####018004081#### FXCA20 KWBC 231901 PMDCA TROPICAL DISCUSSION - INTERNATIONAL DESKS NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 300 PM EDT TUE APR 23 2024 FORECAST BULLETIN 23 APR 2024 AT 1900 UTC: A POTENT MID/UPPER POLAR TROUGH IS PROPAGATING EASTWARD ACROSS THE WESTERN NORTH ATLANTIC. THIS TROUGH IS SUSTAINING A SURFACE FRONT THAT IS PROPAGATING RAPIDLY ACROSS THE BAHAMAS. BY TUESDAY EVENING EXPECT THE BOUNDARY ACROSS THE SOUTHEAST BAHAMAS...NORTHERN CUBA...INTO A WEAKENING BOUNDARY ACROSS THE SOUTHEAST GULF OF MEXICO. BY TUESDAY EVENING...EXPECT THE BOUNDARY TO BECOME STATIONARY ACROSS THE SOUTHEAST BAHAMAS...CENTRAL CUBA...WHERE IT IS TO MEANDER THROUGH FRIDAY. THE SYSTEM WILL ALSO ASSOCIATE WITH A SHEAR LINE. BY TUESDAY EVENING IT IS FORECAST ACROSS EASTERN HISPANIOLA. AFTER THIS PERIOD...EXPECT IT TO GRADUALLY WEAKEN WHILE MEANDERING NORTHWESTWARD. THE HEAVIEST PRECIPITATION WITH THESE SYSTEMS WILL CLUSTER IN THE WARM SIDE OF THE SHEAR LINE AND ALONG A PREFRONTAL TROUGH STRUCTURE...GIVEN THE PRESENCE OF PRECIPITABLE WATER VALUES NEAR/ABOVE 50MM...WHICH IS ABOVE AVERAGE FOR THIS TIME OF THE YEAR. ON TUESDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 30-60MM IN HISPANIOLA IN ASSOCIATION WITH THE SHEAR LINE. ALSO OF RELEVANCE...FRONTAL CONVECTION/PREFRONTAL CONVECTION IN CENTRAL CUBA HAS A POTENTIAL OF BECOMING SEVERE. EXPECT ACCUMULATION GENERALLY IN THE 05-10MM/DAY AND MAXIMA OF 15MM RANGE...ALTHOUGH VERY ISOLATED HIGHER AMOUNTS ARE POSSIBLE. IN PUERTO RICO...THE PREFRONTAL TROUGH STRUCTURE WILL FAVOR MAXIMA OF 15-30MM. ON WEDNESDAY...EXPECT THE HEAVIEST PRECIPITATION IN CENTRAL HISPANIOLA WHERE DIURNAL CONVECTION INTERACTING WITH THE SHEAR LINE WILL FAVOR 10-15MM/DAY AND MAXIMA OF 20-45MM. EXPECT SIMILAR AMOUNTS IN PUERTO RICO...WHILE IN CUBA...EXPECT ISOLATED MAXIMA OF 15-25MM IN THE TAIL OF THE STATIONARY FRONT. ON THURSDAY...EXPECT HEAVY THUNDERSTORMS IN HISPANIOLA THE PREFRONTAL TROUGH AND ASSOCIATED MOIST PLUME MOVE WESTWARD...AND INTERACT WITH THE UPPER DIVERGENT PATTERN AHEAD OF A POLAR TROUGH. THIS WILL FAVOR 25-50MM/DAY AND ISOLATED MAXIMA OF 75-150MM. TO THE EAST...THE AMPLIFIED MID/UPPER PATTERN ACROSS THE ATLANTIC HAS ORGANIZED ANOTHER EXTENSIVE SURFACE FRONT. AS THE ASSOCIATED POLAR HIGH BUILDS...THIS FRONT IS FORECAST TO CONTINUE MEANDERING SOUTHWARD RAPIDLY. ALTHOUGH IT IS FORECAST TO GRADUALLY LOSE BAROCLINICITY...THE FORECAST THERMAL GRADIENT APPEARS SUFFICIENT TO CONSIDER A COLD FRONT OR FRONTAL SHEAR LINE AS IT MEANDERS INTO THE SOUTHERN WINDWARD ISLANDS BY THURSDAY. REGARDLESS...EXPECT A TEMPORARY ENHANCEMENT OF TRADE WIND SHOWERS AS IT PROPAGATES ACROSS THE LEEWARDS AND CENTRAL LESSER ANTILLES ON WEDNESDAY...AND ACROSS THE SOUTHERN WINDWARD ISLANDS ON THURSDAY. ANOTHER REGION OF INTEREST SOUTHERN CENTRAL AMERICA/NORTHWEST COLOMBIA. IN THE UPPER LEVELS...THE DOMINANT FEATURE IS THE SUBEQUATORIAL RIDGE. AS IT INTERACTS WITH AN UNSEASONABLY STRONG SUBTROPICAL RIDGE/BOLIVIAN HIGH IN SOUTH AMERICA...AN ENHANCED UPPER DIVERGENT TIER CONTINUES OVER COLOMBIA AND IS EXPANDING INTO SOUTHERN CENTRAL AMERICA. IN THE LOW AND MID-LEVELS...A TROUGH IS ORGANIZING IN CENTRAL PORTIONS OF COLOMBIA AND IS FORECAST TO MEANDER WESTWARD INTO SOUTHERN CENTRAL AMERICA THROUGH THURSDAY/FRIDAY. IN A SLOW-TO-EVOLVE PROGRESSION...EXPECT MODERATE RAINFALL AMOUNTS DEVELOPING WITH THIS SYSTEM. ON TUESDAY...THE HEAVIEST PRECIPITATION IS EXPECTED IN NORTHERN COLOMBIA/LAKE MARACAIBO REGION WHERE ENHANCED MOISTURE CONVERGENCE WILL FAVOR 15-20MM/DAY AND ISOLATED MAXIMA OF 35-70MM. IN THE MEAN TIME...ONSHORE FLOW IN THE CARIBBEAN BASINS OF COSTA RICA AND PANAMA WILL FAVOR 10-15MM/DAY AND ISOLATED MAXIMA OF 20-45MM. ON WEDNESDAY...EXPECT 15-20MM/DAY AND MAXIMA OF 40-80MM DEVELOPING IN THE DARIEN REGION/NORTHWEST COLOMBIA AND ALSO IN THE CARIBBEAN BASIN OF WEST PANAMA. ON THURSDAY...EXPECT POTENTIAL AMOUNTS OF 15-20MM/DAY AND MAXIMA OF 50-100MM. GALVEZ/CLARKE/ACOSTA...WPC (USA) $$ ####018011165#### FXUS06 KWBC 231903 PMDMRD Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks NWS Climate Prediction Center College Park, MD 300 PM EDT Tue April 23 2024 6-10 DAY OUTLOOK FOR APR 29 - MAY 03, 2024 Dynamical models agree on the overall 500-hPa circulation pattern forecast over the region of North America during the 6-10 day period. At the start of the period a trough is forecast near the coast of the Alaska Panhandle and British Columbia, and weak 500-hPa height anomalies are forecast over the central contiguous U.S. (CONUS) in the ECMWF and NCEP GEFS ensemble means. A broad trough is forecast to the west of Mainland Alaska during the period. A ridge is predicted over the east coast of the contiguous U.S. (CONUS) by ensemble mean forecasts at the start of the period, while a ridge develops over the central CONUS and a trough moves into the west coast later in the period. Above normal temperatures are favored for the Aleutians and most of southern Mainland Alaska during the 6-10 day period under southerly mid-level flow and positive 500-hPa height anomalies. Below normal temperatures are favored for the North Slope, under slightly negative 500-hPa height anomalies. Below normal temperatures are favored for the northwestern CONUS, under a predicted trough during the period. Above normal temperatures are likely across most of the remainder of the CONUS with a ridge predicted over the central and eastern CONUS. Above normal temperatures are slightly favored for northwestern islands of Hawaii supported by the Auto forecast. Near to above normal precipitation is favored for Alaska, consistent with most dynamical model forecasts, and ahead of a predicted trough. Near to below normal precipitation is favored for much of the southwestern CONUS into the central High Plains, where little or no precipitation is expected during the period for climatologically relatively dry regions. Above normal precipitation is favored from the Pacific Northwest across the northern CONUS into the Northern Plains, ahead of a predicted trough, and for the Southern Plains and Mississippi Valley with southerly surface moisture transport, as well as far northern areas of the Northeast, as predicted by the consolidation of calibrated dynamical model precipitation forecasts. Above normal precipitation is slightly favored across Hawaii supported by the Auto forecast. The official 6-10 day 500-hPa height blend consists of 40% of Today's 0z GFS Ensemble Mean centered on Day 8, 40% of Today's 0z European Ensemble Mean centered on Day 8, and 20% of Today's 0z Canadian Ensemble Mean centered on Day 8 FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: About average, 3 out of 5, with good agreement among model forecasts for the circulation pattern during the period, offset by weaker signals and some disagreement among precipitation tools. 8-14 DAY OUTLOOK FOR MAY 01 - 07 2024 The 500-hPa circulation pattern predicted for the 6-10 day period generally persists into the 8-14 day period. A trough is forecast to the west of Mainland Alaska with southerly flow into the state. A predicted trough near the west coast of the CONUS amplifies from the 6-10 day to the 8-14 day forecast in model solutions. Positive 500-hPa height anomalies are predicted over the eastern two-thirds of the CONUS. Above normal temperatures are favored for most of Mainland Alaska and the Alaska Panhandle, while near to below normal temperatures are favored for the North Slope, supported by calibrated GEFS model forecasts. Near to below normal temperatures are favored for the West, under a weak trough. Above normal temperatures continue to be likely over the remainder of the CONUS, under predicted positive 500-hPa height anomalies. Below normal temperatures are slightly favored for Hawaii, supported by the consolidation of calibrated model forecasts. A predicted trough to the west of Alaska increases chances of above normal precipitation across most of the state, excluding the Alaska Panhandle. Above normal precipitation is favored for much of the West across the Northern Rockies into the northern High Plains, ahead of the predicted trough. Above normal precipitation is slightly favored for the Great Plains and upper Mississippi Valley, as moisture streams northward into the region early in the period. Below normal precipitation is favored for much of the eastern CONUS, under a predicted ridge. Above normal precipitation is slightly favored across Hawaii supported by the Auto forecast. The official 8-14 day 500-hPa height blend consists of: 40% of Today's 0z GFS Ensemble Mean centered on Day 11, 40% of Today's 0z European Ensemble Mean centered on Day 11, and 20% of Today's 0z Canadian Ensemble Mean centered on Day 11 FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Slightly below average, 2 out of 5, with general agreement among dynamical models for the overall circulation pattern during the period, offset by weaker signals and some disagreement among precipitation and temperature tools. FORECASTER: D Collins Notes: Automated forecasts are issued on Saturday and Sunday. Occasionally manual intervention is necessary to address quality control and consistency issues. In these cases, forecasts are manually drawn but a full discussion is not issued. The notation for the categorical forecast indicated on the maps is the same as that in the tables: A-above N-near normal B-below The temperature map shows regions with > 33% chance of being warmer (orange, "A"), colder (blue, "B"), or close to (unshaded, "N"). Historical average values for the calendar period of the forecast (dashes, "f"). Labels on the shaded lines give the probability (> 33%) of the more likely category (B or A). Probability of N is always < 40%. The precipitation map shows regions with > 33% chance of being wetter (green, "A"), drier (tan, "B"), or close to (unshaded, "n"). Historical median values for the calendar period of the forecast (dashes, "inches"). Labels on the shaded lines give the probability (> 33%) of the more likely category (B or A). Probability of N is always < 40%. In the southwest and other climatologically dry regions - there will be a greater than 33.3% chance of no precipitation and occasionally even a normal (i.e. Median) value of zero - especially during the dry seasons. In such cases a forecast of near normal is effectively a forecast of little or no precipitation. The climate prediction center uses 1991-2020 base period means as reference in the climate outlooks. The next set of long-lead monthly and seasonal outlooks will be released on May 16. Analogs to the 5 day mean observed pattern centered 3 days ago (D-3) for the region from 20N to 70N latitude and 175E to 60W longitude include the 5 day periods centered on the following dates: 19510403 - 19520403 - 19530403 - 19540403 - 19550403 Analogs to the 7 day mean observed pattern centered 4 days ago (D-4) for the region from 20N to 70N latitude and 175E to 60W longitude include the 7 day periods centered on the following dates: 19510402 - 19520402 - 19530402 - 19540402 - 19550402 6-10 DAY OUTLOOK TABLE Outlook for Apr 29 - May 03, 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF B N SRN CALIF N N IDAHO B A NEVADA A B W MONTANA B A E MONTANA A A WYOMING A B UTAH A B ARIZONA A N COLORADO A B NEW MEXICO A N N DAKOTA A A S DAKOTA A N NEBRASKA A N KANSAS A A OKLAHOMA A A N TEXAS A A S TEXAS A A W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A A ARKANSAS A A LOUISIANA A A WISCONSIN A A ILLINOIS A N MISSISSIPPI A A MICHIGAN A N INDIANA A N OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A N NEW YORK A N VERMONT A N NEW HAMP A N MAINE A N MASS A N CONN A N RHODE IS A N PENN A N NEW JERSEY A N W VIRGINIA A N MARYLAND A N DELAWARE A N VIRGINIA A N N CAROLINA A N S CAROLINA A N GEORGIA A N FL PNHDL A N FL PENIN A N AK N SLOPE B A AK ALEUTIAN A A AK WESTERN A A AK INT BSN A A AK S INT A A AK SO COAST A A AK PNHDL N A 8-14 DAY OUTLOOK TABLE Outlook for May 01 - 07 2024 STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN WASHINGTON B A OREGON B A NRN CALIF B A SRN CALIF B A IDAHO N A NEVADA N A W MONTANA N A E MONTANA A A WYOMING A N UTAH A N ARIZONA N N COLORADO A B NEW MEXICO A N N DAKOTA A A S DAKOTA A A NEBRASKA A A KANSAS A A OKLAHOMA A A N TEXAS A A S TEXAS A A W TEXAS A A MINNESOTA A A IOWA A A MISSOURI A N ARKANSAS A N LOUISIANA A N WISCONSIN A A ILLINOIS A N MISSISSIPPI A N MICHIGAN A N INDIANA A N OHIO A N KENTUCKY A N TENNESSEE A N ALABAMA A B NEW YORK A N VERMONT A N NEW HAMP A N MAINE A N MASS A N CONN A N RHODE IS A N PENN A B NEW JERSEY A B W VIRGINIA A B MARYLAND A B DELAWARE A B VIRGINIA A B N CAROLINA A B S CAROLINA A B GEORGIA A B FL PNHDL A N FL PENIN A B AK N SLOPE N A AK ALEUTIAN N A AK WESTERN A A AK INT BSN A A AK S INT A A AK SO COAST A A AK PNHDL A N LEGEND TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN B - BELOW B - BELOW THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE. FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS PMDMRD. $$