Northern Hemisphere Discussion 16 Dec 2003

[senorpepr]

FSNH01 KGWC 161800

TODAY THERE ARE FOUR MAJOR WAVES IN THE NORTHERN HEMISPHERE. THE BERING SEA IS NOW ICE-COVERED NORTHEAST OF A LINE FROM 64 N ON THE EASTERN TIP OF SIBERIA TO 60 N ON THE WESTERN COAST OF ALASKA. THE SOUTHEAST 20 PERCENT OF HUDSON BAY AND MOST OF JAMES BAY REMAIN ICE-FREE. THE DAVIS STRAITS NORTHWEST OF A LINE FROM 62 N ON THE BAFFIN ISLAND COAST TO 72 N ON THE GREENLAND COAST ARE ICE-COVERED, THE NORWEGIAN SEA HAS ICE NORTHWEST OF A LINE FROM 65 N ON THE EAST COAST OF GREENLAND TO 68 N 20 W IN THE DENMARK STRAITS TO 79 N ON THE WEST COAST OF SVALBARD. THE BARENTS SEA HAS ICE NORTH OF A WAVY LINE FROM 74 N SOUTH OF THE SOUTHERN TIP OF SVALBARD TO 74 N ON THE WEST COAST OF NOVYA ZEMLYA. THE KARA SEA IS FROZEN EXCEPT A TINY AREA EAST OF THE SOUTHERN END OF NOVYA ZEMLYA. Ice has FILLED the northwest corner of the Sea of Okhotsk WEST OF 141 E.

THERE ARE TWO STORM TRACKS AROUND MOST OF THE NORTHERN HEMISPHERE. THEY ARE INTERACTING HEAVILY ONLY OVER THE CENTRAL PACIFIC OCEAN.

COLD AND COOL LOWS ON GFS INITIAL 500-MILLIBAR FIELDS, MODIFIED USING
CONTINUITY AND RAWINSONDE DATA; INCLUDE: A 503DM LOW NEAR 52 N 175 W, OVER THE CENTRAL ALEUTIANS, HAS A -34C CORE TEMPERATURE. A 487DM LOW NEAR 52 N 148 W, IN THE GULF OF ALASKA, HAS A -35C CORE TEMPERATURE. A 498DM LOW NEAR 70 N 85 W, ON THE NORTHWEST END OF BAFFIN ISLAND, HAS A -38C CORE TEMPERATURE. A 524DM LOW NEAR 45 N 65 W, AT THE WEST END OF NOVA SCOTIA, HAS A -38C CORE TEMPERATURE. A 555DM LOW NEAR 42 N 29 W, NORTH OF THE AZORES, HAS AN ESTIMATED -18C CORE TEMPERATURE. A 510 DM LOW NEAR 54 N 27 E, OVER BELARUS, HAS A -39C CORE TEMPERATURE. A 486DM LOW NEAR 85 N 100 E, CLOSE TO THE NORTH POLE, HAS AN ESTIMATED -55C CORE TEMPERATURE. A 522 DM LOW NEAR 45 N 117 E, OVER CHINA NEAR THE EASTERN END OF MONGOLIA, HAS A -36C CORE TEMPERATURE. A 496DM LOW NEAR 56 N 157 E, OVER KAMCHATKA, HAS A -39C CORE TEMPERATURE.

COLD AND COOL SOURCE REGION HIGHS ON 500-MILLIBAR GFS INITIAL FIELDS,
MODIFIED USING CONTINUITY AND RAWINSONDE DATA INCLUDE: A 522DM HIGH NEAR 81 N 158 W, OVER THE NORTHWEST BEAUFORT SEA, HAS A -38C CORE TEMPERATURE.

ALL OTHER SIGNIFICANT HIGHS ARE FOUND ON THE SUBTROPICAL RIDGE AXIS: WEST OF HAWAII, SOUTH OF MEXICO, SENEGAL, YEMEN, SOUTHWEST INDIA, NORTHERN LAOS, AND IN THE WEST PACIFIC NORTHWEST OF KWAJALEIN.

A SW TROUGH NOW OVER THE CENTRAL PLAINS IN THE U.S. IS FORECAST TO DIG TO BILOXI 17 DEC, JACKSONVILLE AND EXIT NORTH AMERICA 18 DEC, REACH BERMUDA 21 DEC, AND THE AZORES 23 DEC.

A SW TROUGH ON A COLDER TRACK NOW OVER MANITOBA AND ONTARIO IS FORECAST TO DIG INTO THE U.S. GREAT LAKES AREA ON 17 DEC, BE REINFORCED BY ANOTHER SW NOW IN THE GULF OF ALASKA, EXIT NEWFOUNDLAND INTO THE DAVIS STRAITS 21 DEC, PASS SOUTH OF GREENLAND AND TURN NORTHEAST TO REACH ICELAND ON 23 DEC.

THE LOW OVER WESTERN NOVA SCOTIA IS FORECAST TO ASSUME SW CHARACTER AS IS THE TROUGH EXTENDING FROM IT TO BERMUDA TODAY. THE LOW AND TROUGH ARE FORECAST TO MOVE SOUTHEAST ACROSS THE ATLANTIC TO THE AZORES ON 19 DEC, MOROCCO AS A CLOSED LOW ON 23 DEC.

A NORTHERN TRACK SW TROUGH SOUTH OF GREENLAND IS FORECAST TO MOVE NORTHEAST ACROSS ICELAND ON 17 DEC, NORTHERN NORWAY ON 19 DEC, FINLAND 20 DEC, THE MOSCOW AREA AND THE URALS 21 DEC, CROSS THE WEST SIBERIAN PLAIN ON 22 DEC, AND CROSS THE CENTRAL SIBERIAN PLATEAU 23 DEC.

A LW RIDGE FROM THE AZORES TO THE NORWEGIAN SEA WEST OF NORWAY IS FORECAST TO MOVE EAST TO LOCATE ITS AXIS OVER THE SARDINIA AND DENMARK, DOMINATING WESTERN EUROPE SOUTH OF THE BALTIC, ON 18 DEC; BECOME MUCH FLATTER AND MOVE SOUTHEAST ACROSS THE BALKANS AND ROMANIA TO TURKEY BY 21 DEC. IT IS FORECAST TO CONTINUE AS A VERY FLAT LW RIDGE TO CROSS IRAQ AND NORTHERN IRAN ON 22-23 DEC WITH A PORTION REDEVELOPING AS A LW RIDGE OVER EASTERN KAZAKHSTAN ON 23 DEC.

A COMPLEX OF LW TROUGHS EXTENDS SOUTH FROM NOVYA ZEMLYA TO CRETE. THE WHOLE COMPLEX IS FORECAST TO MOVE EAST TO PUT ITS TROUGH AXES IN A LINE FROM NOVYA ZEMLYA ALONG THE URALS TO WESTERN KAZAKHSTAN TO EASTERN IRAN BY 20 DEC. THE NORTH AND SOUTH PARTS OF THE TROUGH COMPLEX ARE FORECAST TO BE SEPARATED AS THEY CROSS THE CAUCASUS AND LATER THE ELBURZ MOUNTAINS WITH THE NORTHERN TROUGHS IN THE COMPLEX ADVANCING TO THE LENA BASIN AND CENTRAL MONGOLIA BY 23 DEC WHILE THE SOUTHERN LW TROUGHS ARE FORECAST TO MOVE TO KIRGISTAN, AFGHANISTAN, AND PAKISTAN.

A LW RIDGE IS FORECAST TO DEVELOP FROM BERMUDA TO SOUTHERN GREENLAND ON 20 DEC, MOVE TO THE AZORES AND ICELAND ON 21 DEC, FROM 22-23 DEC THE SOUTH END OF THE RIDGE IS TO REMAIN ANCHORED OVER THE AZORES WHILE THE NORTH END IS TO TILT EAST ACROSS THE BRITISH ISLES AND EXTEND NORTHEAST ALONG THE WEST COAST OF NORWAY.

TODAY THERE IS A LW RIDGE FROM EASTERN KAZAKHSTAN TO THE LENA BASIN. THE NORTH END IS FORECAST TO MOVE EAST ACROSS SIBERIA TO DISSIPATE OVER THE SEA OF OKHOTSK AND MANCHURIA ON 20 DEC WHILE THE SOUTH END IS FORECAST TO MOVE EAST BUT MORE SLOWLY TO REACH CENTRAL MONGOLIA AND THE CENTRAL TIBETAN PLATEAU ON 20 DEC. BY 23 DEC THE RIDGE AXIS IS FORECAST TO MOVE TO A POSITION FROM MANCHURIA TO MYANMAR BUT THE RIDGE IS TO BE VERY FLAT.

A LW TROUGH FROM THE SEA OF OKHOTSK TO THE RYUKYUS IS FORECAST TO BE BROADENED AND FLATTENED WITH PASSAGE OF SHORT WAVE FEATURES ON THROUGH 17 DEC THEN THE SOUTH END WILL SWING EAST TO BE NORTH OF SAIPAN ON 23 DEC.

A SW TROUGH OVER THE BALKANS AND IONIAN SEA TODAY IS FORECAST TO MOVE EAST TO REACH THE BLACK SEA AND TURKEY ON 18 DEC, DIG THE POLAR JET SOUTH OF BAGHDAD ON 18-19 DEC THEN DEPART ACROSS WESTERN IRAN TO THE CASPIAN SEA ON 20 DEC. THE SW TROUGH IS FORECAST TO MOVE EAST ACROSS THE ‘STANS TO WESTERN MONGOLIA BY 23 DEC. GFS FORECASTS A WEAKER SW TROUGH NOW SOMEWHERE IN THE ATLANTIC TO CROSS NORTHERN IRAQ ON 22-23 DEC. IRAQ WILL BE UNDER A LW TROUGH BEFORE AND AFTER THE SW SYSTEMS PASS.

AFGHANISTAN TOO WILL BE UNDER A LW TROUGH FOR THE NEXT WEEK WITH THE SW TROUGH THAT WILL EARLIER CROSS IRAQ TO CROSS NORTHERN AFGHANISTAN ON 21-22 DEC.

SW TROUGHS WITHIN THE LW TROUGH ARE FORECAST TO CROSS THE KOREAN PENINSULA ON 19 AND 23 DEC.

A SW TROUGH THAT EXTENDS SOUTH FROM KAMCHATKA TO BONIN ISLAND IS FORECAST TO MOVE EAST TO CROSS THE DATELINE ON 18 DEC, REACH NORTH AMERICA ON 20 DEC AND BE A WEAK SW TROUGH OVER THE PRAIRIE PROVINCES AND CENTRAL PLAINS ON 22 DEC AND OVER JAMES BAY 23 DEC. A SW TROUGH NOW OVER MANCHURIA IS FORECAST TO FOLLOW THE SAME TRACK FOLLOWING BY TWO DAYS.

TODAY THERE IS ARE STRONG SW TROUGHS IN ALIGNMENT ON THE NORTH AND SOUTH STORM TRACKS FROM THE CENTRAL GULF OF ALASKA TO NORTHEAST OF HAWAII. THE TROUGH COMPLEX IS FORECAST TO MOVE VERY SLOWLY EASTWARD THROUGH 19 DEC AS A RIDGE DEVELOPS OVER CALIFORNIA, NEVADA, OREGON, WASHINGTON, IDAHO, AND BRITISH COLUMBIA. THE RIDGE IS FORECAST TO BOW EASTWARD TO AN ARC FROM SOUTHERN CALIFORNIA TO MONTANA TO NORTHWEST TERRITORIES AND INTO THE BEAUFORT SEA BY 20 DEC. A LW TROUGH REPLACES THE PORTION OF THE RIDGE SOUTH OF 40 N BY 22 DEC WHILE THE RIDGE NORTH OF 40 N IS FORECAST TO DRIFT EASTWARD TO BE OVER MISSOURI, ONTARIO, AND HUDSON BAY ON 23 DEC.

THE LW HIGH OVER THE BEAUFORT SEA IS FORECAST TO MOVE EAST TO NORTH OF GREENLAND BY 22 DEC THEN TO THE POLE ON 23 DEC.

AS THE HIGH MOVES EAST THE LOW OVER THE NORTHWEST END OF BAFFIN ISLAND IS FORECAST TO PIROUETTE NEAR ITS PRESENT LOCATION UNTIL 20 DEC THEN MOVE SOUTHEAST TO THE SOUTHERN TIP OF GREENLAND BY 24 DEC.

HORN