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Summary- We have the wetter pattern with a broad belt of westerlies across most of Calif. The troughing pattern is bi-modal. Most troughs develop near the coast of northcentral and N Calif, but a few develop into S Calif, coming down the coast and deepening over NW Mexico and into Arizona. Forcing for troughs occurring from the N and north-central coast and WSW-ward is from the sea surface temperature anomaly (SSTA) pattern W of north-central Calif. Forcing for troughs over SE Calif, NW Mexico and Arizona and S Great Basin is related to the currently weak El Niño. The combined effect is for wet in N and north-central California, and a drier regime, punctuated by an occasional rain in southcentral and S Calif. We still could see a late season southern storm track condition, usually appearing as an upper low over SOCAL, NW Mexico, or S Arizona in April.

Summary- Strong, stationary, warm upper high pressure continued across Calif on March 13, but will weaken on the 14th. We are seeing a shift to a wetter pattern with resumption of a broad belt of westerlies across most of Calif in by March 18-19. The troughing pattern is bi-modal. Most troughs develop near the coast of northcentral and N Calif, but a few develop in the Great Basin and Rockies area. Forcing for troughs occurring from the N and Calif coast and WSW-ward is from the sea surface temperature anomaly (SSTA) pattern W of Calif. Forcing for troughs over the Great Basin is related to the currently weak El Niño. The combined effect has been wet in N and northcentral California, and drier than normal in southcentral and S Calif, however this is changing to mostly wet in N and central Calif. We still expect occasional southern storm track conditions, with showers and low snow levels in the Sierras in late Mar and Apr.

Summary- Westerlies occur across most of Calif. The troughing pattern is bi-modal, with some troughs developing just off the coast of central and N Calif, and some focusing into the Great Basin. Forcing for troughs occurring from the N and Calif coast and WSW-ward is from the sea surface temperature anomaly (SSTA) pattern W of Calif. Forcing for troughs over the Great Basin is related to the currently weak El Niño. The combined effect will be wet in N and northcentral California, and drier than normal in southcentral and S Calif. Individual troughs contain moisture but their south portions weaken upon reaching the coast. This pattern of development, related to El Niño favors development of troughs in S and SE Calif, NW Mexico, and Arizona with occasional offshore flow at the southcentral Calif coast. We still expect occasional southern storm track conditions, with showers and low snow levels in the Sierras in late March and April.

Summary- Westerlies occur across most of Calif. The troughing pattern is bi-modal, with some troughs developing just off the coast of central and N Calif, and some focusing into the Great Basin. Forcing for troughs occurring from the Calif coast southwestward is from the sea surface temperature anomaly (SSTA) pattern W of Calif. Forcing for troughs over the Great Basin are related to the current new El Niño that has begun. Periods of WNW flow with troughing occur, bringing more occurrence of cold conditions with lower snow levels into N and central Calif, due to troughing over the Great Basin. Individual troughs contain moisture but lack strength as they reach the coast, but intensify while moving inland. This new pattern of development, related to El Niño favors development of troughs in S and SE Calif, NW Mexico, and Arizona, and a colder and occasionally showery pattern in central and N Calif. This maintains a colder than normal pattern with periods of snow showers thru the Sierras. As El Niño becomes more active during late March thru early May, the southern storm track continues. The southern storm track will induce showers and continued snowy conditions in the Sierras in late March thru April. The southern storm track will tend to support the development of severe weather events (thunderstorms and tornadoes), with above normal rainfall in Oklahoma, north Texas in April and Kansas-Nebraska in May.

Summary- High pressure builds into the N Pacific and southern Gulf of Alaska while a weak southern storm track persists along 30N to the W of SOCAL. Troughs are over the Rockies and off the Calif coast. In March, the dry, cold pattern with troughing and a few mountain showers dominates during the first week. Model guidance has shown support for low latitude westerlies and cool conditions during the first half of March, with NW flow from the Gulf of Alaska. This maintains a colder than normal pattern with periods of snow showers thru the Sierras. The developing El Niño anomaly in March will induce troughing into SOCAL and central Calif and abnormally cold weather with some SOCAL showers in early March. As El Niño becomes more active during late March – early May, the southern storm track continues. The southern storm track will induce showers in N and central Calif, and continued snowy conditions in the Sierras in late March thru April. The southern storm track will tend to support the development of severe weather events (thunderstorms and tornadoes), with above normal rainfall in Oklahoma, north Texas and Kansas.

Summary- Troughing continues to focus to the west of California between 130W and 145W. Troughing also increases into the southern deserts and SOCAL as the southern storm track becomes more active.Troughing occurs during Feb 16-23 with wet conditions.Troughing migrates slightly east, putting us in a cold pattern with snow showers in the Sierras and return of cold conditions through all of California, with some offshore flow mixed in during February 24 – March 1.For March, the dry, cold pattern with troughs and showers in the southern deserts dominates during the first week of March. Although northern California turns dry for a while in March, SOCAL and the southern deserts have a tendency for recurrent cold showery conditions.There is support for the next series of storms into all of California during March 19-23, after a long, drier than normal pattern.The La Niña period ends quickly, and the current trend for an El Niño anomaly to develop will continue thru March, to induce more troughing into SOCAL and central California with a continued trend of colder and wetter than normal.As El Niño becomes more active during the next two months (March and April), and the southern storm track continues, the incidence of severe thunderstorms (TSTMS) and tornadoes may shift to above normal, along with above normal rainfall for Oklahoma, Kansas, and north Texas.

Summary- High pressure will dominate the central Pacific near the Dateline and into the Bering Sea, while troughing continues to focus to the west of Calif between 130W and 145W.In the near term, troughing continues thru February 10 with wet conditions. A dry spell with stagnant upper high pressure dominates, with offshore flow, for February 11-15. Wet conditions are most likely during February 16-18, 21, 23, 25-28, and March 3. Most of these rains appear to focus in northern and central California, but may also produce rain into SOCAL (Ventura/LA Counties).

Summary- High pressure will dominate the central Pacific near the Dateline and into the Bering Sea, while troughing continues to focus to the west of California between 130W and 155W. In the near term, troughing returns on February 1-3 with wet conditions. The latest indications are that periods of warm and dry upper high pressure with sunny conditions in the mountains and patchy fog in central valley area of Calif will focus in central and southern California during February 4-6th, followed by rains mostly in the northern half of California on the 7-8th and again on the 12-14th. General wet periods are Possible about February 19-22nd and 25-26th. Most of these rains also appear to focus in the northern portions of California.

Summary- High pressure will dominate the central Pacific near the Dateline and into the Bering Sea, while troughing continues to focus to the west of California between 130W and 150W. In the near term, high pressure will occur over California between 25th and 30th, then troughing will return on January 31st thru the first week of February with wet conditions. Latest indications are that February will be a bit warmer, and less wet. General wet periods occurring in February would be around the 1-8, and 13-14th. Most of the rains in Feb appear to focus in the northern portions of Calif, per our daily rain forecast based on the CFS.

Summary- High pressure will dominate the central Pacific near the Dateline and into the Bering Sea, while troughing continues to focus to the west of California between 130W and 150W. The hard-hitting storm pattern for January 18-23rd is the main near term issue with heavy rains and mountain snows, again with snow accumulating in the Sierras. The latest indications are that February will be a bit warmer, and less wet. General wet periods occurring in February would be around 1-3rd, and 18th. Most of the rains in February appear to focus in northern portions of California, per our daily rain forecast based on the CFS.

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