JANUARY 2001 Newsletter

Transcription

1 LOUISIANA OFFICE OF STATE CLIMATOLOGY NON-PROFIT ORG. Dept. of Geography & Anthropology U.S. Postage PAID Louisiana State University Permit No. 733 Baton Rouge, LA Baton Rouge, LA JANUARY 2001 Newsletter THE LOUISIANA MONTHLY CLIMATE REVIEW is published by the LOSC through funding by Louisiana State University and in full cooperation with the National Weather Service (NWS), the National Climatic Data Center (NCDC), the Southern Regional Climate Center (SRCC), and the LSU Agricultural Center. The LOSC is solely responsible for the information provided herein. This publication is provided free of charge to all interested individuals and agencies. For further information, please contact the LOSC [(225) ]. LOUISIANA OFFICE OF STATE CLIMATOLOGY: Mr. John M. ( Jay ) Grymes III... State Climatologist Dr. Robert A. Muller... SRCC Director (Ret.) Mr. Malcolm B. Moreau... LA Cooperative Program Mgr. (Ret.) Ms. Elizabeth Mons... Research Associate Ms. Lynne Boudreaux... Undergraduate Assistant Ms. Michelle Russo... Undergraduate Assistant Ms. Somer Martin... Undergraduate Assistant Mr. Chris Bell... Undergraduate Assistant LSU AGRICULTURAL CENTER: Mr. James Finney... Agriclimate Associate NATIONAL WEATHER SERVICE: Mr. Gil Barton... NWSFO Slidell (LA), DAPM Mr. Marion Kuykendall... NWSFO Shreveport (LA), DAPM Mr. Bill Knight... NWSFO Jackson (MS), DAPM Mr. Richard Gravitt... NWSFO Lake Charles (LA), DAPM

2 LOUISIANA MONTHLY CLIMATE REVIEW DIVISIONAL PDSIs: Jan Feb 2001 Divisional PDSIs for recent months are "preliminary" estimates. Source: National Climatic Data Center CENTRAL GULF COAST CLIMATE OUTLOOK The NWS/Climate Prediction Center Long-Lead Outlooks (LLOs) are released at mid-month and are prepared for the subsequent month and thirteen three-month periods. Details regarding the LLOs can be found at NWS/CPC assessments indicate that La Niña (ENSO "cold" phase) conditions have re-developed in the central Pacific and will remain through March before trending again towards neutral later during the Spring. Sea-surface temperatures (SSTs) are expected to remain cooler-than-normal through May. 30-Day Outlook: February s temperature outlook projects Louisiana and all of the Gulf Coast to be "normal to warm", with the greatest likelihood of above-normal temperatures posted for the Florida peninsula. February s precipitation forecast calls for "climatology" (no forecast tendencies apparent from the models) across most of Louisiana, western Texas, and southern sections of Mississippi and Alabama. Eastern Texas and most of Florida are expected to be "normal to dry" through the upcoming 30-day period, while north-central Mississippi and Alabama are expected to be "normal to wet". 90-Day Outlook: The 90-day (Feb-Mar-Apr) temperature outlook calls for Louisiana and virtually the entire Gulf Coast region to be "normal to warm" through the end of winter and beginning of spring. The three-month precipitation outlook posts north and central Louisiana, most of Texas, and north-central Mississippi and Alabama under "climatology" (no tendencies suggested). "Normal to dry" conditions are expected for southeast Louisiana, along the Mississippi and Alabama Gulf Coast, and Florida.

3 - 8 - LOUISIANA MONTHLY CLIMATE REVIEW JANUARY 2001 PRELIMINARY CLIMATE DATA PRECIPITATION AROUND THE STATE Monthly MAX Rain Cumulative STATION TOTAL DEPT 1-Day Days TOTAL DEPT Monthly MAX Rain Cumulative STATION TOTAL DEPT 1-Day Days TOTAL DEPT NORTHWEST DIVISION: BENTON BOSSIER CITY COTTON VALLEY 5 NNW COUSHATTA 3 NE GREENWOOD F/TWR HANNA 3 S HOSSTON KEITHVILLE KORAN LOGANSPORT MANSFIELD MARTIN F/TWR MINDEN MOORINGSPORT 1 N RED RIVER RES STA ROBSON SHREVEPORT CARGIL PK SHREVEPORT DOWNTOWN SHREVEPORT DTN AP SHREVEPORT SHV AP SPRINGHILL VIVIAN NORTH CENTRAL DIVISION: ARCADIA BIENVILLE 3 NE CALHOUN RES STA COLUMBIA LOCKS FARMERVILLE HAYNESVILLE HOMER 3 SSW JAMESTOWN JONESBORO 4 ENE MONROE MLU AP MONROE-ULM RUSTON-LA TECH SAILES F/TWR SPEARSVILLE F/TWR STERLINGTON STERLINGTON # WEST MONROE WINNFIELD 2 W WINONA F/TWR NORTHEAST DIVISION: BASTROP 0.92M M LAKE PROVIDENCE OAK GROVE 2 WSW OAK RIDGE RAYVILLE 7.91M M ST JOSEPH 3 N SONDHEIMER TALLULAH TALLULAH TVR AP WINNSBORO 2 S WINNSBORO 5 SSE WEST CENTRAL DIVISION: ASHLAND GORUM F/TWR GRAND ECORE HODGES GARDENS LEESVILLE LEESVILLE 6 SSW MANY MANY 9 WSW NATCHITOCHES ROSEPINE RES STA ZWOLLE 2 NW CENTRAL DIVISION: ALEXANDRIA ALEXANDRIA 5 SSE ALEXANDRIA ESF AP 5.76M M ALEXANDRIA AEX AP BEAVER F/TWR BOYCE 3 WNW BOYCE 7 SW BRUSLY 2 W BUNKIE CLAYTON COLFAX ELMER 2 SW EUNICE GRAND COTEAU JENA 4 WSW JONESVILLE LOCKS LSU-DEAN LEE RES STA MARKSVILLE 5.73M M NEW ROADS 5 ESE OLLA OPELOUSAS PORT ALLEN RED RIVER LOCK #1 4.59M M RED RIVER LOCK # VIDALIA #2 6.20M M VILLE PLATTE 2.53M M EAST CENTRAL DIVISION: ABITA SPRINGS 1 SW ABITA SPRINGS F/TWR AMITE ANGIE BAKER BATON ROUGE BURDEN BATON ROUGE CENTRAL BATON ROUGE CONCORD BATON ROUGE BTR AP BATON ROUGE LSU BATON ROUGE SHERWOOD EAST CENTRAL DIVISION: (continued) BATON ROUGE CCLA BATON ROUGE RIVERBEND BOGALUSA CLINTON 5 SE COVINGTON 4 NNW COVINGTON 4 NE DENHAM SPRINGS FOLSOM 6 S FRANKLINTON #2 5.86M M FRANKLINTON 5 SW GREENWELL SPRINGS HAMMOND 5 E HAMMOND 3.05M M JACKSON 3 E KENTWOOD 5.55M M KILLIAN LIVERPOOL 4 ESE LIVINGSTON LSU-BEN HUR FARM MOUNT HERMON 2 W NORWOOD OAKNOLIA PINE GROVE F/TWR PONCHATOULA 4 SE ST FRANCISVILLE SLIDELL SLIDELL ASD AP SUN TALISHEEK TICKFAW 3 E WATSON 3 ESE ZACHARY SOUTHWEST DIVISION: ABBEVILLE BELL CITY 13 SW 8.31M M CROWLEY 2 NE DE QUINCY DE RIDDER DRY CREEK 5 NW ELIZABETH HACKBERRY 8 SSW JENNINGS KAPLAN LAKE ARTHUR 10 SW LAKE CHARLES 2 N LAKE CHARLES PORT LAKE CHARLES LCH AP LELAND BOWMAN LOCK MOSS BLUFF OAKDALE 6.44M M OBERLIN F/TWR ROCKEFELLER WL REF SULPHUR VINTON 5.90M M SOUTH CENTRAL DIVISION: BAYOU SORREL LOCK BREAUX BRIDGE 4 S BUTTE LA ROSE CARENCRO CARVILLE 2 SW DONALDSONVILLE 4 SW FRANKLIN 3 NW JEANERETTE 5 NW LAFAYETTE LAFAYETTE LFT AP MORGAN CITY NAPOLEONVILLE NEW IBERIA NEW IBERIA ARA AP PLAQUEMINE 2 N ST GABRIEL ST MARTINVILLE 3 SW SALT POINT P SOUTHEAST DIVISION: BOOTHVILLE ASOS BURAS CHALMETTE CONVENT 2 S 4.85M M DONALDSONVILLE 4 E GALLIANO GONZALES GRAND ISLE GRETNA HOUMA LA NATURE CENTER LSU-CITRUS RES STA LUTCHER MARRERO 9 SSW METAIRIE NEW ORLEANS MSY AP NEW ORLEANS AUDUBON NEW ORLEANS ALGIERS NEW ORLEANS NEW AP NEW ORLEANS EASTOVER PARADIS 7 S RESERVE ST BERNARD 1.30M M TERRYTOWN THIBODAUX 3 ESE Selected New Orleans DPS Sites: NO/DPS Algiers 2.38M M NO/DPS No NO/Water Plant NO/Sewerage & WB NO/DPS No NO/DPS No M M NO/DPS No

4 LOUISIANA MONTHLY CLIMATE REVIEW JANUARY 2001 PRELIMINARY CLIMATE DATA TEMPERATURE ( F) PRECIPITATION (in.) AVG AVG MEAN Absolute No.Days Monthly Degree-Days Monthly MAX Rain Cumulative STATION MAX MIN TEMP Dept MAX MIN HDD Dept CDD Dept TOTAL Dept 1-Day Days TOTAL Dept NORTHWEST DIVISION: MANSFIELD MINDEN RED RIVER RES STA SHREVEPORT CARGILL PK SHREVEPORT SHV AP Divisional Summary: NORTH CENTRAL DIVISION: BIENVILLE 3 NE CALHOUN RES STA COLUMBIA LOCKS FARMERVILLE HOMER 3 SSW MONROE MLU AP MONROE-ULM M M M RUSTON-LA TECH STERLINGTON # WINNFIELD 2 W Divisional Summary: NORTHEAST DIVISION: BASTROP M M M M M LAKE PROVIDENCE RAYVILLE M M ST JOSEPH 3 N TALLULAH WINNSBORO 5 SSE Divisional Summary: WEST CENTRAL DIVISION: ASHLAND 51.7M 31.1M 41.4M HODGES GARDENS M M M LEESVILLE MANY NATCHITOCHES ROSEPINE RES STA Divisional Summary: CENTRAL DIVISION: ALEXANDRIA ALEXANDRIA 5 SSE ALEXANDRIA ESF AP M M BOYCE 3 WNW BOYCE 7 SW BRUSLY 2 W BUNKIE EUNICE GRAND COTEAU JENA 4 WSW JONESVILLE LOCKS LSU-DEAN LEE RES STA NEW ROADS 5 ESE OLLA Divisional Summary: EAST CENTRAL DIVISION: AMITE BATON ROUGE BTR AP BOGALUSA 56.3M 34.2M 45.3M CLINTON 5 SE COVINGTON 4 NNW FRANKLINTON 5 SW HAMMOND 5 E LSU-BEN HUR FARM SLIDELL SLIDELL LIX/ASD AP Divisional Summary: SOUTHWEST DIVISION: CROWLEY 2 NE 56.8M 37.5M 47.2M DE QUINCY 56.7M 34.9M 45.8M DE RIDDER ELIZABETH HACKBERRY 8 SSW JENNINGS LAKE ARTHUR 10 SW M M M LAKE CHARLES LCH AP LELAND BOWMAN LOCK OBERLIN F/TWR ROCKEFELLER WL REF 58.2M 40.9M 49.6M Divisional Summary: SOUTH CENTRAL DIVISION: BREAUX BRIDGE 4 S CARVILLE 2 SW DONALDSONVILLE 4 SW FRANKLIN 3 NW JEANERETTE 5 NW LAFAYETTE LAFAYETTE LFT AP MORGAN CITY NEW IBERIA Divisional Summary: SOUTHEAST DIVISION: BOOTHVILLE ASOS BURAS GALLIANO HOUMA LSU-CITRUS RES STA 60.0M 42.4M 51.2M MARRERO 9 SSW 59.7M 38.3M 49.0M NEW ORLEANS MSY AP NEW ORLEANS AUDUBON NEW ORLEANS NEW AP RESERVE 60.1M 38.7M 49.4M ST BERNARD M M M M M TERRYTOWN THIBODAUX 3 ESE Divisional Summary: Statewide Averages: ( M ) - indicates that daily observations are missing from the monthly or cumulative record

5 - 6 - LOUISIANA MONTHLY CLIMATE REVIEW JANUARY 2001 DAILY CLIMOGRAPHS

6 LOUISIANA MONTHLY CLIMATE REVIEW DAILY WATER BUDGETS Soil Moisture Storage (6" Capacity) MOISTURE STATUS SUMMARY Impacts of the drought are still apparent across portions of the Louisiana landscape, but most drought indicators suggest that the severity of the long-term moisture stresses continues to slowly decline. This is particularly true for central and western parishes, where January rains were near-normal to above-normal, pushing a number of rivers and bayous into flood. Improvement is less certain for the state s southeastern parishes (EC & SE Divisions), where monthly rains were below-average once again. Thornthwaite-Mather water-balance assessments suggest that soilmoisture levels across the state were at or near field-capacity at the start of January and remained there through the month, even in areas that recorded below-normal rainfall. This is not surprising, however, as low evapotranspiration rates during the winter season means reduced moisture demand. However, moisture surpluses continue to be below seasonal norms across the southern parishes. Shorter-term drought measures, such as CPC s weekly Palmer and Crop-Moisture Indices, suggest that most of the state is "normal to wet" in terms of moisture status. By comparison, longer-term measures, like NCDC s monthly Palmer Drought Indices (p. 9) suggest that most of the southern half of the state remains in "Moderate to Severe Drought". The USDA s weekly Drought Monitor (DM) -- as of early February -- serves as an intermediate compromise between these weekly and monthly Palmer measures, indicating "abnormally dry" but "improving" conditions in effect across the southeastern quarter of Louisiana. Northern, central and western parishes are posted as "near normal". PDSI OUTLOOK Projections through April 2001 suggest that "Near Normal to Moist" conditions are likely to persist across northern Louisiana into the Spring, while slow, continued improvement (in terms of moisture availability compared to seasonal norms) is suggested for the southern parishes. There remains a potential for drought conditions to continue for sections of southern Louisiana, but there is only a 1-in-3 probability for such an outcome. The outlook suggests that Louisiana farmers can expect to find water supplies in good-to-excellent shape over the upcoming weeks. (CMI) (PDSI) *PRECIP CROP MOISTURE PALMER DROUGHT to END DIV INDEX SEVERITY INDEX DROUGHT NW Excessively Wet Very Moist Spell NC Excessively Wet Unusually Moist NE Too Wet Moist Spell WC Fields Wet Moist Spell C Fields Wet Normal-to-Dry 0.67" EC Favorable Normal-to-Dry 0.70" SW Favorable Near Normal SC Favorable Near Normal SE Favorable Normal-to-Dry 2.12" (*) - rainfall needed in addition to the normal weekly total to bring the drought to an end PAN EVAPORATION: JANUARY 2001 DV Station Total Mean NW LSU-RED RIVER Res Sta 2.1"E 2.0" NC LSU-CALHOUN Res Sta M 2.0" EC LSU-BEN HUR Farm 2.2"E 2.5" SW JENNINGS M 2.6" SE USDA-HOUMA Field Sta 2.0" 2.4" E - Estimated monthly total

7 - 4 - LOUISIANA MONTHLY CLIMATE REVIEW PRECIPITATION SUMMARY January s statewide rainfall averaged 5.6", 0.6" above the mean, and starting the New Year with some much-needed moisture for many central and southwestern parishes which have been suffering through the prolonged drought. Unfortunately, rains over many southeastern parishes -- where the drought reached its greatest severity -- were below-normal once again. January divisional totals averaged above 6" for five divisions (NC, NE, WC, C & SW), with six divisions reporting rainfall departures of +1" or more for the month. By comparison, the southeastern quarter of the state -- represented by the EC, SC and SE divisions -- again recorded below-average rainfall, with the SE running nearly 2" below the regional norm. Cooperative stations around the state displayed a wide range of monthly totals for January. Every Cooperative site with 30-year normals in the NW, NC, NE, WC, and C Divisions reported above normal rainfall for January. Four sites scattered across the state received more than 8" of rain for the month, led by 9.45" at Spearsville F/TWR (NC Div). Olla (C Div), Bell City 13 SW and Hackberry 8 SSW (both in the SW) also topped the 8". At the opposite extreme, rains were below-normal for all longterm (i.e., having 30-year normals) sites in the EC and SE Divisions and all but one site in the SC Division. The state s "driest" weather held through January along the coastal margin of the SE Division, where both Grand Isle and Boothville reported less than 2" of rain for the month. Rainday counts indicate that the majority of Cooperative sites recorded measurable rainfall (0.01" or more) on ten or more dates. January s first significant rains developed across the state on Jan 9-11, with most areas reporting totals of roughly ½" to about 1½" for the period. Climographs (p. 6) of selected stations indicate that -- for most of Louisiana -- a large portion of January s rains fell during the mid-month stormy period of Jan Over northern and western Louisiana, five-day totals for this period typically fell within the 3" to 5" range, with isolated totals approaching or exceeding 6" for the period. By comparison, totals were more on the order of 1" to 3" for the southeastern quarter of the state. January s last statewide "wet" period occurred during the final days of the month. Northern stations typically reported four-day totals of 1" to 2" between Jan 27-30, while stations in the southern half of the state were slightly drier, tending to run on the order of ½" to 1½" for the period. Nearly a dozen sites around the state reported single-day totals of 3" or more, with most of these large one-day accumulations occurring during the stormy run of Jan Olla (C Div) recorded the largest one-day total for the month, capturing 3.85" during the 24- hour period ending on the morning of Jan 19th Monthly PCT% Divisional DIV Total Normal DFN Norm MAX MIN NW % NC % NE % WC % C % EC % SW % SC % SE %

8 LOUISIANA MONTHLY CLIMATE REVIEW TEMPERATURE SUMMARY January s statewide average temperature was 45.2 F, 2.3 below the monthly norm. January was the third consecutive "cooler-thannormal" month, reflecting a well-established shift from the "warmerthan-normal" weather which dominated most of Although a cool month by long-term standards, the -2 departure is rather modest compared to extremes exhibited in some past Januarys, and is even significantly smaller than the -7 departure reported in December Divisional monthly averages ranged from 41 (NC Div) up to 50 (SE Div), with the typical north-to-south winter gradient of increasing temperatures. Monthly divisional departures ranged from a minimum of -1.7 (NW Div) to -2.9 (SC Div), and were relatively consistent statewide. Monthly station summaries suggest that -- on average -- January monthly minimums tended to be 1 to 3 below-normal. Monthly maximums, by comparison, tended to display slightly larger departures across the state, typically ranging from -2 to -4. In addition to beginning 2001 with snow on the ground, the first days of January were especially cold. Daytime highs were as much as 20 below the mean on several dates, with windchill temperatures across most northern parishes in the single-digits during the midmorning hours of Jan 1st and 2nd. Minimums dipped into the teens across northern parishes and as low as the 20 s across most of the coastal sections of the state on the morning of the 3rd, with Calhoun Res Sta (NC Div) recording the state s lowest January reading 10 F. Every site in Louisiana reported freezes during January, with minimums dipping below 32 on roughly half or more of all dates during the month across the northern half of the state. Climographs for selected sites (p. 6) show that daily temperatures through much of the month were below-normal, particularly through the first three weeks of January. Yet occasional brief surges of Gulf air allowed afternoon highs to reach the 60 s and 70 s during this three-week period. A short run of Spring-like days at mid-month saw highs reach the upper 70 s across portions of southeast LA, with New Orleans Audubon Park reporting that state s highest reading of 79 on the 17th. Absolute MEAN Divisional Divisional DIV TEMP Normal Depart MAX MIN NW NC NE WC C EC SW SC SE JANUARY DEWPOINTS January average dewpoints ranged from the mid 30 s across the northern parishes to just above 40 for southern Louisiana, with monthly averages near the norm for northern sits but as much as 2 to 3 below monthly means for coastal locations. The Arctic surge that delivered snow and bitter-cold windchills at the start of January also pushed dewpoints down into the teens across all but the extreme coastal sections on Jan 2nd. Dewpoints rebounded quickly, however, reaching the 50 s and 60 s across much of the state by midmonth. Another shot of cold-and-dry air pushed dewpoints down to the 20 s and teens between Jan 19-21, followed by another rebound by month s end. MONTHLY and SEASONAL DEGREE-DAYS for SELECTED STATIONS Monthly HDDs Seasonal HDDs Monthly CDDs Seasonal CDDs TOTAL DEPT %Nrml TOTAL DEPT %Nrml TOTAL DEPT %Nrml TOTAL DEPT %Nrml SHREVEPORT SHV AP % % 0-6 ** 0-6 ** MONROE MLU AP % % 0 0 ** 0 0 ** NATCHITOCHES % % 0-6 ** 0-6 ** ALEXANDRIA % % 0-7 ** 0-7 ** BATON ROUGE BTR AP % % 0-19 ** 0-19 ** LAKE CHARLES LCH AP % % 0-15 ** 0-15 ** LAFAYETTE LFT AP % % 0-19 ** 0-19 ** HOUMA % % 1-27 ** 1-27 ** NEW ORLEANS MSY AP % % 0-25 ** 0-25 ** HDD Season: Jul Jun 2001 CDD Season: Jan Dec 2001

9 - 2 - LOUISIANA MONTHLY CLIMATE REVIEW SYNOPTIC WEATHER The very long-lived upper-air pattern that developed in mid- November finally began to change a bit about January 10. For Louisiana, the very winter-like cold pattern was controlled by a strong and persistent upper-air trough over the central and eastern United States, bringing wave after wave of cold Canadian air to the Gulf Coast. After January 10, the trough broke down several times, allowing brief incursions of warmer and more moist Gulf air over southern Louisiana. The table of synoptic weather-type frequencies indicates that in terms of monthly weather-type frequency distributions, January was much more like an average January than Louisiana has seen in recent years. For New Orleans, the Continental Index (CI) frequency of 69% is the highest since 1992, and the Tropical Index (TI) frequency of 15% is the lowest since The Storminess Index (SI) of 50% is the highest since 1995, with January being the third consecutive month with an above-average SI frequency --- this following 20 consecutive months of below-average SI percentages! R.A. Muller SYNOPTIC WEATHER TYPE CALENDAR: JANUARY 2001 SHREVEPORT MONROE LAKE CHARLES BATON ROUGE NEW ORLEANS Date FOR CH FOR CH FOR CH FOR CH FOR CH CH CH CH CH CH FOR CH CH CH FOR CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH 5 GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH GH FGR FOR FGR FOR GR FGR CR FGR CR FGR PH CH PH CH PH CH PH CH PH CH CH CH CH CH CH CH CH CH CH CH 10 FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR PH FOR FOR FOR PH FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR PH PH FGR PH FGR FOR FGR FOR GR FGR 15 CH CH CH CH FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FGR FOR FOR FOR FOR FOR FOR FOR FGR FGR FGR FOR CH FOR FOR FOR FOR FOR FOR FOR FOR 20 CH CH CH CH CH CH CH CH CH CH CH FOR CH FOR CH FOR CH CH CH CH CH CH CH CH FOR CH FOR CH FOR CH CH CH CH CH CH CH CH FOR CH FOR CH GH CH GH FOR GH CH GH CH GH 25 CH CR CH CH CH CR CH CH CH CH FOR FGR FOR FGR GR GR FOR GR FOR GR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FOR FGR FOR GR FOR GR FOR GR FOR GR FOR GH FGR GH FGR FOR FGR FOR FGR FOR 30 GH PH GH GH GH GH GH GH GH GH PH PH PH PH PH PH PH PH FOR FOR SYNOPTIC WEATHER TYPES by PERCENT: JANUARY 2001 Shreveport Monroe Lake Charles Baton Rouge New Orleans Pacific High (PH) Continental High (CH) Frontal Overrunning (FOR) Coastal Return (CR) Gulf Return (GR) Frontal Gulf Return (FGR) Gulf High (GH) Gulf Tropical Disturbance (GTD) Continental Index (CH+FOR) Tropical Index (GR+FGR+GTD) Storminess Index (FOR+FGR+GTD)

10 LOUISIANA MONTHLY CLIMATE REVIEW LOUISIANA OFFICE OF STATE CLIMATOLOGY Department of Geography & Anthropology Louisiana State University Vol. 21 No. 1 LSU JANUARY 2001 JANUARY HIGHLIGHTS January proved to be a relatively wet month for much of northern Louisiana, but most southeastern parishes reported belownormal rainfall once again. Statewide monthly rainfall averaged 5.6", more than ½" above the norm. Station totals tended to be 1" or more above the mean for northern and western areas of the state, but up to 1" or more below average for many southeastern parishes. Although southeast LA rainfall was below the mean, drought conditions did not intensify there. Winter rains eased or alleviated drought conditions in marginally-dry portions of central and western LA. January s statewide average temperature was 45, 2 below normal, and the third consecutive "cooler-than-normal" month for the Bayou State. JANUARY WEATHER NOTES Most north Louisiana residents awoke to snowcover on New Year s Day. Snows on the previous evening reached depths of 2" to 4" for a number of locations, with accumulations of 6" or more at a handful of stations. The snows accompanied an Arctic air mass, which produced the coldest weather of the season thus far, as thermometers dipped into the teens on Jan 2nd and 3rd across many of the northernmost parishes. With the exception of this "taste of real winter" at the start of the month, however, the first half of January was devoid of severe or extreme weather. Although the severity of drought conditions for many southern parishes decreased during January, some moisture indices continue to suggest that "moderate to severe drought" conditions (as compared to seasonal norms) remain in effect for most of the southeastern quarter of the state. In stark contrast with the continued dryness experienced in the southeast, Flood Warnings were in effect for a number of northwestern rivers and bayous throughout January. Heavy rains at mid-month increased the number of rivers on the rise across the state, with minor flooding reported along sections of the Red, Sabine, Calcasieu and Mermentau by the 18th. Flood and Flash-Flood Watches were in effect for most of the state by the morning of the 18th as a "wet" winter storm system pushed through the state. Waterway flooding extended into the central and southwestern parishes, and Flood Warnings were posted on the 19th for the upper Oauchita River and for sections of the Bogue Chitto and Pearl rivers in the Florida Parishes. For a number of watersheds, these warnings remained in effect through the end of the month. Severe weather the entered the state on the 29th. Most of the state was included within three Severe Thunderstorm Watch boxes issued that morning, with the first round of Severe Thunderstorms hitting several central, southwestern and northeastern parishes between 7:00 and 8:00am. Later that same morning, a powerful squall line developed over the Atchafalaya Basin and marched eastward, driving strong thunderstorms through the Baton Rouge metro area and across southeastern Louisiana. By late afternoon, Severe Thunderstorm and/or Tornado Warnings had been posted for every parish in the southeastern quarter of the state, with widespread reports of windgenerated damage across the region. In addition to downed trees and powerlines, storm damage included an overturned mobile home at 11:31am in White Castle (Iberville P.). A small tornado was reported in western Livingston Parish at 11:28am, but apparently produced no significant damage. At 12:15pm, another twister hit Amite (Tangipahoa P.), where it damaged a theater and a gas station. Moments later, in the same parish, thunderstorm winds damaged a number of mobile homes and houses in Ponchatoula.