly drift along in the weak steering winds. As shown below, this has allowed a large portion of the state to be above average for July precipitation, up to 300% above average in parts of the western slope as well as southeast Colorado. Interestingly, regions north of the Palmer Ridge and northeast Colorado have seen a pronounced minimum in precipitation due to a variety of reasons (which will unfortunately not be discussed here).<\/p>\n As shown in this afternoon’s water vapor image, below, we continue to foresee moisture levels to remain at elevated levels. This is being supported by two main features. First a weak upper-level ridge will provide a south\/southwesterly fetch of very high moisture content into western Colorado (a.k.a. monsoon<\/span> flow). PW<\/span> values as high as 1.4 inches are expected over the next 48 hours, especially closer to the Utah border. Some of this moisture will be able to make it over the Continental Divide<\/span> and provide heavy rainfall along the eastern foothills and mountains. In addition, a surface high pressure is expected to move south-southeast out of Canada starting Wednesday. This will deliver a weak cool front across eastern Colorado, providing a focus for thunderstorm activity. As the front slows on its movement southward, plenty of moisture will be available to the daily upslope circulation formed due to our higher terrain. Thus, although we do not foresee an organized flood threat, a High flood threat is in place for the next 72 hours for isolated<\/span>, but very heavy rainfall capable of causing flash flooding<\/span>. After this event wanes towards the end of the week, long range guidance is indicating a potential shift to a drier weather pattern. Thus, only one Event is identified for this Outlook. It is described in more detail below.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n