JUNE 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 JUNE 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. Ramin Zamanian... 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 Thibodaux 3 ESE (SE Division) posted a monthly total of 33.06" for June a remarkable total (equal to 6 months of normal rainfall), but not a state record! A preliminary review of Louisiana climate records suggests that there have been a handful of locations within the state to record more than 30" of rain in a single month, led by Lafayette (SC Div), which recorded 37.99" in August Because of Allison, Louisiana s statewide-averaged June rainfall was 12.2", the state s second "wettest" June and the ninth all-time "wettest" month of record (dating back to 1889). By coincidence, Louisiana s "wettest" June was in in part the result of 1989 s Allison, a storm that also made its landfall along the Texas coast! In addition, a subjective assessment of June 2001 s flooding rains suggests that 2001 s Allison almost certainly ranks among the five "biggest" rainstorms of the past 100 years for Louisiana, and likely ranks among the top three. Other "contenders" for the top three rain events include September 1998 s T.S. Frances (possibly Louisiana s most widespread event) which hit the New Orleans area with upwards of 30" of rain and August 1940 s unnamed hurricane, which dumped more than 30" of rain in sections of southcentral Louisiana.

2 LOUISIANA MONTHLY CLIMATE REVIEW JUNE 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 M BOSSIER CITY COTTON VALLEY 5 NNW COUSHATTA 3 NE GREENWOOD F/TWR HANNA 3 S HOSSTON KEITHVILLE LOGANSPORT MANSFIELD MARTIN F/TWR MINDEN MOORINGSPORT 1 N RED RIVER RES STA ROBSON SHREVEPORT CARGILL PK SHREVEPORT DOWNTOWN SHREVEPORT DTN AP SHREVEPORT SHV AP SPRINGHILL VIVIAN NORTH CENTRAL DIVISION: ARCADIA M 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 5.65M M WINNFIELD 2 W WINONA F/TWR NORTHEAST DIVISION: LAKE PROVIDENCE OAK GROVE 2 WSW OAK RIDGE RAYVILLE 2.70M 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 M ALEXANDRIA AEX AP 6.73M M BEAVER F/TWR BOYCE 3 WNW BOYCE 7 SW BRUSLY 2 W BUNKIE CLAYTON 3.31M M COLFAX ELMER 2 SW EUNICE GRAND COTEAU M JENA 4 WSW JONESVILLE LOCKS LSU-DEAN LEE RES STA MARKSVILLE M NEW ROADS 5 ESE OLLA OPELOUSAS PORT ALLEN M RED RIVER LOCK # M RED RIVER LOCK # VIDALIA # M EAST CENTRAL DIVISION: ABITA SPRINGS 1 SW ABITA SPRINGS F/TWR AMITE ANGIE BAKER 21.66M M BATON ROUGE BURDEN BATON ROUGE CENTRAL M BATON ROUGE CONCORD BATON ROUGE BTR AP BATON ROUGE LSU BATON ROUGE SHERWOOD BATON ROUGE CCLA M BATON ROUGE RIVERBEND EAST CENTRAL LOUISIANA: (continued) BOGALUSA CLINTON 5 SE COVINGTON 4 NNW COVINGTON 4 NE DENHAM SPRINGS FOLSOM 6 S FRANKLINTON # M M FRANKLINTON 5 SW GREENWELL SPRINGS HAMMOND 5 E HAMMOND M JACKSON 3 E KENTWOOD 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 LIX/ASD AP SUN TALISHEEK TICKFAW 3 E WATSON 3 ESE 19.29M M ZACHARY 23.18M M SOUTHWEST DIVISION: ABBEVILLE BELL CITY 13 SW 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 M LAKE CHARLES PORT LAKE CHARLES LCH AP LELAND BOWMAN LOCK MOSS BLUFF OAKDALE M OBERLIN F/TWR ROCKEFELLER WL REF SULPHUR VINTON 12.36M M SOUTH CENTRAL DIVISION: BAYOU SORREL LOCK M 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 M NEW IBERIA NEW IBERIA ARA AP M PLAQUEMINE 2 N ST GABRIEL ST MARTINVILLE 3 SW SALT POINT P M M SOUTHEAST DIVISION: BOOTHVILLE ASOS M BURAS CHALMETTE CONVENT 2 S M DONALDSONVILLE 4 E 22.39M M GALLIANO GONZALES GRAND ISLE 8.58M M GRETNA M HOUMA LA NATURE CENTER M LSU-CITRUS RES STA LUTCHER MARRERO 9 SSW M METAIRIE NEW ORLEANS MSY AP NEW ORLEANS AUDUBON NEW ORLEANS ALGIERS NEW ORLEANS NEW AP PARADIS 7 S M RESERVE ST BERNARD 2.95M M TERRYTOWN THIBODAUX 3 ESE Selected New Orleans DPS Sites: NO/DPS Algiers M NO/DPS No M NO/Water Plant M NO/Sewerage & WB M NO/DPS No M NO/DPS No M NO/DPS No

3 - 8 - LOUISIANA MONTHLY CLIMATE REVIEW JUNE 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 RUSTON-LA TECH STERLINGTON # WINNFIELD 2 W 85.7M 65.9M 75.8M Divisional Summary: NORTHEAST DIVISION: LAKE PROVIDENCE RAYVILLE M M M 2.70M M ST JOSEPH 3 N TALLULAH WINNSBORO 5 SSE Divisional Summary: WEST CENTRAL DIVISION: ASHLAND HODGES GARDENS 87.1M 68.5M 77.8M LEESVILLE MANY NATCHITOCHES ROSEPINE RES STA Divisional Summary: CENTRAL DIVISION: ALEXANDRIA ALEXANDRIA 5 SSE ALEXANDRIA ESF AP M BOYCE 3 WNW BOYCE 7 SW BRUSLY 2 W BUNKIE EUNICE GRAND COTEAU M 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 CLINTON 5 SE COVINGTON 4 NNW FRANKLINTON 5 SW HAMMOND 5 E LSU-BEN HUR FARM SLIDELL SLIDELL ASD AP Divisional Summary: SOUTHWEST DIVISION: CROWLEY 2 NE DE QUINCY DE RIDDER ELIZABETH HACKBERRY 8 SSW JENNINGS LAKE ARTHUR 10 SW 87.4M 71.9M 79.7M LAKE CHARLES LCH AP LELAND BOWMAN LOCK OBERLIN F/TWR ROCKEFELLER WL REF 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 85.2M 74.8M 80.0M M BURAS 86.8M 75.1M 81.0M GALLIANO HOUMA LSU-CITRUS RES STA MARRERO 9 SSW M NEW ORLEANS MSY AP NEW ORLEANS AUDUBON NEW ORLEANS NEW AP RESERVE ST BERNARD M M TERRYTOWN THIBODAUX 3 ESE Divisional Summary: Statewide Averages: ( M ) - indicates that daily observations are missing from the monthly or cumulative record

4 LOUISIANA MONTHLY CLIMATE REVIEW JUNE 2001 DAILY CLIMOGRAPHS

5 - 6 - LOUISIANA MONTHLY CLIMATE REVIEW 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: The NWS/CPC s ENSO discussion states that tropical Pacific ocean temperatures remain near normal, with sea surface temperature (SSTs) anomalies averaging less than ±1 C at most locations. SSTs are expected to be "ear normal" normal for the rest of the summer and into early fall, with models suggesting a slow turn toward El Niño ("warm" phase) conditions later in the year. 30-Day Outlook: The outlook for August forecasts "normal to warm" temperatures for most of Louisiana, Texas, Florida, and southern sections of Mississippi and Alabama, with the greatest likelihood of "warmer" temperatures posted for south Florida. "Climatology" (no forecast trend) is posted for northeast Louisiana and the remaining areas of Mississippi and Alabama. The precipitation outlook for the next thirty days continues to show Louisiana and the entire South under "climatology". 90-Day Outlook: The 90-day (Aug-Sep-Oct) temperature outlook indicates "normal to warm" temperatures are most likely for southern Louisiana, most of Texas, and Florida. North-central Louisiana, Mississippi, and Alabama were posted under "climatology". With regard to rainfall over the next three months, most of Louisiana, Texas and the northern sections of Mississippi and Alabama continue to be posted under climatology. "Normal to wet" conditions are anticipated for southeast Louisiana, Florida, and southern sections of Mississippi and Alabama. 1 SYNOPTIC WEATHER TYPE CALENDAR: JUNE 2001 SHREVEPORT MONROE LAKE CHARLES BATON ROUGE NEW ORLEANS Date CH CR CH CR FGR GR FGR GR FGR GR 5 GR GR GR GR GTD GR GR GR GR GR GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD GTD 10 GH GH GH GH GTD GH GTD GTD GTD GTD GH GH GH GH GH GH GH GH GTD GH GH GR GH GH GH GR GH GR GH GR GR GR GH GH GR GR GR GR GR GR GR GR GH GH GR GR GR GR GR GR 15 FGR CH FGR CH FGR CH GR FGR GR FGR CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CR CH CR CH CR CH CR CH GTD GR GR GR GR GTD GTD GR GTD GTD GTD 20 GH GH GH GH GTD GH GH GH GH GH GH FGR GH FGR GH FGR GH GH GH GH CH CH CH CH FOR CH FGR CH FGR CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH CH 25 CH CR CH CR CH CR CH CR CH CR CR GR CR GR CR GR CR GR CR GR 30 SYNOPTIC WEATHER TYPES by PERCENT: JUNE 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+GH+CR) Storminess Index (FOR+FGR+GTD)

6 LOUISIANA MONTHLY CLIMATE REVIEW DAILY WATER BUDGETS Soil Moisture Storage (6" Capacity) MOISTURE STATUS SUMMARY After two unusually dry months (April & May), drought conditions had re-developed across much of Louisiana by the beginning of June, prompting fears that Louisiana was about to begin a fourth "dry" summer. But rains from the remnants of Allison put an end to the drought threat for most of the state. In fact, not only did rains from Allison saturate soils across south Louisiana, but she also forced a number of southern parishes to deal with extensive flooding as most south Louisiana waterways rose well-above floodstage. Thornthwaite-Mather water budget assessments clearly show the effects of Allison for many southern locations, with soil-moisture levels showing smaller rates of recovery in the northern half of the state. In fact, data suggest only very limited recharge for the extreme northern and northeastern parishes (e.g., Winnsboro 5 SSE), where storm totals were generally less than 3" for the event. As rains were far more variable during the latter half of June, many of those areas that did not receive soil-saturating rains from Allison (June 4-12) ended June with soil-moisture shortages. For example, the NE division ended the month posted under "Mild Drought" based on the weekly PDSI as of month s end, while the NC Division slipped towards drought classification. Weekly CMI s also suggest "dry" upper-soil layers across northern Louisiana by month s end. By contrast, the southern half of the state begins July with generally "wet" soil-moisture conditions. While weekly PDSI and CMI classifications suggest the onset of drought conditions in sections of northern Louisiana as of the end of June, the USDA s weekly Drought Monitor -- a composite index of various moisture indicators -- suggests "near normal" conditions statewide. PDSI OUTLOOK PDSI projections through September indicate that drought conditions are very unlikely (less than a 20% chance) for the southern two-thirds of the state, with the potential for continued drought in the three northern divisions posted at only a 30% to 35% likelihood. Louisiana rainfall is expected to run relatively "near the norm" through the upcoming months. (Note: tropical weather -- which is not factored into these projections -- could further reduce the drought threat in the upcoming months, as nearly two-thirds of Louisiana s historical landfalls have occurred in August and September.) (CMI) (PDSI) *PRECIP CROP MOISTURE PALMER DROUGHT to END DIV INDEX SEVERITY INDEX DROUGHT NW Moisture Short Near Normal NC Moisture Adequate Incipient Drought 2.11" NE Moisture Short Mild Drought 2.76" WC Fields Wet Moist Spell C Fields Wet Near Normal EC Favorable-to-Wet Very Moist Spell SW Too Wet Moist Spell SC Favorable-to-Wet Unusually Moist SE Favorable-to-wet Unusually Moist (*) - rainfall needed in addition to the normal weekly total to bring the drought to an end PAN EVAPORATION: JUNE 2001 DV Station Total Mean NW LSU-RED RIVER Res Sta 8.0"E 7.8" NC LSU-CALHOUN Res Sta 6.8"E 7.4" EC LSU-BEN HUR Farm 7.9"E 7.5" SW JENNINGS 7.4"E 7.6" SE USDA-HOUMA Field Sta 6.5"E 6.6" E - Estimated monthly total

7 - 4 - LOUISIANA MONTHLY CLIMATE REVIEW TEMPERATURE SUMMARY June s statewide average temperature was 78.5 F, 0.9 below the norm. Departures were modest, with monthly divisional temperatures all running within 2 of their respective normals, and within 1 of normal for five divisions (NW, NE, WC, SW & SE). Most temperature-recording sites reported monthly maximums that were below the mean, with a number of sites in the southern half of Louisiana reporting monthly maximums that were as much as 3 to 4 below average. By contrast, monthly minimums were generally near normal to as much as 2 above the mean across the state. Climographs (p. 6) suggest that temperatures were a bit less consistent -- from a day-to-day basis -- than is typical in summer, particularly in southern sections of the state. Cloud cover and high dewpoints during the heavy rains of Allison minimized diurnal ranges during the flood event. During the last two weeks of June, drier continental air masses (Continental High weather type) allowed afternoon highs to reach normal levels, but the lowered dewpoints associated with these air masses allowed for pleasant overnight and early morning temperatures. Although numerous sites reached the mid to upper 90 s during the month, no triple-digit highs were reported. Many (WC Div) recorded the state s highest afternoon temperature F -- on the afternoons of June 13th and 18th. The dry CH air masses during the latter half of the month allowed minimums to slip to the lower 60 s on one or more nights over many southern parishes, with lows dipping to the upper 50 s for a few locations. Jean 4 WSW and Alexandria 5 SSE (both in the C Div), reported the state s absolute minimum of 57 on the mornings of June 23rd and 24th, respectively. Absolute MEAN Divisional Divisional DIV TEMP Normal Depart MAX MIN NW NC NE WC C EC SW SC SE JUNE DEWPOINTS and HEAT INDICES (HI) June monthly dewpoints ranged from the upper 60 s across northern parishes to the lower 70 s near the coast -- near normal for north Louisiana, and near normal to 1 to 3 above normal for coastal Louisiana. A mid-month peak in dewpoints (Jun 12-14) is associated with the remnants of Allison, when hourly dewpoints reached the mid to upper 70 s statewide; the dry Continental air masses over the state later in the month are also clearly evident, with dewpoints falling to the upper 50 s and 60 s across the state (June 23-25). HI temperatures of 90 or above were common across the state, accounting for 20% to 30% of all hours during June. In fact, HIs topped 100 virtually statewide on June 13 and 14, but HIs of 100 and above accounted for less than 5% of all hours during the month. PRELIM DEGREE-DAY SUMMARIES for SELECTED STATIONS: JUNE 2001 Monthly HDDs Seasonal HDDs Monthly CDDs Seasonal CDDs TOTAL DEPT %Nrml TOTAL DEPT %Nrml TOTAL DEPT %Nrml TOTAL DEPT %Nrml SHREVEPORT WSO AP 0 0 ** % % % RUSTON-LA TECH UNIV 0 0 ** % % % MONROE FCWOS 0 0 ** 2785E % 407Z % 856E 2 100% NATCHITOCHES 0 0 ** 2554E % % % LEESVILLE 0 0 ** % % % ALEXANDRIA 0 0 ** % % % BATON ROUGE WSO AP 0 0 ** % % % SLIDELL 0 0 ** % % % LAKE CHARLES WSO AP 0 0 ** % 437Z % % LAFAYETTE LFT AP 0 0 ** % 401Z % % MORGAN CITY 0 0 ** 1673E % % % HOUMA 0 0 ** % % % NEW ORLEANS WSCMO AP 0 0 ** % % % NEW ORLEANS AUDUBON 0 0 ** 1437E % % % HDD Season: Jul Jun 2001 CDD Season: Jan Dec 2001

8 LOUISIANA MONTHLY CLIMATE REVIEW PRECIPITATION SUMMARY June was an exceptionally wet month, averaging 12.2" for the state as a whole " above the statewide norm (264% of normal). This makes June 2001 the second "wettest" June in more than 100 years from a statewide perspective (June 1989 had 13.6"), and ranks as the 9th "wettest" month since 1889! More importantly, June s excessive rains -- mainly the result of the remnants of T.S. Allison -- effectively ending concerns about the potential for a re-developing drought following April and May s unusually dry weather. (A review of Allison is included in this issue on p. 9) Although a near-record month in terms of statewide-averaged rainfall, divisional data display a very steep north-to-south gradient, with totals for the EC, SC and SE divisions running two to three times those for the three northernmost divisions. June divisional totals ranked among the five "wettest" Junes ever for the six southernmost divisions, and established new June records for the EC, SC and SE, while ranking just behind June 1989 s records for the WC and C Divisions. In comparison with the big rains across most of the southern two-thirds of the state, monthly totals for the three northernmost divisions were just slightly-above normal, with departures running less than 2" above the mean. Of roughly 200 reporting sites, nearly 80 recorded more than 15" of rain for the month. June rainfall over most of the southeastern quarter of the state averaged nearly 20", with locally higher totals. Most long-term stations in the southeast (EC, SC & SE Divisions) reported monthly totals more than 12" above the mean. A dozen NWS Cooperative sites reported in excess of 25" for the month, with Thibodaux 3 ESE reporting 33.06" for June -- nearly 28" above the monthly norm and roughly equivalent to 6 months of normal rain! At the other extreme for the month, a handful of sites in the northern half of the state reported under 4" of rain for the month, with the area around Tallulah proving to be June s "dry" spot. The Tallulah NWS Coop site reported a mere 3.56" for the month, and the unofficial airport site (Tallulah TVR AP) posted just 2.10" for June! Statewide cumulative rainfall through June stands at 34.5", 5.3" above the mid-year norm -- again, reflecting a "closing of the book" on the prolonged La Niña drought for all but a few northern parishes. June is the second month of 2001 with a monthly statewide total averaging above 9", more than off-setting the run of very dry weeks in April and May for most parishes. Cumulative divisional totals are near normal to above normal statewide, with year-to-date departures exceeding 6" for the NC, EC and SC Divisions. A very modest north-to-south trend of increasing totals is suggested, reflecting the effects of June s (i.e., T.S. Allison) regional differences. Station data continue to highlight within-state and withindivisional variability as well. Two sites -- Breaux Bridge 4 S (SC Div) and Thibodaux 3 ESE (SE (Div) have received more than 50" of rainfall thus far, with a substantial number of sites around the state over 40" for the year. Yet 9 of the 65 long-term stations (i.e., having 30-year normals) are reporting below-normal totals through June. At least 20 stations have received less than 30" of rain as of June 30, with Buras (SE Div) listing a mere 18.64" through June -- roughly 12" below normal and more than 30" less than the six-month total for Thibodaux 3 ESE, located less than 90 miles to the west-northwest Monthly PCT% Divisional DIV Total Normal DFN Norm MAX MIN NW % NC % NE % WC % C % EC % SW % SC % SE % Cumulative Pct% Prior Years Div Total Norm DFN Norm NW % NC % NE % WC % C % EC % SW % SC % SE %

9 - 2 - LOUISIANA MONTHLY CLIMATE REVIEW A new round of severe weather moved into northwestern Louisiana late on the 14th through sunrise on the 15th, with Severe Thunderstorm Warnings posted for a dozen parishes in the western half of the state. NWS offices received numerous reports of localized wind damage, with estimated gusts of 60 to 75 mph from a handful of parishes. The weather remained relatively quiet across the Bayou State for the next several days, with only the very occasional Severe Thunderstorm Warning posted by the NWS. Two distinct areas of severe weather developed on the 21st. In southeast Louisiana, Severe Thunderstorms Warnings were posted for a half dozen parishes during the afternoon, with a report from the public noting minimal tree damage as a result of a brief tornado touchdown in Metairie (Jefferson P.). Small hail was also reported in the region, as was localized street flooding due to isolated excessive rains. The second cluster of storms was located over eight northeastern parishes later that afternoon and into the early evening hours. Severe Thunderstorms over this area produced localized damaging winds (with gusts estimated to 70 mph) and small hail. A series of Severe Thunderstorms developed from east to west across Louisiana through the day on the 27th, with most of the activity focused over the southern parishes. June closed with isolated strong thunderstorms developing each day through the end of the month, but none produced any significant damage. Allison: 4-11 June 2001 (This preliminary report was prepared in mid-july and is based on selected information available at that time). The tropical wave that eventually spawned Allison can be traced back to a thunderstorm cluster that moved off the coast of Africa on May 21. That wave worked its way across the Atlantic and over the Gulf of Mexico over the next two weeks. A surface low developed from the wave between June 3-4 over the northwestern Gulf, and the convective field quickly became organized, producing T.S. Allison on June 5th, approximately 80 miles east of Galveston. Allison made landfall along the Texas coast that evening and was downgraded to a depression the next day. Although there were isolated reports of tornadoes and windrelated damage associated with the storm, the record and near-record rains over Texas and Louisiana -- and the subsequent flooding -- were produced primarily during the storm s depression stage following landfall. The Houston area took the worst that Allison could deliver, with damage and losses estimated in the billions of dollars and more than 30 fatalities. Allison s remnants looped through eastern Texas between June 5-9 before moving back over the Gulf; she then headed east-northeast along a track that took the center of the low across southeast Louisiana between June Although no longer "officially" a tropical system, Allison s remnants remained well-defined as the system tracked eastward across the Gulf states, then northward along the Atlantic Coast. Flooding and damage linked to the system were reported along much of the Atlantic seaboard and eastern U.S., with Pennsylvania being especially hard-hit. Louisiana was hammered by the storm, with preliminary losses estimated in excess of $65 million, mainly due to flooding. By the end of the event, 27 south Louisiana parishes were designated as qualified for some level of federal assistance, with three additional parishes included on the governor s disaster declaration. Louisiana rains linked to Allison began falling as early as June 4th and extended through the 11th for several southeastern parishes. Rains continued each day throughout the event, but there were periods when downpours were especially heavy for some areas. For example, radar returns for several southcentral parishes suggested that 10" or more had fallen between the mornings of June 6th and 7th. For the storm event as a whole, the core of heaviest storm totals -- with accumulations in excess of 25" -- extended from Terrebonne Parish northward through northern LaFourche, St. James and St. John/Baptist parishes and into Ascension and Livingston. Thibodaux 3 ESE reported nearly 30" of rain for the event, with more than half of that total falling during the 24-hour period ending on the morning of June 7th! Extensive flooding occurred in Lafayette, Vermilion, Ascension and Livingston parishes, with pockets of localized flooding reported in a number of other parishes; in all, several hundred homes across the southern half of the state were inundated during the event. Virtually every south Louisiana river went into flood for a number of days. Even two weeks after the storm cut through the state, flood waters remained in a few Ascension Parish homes. But the flooding could have been far worse had it not been for the unusually-dry weather pattern that persisted through April and May. Indeed, had rainfall been nearer-the-norm during these months, it is likely that a number of south Louisiana waterways would have experienced stages approaching or topping their floods-of-record. The LOSC would like to thank the following contributors: -- NWS offices in Lake Charles, Slidell, Shreveport & Jackson -- NWS/Tropical Prediction Center and FEMA -- the Times-Picayune & Advocate newspapers -- USGS/Louisiana and the Amite River Basin Commission -- Louisiana OEP and several parish OEPs

10 LOUISIANA MONTHLY CLIMATE REVIEW LOUISIANA OFFICE OF STATE CLIMATOLOGY Department of Geography & Anthropology Louisiana State University Vol. 21 No. 6 LSU JUNE 2001 JUNE HIGHLIGHTS June s statewide temperature averaged 79 F, roughly 1 below the monthly norm. Rainfall was the big weather story for the month, as T.S. Allison and her remnants dumped as much as 15" to 25" (and more!) of rain over sections of southcentral and southeastern Louisiana between June 4-11, causing widespread flooding. A few northernmost parishes recorded less than 5" for the month, but June s excessive rains across the southern half of the state pushed statewideaveraged rainfall above 12". From a statewide perspective, June 2001 ranks as the second "wettest" June of record, and the ninth "wettest" month in the series dating back to 1889! Louisiana s cumulative statewide total through June stands at nearly 35", roughly 5" above the mean, putting an end to any drought threats around the state -- at least for the time being. JUNE WEATHER NOTES... Louisiana concerns shift from fears of a re-developing drought to flooding woes in one week s time... The first four days of June were generally uneventful, until T.S. Allison quickly spun up in the northwestern Gulf. Remnants of Allison -- which initially appeared to be nothing more than a shortlived tropical system -- would prove to be the biggest flood producer for Louisiana since 1998 s T.S. Frances, and rank among the biggest flood events of all time for the Bayou State. (A "preliminary" review of Allison s impacts is provided on p. 2). The first reports of severe weather associated with the system (that would become Allison) began arriving on June 4th, with the system still logged as a tropical wave at that point. Isolated Severe Thunderstorms and reports of wind damage began at mid-day. One person was injured just before 11:00am near Alexandria (Rapides P.) when a tree fell on a passing vehicle. The National Hurricane Center upgraded the system to T.S. Allison early in the afternoon on June 5th. Through the remainder of the day, local NWS offices began issuing Coastal Flood, River Flood and Flash Flood Watches for various sections of the state. By the 6th, NWS offices were issuing Severe Thunderstorm, Tornado, Flood and Flash-Flood Warnings as storms developed and re-developed over the state s southern parishes. Some of the first reports of residential and commercial flooding came from Lafayette Parish on the 6th, as locally-heavy rains continued to fall, with reports of rains in excess of 10" in just a 12-hour period for sections of southcentral Louisiana. Allison s remnants were responsible for one Louisiana fatality. The driver of a pick-up was killed on the morning of the 7th when a tree fell on his moving vehicle. The downed tree was attributed to one of two confirmed tornado touchdowns just north of Zachary (E. Baton Rouge P.) that occurred between 6:00-6:30am. Trees downed by the twister(s) also damaged a number of homes in the area. By mid-morning on the 7th, Flood and Flash-Flood Warnings were being posted throughout southern Louisiana, and rivers across the region were rising quickly. Localized flooding was also being reported on the 7th in a few northwestern parishes as well. By the 8th, not only were various Flood Warnings and Watches being extended, but NWS river forecasters were adjusting anticipated river and bayou crests upward across south Louisiana, prompted by the continuous rains. A tornado briefly touched-down near Port Sulphur (Plaquemines P.) at about 4:30pm on the 9th, but the small, short-lived twister produced no discernible damage. In general, thunderstorm intensities had begun subsiding by the 9th, but these storms were still dumping considerable amounts of rain. And while thunderstorm activity continued to taper off over the next two days, many rivers and bayous continued rising, with several remaining "in flood" through midmonth. Most notable was the Vermilion at Lafayette, which remained above floodstage until June 26th!