:: We've Been Cut-Off
Very a-typical pattern this week to analyze synopically. Currently, surface based low spinning over KGFK with a secondary downstream MCS/outflow borne low over Sioux Narrows, Ont. From these cyclones comes a very slight boundary along the MN/Dak borders. Ahead of the surface front, strong southerly flow from Gulf raised dewpoints dramatically overnight. Most stations now reporting low 60's from KCWA westward this morning at 11Z. Upper trough will make its last move before cutting off from the polar jet today, advancing the front only slightly and causing enough of a ripple effect to trigger late-day convection.
After this happens, models show the trough cutting off at H50 and upwards initially, and parking over the KRAP area by late tomorrow. Good news - warm/mild conditions will persist through the week. Bad news (or maybe good news for some) rainy conditions will persist as well for our area as we remain on the eastern side of the low. NAM has the system deepening to the H70-H85 levels by the weekend. GFS long-range shows the cutoff and stacked low moving off to the Great Lakes by late Saturday, and a resurgence of the upper jet nosing in by Monday.
Over the period, challenge will be incorporating mesoanalysis with the synoptic, and formulating better if and when statements on precip and max temps. For now, we are going to tweak the MOS ensembles a bit to give you a quick 3-day forecast:
Tuesday...Mostly cloudy, muggy, and warm. High 82. Rain moves in after 4pm. Chance of rain and thunder 50%. Low 60. Wind south 5-10mph.
Wednesday...Mostly cloudy. Still humid and warm. High 76. 40% chance of rain. Low 57. Wind south-southwest 5-10.
Thursday...Mostly cloudy. High 72. 30% chance of rain. Low 55.