ticka1
12-16-2004, 09:06 PM
00Z GFS and EURO runs are very impressive this morning with respect to the cold air outbreak next week.
To get you interested the forecasted high for KIAH is now 17 on the 26th with .2 inches of liquid snow roughly 2.0 "snow" inches. Zero to sub zero temps. are forecasted into central TX around Austin with Dallas 2-5 degrees below zero. Should these temps. verify all time record lows would be set.
Pattern setup:
Rex block will be developing over the E PAC over the next 2-3 days with high pressure building deep into Alaska and the Arctic. Downstream troughing over the lower 48 will gradually amplify with the first shot of arctic air on Saturday evening which is still forecast to give the state a glancing blow. After Monday the ridge to the west builds into northern Russia with very cold Siberian air being unlocked and forced over the north pole into NW Canada. The strong polar vortex near Hudson Bay retrogrades WSW to N Minnesota grabbing the building arctic air and dropping it to the US border by the 24th. Surface low pressure will then form in the TX panhandle and deepen rapidly while dropping through the mean trough and carving the trough back to the west of the state. This is the final piece to the puzzle and the arctic air is unleashed southward first entering MT late on the 24th and arriving in TX on the 25th. The GFS has 850mb temps of -36 C into central KS by late on the 25th and -14 C into N TX by early on the 26th. Cold air advection will be impressive with gradient winds of 40-50mph behind the arctic boundary late on the 25th and the 26th.
As for the precip. an upper level short wave will drop through the mean trough over the W US late on the 25th and be located over AZ on the morning of the 26th. Precip (all frozen) is forecasted to break out over SW and W TX late on the 26th and spread across the state late ont he 26th and the 27th. Forecast amounts of 12-15 inches by the GFS over central TX appear to be extremely high.
I am not terribly confident in the snowfall probabilities, but the cold air outbreak looks more than possible given the upper air setup. As always this is a medium range forecast and is subject to large changes, however most global runs have been consistent with this forecast over the last week.
JL
To get you interested the forecasted high for KIAH is now 17 on the 26th with .2 inches of liquid snow roughly 2.0 "snow" inches. Zero to sub zero temps. are forecasted into central TX around Austin with Dallas 2-5 degrees below zero. Should these temps. verify all time record lows would be set.
Pattern setup:
Rex block will be developing over the E PAC over the next 2-3 days with high pressure building deep into Alaska and the Arctic. Downstream troughing over the lower 48 will gradually amplify with the first shot of arctic air on Saturday evening which is still forecast to give the state a glancing blow. After Monday the ridge to the west builds into northern Russia with very cold Siberian air being unlocked and forced over the north pole into NW Canada. The strong polar vortex near Hudson Bay retrogrades WSW to N Minnesota grabbing the building arctic air and dropping it to the US border by the 24th. Surface low pressure will then form in the TX panhandle and deepen rapidly while dropping through the mean trough and carving the trough back to the west of the state. This is the final piece to the puzzle and the arctic air is unleashed southward first entering MT late on the 24th and arriving in TX on the 25th. The GFS has 850mb temps of -36 C into central KS by late on the 25th and -14 C into N TX by early on the 26th. Cold air advection will be impressive with gradient winds of 40-50mph behind the arctic boundary late on the 25th and the 26th.
As for the precip. an upper level short wave will drop through the mean trough over the W US late on the 25th and be located over AZ on the morning of the 26th. Precip (all frozen) is forecasted to break out over SW and W TX late on the 26th and spread across the state late ont he 26th and the 27th. Forecast amounts of 12-15 inches by the GFS over central TX appear to be extremely high.
I am not terribly confident in the snowfall probabilities, but the cold air outbreak looks more than possible given the upper air setup. As always this is a medium range forecast and is subject to large changes, however most global runs have been consistent with this forecast over the last week.
JL