000 FXUS03 KWBC 052006 PMDHMD HEMISPHERIC MAP DISCUSSION NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION HYDROMETEOROLOGICAL PREDICTION CENTER..NCEP..NWS..WASHINGTON DC 100 PM EST SUN NOV 5 1995 THE BROADLY CYCLONIC MEAN FLOW PATN WHICH HAS SET UP ACRS THE NATION IS EXPECTED TO CONTINUE FOR MUCH OF THIS WEEK. THE LATEST MEAN CHARTS FROM THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT IN DEPICTING BELOW NORMAL HGTS OVR THE MAJORITY OF THE COUNTRY...WITH THE ONLY EXCEPTION BEING IN THE GULF COAST STATES. HERE...THE MEAN UPR RIDGE WHICH IS CNTRD JUST S OF THE FL PENINSULA WILL REMAIN STG...BUT LIKELY SHIFT A LITTLE SWD DURING THE MIDDLE PART OF THE WEEK. ELSEWHERE...ONE OF THE MOST PROMINENT FEATURES FCSTD IN THE MEANS TODAY IS THE STRENGTHENING HI LAT BLOCKING RIDGE OVR THE CHUKCHI SEA (LOCATED BTWN THE BERING STRAIT AND THE ARCTIC OCEAN). THIS RIDGE IS SHOWING SIGNS OF BRIDGING ACRS EXTREME NRN CANADA TWD A RIDGE OVR GREENLAND...WHICH WILL FORCE A SIGNIFICANT CHUNK OF THE POLAR VORTEX TO REMAIN DISPLACED SOUTH OF NORMAL (VCNTY HUDSON BAY THIS WEEK). THE MODELS ARE ALSO IN PRETTY GOOD AGREEMENT FCSTG A STRENGTHENING OF THE MEAN RIDGE OVR THE CNTRL/ERN PAC...WHICH SUPPORTS A GRADUAL TREND TWD THE RE- DEVELOPMENT OF A MEAN TROF OVR THE WRN HALF OF THE NATION BY WEEK'S END. IN THE DAILY FCSTS...THERE ARE SOME DIFFERENCES WITH SPEED OF THE SHORT WAVE TROF AND IT'S ATTENDANT FRONTAL SYS PUSHING OFF THE EAST COAST EARLY WED. THE MRF IS FASTER (BY ABT 6-12 HOURS) THAN EITHER OF THE EURO MODELS...AND IS SLIGHTLY FASTER THAN ALL OF THE MEMBERS FROM TODAY'S ENSEMBLE RUNS. AT THIS TIME...THE NEW SHORT RANGE GUIDANCE SUPPORTS THE FASTER MRF SOLN...BUT INDICATES THAT THE TROF MAY BE A LITTLE SHARPER THAN ANY OF THE MODELS ARE FCSTG. MANUAL PROGS HAVE OPTED TO CLOSELY FOLLOW THE MRF'S SPEED...BUT LOWER PRESSURES OVER NEW ENGLAND SOMEWHAT TO ACCOUNT FOR THE SHARPER TROF HINTED AT IN THE LATEST ETA/NGM. MORE IMPORTANT MODEL DISCREPANCIES SHOW UP IN THE WEST. THE LATEST UKMET RUNS HAVE TRENDED TWD YESTERDAY'S ECMWF SOLN BRINGING A POTENT CLOSED SYS FROM THE GULF OF AK TUE SEWD INTO B.C. ON WED. THIS OCCURS AS A SHORT WAVE RIDGE IN THE CNTRL PAC PARTIALLY PHASES WITH THE HI LAT BLOCK OVR NWRN AK. THE UKMET THEN SHOWS THE CLOSED LOW OPENING UP/SHEARING OUT ON THU/FRI AS IT PUSHES ACRS SRN CAN/NRN PLAINS. MEANWHILE...AN UPSTREAM SHORT WAVE DIVES SEWD AND CARVES OUT A BROAD TROF OVR THE WRN HALF OF THE COUNTRY BY FRI. THE MRF HANDLES THE CLOSED SYS IN THE GULF OF AK QUITE DIFFERENTLY. THE LOW PUSHES WWD UNDER THE BLOCKING RIDGE TO THE NORTH...ENDING UP NR THE BERING STRAIT ON SAT. HOWEVER...THE MRF DOES BEGIN CARVING OUT A TROF IN THE WEST SIMILAR TO THE UKMET BY LATE IN THE WEEK...AS THE UPSTREAM RIDGE OVR THE E PAC BUILDS IN RESPONSE TO A STG TROF LIFTING NEWD THRU THE CNTRL PAC. THE MRF'S TROF IN THE WEST...HOWEVER...FARTHER WEST THAN THE UKMET...MORE POSITIVELY TILTED AND OVERALL A LITTLE WKR. THE ECMWF HAS TRENDED AWAY FROM IT'S SOLN FROM THE PAST FEW RUNS WITH THE CLOSED LOW IN THE PAC. INSTEAD OF TAKING IT BODILY SEWD...TODAY IT LEAVES THE SYS IN THE GULF OF AK AND SLOWLY WKNS IT THRU MIDWEEK. HOWEVER...THE ECMWF BRINGS A VRY POTENT SHORT WAVE THRU THE WESTERLIES...SLAMMING A MASSIVE SFC LOW INTO THE PAC NW THU...WHICH IS MUCH STGR/SLOWER THAN THE MRF THIS SYS THEN WKNS AND MOVES RAPIDLY INTO THE CNTRL STATES FRI. INTERESTINGLY...ALL OF THE MODEL SOLNS END UP CONVERGING ON DAY 5 (FRI)...ALL BASICALLY HAVING A TROF IN THE WEST; THEY JUST ARRIVE AT THE SOLN DIFFERENTLY. AT THIS TIME...WE FEEL THE UKMET (LIKE PREVIOUS ECMWF RUNS) IS INCORRECT IN TAKING THE GULF OF AK LOW SEWD. MORE ENERGY SHOULD WRAP WWD UNDERNEATH THE BLOCKING HIGH AS PER ECMWF/MRF. ALSO...WE ARE SKEPTICAL OF THE ECMWF'S VRY STG SYS HITTING THE PAC NW COAST THU. MANUAL PROGS HAVE OPTED FOR THE MRF THRU DAY 4 (THU)...BUT THEN SPEED UP THE TROF MVG INTO THE CNTRL STATES DAY 5 AS A LARGE MAJORITY OF THE ENSEMBLE MEMBERS SUPPORT A SLIGHTLY FASTER SOLN. OVR HI...UPR LOW TO THE NW OF THE STATE WILL CONT WKNG AND LIFT NEWD THE NEXT COUPLE OF DAYS. HOWEVER...WK UPR TROFFING WILL REMAIN ACRS OR JUST EAST OF THE STATE THRU MIDWEEK...PRECLUDING THE DEVELOPMENT OF ANY NORMAL TRADE FLOW. DURING THE LATTER PART OF THE WEEK...ANOTHER POTENT SHORT WAVE TROF WILL DIG SEWD THRU THE WESTERLIES...PROBABLY CLOSING OFF NW OF THE ISLANDS ON FRI. THIS SYS WILL HELP DISRUPT ANY TRADE INVERSION AND HELP DRAW NWD TROPICAL MOISTURE (AS LOW-LVL WINDS VEER ARND TO THE SE). EXPECT GENERALLY LGT PCPN ALL SECTIONS THRU MIDWEEK...WITH AN INCREASING THREAT FOR SHWRS/TSHWRS BY THU/FRI. OVR AK...PCPN OVR THE NEXT 5 DAYS WILL BE LGT ACRS MUCH OF THE STATE AS A STG UPR RIDGE REMAINS CNTRD JUST NW OF THE STATE. SOME LGT AMTS MAY FALL ACRS SRN COASTAL SECTIONS DURING THE EARLY/MID PORTION OF THIS WEEK AS A SHORT WAVE TROF ROTATES W-SWWD ARND THE RIDGE TO THE NORTH. AN APPROACHING STORM FROM THE SW WILL LIKELY BRING MDT RAINS TO THE SERN COASTAL SECTIONS LATE IN THE WEEK. IN THE SHORT RANGE...MODELS DIFFER LATE IN THE PD WITH THE PSN OF THE VORT RACING ESEWD INTO THE MID MS VALLEY. THE AVN IS THE FARTHEST NORTH WITH THE SYS AND ASSOCIATED SFC LOW (NRN MI) AT 48 HOURS...WHILE THE ETA IS FARTHEST SOUTH (NW OH WITH THE SFC LOW). THE NGM IS SIMILAR TO THE AVN WITH THE SFC WAVE...BUT FARTHER SOUTH (CLOSER TO THE ETA) WITH THE VORT. AT THIS TIME...THERE IS MUCH UNCERTAINTY AS TO THE STRENGTH/TIMING AND INTERACTION OF SHORT WAVES IN THE NRN AND SRN STREAMS IN THIS FAST FLOW...SO WE HAVE LITTLE CONFIDENCE IN ANY MODEL SOLN OF THE SFC PATN...AND HAVE OPTED FOR A COMPROMISE SOLN. THE OTHER AREA OF DISCREPANCY IS IN THE PAC NW. THE MODELS DIFFER AS TO THE STRENGTH/PSN OF SFC WAVES MVG THRU THE FAST FLOW IN THE E PAC. WE FEEL THE ETA MAY BE TOO STG WITH IT'S WAVE ARND 130W AT 48H AS THE UPR FLOW IS VRY CONFLUENT. THE NGM APPEARS TOO ILL- DEFINED WITH IT'S FCST LATE IN THE PD...HAVING A SERIES OF STRUNG-OUT LOWS. CONSIDERING IT'S VORT FCST...THE AVN SEEMS TOO FAR WEST WITH IT'S SFC SYS AT 36-48H. WE ARE LEANING TWD THE ETA'S SFC SOLN...BUT WKNG IT'S LOW OFF THE PAC COAST. KLEIN/FORECAST OPERATIONS BRANCH