{"id":2504,"date":"2012-02-17T20:59:59","date_gmt":"2012-02-18T01:59:59","guid":{"rendered":"https:\/\/kyweathercenter.com\/?p=2504"},"modified":"2012-02-17T20:59:59","modified_gmt":"2012-02-18T01:59:59","slug":"hpc-snowfall-forecast","status":"publish","type":"post","link":"https:\/\/kyweathercenter.com\/?p=2504","title":{"rendered":"HPC Snowfall Forecast"},"content":{"rendered":"

Good evening… again. While we await the latest model runs, I thought it would be good to show you forecast from the HPC. The Hydrometeorological Prediction Center puts out forecasts on heavy rain or snow events across the country.<\/p>\n

Here is their snowfall probability map for the upcoming winter storm…<\/p>\n

\"\"<\/a><\/p>\n

Think of that as being similar to the severe weather risk maps coming from the Storm Prediction Center. Those maps show a good risk for significant snowfall for much of the state.<\/p>\n

Here is the HPC Discussion about the upcoming winter storm:<\/p>\n

…CENTRAL APPALACHIANS\/MID ATLANTIC STATES DAYS 2 INTO EARLY DAY
\n3 (SUN NIGHT)…<\/p>\n

INGREDIENTS CURRENTLY TAKING SHAPE FOR THE MUCH-ADVERTISED\/LONG
\nAWAITED WINTER WEATHER EVENT FOR THE LOWER OH\/NRN\u00a0TN VLYS EAST TO
\nTHE MID ATLC REGION. THE DEEP UPPER TROUGH OUT WEST HAS NOW
\nSHIFTED E OF BAJA…WITH AN ELONGATED…NARROW COLD CONVEYOR BELT
\nAXIS EXTENDING FROM NRN\u00a0TX SW THROUGH SRN NM\/AZ PER THE LATEST
\nSTLT WV\/IR IMAGERY. MEANWHILE…OUT AHEAD OF THE UPPER SYSTEM A
\nLENGTHY SUBTROPICAL CONNECTION CAN BE SEEN WITH THE WARM CONVEYOR
\nBELT…ONE THAT WILL ULTIMATELY WILL TAP THE GULF AS THE TROUGH
\nMOVES E.<\/p>\n

IN TERMS OF THE LATEST MODEL SUITE…WHILE THE OPERATIONAL RUNS
\nWERE IN DECENT ALIGNMENT WITH RESPECT TO THE MASS FIELDS…THERE
\nAGAIN WERE DIFFERENCES IN S-N DISTRIBUTION OF QPF AND TO SOME
\nEXTEND THE LLVL\u00a0THERMAL PROFILE. HPC\u00a0LEANED TOWARD A GFS-UKMET
\nBLEND…WHICH CLUSTERED FAIRLY WELL IN TERMS OF THE QPF COMPARED
\nTO THE NAM (A BIT MORE ROBUST FARTHER N) AND THE ECMWF (HEAVIER
\nPCPN SHIFTED S). WHILE THE CONFIDENCE IN THE MODELS (MASS FIELDS
\nIN PARTICULAR) ARE INCREASING…SUBTLE YET SIGNIFICANT DIFFERENCES
\nIN THE LLVL\u00a0THERMAL AND MSTR PROFILES REMAIN DISCONCERTING.
\nESPECIALLY WITH A SYSTEM THAT WILL GENERATE PREDOMINANTLY RAIN ON
\nTHE FRONT END WITH THE WAA\/WCB…ALONG WITH THE ANTECEDENT WARM
\nGROUND WITH THE MILD CONDITIONS TODAY AND SAT. THE MAIN PLAYER
\nFROM A SNOWFALL STANDPOINT WILL BE THE EVOLVING CCB\u00a0(TROWAL
\nPOTENTIAL)…WHICH THE ORIENTATION…STRENGTH…AND SPEED WILL BE
\nBASED HEAVILY ON THE THE\u00a0PROGRESSION AND SRN EXTENT OF A SECONDARY
\nNRN STREAM SHORTWAVE. THE MORE CONFLUENCE ALOFT…THE TIGHTER THE
\nN-S GRADIENT IN TERMS OF DEEP MOISTURE (FAVORING A DEEPER NRLY
\nISALOBARIC\u00a0COMPONENT WITH DRIER LLVL AIR PUSHED SOUTH).<\/p>\n

MEANWHILE…INCREASED MID\/UPPER LEVEL DEFORMATION WILL HAVE AN
\nEFFECT ON THE ORIENTATION AND N-S EXTEND OF THE
\nCCB\/COMMA-HEAD…I.E. RESULTING IN A NARROWER…
\nMORE W-E VICE NW-SE ORIENTED PCPN FIELD. THE UPSHOT WITH THE
\nGFS\/UKMET BLEND IS A COMPROMISE BETWEEN THE NAM (FARTHER N WITH
\nTHE MSTR) AND ECMWF (FARTHER S). THE NAM ALSO CONTINUES TO HAVE
\nISSUES WITH THE DEGREE OF BNDRY\u00a0LAYER COOLING OVER THE SRN
\nPERIPHERY OF THE CCB (CLOSER TO THE 850 MB LOW TRACK). IN ORDER TO
\nCAPITALIZE ON THE DYNAMICAL COOLING…PCPN RATES NEED TO BE
\nSUFFICIENTLY HIGH…WHICH IS IN QUESTION GIVEN WHAT THE MODELS ARE
\nSHOWING IN TERMS OF A VERY SLOW CYCLOGENIC PROCESS UNTIL THE LOW
\nREACHES THE COAST. THEREFORE…A DEPICTION OF A MORE PROGRESSIVE
\nCCB\/DEFORMATION BANDED PCPN WITH LITTLE EVIDENCE OF A PERSISTENT
\nNOR ELONGATED TROWAL.
\nAGAIN…PREFERRED A GFS\/UKMET SCENARIO WHERE THE RAIN WOULD CHANGE
\nOVER TO SNOW ACROSS NRN\u00a0TN\/NC AND SRN VA…WHILE UNDERCUTTING THE
\nNAM ACCUMS IN THESE REGIONS.<\/p>\n

CONVECTION WILL ALSO ADD TO THE UNCERTAINTY…I.E. IN TERMS OF THE
\nEFFECTS ON THE NORTHWARD MOISTURE TRANSPORT AND DEEPENING OF THE
\nSYSTEM (AND THUS EFFECTS ON ENHANCING THE POTENTIAL VORTICITY).
\nELEVATED CONVECTION AND POTENTIAL FOR ENHANCED MESOSCALE BANDING
\nWILL ALSO BE A CONCERN…ESPECIALLY AT THE APEX OF THE DRY SLOT
\nABOVE THE -10C ISOTHERM. ALL-IN-ALL…POTENTIAL FOR 6-12 INCHES
\nWILL REMAIN HIGHEST ACROSS THE MNTNS\u00a0IN WRN VA…ACROSS MUCH OF
\nSRN\u00a0WV…AND ERN KY. FCST CONFIDENCE DECREASES TOWARD I-95
\nINCLUDING THE MID ATLC CITIES…THOUGH BECAUSE OF THE SPREAD OF
\nPOSSIBILITIES HPC\u00a0HAS INCLUDED A MOD RISK OF AT LEAST 4″ INTO NRN
\nAND CEN VA…ALONG WITH A SLIGHT (1 IN 10) RISK OF 8 INCHES. STAY
\nTUNED.<\/p>\n

I will have a full update later tonight and will be tweeting information coming from the new model runs filtering in. Take care.<\/p>\n","protected":false},"excerpt":{"rendered":"

Good evening… again. While we await the latest model runs, I thought it would be good to show you forecast from the HPC. The Hydrometeorological Prediction Center puts out forecasts on heavy rain or snow events across the country. Here is their snowfall probability map for the upcoming winter storm… Think of that as being […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-2504","post","type-post","status-publish","format-standard","hentry","category-uncategorized","et-doesnt-have-format-content","et_post_format-et-post-format-standard"],"_links":{"self":[{"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=\/wp\/v2\/posts\/2504","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2504"}],"version-history":[{"count":0,"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=\/wp\/v2\/posts\/2504\/revisions"}],"wp:attachment":[{"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kyweathercenter.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}