Investors looked to Janet Yellen, the Federal Reserve Chair, this week, as she claimed that the abnormally cold weather was to blame for the weakness seen in the U.S. economy this winter. Yellen's comments helped to propel the S&P 500 above its 2013 close on Thursday, putting the index in positive territory for the year. In macro news, investors were dealt a mixed hand, as Initial Jobless Claims came in above expectations at 348,000 and January new home sales posted a 9.6% gain versus expectations of 3.4% decline. The Bureau of Economic Analysis released its second estimate for 2013 fourth quarter U.S. GDP, reporting that GDP rose 2.4%. This figure is lower than the 4.1% reported for 2013's third quarter, and is down from the 3.2% growth that the bureau reported last month. Lower consumer spending and exports were the reasons behind the lower GDP estimate. In Treasury news, 10-year yields moved lower throughout the week, starting on Monday at 2.75 and closing Thursday at 2.65. Below, we look at all of Moody's municipal bond upgrades and downgrades from the past week.

Upgrades

• Covington, WA: Moody's upgraded this city's issuer rating to Aa2 from Aa3 and its Limited Tax General Obligation bonds to Aa3 from A1. The upgrades primarily reflect the city's significantly improved financial profile and positive multi-year financial trends, which are credit factors with increased weight in the new methodology.
• Easton, MD: Moody's upgraded this town to Aa2 from Aa3. The upgrade to Aa2 reflects the town's strengthened financial position supported by strong reserve levels. The rating also reflects the town's moderately-sized economic base that serves as a regional center, improved wealth levels, and low debt burden.
• Paradise Elementary School District, CA: Moody's upgraded this school district to A3 from Baa1. The upgrade is driven by the District's long history of sound operating performance and very low debt burden. These positive credit factors are now more pronounced when assessed with the updated methodology. However, the A3 rating still reflects the exceptionally small tax base and its concentration in agriculture, negative credit factors that have long tempered the District's rating.
• North Country Community College, NY: Moody's upgraded this organization to Baa1 from Baa2. The rating upgrade on college Foundation's bonds is based on steady funding from the state and counties despite declining enrollment, consistently healthy operating cash flow, growth in liquidity, and strategic importance of the financed facilities.
• Lewistown Hospital, PA: Moody's upgraded this hospital to Aa2 from Ba1. The Aa2 debt rating and stable rating outlook reflect Lewistown's change in bondholder security following the substitution of the Master Note issued under Geisinger's MTI for the Lewistown MTI. Coincidental to the substitution, the Lewistown Series 2007 bonds were certified as parity obligations to outstanding Geisinger obligations.
• Sanford-Burnham Medical Research Institute, CA: Moody's upgraded this institute to Baa1 from Baa2. The upgrade to Baa1 reflects the Institute's growing market position as a nationally recognized biomedical research center with three campuses, improved revenue diversification and a substantial new gift that will mitigate declining federal research awards.
• Watonwan County, MN: Moody's upgraded this county to Aa3 from A1. The Aa3 rating is based on the county's rural tax base in south central Minnesota that is highly dependent on agriculture, healthy financial operations with strong reserves, and a low debt burden with a lack of future borrowing needs.
• City of Chickamauga, GA: Moody's upgraded this city to A1 from A2. The upgrade to A1 from A2 reflects the city's historically conservative budget process supported by very strong reserve levels, which alleviates risk associated with economically sensitive revenues. The rating also incorporates a limited tax base with taxpayer concentration and a moderate debt burden.

Downgrades

• Madison and Fremont Counties Joint School District 322, ID: Moody's downgraded this joint school district to Baa1 from A3. The downgrade primarily reflects the district's very narrow general fund reserves, economic concentration, and below average socio-economic indicators. The rating also incorporates the district's modest debt profile with rapid amortization and the recent trend of enrollment growth.
• Canyon County School District, ID: Moody's downgraded this school district to A2 from A1. The downgrade primarily reflects the district's narrow financial reserves, moderately sized tax base which has decline significantly in recent years and is somewhat concentrated, and below average socio-economic indicators. The rating also incorporates the district's modest debt burden with rapid amortization.
• Puerto Rico: Moody's downgraded to A1 from Aa3 the long-term letter of credit-backed rating of the Commonwealth of Puerto Rico Public Improvement Refunding Bonds. Moody's review of the long-term ratings of the Bonds resulted from Moody's downgrade of the Commonwealth of Puerto Rico's (Puerto Rico) general obligation rating to Ba2 from Baa3 on February 7, 2014.
• Manitowoc County, WI: Moody's downgraded this county to A1 from Aa3. The downgrade to A1 from Aa3 and the removal of the negative outlook reflects the county's reduced General Fund reserve balance and management's intention to maintain reserves at current levels going forward. The A1 rating also incorporates the county's large and diverse tax base located 20 miles south of Green Bay (GO rated Aa2); narrow unassigned General Fund reserve balance; and manageable debt and pension obligations.
• Coral Springs, FL: Moody's downgraded this city to Aa1 from Aaa. The Aa1 G.O. rating is based on the city's sizable tax base, sound financial management practices with historically strong financial reserves, a minimal debt position and higher than average pension liabilities. The downgrade to Aa1 reflects the city's declining tax base, reduced reserve levels, higher than average pension liabilities and material future borrowing plans.
• Fayette County School District, KY: Moody's downgraded this school district to A1 from Aa3. The downgrade to A1 reflects the district's narrow financial position from the continued erosion of operating fund reserves.
• Bowie County, TX: Moody's downgraded this county to A3 from A1. The downgrade to A3 reflects the county's severely strained financial position challenged by volatile jail operations and projected negative fund balance for fiscal year 2013. The rating also considers the county's sizeable and steadily growing tax base, average socioeconomic profile, and slow debt payout.
• Village of Oak Park, IL: Moody's downgraded this village to Aa3 from Aa2. The Aa3 GO rating reflects a steady narrowing of financial reserves and liquidity over the past few years; challenged, though improving enterprise fund operations; a sizable tax base in the Chicago (A3 negative outlook) metropolitan area; affluent demographic profile; and manageable debt profile.
• Sioux City, IA: Moody's downgraded this city to Aa2 from Aa1. The Aa2 rating reflects the city's above-average debt burden with fixed costs related to debt and pensions comprising nearly 40% of the city's operating expenditures; stable tax base and role as regional economic center; below average demographics; sound financial operations but modest reserves; and strong management.
• Pine City, MN: Moody's downgraded this city to A3 from A2. The A3 rating reflects the city's small and concentrated tax base, below average socioeconomic profile, high debt burden, and strained Enterprise Fund operations. The rating also reflects the city's recent history of reserve volatility stemming from planned capital spending.
• Farmington Public School District, MI: Moody's downgraded this school district to Aa2 from Aa1. The downgrade to Aa2 reflects a steady narrowing of financial reserves over the past few years, a moderately negative enrollment trend that has and may continue to pressure operating revenue, and the district's exposure to a considerably underfunded cost-sharing retirement system.
• St. Joseph's College, NY: Moody's downgraded this college to Baa3 from Baa1. The downgrade reflects the significant deterioration of liquidity within the last two years that is a direct result of continued enrollment declines, stagnant net tuition revenue in a highly competitive and price sensitive student market, and markedly weakened operating performance. Additionally, the college failed to meet a minimum debt service coverage covenant for its fixed rate bonds.
• Earlham College, IN: Moody's downgraded this college to Baa1 from A1. The downgrade to Baa1 from A1 is driven by Earlham's challenged student demand, with declining net tuition revenue since 2009 leading the college to a position of fundamental financial imbalance. As the college works to implement its strategic plan that invests in its campus facilities, academics and the student experience, expenses will continue to grow.
• Village of Calumet Park, IL: Moody's downgraded this village to A2 from A1. The A2 rating is based on ongoing declines in the village's tax base value, yielding a reduction of over 25% in valuation since 2010 and continued General Fund support for certain enterprise operations. The rating also reflects the village's substantial debt burden as a percent of full value, solid financial operations with strong reserves, and somewhat elevated but manageable pension liabilities.